deal with static analyzer warnings (part 1)

[taylor/freespace2.git] / src / ship / aigoals.cpp

/*
 * Copyright (C) Volition, Inc. 1999.  All rights reserved.
 *
 * All source code herein is the property of Volition, Inc. You may not sell 
 * or otherwise commercially exploit the source or things you created based on
 * the source.
 */

/*
 * $Logfile: /Freespace2/code/Ship/AiGoals.cpp $
 * $Revision$
 * $Date$
 * $Author$
 *
 * File to deal with manipulating AI goals, etc.
 *
 * $Log$
 * Revision 1.6  2006/04/26 19:46:52  taylor
 * address a Windows qsort() issue that Volition got around before, this will correct numerous mission bugs due to goal sorting for non-Windows systems
 *
 * Revision 1.5  2003/08/03 16:10:30  taylor
 * cleanup; compile warning fixes
 *
 * Revision 1.4  2002/06/09 04:41:26  relnev
 * added copyright header
 *
 * Revision 1.3  2002/05/26 22:06:17  relnev
 * makefile: disable stand_gui for now.
 *
 * rest: staticize some globals
 *
 * Revision 1.2  2002/05/07 03:16:52  theoddone33
 * The Great Newline Fix
 *
 * Revision 1.1.1.1  2002/05/03 03:28:10  root
 * Initial import.
 *
 * 
 * 12    7/19/99 12:02p Andsager
 * Allow AWACS on any ship subsystem. Fix sexp_set_subsystem_strength to
 * only blow up subsystem if its strength is > 0
 * 
 * 11    7/09/99 5:54p Dave
 * Seperated cruiser types into individual types. Added tons of new
 * briefing icons. Campaign screen.
 * 
 * 10    7/07/99 2:55p Andsager
 * fix ai_get_subsystem_type to recognize "radara" as an awacs type
 * subsystem as model_read.
 * 
 * 9     6/03/99 8:58p Andsager
 * Fix bug where player's target is lost.  Alpha wing had clear wing
 * goals, and this was applied to alpha1.
 * 
 * 8     5/27/99 12:14p Andsager
 * Some fixes for live debris when more than one subsys on ship with live
 * debris.  Set subsys strength (when 0) blows off subsystem.
 * sexp_hits_left_subsystem works for SUBSYSTEM_UNKNOWN.
 * 
 * 7     4/23/99 12:01p Johnson
 * Added SIF_HUGE_SHIP
 * 
 * 6     3/26/99 4:49p Dave
 * Made cruisers able to dock with stuff. Made docking points and paths
 * visible in fred.
 * 
 * 5     1/07/99 1:52p Andsager
 * Initial check in of Sexp_variables
 * 
 * 4     12/23/98 2:53p Andsager
 * Added ship activation and gas collection subsystems, removed bridge
 * 
 * 3     11/05/98 5:55p Dave
 * Big pass at reducing #includes
 * 
 * 2     10/07/98 10:53a Dave
 * Initial checkin.
 * 
 * 1     10/07/98 10:51a Dave
 * 
 * 173   6/09/98 10:31a Hoffoss
 * Created index numbers for all xstr() references.  Any new xstr() stuff
 * added from here on out should be added to the end if the list.  The
 * current list count can be found in FreeSpace.cpp (search for
 * XSTR_SIZE).
 * 
 * 172   6/01/98 11:43a John
 * JAS & MK:  Classified all strings for localization.
 * 
 * 171   5/21/98 9:57a Mike
 * Massively improve firing of bombs at big ships.  Improve willingness to
 * take incoming fire to deliver bomb.  Make a little easier to gain
 * aspect lock.
 * 
 * 170   5/12/98 10:06a Mike
 * Fix a jillion bugs preventing ships from firing bombs at Lucifer in
 * sm3-09.
 * 
 * 169   5/11/98 11:20a Sandeep
 * 
 * 168   5/10/98 12:02a Mike
 * Only Alpha wing will form on player's wing, not any player wing.
 * 
 * 167   4/23/98 1:49a Allender
 * major rearm/repair fixes for multiplayer.  Fixed respawning of AI ships
 * to not respawn until 5 seconds after they die.  Send escort information
 * to ingame joiners
 * 
 * 166   4/23/98 12:31a Mike
 * Fix the sm1-04a Comet:Omega bug.  Was putting a goal on hold if a ship
 * was docked, but should only have done that if not docked with self.
 * 
 * 165   4/22/98 5:00p Allender
 * new multiplayer dead popup.  big changes to the comm menu system for  *
 * team vs. team.  Start of debriefing stuff for team vs. team  Make form
 * on my wing work with individual ships who have high priority 
 * orders
 * 
 * 164   4/18/98 9:53p Mike
 * Add debug code to track down Comet warpout problems in sm1-04a, then
 * comment it out for checkin.
 * 
 * 163   4/09/98 12:36p Allender
 * nasty repair problems fixed when ordering it to warp out while
 * repairing (and on way) and when aborting process while he's completing
 * the rearm
 * 
 * 162   3/31/98 5:19p John
 * Removed demo/save/restore.  Made NDEBUG defined compile.  Removed a
 * bunch of debug stuff out of player file.  Made model code be able to
 * unload models and malloc out only however many models are needed.
 *  
 * 
 * 161   3/19/98 4:43p Allender
 * allow player ships to follow certain orders
 * 
 * 160   3/19/98 2:55p Allender
 * when ship gets disabled, have him put dock goals on hold
 * 
 * 159   3/09/98 9:35p Mike
 * Suppress warning messages.
 * 
 * 158   3/09/98 5:12p Mike
 * Make sure Pl_objp uses are valid.
 * Throw asteroids at ships in asteroid field, not "Gal"
 * Support ships warp out if no goals after 30 seconds.
 * 
 * 157   3/07/98 3:50p Lawrance
 * Add lead indicator for asteroids
 * 
 * 156   3/06/98 2:58p Allender
 * moved assert to more appropriate place
 * 
 * 155   3/06/98 11:55a Lawrance
 * Don't process mission orders for player ships
 * 
 * 154   3/05/98 9:35a Allender
 * don't allow ships to be repaired when departing or dying
 * 
 * 153   2/26/98 10:08p Hoffoss
 * Rewrote state saving and restoring to fix bugs and simplify the code.
 * 
 * 152   2/23/98 8:59p Allender
 * fixed two docking bugs:  1) don't move cargo when ship it's docked with
 * is undocking.  2) aigoal code was clearing dock goals when it shouldn't
 * have been
 * 
 * 151   2/22/98 4:17p John
 * More string externalization classification... 190 left to go!
 * 
 * 150   2/19/98 12:04a Allender
 * more multiplayer rearm/dock stuff.  Fix bug in HUD code when finding
 * support ship reaming player.  show repair as order on Hud extended
 * target info
 * 
 * 149   2/18/98 10:34p Allender
 * repair/rearm system (for single and multi) about finished.
 * dock/undock and ai goals packets implemented for multiplayer
 * 
 * 148   2/16/98 10:13p Allender
 * initial work on being able to target weapons (bombs specifically).
 * Work on getting rearm/repair working under multiplayer
 * 
 * 147   2/16/98 4:07p Sandeep
 * fixed a bug with deleting waypoints
 * 
 * 146   2/16/98 3:43p Sandeep
 * Fixed bug with Ai_warp still expected to have an object reference in a
 * bit of the code.
 * 
 * 145   2/13/98 3:21p Lawrance
 * Set up allowed goals for escape pods.
 * 
 * 144   2/13/98 2:57p Allender
 * correct code using unitialized variable
 * 
 * 143   2/09/98 10:46a Allender
 * fixed bug with docking where multiple orders to dock with same object
 * caused strageness
 * 
 * 142   2/05/98 12:52p Jim
 * fix race conditions to get to subsystem index for attacking subsystem
 * goals
 * 
 * 141   2/02/98 4:02p Mike
 * Allender: Fix bug which caused ships to sometimes undock just as they
 * were docking.
 * 
 * 140   1/30/98 11:00a Allender
 * tidied up the code to get an index for a new goal.  Made all code (for
 * both ships and wings) go through this function.
 * 
 * 139   1/30/98 10:01a Allender
 * made large ships able to attack other ships.  Made goal code recognize
 * when ships removed from wings during ship select
 * 
 * 138   1/29/98 12:14p Lawrance
 * show 'waypoints' as a mission order.
 * 
 * 137   1/20/98 9:33a Allender
 * fixed bug with wing goals from players
 * 
 * 136   1/16/98 1:11p Sandeep
 * fix bug when trying to purge goals with no ship_name
 * 
 * 135   1/16/98 11:43a Allender
 * made it so certain orders (see PURGE_ORDERS) cause other ai goals to
 * get purged.  This step it to help the AI do the right thing.
 * 
 * 134   1/16/98 11:33a Mike
 * Fix bug in targeting subsystems on protected ships.
 * 
 * 133   1/13/98 5:36p Lawrance
 * Change Ai_goal_text[] to not return anything for waypoints.
 * 
 * 132   1/05/98 10:10p Mike
 * Comment out an obsolete function (discovered while searching for
 * something else.)
 * 
 * 131   1/02/98 1:55p Duncan
 * added back in case for undocking when checking for goal complete status
 * 
 * 130   12/30/97 4:48p Allender
 * work with ignore my target command.  Added new keyboard hotkey.  Made
 * it work globally
 * 
 * 129   12/26/97 12:15p Mike
 * Put in debug code for tracking down ships disabling, rather than
 * destroying, enemies.
 * 
 * 128   12/15/97 5:25p Allender
 * fix problem with docked ships receiving another dock goal.  They now
 * properly undock
 * 
 * 127   12/12/97 5:21p Lawrance
 * fix some problems with ai mode changing when arriving/departing from
 * docking bays
 * 
 * 126   12/04/97 12:24p Allender
 * made support ship orders other than rearm be super low priority.
 * Support ship orders now won't get removed incorrectly either
 * 
 * 125   11/26/97 9:55a Allender
 * minor changed to comm window for rearming.  Fixed some repair bugs --
 * player's repair was getting aborted by code when he was hit.  Repair
 * ship wasn't properly removing repair goals
 * 
 * 124   11/23/97 6:21p Lawrance
 * update goal text, used on HUD
 * 
 * 123   11/17/97 6:39p Lawrance
 * add AI_goal_text[] array, used by HUD code to show text description of
 * order
 * 
 * 122   11/09/97 2:21p Mike
 * Comment out Int3() and email Mark about it.
 * 
 * 121   11/05/97 9:30p Mike
 * Add play dead mode.
 * Enable undock to complete when dockee moves.
 * Make ships in waypoint mode react to enemy fire.
 * Support ships not form on player's wing.
 * 
 * 120   11/05/97 4:43p Allender
 * reworked medal/rank system to read all data from tables.  Made Fred
 * read medals.tbl.  Changed ai-warp to ai-warp-out which doesn't require
 * waypoint for activation
 * 
 * 119   10/31/97 4:03p Allender
 * test code to help find rearm/repair problems
 * 
 * 118   10/29/97 10:02p Allender
 * be sure that player starting wings that arrive late also form on the
 * players wing if there are no goals
 * 
 * 117   10/29/97 9:32p Allender
 * remove undock goal if we can't find docked sihp when docker trying to
 * undock.  Could be that docked ship was destroyed
 * 
 * 116   10/29/97 3:41p Sandeep
 * Allender put in dock debug code
 * 
 * 115   10/28/97 10:30a Allender
 * rest AIF_FORMATION_OBJECT bit when new order is given to a ship
 * 
 * 114   10/24/97 10:40a Allender
 * player wings with no initial orders now form on players wing by
 * default.
 * 
 * 113   10/23/97 4:41p Allender
 * lots of new rearm/repair code.  Rearm requests now queue as goals for
 * support ship.  Warp in of new support ships functional.  Support for
 * stay-still and play-dead.  
 * 
 * 112   10/23/97 4:12p Mike
 * Support for AIM_STAY_NEAR.
 * 
 * 111   10/22/97 1:46p Allender
 * get ship_name field for ai-stay-still
 * 
 * 110   10/22/97 1:44p Allender
 * more work on stay-still and play-dead
 * 
 * 109   10/22/97 11:07a Allender
 * Hooked in form on my wing into Mikes AI code
 * 
 * 108   10/22/97 1:03a Mike
 * ai-stay-still
 * form-on-my-wing
 * fix mysterious code in find_enemy that used goal_objnum instead of
 * target_objnum.
 * 
 * 107   10/12/97 11:23p Mike
 * About ten fixes/changes in the docking system.
 * Also, renamed SIF_REARM_REPAIR to SIF_SUPPORT.
 * 
 * 106   10/10/97 5:03p Allender
 * started work on ai-stay-still
 * 
 * 105   9/24/97 4:51p Allender
 * got rid pf default_player_ship_name variable.
 * 
 * 104   9/23/97 4:35p Allender
 * added two function to add "internal" goals to ships and wings.  Used by
 * AI when it needs to do something special
 * 
 * 103   9/09/97 2:42p Allender
 * fix bug where guarding a wing that hasn't arrived caused goal code to
 * crash
 * 
 * 102   9/09/97 11:28a Johnson
 * Fixed bug: Code is not Fred-aware.
 * 
 * 101   9/08/97 1:04p Allender
 * put code in ai_post_process_mission() to set orders for ships before
 * mission starts.  Prevents ships from following orders N seconds after
 * mission actually starts
 * 
 * 100   9/05/97 5:05p Lawrance
 * memset string to 0 during restore for safety
 * 
 * 99    8/18/97 1:16p Allender
 * added ignore goal into sexpressions
 * 
 * 98    8/16/97 3:09p Mike
 * If telling a ship to attack a protected ship, unprotect that ship.
 * 
 * 97    8/16/97 2:40p Mike
 * Move unmoving ship if it's attacking a large ship and it sees incoming
 * fire.
 * Also, don't set protected bit in a ship if someone has attacked a
 * subsystem.  Only do if someone was told to disarm or disable.
 * 
 * 96    8/15/97 11:50a Duncan
 * Fixed bug with ai functions assuming ai_goal_undock takes a ship
 * target, which it doesn't.
 * 
 * 95    8/15/97 10:05a Hoffoss
 * One more change to ai_query_goal_valid() to allow for AI_GOAL_NONE.
 * 
 * 94    8/15/97 9:59a Hoffoss
 * Changed ai_query_goal_valid() again.  I can't think of any time you
 * wouldn't find it easier just to pass in a ship instead of a ship_info
 * flag structure filtered of all flags that aren't ship type bits.  Since
 * I'll call this quite a few times, it will make my life easier.
 * 
 * 93    8/15/97 9:49a Hoffoss
 * Changed ai_query_goal_valid() slightly for Fred.  Fred can be more
 * detailed with error messages should these situations happen, and
 * recover from them better.
 * 
 * 92    8/14/97 10:00p Allender
 * made ai goals bitfields so that we can have set of orders that certain
 * ship types are allowed to receive.  Added function for Hoffoss to check
 * goal vs. ship type validity
 * 
 * 91    8/12/97 9:58a Hoffoss
 * Fixed ai_update_goal_references() and query_referended_in_ai_goals().
 * 
 * 90    8/12/97 8:01a Allender
 * when adding goals to wing structures, replace the oldest entry of the
 * goals if there are no empty entries
 * 
 * 89    8/12/97 1:55a Hoffoss
 * Made extensive changes to object reference checking and handling for
 * object deletion call.
 * 
 * 88    8/10/97 4:24p Hoffoss
 * Made initial orders revert back to none if it has invalid data
 * anywhere.
 * 
 * 87    8/08/97 1:30p Allender
 * added commands (and ai goals) for support ships.  stay near ship (which
 * could be player or current target), and keep safe distance
 * 
 * 86    8/07/97 11:11a Allender
 * fixed problem with wings completing waypoint goals
 * 
 * 85    8/06/97 9:41a Allender
 * renamed from ai_goal function.  made a function to remove a goal from a
 * wing (used strictly for waypoints now).  ai-chase-wing and
 * ai-guard-wing now appear to user as ai-chase and ai-guard.  Tidied up
 * function which deals with sexpression goals
 * 
 * 84    8/06/97 8:06a Lawrance
 * add more stuff to save/restore
 * 
 * 83    8/01/97 11:51a Dave
 * Changed calls to timer_get_fixed_seconds() to simply Missiontime.
 * Solves a lot of demo related problems.
 * 
 * 82    7/30/97 11:01p Mike
 * Set submode when setting mode from player order.
 * Increase distance to circle when ignoring player's target.
 * 
 * 81    7/28/97 10:28a Mike
 * Use forward_interpolate() to prevent weird banking behavior.
 * 
 * Suppress a couple annoying mprints and clarify another.
 * 
 * 80    7/25/97 12:10p Mike
 * Better default behavior.
 * 
 * 79    7/24/97 4:55p Allender
 * added ai-evade-ship to fred and to Freespace
 * 
 * 78    7/24/97 4:20p Mike
 * Add goal and Fred hook for evade behavior.
 * 
 * 77    7/24/97 2:17p Jasen
 * Fixed a bug with mission loading.
 * 
 * 76    7/24/97 12:10a Mike
 * Suppress problems when loadign pain.fsm.
 * 
 * 75    7/23/97 6:49p Hoffoss
 * Fixed bug in ai goal adding code.  It was using a pointer that was
 * temporary.
 * 
 * 74    7/23/97 11:25a Allender
 * more robust sexpression checking.  Fixed problem with some ai goals not
 * being named properly
 *
 * $NoKeywords: $
 */

#include "aigoals.h"
#include "freespace.h"
#include "ai.h"
#include "sexp.h"
#include "missionlog.h"
#include "missionparse.h"
#include "model.h"                              // for subsystem types
#include "linklist.h"
#include "timer.h"
#include "player.h"
#include "multimsgs.h"
#include "multi.h"

// all ai goals dealt with in this code are goals that are specified through
// sexpressions in the mission file.  They are either specified as part of a
// ships goals in the #Object section of the mission file, or are created (and
// removed) dynamically using the #Events section.  Default goal behaviour and
// dynamic goals are not handled here.

// defines for player issued goal priorities
#define PLAYER_PRIORITY_MIN                             90
#define PLAYER_PRIORITY_SHIP                            100
#define PLAYER_PRIORITY_WING                            95
#define PLAYER_PRIORITY_SUPPORT_LOW             10

// define for which goals cause other goals to get purged
#define PURGE_GOALS             (AI_GOAL_IGNORE | AI_GOAL_DISABLE_SHIP | AI_GOAL_DISARM_SHIP)

// goals given from the player to other ships in the game are also handled in this
// code


#define AI_GOAL_ACHIEVABLE                      1
#define AI_GOAL_NOT_ACHIEVABLE  2
#define AI_GOAL_NOT_KNOWN                       3
#define AI_GOAL_SATISFIED                       4

int     Ai_goal_signature;
int     Num_ai_dock_names = 0;
char    Ai_dock_names[MAX_AI_DOCK_NAMES][NAME_LENGTH];

// AL 11-17-97: A text description of the AI goals.  This is used for printing out on the
// HUD what a ship's current orders are.  If the AI goal doesn't correspond to something that
// ought to be printable, then NULL is used.
// JAS: Converted to a function in order to externalize the strings
const char *Ai_goal_text(int goal)
{
        switch(goal)    {
        case 1:
                return XSTR( "attack ", 474);
        case 2:
                return XSTR( "dock ", 475);
        case 3:
                return XSTR( "waypoints", 476);
        case 4:
                return XSTR( "waypoints", 476);
        case 6:
                return XSTR( "destroy ", 477);
        case 7:
                return XSTR( "form on ", 478);
        case 8:
                return XSTR( "undock ", 479);
        case 9:
                return XSTR( "attack ", 474);
        case 10:
                return XSTR( "guard ", 480);
        case 11:
                return XSTR( "disable ", 481);
        case 12:
                return XSTR( "disarm ", 482);
        case 15:
                return XSTR( "guard ", 480);
        case 16:
                return XSTR( "evade ", 483);
        case 19:
                return XSTR( "rearm ", 484);
        }

        // Avoid compiler warning
        return NULL;
};

// function to maybe add the form on my wing goal for a player's starting wing.  Called from below and when a
// player wing arrives.
void ai_maybe_add_form_goal( wing *wingp )
{
        int j;

        // iterate through the ship_index list of this wing and check for orders.  We will do
        // this for all ships in the wing instead of on a wing only basis in cases some ships
        // in the wing actually have different orders than others
        for ( j = 0; j < wingp->current_count; j++ ) {
                ai_info *aip;

                SDL_assert( wingp->ship_index[j] != -1 );                                               // get Allender

                aip = &Ai_info[Ships[wingp->ship_index[j]].ai_index];
                // don't process Player_ship
                if ( aip == Player_ai )
                        continue;
                
                // it is sufficient enough to check the first goal entry to see if it has a valid
                // goal
                if ( aip->goals[0].ai_mode == AI_GOAL_NONE ) {
                        // need to add a form on my wing goal here.  Ships are always forming on the player's wing.
                        ai_add_ship_goal_player( AIG_TYPE_PLAYER_SHIP, AI_GOAL_FORM_ON_WING, -1, Player_ship->ship_name, aip );
                }
        }
}

void ai_post_process_mission()
{
        object *objp;
        int i;

        // Check ships in player starting wings.  Those ships should follow these rules:
        // (1) if they have no orders, they should get a form on my wing order
        // (2) if they have an order, they are free to act on it.
        //
        // So basically, we are checking for (1)
        if ( !Fred_running ) {
                for ( i = 0; i < 1; i++ ) {     //      MK, 5/9/98: Used to iterate through MAX_PLAYER_WINGS, but this was too many ships forming on player.
                        if ( Starting_wings[i] != -1 ) {
                                wing *wingp;

                                wingp = &Wings[Starting_wings[i]];

                                ai_maybe_add_form_goal( wingp );

                        }
                }
        }

        // for every valid ship object, call process_mission_orders to be sure that ships start the
        // mission following the orders in the mission file right away instead of waiting N seconds
        // before following them.  Do both the created list and the object list for safety
        for ( objp = GET_FIRST(&obj_used_list); objp != END_OF_LIST(&obj_used_list); objp = GET_NEXT(objp) ) {
                if ( objp->type != OBJ_SHIP )
                        continue;
                ai_process_mission_orders( OBJ_INDEX(objp), &Ai_info[Ships[objp->instance].ai_index] );
        }
        for ( objp = GET_FIRST(&obj_create_list); objp != END_OF_LIST(&obj_create_list); objp = GET_NEXT(objp) ) {
                if ( (objp->type != OBJ_SHIP) || Fred_running )
                        continue;
                ai_process_mission_orders( OBJ_INDEX(objp), &Ai_info[Ships[objp->instance].ai_index] );
        }

        return;
}

// function which determines is a goal is valid for a particular type of ship
int ai_query_goal_valid( int ship, int ai_goal )
{
        int accepted;

        if (ai_goal == AI_GOAL_NONE)
                return 1;  // anything can have no orders.

        accepted = 0;
        switch (Ship_info[Ships[ship].ship_info_index].flags & SIF_ALL_SHIP_TYPES) {
        case SIF_CARGO:
                if (!Fred_running)
                        Int3();                 // get Hoffoss or Allender -- cargo containers shouldn't have a goal!!!
                break;

        case SIF_FIGHTER:
                if ( ai_goal & AI_GOAL_ACCEPT_FIGHTER ){
                        accepted = 1;
                }
                break;
        case SIF_BOMBER:
                if ( ai_goal & AI_GOAL_ACCEPT_BOMBER ){
                        accepted = 1;
                }
                break;
        case SIF_CRUISER:
                if ( ai_goal & AI_GOAL_ACCEPT_CRUISER ){
                        accepted = 1;
                }
                break;
        case SIF_FREIGHTER:
                if ( ai_goal & AI_GOAL_ACCEPT_FREIGHTER ){
                        accepted = 1;
                }
                break;
        case SIF_CAPITAL:
                if ( ai_goal & AI_GOAL_ACCEPT_CAPITAL ){
                        accepted = 1;
                }
                break;
        case SIF_TRANSPORT:
                if ( ai_goal & AI_GOAL_ACCEPT_TRANSPORT ){
                        accepted = 1;
                }
                break;
        case SIF_SUPPORT:
                if ( ai_goal & AI_GOAL_ACCEPT_SUPPORT ){
                        accepted = 1;
                }
                break;
        case SIF_ESCAPEPOD:
                if ( ai_goal & AI_GOAL_ACCEPT_ESCAPEPOD ){
                        accepted = 1;
                }
                break;
        case SIF_SUPERCAP:
                if ( ai_goal & AI_GOAL_ACCEPT_SUPERCAP ){
                        accepted = 1;
                }
                break;
        case SIF_STEALTH:
                if ( ai_goal & AI_GOAL_ACCEPT_STEALTH ){
                        accepted = 1;
                }
                break;          
        case SIF_CORVETTE:
                if ( ai_goal & AI_GOAL_ACCEPT_CORVETTE ){
                        accepted = 1;
                }
                break;
        case SIF_GAS_MINER:
                if ( ai_goal & AI_GOAL_ACCEPT_GAS_MINER ){
                        accepted = 1;
                }
                break;
        case SIF_AWACS:
                if ( ai_goal & AI_GOAL_ACCEPT_AWACS ){
                        accepted = 1;
                }
                break;
        case SIF_NO_SHIP_TYPE:
                if (!Fred_running){
                        Int3();                 // HUH?  doesn't make sense
                }
                break;
        default:
                if (!Fred_running){
                        Int3();                 // get allender or hoffos -- unknown ship type
                }
                break;
        }

        return accepted;
}

// remove an ai goal from it's list.  Uses the active_goal member as the goal to remove
void ai_remove_ship_goal( ai_info *aip, int index )
{
        // only need to set the ai_mode for the particular goal to AI_GOAL_NONE
        // reset ai mode to default behavior.  Might get changed next time through
        // ai goal code look
        SDL_assert ( index >= 0 );                      // must have a valid goal

        aip->goals[index].ai_mode = AI_GOAL_NONE;
        aip->goals[index].signature = -1;
        aip->goals[index].priority = -1;
        aip->goals[index].flags = 0;                            // must reset the flags since not doing so will screw up goal sorting.
        if ( index == aip->active_goal )
                aip->active_goal = AI_GOAL_NONE;

        // mwa -- removed this line 8/5/97.  Just because we remove a goal doesn't mean to do the default
        // behavior.  We will make the call commented out below in a more reasonable location
        //ai_do_default_behavior( &Objects[Ships[aip->shipnum].objnum] );
}

void ai_clear_ship_goals( ai_info *aip )
{
        int i;

        for (i = 0; i < MAX_AI_GOALS; i++)
                ai_remove_ship_goal( aip, i );                  // resets active_goal and default behavior

        aip->active_goal = AI_GOAL_NONE;                                        // for good measure

        // next line moved here on 8/5/97 by MWA
        // Dont reset player ai (and hence target)
        if ( !((Player_ship != NULL) && (&Ships[aip->shipnum] == Player_ship)) ) {
                ai_do_default_behavior( &Objects[Ships[aip->shipnum].objnum] );
        }
}

void ai_clear_wing_goals( int wingnum )
{
        int i;
        wing *wingp = &Wings[wingnum];
        //p_object *objp;

        // clear the goals for all ships in the wing
        for (i = 0; i < wingp->current_count; i++) {
                int num = wingp->ship_index[i];

                if ( num > -1 )
                        ai_clear_ship_goals( &Ai_info[Ships[num].ai_index] );

        }

                // clear out the goals for the wing now
        for (i = 0; i < MAX_AI_GOALS; i++) {
                wingp->ai_goals[i].ai_mode = AI_GOAL_NONE;
                wingp->ai_goals[i].signature = -1;
                wingp->ai_goals[i].priority = -1;
        }


}

// routine which marks a wing goal as being complete.  We get the wingnum and a pointer to the goal
// structure of the goal to be removed.  This process is slightly tricky since some member of the wing
// might be pursuing a different goal.  We will have to compare based on mode, submode, priority,
// and name.. This routine is only currently called from waypoint code!!!
void ai_mission_wing_goal_complete( int wingnum, ai_goal *remove_goalp )
{
        int mode, submode, priority, i;
        const char *name;
        ai_goal *aigp;
        wing *wingp;

        wingp = &Wings[wingnum];

        // set up locals for faster access.
        mode = remove_goalp->ai_mode;
        submode = remove_goalp->ai_submode;
        priority = remove_goalp->priority;
        name = remove_goalp->ship_name;

        SDL_assert ( name );                    // should not be NULL!!!!

        // remove the goal from all the ships currently in the wing
        for (i = 0; i < wingp->current_count; i++ ) {
                int num, j;
                ai_info *aip;

                num = wingp->ship_index[i];
                SDL_assert ( num >= 0 );
                aip = &Ai_info[Ships[num].ai_index];
                for ( j = 0; j < MAX_AI_GOALS; j++ ) {
                        aigp = &(aip->goals[j]);

                        // don't need to worry about these types of goals since they can't possibly be a goal we are looking for.
                        if ( (aigp->ai_mode == AI_GOAL_NONE) || !aigp->ship_name )
                                continue;

                        if ( (aigp->ai_mode == mode) && (aigp->ai_submode == submode) && (aigp->priority == priority) && !SDL_strcasecmp(name, aigp->ship_name) ) {
                                ai_remove_ship_goal( aip, j );
                                ai_do_default_behavior( &Objects[Ships[aip->shipnum].objnum] );         // do the default behavior
                                break;                  // we are all done
                        }
                }
        }

        // now remove the goal from the wing
        for (i = 0; i < MAX_AI_GOALS; i++ ) {
                aigp = &(wingp->ai_goals[i]);
                if ( (aigp->ai_mode == AI_GOAL_NONE) || !aigp->ship_name )
                        continue;

                if ( (aigp->ai_mode == mode) && (aigp->ai_submode == submode) && (aigp->priority == priority) && !SDL_strcasecmp(name, aigp->ship_name) ) {
                        wingp->ai_goals[i].ai_mode = AI_GOAL_NONE;
                        wingp->ai_goals[i].signature = -1;
                        wingp->ai_goals[i].priority = -1;
                        break;
                }
        }
                        
}

// routine which is called with an ai object complete it's goal.  Do some action
// based on the goal what was just completed

void ai_mission_goal_complete( ai_info *aip )
{
        // if the active goal is dynamic or none, just return.  (AI_GOAL_NONE is probably an error, but
        // I don't think that this is a problem)
        if ( (aip->active_goal == AI_GOAL_NONE) || (aip->active_goal == AI_ACTIVE_GOAL_DYNAMIC) )
                return;

        ai_remove_ship_goal( aip, aip->active_goal );
        ai_do_default_behavior( &Objects[Ships[aip->shipnum].objnum] );         // do the default behavior

}

int ai_get_subsystem_type( const char *subsystem )
{
        if ( strstr(subsystem, "engine") ) {
                return SUBSYSTEM_ENGINE;
        } else if ( strstr(subsystem, "radar") ) {
                return SUBSYSTEM_RADAR;
        } else if ( strstr(subsystem, "turret") ) {
                return SUBSYSTEM_TURRET;
        } else if ( strstr(subsystem, "navigation") ) {
                return SUBSYSTEM_NAVIGATION;
        } else if ( !SDL_strncasecmp(subsystem, NOX("communication"), 13) ) {
                return SUBSYSTEM_COMMUNICATION;
        } else if ( !SDL_strncasecmp(subsystem, NOX("weapons"), 7) )  {
                return SUBSYSTEM_WEAPONS;
        } else if ( !SDL_strncasecmp(subsystem, NOX("sensors"), 7) )  {
                return SUBSYSTEM_SENSORS;
        } else if ( !SDL_strncasecmp(subsystem, NOX("solar"), 5) )  {
                return SUBSYSTEM_SOLAR;
        } else if ( !SDL_strncasecmp(subsystem, NOX("gas"), 3) )  {
                return SUBSYSTEM_GAS_COLLECT;
        } else if ( !SDL_strncasecmp(subsystem, NOX("activator"), 9) )  {
                return SUBSYSTEM_ACTIVATION;
        } else {                                                                        // If unrecognized type, set to engine so artist can continue working...
                if (!Fred_running) {
//                      Int3();                                                 // illegal subsystem type -- find allender
                }

                return SUBSYSTEM_UNKNOWN;
        }
}

// function to prune out goals which are no longer valid, based on a goal pointer passed in.
// for instance, if we get passed a goal of "disable X", then any goals in the given goal array
// which are destroy, etc, should get removed.  goal list is the list of goals to purge.  It is
// always MAX_AI_GOALS in length.  This function will only get called when the goal which causes
// purging becomes valid.
void ai_goal_purge_invalid_goals( ai_goal *aigp, ai_goal *goal_list )
{
        int i;
        ai_goal *purge_goal;
        const char *name;
        int mode, ship_index, wingnum;

        // get locals for easer access
        name = aigp->ship_name;
        mode = aigp->ai_mode;

        // these goals cannot be associated to wings, but can to a ship in a wing.  So, we should find out
        // if the ship is in a wing so we can purge goals which might operate on that wing
        ship_index = ship_name_lookup(name);
        if ( ship_index == -1 ) {
                Int3();                                         // get allender -- this is sort of odd
                return;
        }
        wingnum = Ships[ship_index].wingnum;

        purge_goal = goal_list;
        for ( i = 0; i < MAX_AI_GOALS; purge_goal++, i++ ) {
                int purge_ai_mode, purge_wing;

                purge_ai_mode = purge_goal->ai_mode;

                // don't need to process AI_GOAL_NONE
                if ( purge_ai_mode == AI_GOAL_NONE )
                        continue;

                // goals must operate on something to be purged.
                if ( purge_goal->ship_name == NULL )
                        continue;

                // determine if the purge goal is acting either on the ship or the ship's wing.
                purge_wing = wing_name_lookup( purge_goal->ship_name, 1 );

                // if the target of the purge goal is a ship (purge_wing will be -1), then if the names
                // don't match, we can continue;  if the wing is valid, don't process if the wing numbers
                // are different.
                if ( purge_wing == -1 ) {
                        if ( SDL_strcasecmp(purge_goal->ship_name, name ) )
                                continue;
                } else if ( purge_wing != wingnum )
                        continue;

                switch( mode ) {
                // ignore goals should get rid of any kind of attack goal
                case AI_GOAL_IGNORE:
                        if ( purge_ai_mode & (AI_GOAL_DISABLE_SHIP | AI_GOAL_DISARM_SHIP | AI_GOAL_CHASE | AI_GOAL_CHASE_WING | AI_GOAL_DESTROY_SUBSYSTEM) )
                                purge_goal->flags |= AIGF_PURGE;
                        break;

                // disarm/disable goals should remove any general attack
                case AI_GOAL_DISABLE_SHIP:
                case AI_GOAL_DISARM_SHIP:
                        if ( purge_ai_mode & (AI_GOAL_CHASE | AI_GOAL_CHASE_WING) )
                                purge_goal->flags |= AIGF_PURGE;
                        break;
                }
        }
}

// function to purge the goals of all ships in the game based on the incoming goal structure
void ai_goal_purge_all_invalid_goals( ai_goal *aigp )
{
        int mode, i;
        ship_obj *sop;

        mode = aigp->ai_mode;

        // only purge goals if a new goal is one of the types in next statement
        if ( !(mode & PURGE_GOALS) )
                return;

        for ( sop = GET_FIRST(&Ship_obj_list); sop != END_OF_LIST(&Ship_obj_list); sop = GET_NEXT(sop) ) {
                ship *shipp;

                shipp = &Ships[Objects[sop->objnum].instance];
                ai_goal_purge_invalid_goals( aigp, Ai_info[shipp->ai_index].goals );
        }

        // we must do the same for the wing goals
        for (i = 0; i < num_wings; i++ )
                ai_goal_purge_invalid_goals( aigp, Wings[i].ai_goals );
}

// function to fix up dock point references for objects.
// passed are the pointer to goal we are working with.  aip if the ai_info pointer
// of the ship with the order.  aigp is a pointer to the goal (of aip) of which we are
// fixing up the docking points
void ai_goal_fixup_dockpoints(ai_info *aip, ai_goal *aigp)
{
        int shipnum, dockee_index, docker_index;

        SDL_assert ( aip->shipnum != -1 );
        shipnum = ship_name_lookup( aigp->ship_name );
        docker_index = -1;
        dockee_index = -1;

        // look for docking points of the appriopriate type.  Use cargo docks for cargo ships.
        // use 
        if ( Ship_info[Ships[shipnum].ship_info_index].flags & SIF_CARGO ) {
                docker_index = model_find_dock_index(Ships[aip->shipnum].modelnum, DOCK_TYPE_CARGO );
                dockee_index = model_find_dock_index(Ships[shipnum].modelnum, DOCK_TYPE_CARGO );
        } else if ( Ship_info[Ships[aip->shipnum].ship_info_index].flags & SIF_SUPPORT ) {
                docker_index = model_find_dock_index( Ships[aip->shipnum].modelnum, DOCK_TYPE_REARM );
                dockee_index = model_find_dock_index( Ships[shipnum].modelnum, DOCK_TYPE_REARM );
        }

        // if we didn't find dockpoints above, then we should just look for generic docking points
        if ( docker_index == -1 )
                docker_index = model_find_dock_index(Ships[aip->shipnum].modelnum, DOCK_TYPE_GENERIC );
        if ( dockee_index == -1 )
                dockee_index = model_find_dock_index(Ships[shipnum].modelnum, DOCK_TYPE_GENERIC );
                
        aigp->docker.index = docker_index;
        aigp->dockee.index = dockee_index;
        aigp->flags &= ~(AIGF_DOCKER_NAME_VALID | AIGF_DOCKEE_NAME_VALID);
}

// these functions deal with adding goals sent from the player.  They are slightly different
// from the mission goals (i.e. those goals which come from events) in that we don't
// use sexpressions for goals from the player...so we enumerate all the parameters

void ai_add_goal_sub_player(int type, int mode, int submode, const char *shipname, ai_goal *aigp )
{
        SDL_assert ( (type == AIG_TYPE_PLAYER_WING) || (type == AIG_TYPE_PLAYER_SHIP) );

        aigp->time = Missiontime;
        aigp->type = type;                                                                                      // from player for sure -- could be to ship or to wing
        aigp->ai_mode = mode;                                                                           // major mode for this goal
        aigp->ai_submode = submode;                                                             // could mean different things depending on mode

        if ( mode == AI_GOAL_WARP )
                aigp->wp_index = submode;

        if ( mode == AI_GOAL_CHASE_WEAPON ) {
                aigp->wp_index = submode;                                                               // submode contains the instance of the weapon
                aigp->weapon_signature = Objects[Weapons[submode].objnum].signature;
        }

        if ( shipname != NULL )
                aigp->ship_name = ai_get_goal_ship_name( shipname, &aigp->ship_name_index );
        else
                aigp->ship_name = NULL;

        // special case certain orders from player so that ships continue to do the right thing

        // make priority for these two support ship orders low so that they will prefer repairing
        // a ship over staying near a ship.
        if ( (mode == AI_GOAL_STAY_NEAR_SHIP) || (mode == AI_GOAL_KEEP_SAFE_DISTANCE) )
                aigp->priority = PLAYER_PRIORITY_SUPPORT_LOW;

        else if ( aigp->type == AIG_TYPE_PLAYER_WING )
                aigp->priority = PLAYER_PRIORITY_WING;                  // player wing goals not as high as ship goals
        else
                aigp->priority = PLAYER_PRIORITY_SHIP;
}

int ai_goal_find_empty_slot( ai_goal *goals )
{
        int gindex, empty_index, oldest_index;

        empty_index = -1;
        oldest_index = 0;
        for ( gindex = 0; gindex < MAX_AI_GOALS; gindex++ ) {
                if ( goals[gindex].time < goals[oldest_index].time )
                        oldest_index = gindex;

                if ( (empty_index == -1) && (goals[gindex].ai_mode == AI_GOAL_NONE) )                   // get the index for this goal
                        empty_index = gindex;
        }

        // if we didn't find an empty slot, find the oldest goal and use it's slot
        if ( empty_index == -1 )
                empty_index = oldest_index;

        SDL_assert ( empty_index < MAX_AI_GOALS );

        return empty_index;
}

// adds a goal from a player to the given ship's ai_info structure.  'type' tells us if goal
// is issued to ship or wing (from player),  mode is AI_GOAL_*. submode is the submode the
// ship should go into.  shipname is the object of the action.  aip is the ai_info pointer
// of the ship receiving the order
void ai_add_ship_goal_player( int type, int mode, int submode, const char *shipname, ai_info *aip )
{
        int empty_index;
        ai_goal *aigp;

        empty_index = ai_goal_find_empty_slot( aip->goals );

        // get a pointer to the goal structure
        aigp = &aip->goals[empty_index];
        ai_add_goal_sub_player( type, mode, submode, shipname, aigp );

        // if the goal is to dock, then we must determine which dock points on the two ships to use.
        // If the target of the dock is a cargo type container, then we should use DOCK_TYPE_CARGO
        // on both ships.  Code is here instead of in ai_add_goal_sub_player() since a dock goal
        // should only occur to a specific ship.

        if ( (mode == AI_GOAL_REARM_REPAIR) || ((mode == AI_GOAL_DOCK) && (submode == AIS_DOCK_0)) ) {
                ai_goal_fixup_dockpoints( aip, aigp );
        }

        aigp->signature = Ai_goal_signature++;

}

// adds a goal from the player to the given wing (which in turn will add it to the proper
// ships in the wing
void ai_add_wing_goal_player( int type, int mode, int submode, const char *shipname, int wingnum )
{
        int i, empty_index;
        wing *wingp = &Wings[wingnum];

        // add the ai goal for any ship that is currently arrived in the game.
        if ( !Fred_running ) {                                                                          // only add goals to ships if fred isn't running
                for (i = 0; i < wingp->current_count; i++) {
                        int num = wingp->ship_index[i];
                        if ( num == -1 )                        // ship must have been destroyed or departed
                                continue;
                        ai_add_ship_goal_player( type, mode, submode, shipname, &Ai_info[Ships[num].ai_index] );
                }
        }

        // add the sexpression index into the wing's list of goal sexpressions if
        // there are more waves to come.  We use the same method here as when adding a goal to
        // a ship -- find the first empty entry.  If none exists, take the oldest entry and replace it.
        empty_index = ai_goal_find_empty_slot( wingp->ai_goals );
        ai_add_goal_sub_player( type, mode, submode, shipname, &wingp->ai_goals[empty_index] );
}


// common routine to add a sexpression mission goal to the appropriate goal structure.
void ai_add_goal_sub_sexp( int sexp, int type, ai_goal *aigp )
{
        int node, dummy, op;
        char *text;

        SDL_assert ( Sexp_nodes[sexp].first != -1 );
        node = Sexp_nodes[sexp].first;
        text = CTEXT(node);

        aigp->signature = Ai_goal_signature++;

        aigp->time = Missiontime;
        aigp->type = type;
        aigp->flags = 0;

        op = find_operator( text );

        switch (op) {

        case OP_AI_WAYPOINTS_ONCE:
        case OP_AI_WAYPOINTS: {
                int ref_type;

                ref_type = Sexp_nodes[CDR(node)].subtype;
                if (ref_type == SEXP_ATOM_STRING) {  // referenced by name
                        // save the waypoint path name -- the index will get resolved when the goal is checked
                        // for acheivability.
                        aigp->ship_name = ai_get_goal_ship_name(CTEXT(CDR(node)), &aigp->ship_name_index);  // waypoint path name;
                        aigp->wp_index = -1;

                } else
                        Int3();

                aigp->priority = atoi( CTEXT(CDR(CDR(node))) );
                aigp->ai_mode = AI_GOAL_WAYPOINTS;
                if ( op == OP_AI_WAYPOINTS_ONCE )
                        aigp->ai_mode = AI_GOAL_WAYPOINTS_ONCE;
                break;
        }

        case OP_AI_DESTROY_SUBSYS:
                aigp->ai_mode = AI_GOAL_DESTROY_SUBSYSTEM;
                aigp->ship_name = ai_get_goal_ship_name( CTEXT(CDR(node)), &aigp->ship_name_index );
                // store the name of the subsystem in the docker_name field for now -- this field must
                // get fixed up when the goal is valid since we need to locate the subsystem on the ship's
                // model.
                aigp->docker.name = ai_get_goal_ship_name(CTEXT(CDR(CDR(node))), &dummy);
                aigp->flags |= AIGF_SUBSYS_NAME_VALID;
                aigp->priority = atoi( CTEXT(CDR(CDR(CDR(node)))) );
                break;

        case OP_AI_DISABLE_SHIP:
                aigp->ai_mode = AI_GOAL_DISABLE_SHIP;
                aigp->ship_name = ai_get_goal_ship_name( CTEXT(CDR(node)), &aigp->ship_name_index );
                aigp->ai_submode = -SUBSYSTEM_ENGINE;
                aigp->priority = atoi( CTEXT(CDR(CDR(node))) );
                break;

        case OP_AI_DISARM_SHIP:
                aigp->ai_mode = AI_GOAL_DISARM_SHIP;
                aigp->ship_name = ai_get_goal_ship_name( CTEXT(CDR(node)), &aigp->ship_name_index );
                aigp->ai_submode = -SUBSYSTEM_TURRET;
                aigp->priority = atoi( CTEXT(CDR(CDR(node))) );
                break;

        case OP_AI_WARP_OUT:
                aigp->ai_mode = AI_GOAL_WARP;
                aigp->priority = atoi( CTEXT(CDR(node)) );
                break;

                // the following goal is obsolete, but here for compatibility
        case OP_AI_WARP:
                aigp->ai_mode = AI_GOAL_WARP;
                aigp->ship_name = ai_get_goal_ship_name(CTEXT(CDR(node)), &aigp->ship_name_index);  // waypoint path name;
                //aigp->wp_index = atoi( CTEXT(CDR(node)) );            // this is the index into the warp points
                aigp->wp_index = -1;
                aigp->priority = atoi( CTEXT(CDR(CDR(node))) );
                break;

        case OP_AI_UNDOCK:
                aigp->ship_name = NULL;
                aigp->priority = atoi( CTEXT(CDR(node)) );
                aigp->ai_mode = AI_GOAL_UNDOCK;
                aigp->ai_submode = AIS_UNDOCK_0;
                break;

        case OP_AI_STAY_STILL:
                aigp->ai_mode = AI_GOAL_STAY_STILL;
                aigp->ship_name = ai_get_goal_ship_name(CTEXT(CDR(node)), &aigp->ship_name_index);  // waypoint path name;
                aigp->priority = atoi( CTEXT(CDR(CDR(node))) );
                break;

        case OP_AI_DOCK:
                aigp->ship_name = ai_get_goal_ship_name( CTEXT(CDR(node)), &aigp->ship_name_index );
                aigp->docker.name = ai_add_dock_name(CTEXT(CDR(CDR(node))));
                aigp->dockee.name = ai_add_dock_name(CTEXT(CDR(CDR(CDR(node)))));
                aigp->flags |= ( AIGF_DOCKER_NAME_VALID | AIGF_DOCKEE_NAME_VALID );
                aigp->priority = atoi( CTEXT(CDR(CDR(CDR(CDR(node))))) );

                aigp->ai_mode = AI_GOAL_DOCK;
                aigp->ai_submode = AIS_DOCK_0;          // be sure to set the submode
                break;

        case OP_AI_CHASE_ANY:
                aigp->priority = atoi( CTEXT(CDR(node)) );
                aigp->ai_mode = AI_GOAL_CHASE_ANY;
                break;

        case OP_AI_PLAY_DEAD:
                aigp->priority = atoi( CTEXT(CDR(node)) );
                aigp->ai_mode = AI_GOAL_PLAY_DEAD;
                break;

        case OP_AI_KEEP_SAFE_DISTANCE:
                aigp->priority = atoi( CTEXT(CDR(node)) );
                aigp->ai_mode = AI_GOAL_KEEP_SAFE_DISTANCE;
                break;

        case OP_AI_CHASE:
        case OP_AI_GUARD:
        case OP_AI_GUARD_WING:
        case OP_AI_CHASE_WING:
        case OP_AI_EVADE_SHIP:
        case OP_AI_STAY_NEAR_SHIP:
        case OP_AI_IGNORE:
                aigp->ship_name = ai_get_goal_ship_name( CTEXT(CDR(node)), &aigp->ship_name_index );
                aigp->priority = atoi( CTEXT(CDR(CDR(node))) );

                if ( op == OP_AI_CHASE ) {
                        aigp->ai_mode = AI_GOAL_CHASE;

                        // in the case of ai_chase (and ai_guard) we must do a wing_name_lookup on the name
                        // passed here to see if we could be chasing a wing.  Hoffoss and I have consolidated
                        // sexpression operators which makes this step necessary
                        if ( wing_name_lookup(aigp->ship_name, 1) != -1 )
                                aigp->ai_mode = AI_GOAL_CHASE_WING;

                } else if ( op == OP_AI_GUARD ) {
                        aigp->ai_mode = AI_GOAL_GUARD;
                        if ( wing_name_lookup(aigp->ship_name, 1) != -1 )
                                aigp->ai_mode = AI_GOAL_GUARD_WING;

                } else if ( op == OP_AI_EVADE_SHIP ) {
                        aigp->ai_mode = AI_GOAL_EVADE_SHIP;

                } else if ( op == OP_AI_GUARD_WING ) {
                        aigp->ai_mode = AI_GOAL_GUARD_WING;
                } else if ( op == OP_AI_CHASE_WING ) {
                        aigp->ai_mode = AI_GOAL_CHASE_WING;
                } else if ( op == OP_AI_STAY_NEAR_SHIP ) {
                        aigp->ai_mode = AI_GOAL_STAY_NEAR_SHIP;
                } else if ( op == OP_AI_IGNORE ) {
                        aigp->ai_mode = AI_GOAL_IGNORE;
                } else
                        Int3();         // this is impossible

                break;

        default:
                Int3();                 // get ALLENDER -- invalid ai-goal specified for ai object!!!!
        }

        if ( aigp->priority >= PLAYER_PRIORITY_MIN ) {
                nprintf (("AI", "bashing sexpression priority of goal %s from %d to %d.\n", text, aigp->priority, PLAYER_PRIORITY_MIN-1));
                aigp->priority = PLAYER_PRIORITY_MIN-1;
        }
}

// adds an ai goal for an individual ship
// type determines who has issues this ship a goal (i.e. the player/mission event/etc)
void ai_add_ship_goal_sexp( int sexp, int type, ai_info *aip )
{
        int gindex;

        gindex = ai_goal_find_empty_slot( aip->goals );
        ai_add_goal_sub_sexp( sexp, type, &aip->goals[gindex] );
}

// code to add ai goals to wings.
void ai_add_wing_goal_sexp(int sexp, int type, int wingnum)
{
        int i;
        wing *wingp = &Wings[wingnum];

        // add the ai goal for any ship that is currently arrived in the game (only if fred isn't running
        if ( !Fred_running ) {
                for (i = 0; i < wingp->current_count; i++) {
                        int num = wingp->ship_index[i];
                        if ( num == -1 )                        // ship must have been destroyed or departed
                                continue;
                        ai_add_ship_goal_sexp( sexp, type, &Ai_info[Ships[num].ai_index] );
                }
        }

        // add the sexpression index into the wing's list of goal sexpressions if
        // there are more waves to come
        if ((wingp->num_waves - wingp->current_wave > 0) || Fred_running) {
                int gindex;

                gindex = ai_goal_find_empty_slot( wingp->ai_goals );
                ai_add_goal_sub_sexp( sexp, type, &wingp->ai_goals[gindex] );
        }
}

// function for internal code to add a goal to a ship.  Needed when the AI finds itself in a situation
// that it must get out of by issuing itself an order.
//
// objp is the object getting the goal
// goal_type is one of AI_GOAL_*
// other_name is a character string objp might act on (for docking, this is a shipname, for guarding
// this name can be a shipname or a wingname)
// docker_point and dockee_point are used for the AI_GOAL_DOCK command to tell two ships where to dock
// immediate means to process this order right away
void ai_add_goal_ship_internal( ai_info *aip, int goal_type, const char *name, int docker_point, int dockee_point, int immediate )
{
        int gindex;
        ai_goal *aigp;

        // find an empty slot to put this goal in.
        gindex = ai_goal_find_empty_slot( aip->goals );

        aigp = &(aip->goals[gindex]);

        aigp->signature = Ai_goal_signature++;

        aigp->time = Missiontime;
        aigp->type = AIG_TYPE_DYNAMIC;
        aigp->flags = AIGF_GOAL_OVERRIDE;

        switch ( goal_type ) {
        case AI_GOAL_DOCK:
                aigp->ship_name = name;
                aigp->docker.index = docker_point;
                aigp->dockee.index = dockee_point;
                aigp->priority = 100;

                aigp->ai_mode = AI_GOAL_DOCK;
                aigp->ai_submode = AIS_DOCK_0;          // be sure to set the submode
                break;

        case AI_GOAL_UNDOCK:
                aigp->ship_name = NULL;
                aigp->priority = 100;
                aigp->ai_mode = AI_GOAL_UNDOCK;
                aigp->ai_submode = AIS_UNDOCK_0;
                break;

        case AI_GOAL_GUARD:
                aigp->ai_mode = AI_GOAL_GUARD;
                if ( wing_name_lookup(name, 1) != -1 )
                        aigp->ai_mode = AI_GOAL_GUARD_WING;
                break;

        case AI_GOAL_REARM_REPAIR:
                aigp->ai_mode = AI_GOAL_REARM_REPAIR;
                aigp->ai_submode = 0;
                aigp->ship_name = name;
                aigp->priority = PLAYER_PRIORITY_MIN-1;         // make the priority always less than what the player's is
                aigp->flags &= ~AIGF_GOAL_OVERRIDE;                             // don't override this goal.  rearm repair requests should happen in order
                ai_goal_fixup_dockpoints( aip, aigp );
                break;

        default:
                Int3();         // unsupported internal goal -- see Mike K or Mark A.
                break;
        }


        // process the orders immediately so that these goals take effect right away
        if ( immediate )
                ai_process_mission_orders( Ships[aip->shipnum].objnum, aip );
}

// function to add an internal goal to a wing.  Mike K says that the goal doesn't need to persist
// across waves of the wing so we merely need to add the goal to each ship in the wing.  Certain
// goal are simply not valid for wings (like dock, undock).  Immediate parameter gets passed to add_ship_goal
// to say whether or not we should process this goal right away
void ai_add_goal_wing_internal( wing *wingp, int goal_type, const char *name, int immediate )
{
        int i;

        // be sure we are not trying to issue dock or undock goals to wings
        SDL_assert ( (goal_type != AI_GOAL_DOCK) || (goal_type != AI_GOAL_UNDOCK) );

        for (i = 0; i < wingp->current_count; i++) {
                int num = wingp->ship_index[i];
                if ( num == -1 )                        // ship must have been destroyed or departed
                        continue;
                ai_add_goal_ship_internal(  &Ai_info[Ships[num].ai_index], goal_type, name, -1, -1, immediate);
        }
}

// this function copies goals from a wing to an ai_info * from a ship.
void ai_copy_mission_wing_goal( ai_goal *aigp, ai_info *aip )
{
        int j;

        for ( j = 0; j < MAX_AI_GOALS; j++ ) {
                if ( aip->goals[j].ai_mode == AI_GOAL_NONE )
                        break;
        }
        SDL_assert ( j < MAX_AI_GOALS );
        aip->goals[j] = *aigp;
}


#define SHIP_STATUS_GONE                                1
#define SHIP_STATUS_NOT_ARRIVED         2
#define SHIP_STATUS_ARRIVED                     3
#define SHIP_STATUS_UNKNOWN                     4

// function to determine if an ai goal is achieveable or not.  Will return
// one of the AI_GOAL_* values.  Also determines is a goal was successful.

int ai_mission_goal_achievable( int objnum, ai_goal *aigp )
{
        int status;
        //char *ai_shipname;
        int return_val;
        object *objp;
        ai_info *aip;

        //  these orders are always achievable.
        if ( (aigp->ai_mode == AI_GOAL_KEEP_SAFE_DISTANCE) || (aigp->ai_mode == AI_GOAL_WARP)
                || (aigp->ai_mode == AI_GOAL_CHASE_ANY) || (aigp->ai_mode == AI_GOAL_STAY_STILL)
                || (aigp->ai_mode == AI_GOAL_PLAY_DEAD) )
                return AI_GOAL_ACHIEVABLE;

        // form on my wing is always achievable, but need to set the override bit so that it
        // always gets executed next
        if ( aigp->ai_mode == AI_GOAL_FORM_ON_WING ) {
                aigp->flags |= AIGF_GOAL_OVERRIDE;
                return AI_GOAL_ACHIEVABLE;
        }

        // check to see if we have a valid index.  If not, then try to set one up.  If that
        // fails, then we must pitch this order
        if ( (aigp->ai_mode == AI_GOAL_WAYPOINTS_ONCE) || (aigp->ai_mode == AI_GOAL_WAYPOINTS) ) {
                if ( aigp->wp_index == -1 ) {
                        int i;

                        for (i = 0; i < Num_waypoint_lists; i++) {
                                if (!SDL_strcasecmp(aigp->ship_name, Waypoint_lists[i].name)) {
                                        aigp->wp_index = i;
                                        break;
                                }
                        }
                        if ( i == Num_waypoint_lists ) {
                                Warning(LOCATION, "Unknown waypoint %s.  not found in mission file.  Killing ai goal", aigp->ship_name );
                                return AI_GOAL_NOT_ACHIEVABLE;
                        }
                }
                return AI_GOAL_ACHIEVABLE;
        }

        objp = &Objects[objnum];
        SDL_assert( objp->instance != -1 );
        //ai_shipname = Ships[objp->instance].ship_name;
        aip = &Ai_info[Ships[objp->instance].ai_index];

        return_val = AI_GOAL_SATISFIED;

        // next, determine if the goal has been completed successfully
        switch ( aigp->ai_mode ) {

        case AI_GOAL_DOCK:
        case AI_GOAL_CHASE_WING:
        case AI_GOAL_UNDOCK:
                //status = mission_log_get_time( LOG_SHIP_DOCK, ai_shipname, aigp->ship_name, NULL);
                //status = mission_log_get_time( LOG_SHIP_UNDOCK, ai_shipname, aigp->ship_name, NULL );
                //MWA 3/20/97 -- cannot short circuit a dock or undock goal already succeeded -- we must
                // rely on the goal removal code to just remove this goal.  This is because docking/undock
                // can happen > 1 time per mission per pair of ships.  The above checks will find only
                // if the ships docked or undocked at all, which is not what we want.
                status = 0;
                break;
        case AI_GOAL_DESTROY_SUBSYSTEM: {
                int shipnum;
                ship_subsys *ssp;

                // shipnum could be -1 depending on if the ship hasn't arrived or died.  only look for subsystem
                // destroyed when shipnum is valid
                shipnum = ship_name_lookup( aigp->ship_name );

                // can't determine the status of this goal if ship not valid or the subsystem
                // name *is* still valid (meaning we haven't found a valid index yet).
                if ( (shipnum == -1) || (aigp->flags & AIGF_SUBSYS_NAME_VALID) ) {
                        status = 0;
                        break;
                }

                // if the ship is not in the mission or the subsystem name is still being stored, mark the status
                // as 0 so we can continue.  (The subsystem name must be turned into an index into the ship's subsystems
                // for this goal to be valid).
                SDL_assert ( aigp->ai_submode >= 0 );
                ssp = ship_get_indexed_subsys( &Ships[shipnum], aigp->ai_submode );
                status = mission_log_get_time( LOG_SHIP_SUBSYS_DESTROYED, aigp->ship_name, ssp->system_info->name, NULL );

                break;
        }
        case AI_GOAL_DISABLE_SHIP:
                status = mission_log_get_time( LOG_SHIP_DISABLED, aigp->ship_name, NULL, NULL );
                break;
        case AI_GOAL_DISARM_SHIP:
                status = mission_log_get_time( LOG_SHIP_DISARMED, aigp->ship_name, NULL, NULL );
                break;

                // to guard or ignore a ship, the goal cannot continue if the ship being guarded is either destroyed
                // or has departed.
        case AI_GOAL_GUARD:
        case AI_GOAL_IGNORE:
        case AI_GOAL_EVADE_SHIP:
        case AI_GOAL_CHASE:
        case AI_GOAL_STAY_NEAR_SHIP:
        case AI_GOAL_REARM_REPAIR: {
                int shipnum;

                // MWA -- 4/22/98.  Check for the ship actually being in the mission before
                // checking departure and destroyed.  In multiplayer, since ships can respawn,
                // they get log entries for being destroyed even though they have respawned.
                shipnum = ship_name_lookup( aigp->ship_name );
                if ( shipnum == -1 ) {
                        status = mission_log_get_time( LOG_SHIP_DEPART, aigp->ship_name, NULL, NULL);
                        if ( !status ) {
                                status = mission_log_get_time( LOG_SHIP_DESTROYED, aigp->ship_name, NULL, NULL);
                                if ( status )
                                        return_val = AI_GOAL_NOT_ACHIEVABLE;
                        }
                } else {
                        status = 0;
                }
                break;
        }

        case AI_GOAL_GUARD_WING:
                status = mission_log_get_time( LOG_WING_DEPART, aigp->ship_name, NULL, NULL );
                if ( !status ) {
                        status = mission_log_get_time( LOG_WING_DESTROYED, aigp->ship_name, NULL, NULL);
                        if ( status )
                                return_val = AI_GOAL_NOT_ACHIEVABLE;
                }
                break;

                // the following case statement returns control to caller on all paths!!!!
        case AI_GOAL_CHASE_WEAPON:
                // for chase weapon, we simply need to look at the weapon instance that we are trying to
                // attack and see if the object still exists, and has the same signature that we expect.
                if ( Weapons[aigp->wp_index].objnum == -1 )
                        return AI_GOAL_NOT_ACHIEVABLE;

                // if the signatures don't match, then goal isn't achievable.
                if ( Objects[Weapons[aigp->wp_index].objnum].signature != aigp->weapon_signature )
                        return AI_GOAL_NOT_ACHIEVABLE;

                // otherwise, we should be good to go
                return AI_GOAL_ACHIEVABLE;

                break;

        default:
                Int3();
                status = 0;
                break;
        }

        // if status is true, then the mission log event was found and the goal was satisfied.  return
        // AI_GOAL_SATISFIED which should allow this ai object to move onto the next order
        if ( status )
                return return_val;

        // determine the status of the shipname that this object is acting on.  There are a couple of
        // special cases to deal with.  Both the chase wing and undock commands will return from within
        // the if statement.
        if ( (aigp->ai_mode == AI_GOAL_CHASE_WING) || (aigp->ai_mode == AI_GOAL_GUARD_WING) ) {
                int num = wing_name_lookup( aigp->ship_name );
                wing *wingp = &Wings[num];

                if ( wingp->flags & WF_WING_GONE )
                        return AI_GOAL_NOT_ACHIEVABLE;
                else if ( wingp->total_arrived_count == 0 )
                        return AI_GOAL_NOT_KNOWN;
                else
                        return AI_GOAL_ACHIEVABLE;
        } else if ( aigp->ai_mode == AI_GOAL_UNDOCK ) {
                        return AI_GOAL_ACHIEVABLE;
        } else {
                if ( ship_name_lookup( aigp->ship_name ) != -1 )
                        status = SHIP_STATUS_ARRIVED;
                else if ( !mission_parse_ship_arrived(aigp->ship_name) )
                        status = SHIP_STATUS_NOT_ARRIVED;
                else if ( ship_find_exited_ship_by_name(aigp->ship_name) != -1 )
                        status = SHIP_STATUS_GONE;
                else {
                        Int3();         // get ALLENDER
                        status = SHIP_STATUS_UNKNOWN;
                }
        }

        // if the goal is an ignore/disable/disarm goal, then 
        if ( (status == SHIP_STATUS_ARRIVED) && (aigp->ai_mode & PURGE_GOALS) && !(aigp->flags & AIGF_GOALS_PURGED) ) {
                ai_goal_purge_all_invalid_goals( aigp );
                aigp->flags |= AIGF_GOALS_PURGED;
        }
                

        // if we are docking, validate the docking indices on both ships.  We might have to change names to indices.
        // only enter this calculation if the ship we are docking with has arrived.  If the ship is gone, then
        // this goal will get removed.
        if ( (aigp->ai_mode == AI_GOAL_DOCK) && (status == SHIP_STATUS_ARRIVED) ) {
                int index, modelnum, shipnum;
                char docker_name[NAME_LENGTH], dockee_name[NAME_LENGTH];

                // debug code to save off the name of the dockpoints (if they exist).
                docker_name[0] = dockee_name[0] = '\0';
                if ( aigp->flags & AIGF_DOCKER_NAME_VALID ) {
                        SDL_strlcpy(docker_name, aigp->docker.name, SDL_arraysize(docker_name));
                        modelnum = Ships[objp->instance].modelnum;
                        index = model_find_dock_name_index(modelnum, aigp->docker.name);
                        aigp->docker.index = index;
                        aigp->flags &= ~AIGF_DOCKER_NAME_VALID;
                }
                if ( aigp->flags & AIGF_DOCKEE_NAME_VALID ) {
                        shipnum = ship_name_lookup(aigp->ship_name);
                        if ( shipnum != -1 ) {
                                SDL_strlcpy(dockee_name, aigp->dockee.name, SDL_arraysize(dockee_name));
                                modelnum = Ships[shipnum].modelnum;
                                index = model_find_dock_name_index(modelnum, aigp->dockee.name);
                                aigp->dockee.index = index;
                                aigp->flags &= ~AIGF_DOCKEE_NAME_VALID;
                        } else
                                aigp->dockee.index = -1;                // this will force code into if statement below making goal not achievable.
                }
                if ( (aigp->dockee.index == -1) || (aigp->docker.index == -1) ) {
                        Int3();                 // for now, allender wants to know about these things!!!!
                        return AI_GOAL_NOT_ACHIEVABLE;
                }

                // we must also determine if this ship which is supposed to dock with something is currently
                // docked with something else.  If so, then return the ON_HOLD until it is not docked anymore
                shipnum = ship_name_lookup(aigp->ship_name);
                SDL_assert( shipnum != -1 );

                // if ship is disabled, dont' know if it can dock or not
                if ( Ships[objp->instance].flags & SF_DISABLED )
                        return AI_GOAL_NOT_KNOWN;

                // if the ship that I am supposed to dock with is docked with something else, then I need to put my
                // goal on hold
                //      [MK, 4/23/98: With Mark, we believe this fixes the problem of Comet refusing to warp out after docking with Omega.
                //      This bug occurred only when mission goals were validated in the frame in which Comet docked, which happened about
                // once in 10-20 tries.]
                if ( Ai_info[Ships[shipnum].ai_index].ai_flags & AIF_DOCKED )
                        if (aip->dock_objnum != Ships[shipnum].objnum)
                                return AI_GOAL_NOT_KNOWN;

                // if this ship is docked and needs to get docked with something else, then undock this
                // ship
                if ( aip->ai_flags & AIF_DOCKED ) {

                        // if we are trying to dock with a different ship, then force this ship to undock
                        if ( aip->dock_objnum != Ships[shipnum].objnum ) {
                                // if this goal isn't on hold yet, then issue the undock goal and return NOT_KNOWN
                                // which will then place the goal on hold until the undocking is complete.
                                if ( !(aigp->flags & AIGF_GOAL_ON_HOLD) )
                                        ai_add_goal_ship_internal( aip, AI_GOAL_UNDOCK, NULL, -1, -1, 0 );

                                return AI_GOAL_NOT_KNOWN;
                        } else {
                                // if this ship is already docked with the guy this order tells him to dock with,
                                // then mark the goal as satisfied.
                                // MWA 2/23/98 -- don't return anything.  Since this item is a goal, the ai_dock code
                                // should remove the goal!!!!
                                //return AI_GOAL_SATISFIED;
                        }
                }

        } else if ( (aigp->ai_mode == AI_GOAL_DESTROY_SUBSYSTEM) && (status == SHIP_STATUS_ARRIVED) ) {
                // if the ship has arrived, and the goal is destroy subsystem, then check to see that we
                // have fixed up the subsystem name (of the subsystem to destroy) into an index into
                // the ship's subsystem list
                if ( aigp->flags & AIGF_SUBSYS_NAME_VALID ) {
                        int shipnum;                    

                        shipnum = ship_name_lookup( aigp->ship_name );
                        if ( shipnum != -1 ) {
                                aigp->ai_submode = ship_get_subsys_index( &Ships[shipnum], aigp->docker.name );
                                aigp->flags &= ~AIGF_SUBSYS_NAME_VALID;
                        } else {
                                Int3();
                                return AI_GOAL_NOT_ACHIEVABLE;                  // force this goal to be invalid
                        }
                }
        } else if ( (aigp->ai_mode == AI_GOAL_IGNORE) && (status == SHIP_STATUS_ARRIVED) ) {
                int shipnum;
                object *ignored;

                // for ignoring a ship, call the ai_ignore object function, then declare the goal satisfied
                shipnum = ship_name_lookup( aigp->ship_name );
                SDL_assert( shipnum != -1 );            // should be true because of above status
                ignored = &Objects[Ships[shipnum].objnum];
                ai_ignore_object(objp, ignored, 100);
                return AI_GOAL_SATISFIED;
        }

        switch ( aigp->ai_mode ) {

        case AI_GOAL_CHASE:
        case AI_GOAL_DOCK:
        case AI_GOAL_DESTROY_SUBSYSTEM:
        case AI_GOAL_UNDOCK:
        case AI_GOAL_GUARD:
        case AI_GOAL_GUARD_WING:
        case AI_GOAL_DISABLE_SHIP:
        case AI_GOAL_DISARM_SHIP:
        case AI_GOAL_IGNORE:
        case AI_GOAL_EVADE_SHIP:
        case AI_GOAL_STAY_NEAR_SHIP:
                if ( status == SHIP_STATUS_ARRIVED )
                        return AI_GOAL_ACHIEVABLE;
                else if ( status == SHIP_STATUS_NOT_ARRIVED )
                        return AI_GOAL_NOT_KNOWN;
                else if ( status == SHIP_STATUS_GONE )
                        return AI_GOAL_NOT_ACHIEVABLE;
                else if ( status == SHIP_STATUS_UNKNOWN )
                        return AI_GOAL_NOT_KNOWN;
                        Int3();         // get allender -- bad logic
                break;

        // for rearm repair ships, a goal is only achievable if the support ship isn't repairing anything
        // else at the time, or is set to repair the ship for this goal.  All other goals should be placed
        // on hold by returning GOAL_NOT_KNOWN.
        case AI_GOAL_REARM_REPAIR: {
                int shipnum;

                // short circuit a couple of cases.  Ship not arrived shouldn't happen.  Ship gone means
                // we mark the goal as not achievable.
                if ( status == SHIP_STATUS_NOT_ARRIVED ) {
                        Int3();                                                                         // get Allender.  this shouldn't happen!!!
                        return AI_GOAL_NOT_ACHIEVABLE;
                }

                if ( status == SHIP_STATUS_GONE )
                        return AI_GOAL_NOT_ACHIEVABLE;

                SDL_assert( aigp->ship_name );
                shipnum = ship_name_lookup( aigp->ship_name );

                // if desitnation currently being repaired, then goal is stil active
                if ( Ai_info[Ships[shipnum].ai_index].ai_flags & AIF_BEING_REPAIRED )
                        return AI_GOAL_ACHIEVABLE;

                // if the destination ship is dying or departing (but not completed yet), the mark goal as
                // not achievable.
                if ( Ships[shipnum].flags & (SF_DYING | SF_DEPARTING) )
                        return AI_GOAL_NOT_ACHIEVABLE;

                // if the destination object is no longer awaiting repair, then remove the item
                if ( !(Ai_info[Ships[shipnum].ai_index].ai_flags & AIF_AWAITING_REPAIR) )
                        return AI_GOAL_NOT_ACHIEVABLE;

                // not repairing anything means that he can do this goal!!!
                if ( !(aip->ai_flags  & AIF_REPAIRING) )
                        return AI_GOAL_ACHIEVABLE;

                // test code!!!
                if ( aip->goal_objnum == -1 ) {
                        // -- MK, 11/9/97 -- I was always hitting this: Int3();
                        return AI_GOAL_ACHIEVABLE;
                }

                // if he is repairing something, he can satisfy his repair goal (his goal_objnum)
                // return GOAL_NOT_KNOWN which is kind of a hack which puts the goal on hold until it can be
                // satisfied.  
                if ( aip->goal_objnum != Ships[shipnum].objnum )
                        return AI_GOAL_NOT_KNOWN;

                return AI_GOAL_ACHIEVABLE;
        }

        default:
                Int3();                 // invalid case in switch:
        }

        return AI_GOAL_NOT_KNOWN;
}

//      Compare function for system qsort() for sorting ai_goals based on priority.
//      Return values set to sort array in _decreasing_ order.
int ai_goal_priority_compare(const void *a, const void *b)
{
        ai_goal *ga, *gb;

        ga = (ai_goal *) a;
        gb = (ai_goal *) b;

        // first, sort based on whether or not the ON_HOLD flag is set for the goal.
        // If the flag is set, don't push the goal higher in the list even if priority
        // is higher since goal cannot currently be achieved.

        if ( (ga->flags & AIGF_GOAL_ON_HOLD) && !(gb->flags & AIGF_GOAL_ON_HOLD) )
                return 1;
        else if ( !(ga->flags & AIGF_GOAL_ON_HOLD) && (gb->flags & AIGF_GOAL_ON_HOLD) )
                return -1;

        // check whether or not the goal override flag is set.  If it is set, then push this goal higher
        // in the list

        else if ( (ga->flags & AIGF_GOAL_OVERRIDE) && !(gb->flags & AIGF_GOAL_OVERRIDE) )
                return -1;
        else if ( !(ga->flags & AIGF_GOAL_OVERRIDE) && (gb->flags & AIGF_GOAL_OVERRIDE) )
                return 1;

        // now normal priority processing

        if (ga->priority > gb->priority)
                return -1;
        else if ( ga->priority < gb->priority )
                return 1;
        else {
                if ( ga->time > gb->time )
                        return -1;
#ifdef PLAT_UNIX
                else if ( ga->time > gb->time )
                        return 1;
                else
                        return 0;
#else
                else // if ( ga->time < gb->time )                      // this way prevents element swapping if times happen to be equal (which they should not)
                        return 1;
#endif
        }
}

//      Prioritize goal list.
//      First sort on priority.
//      Then sort on time for goals of equivalent priority.
//      objnum  The object number to act upon.  Redundant with *aip.
//      *aip            The AI info to act upon.  Goals are stored at aip->goals
void prioritize_goals(int objnum, ai_info *aip)
{

        //      First sort based on priority field.
        qsort(aip->goals, MAX_AI_GOALS, sizeof(ai_goal), ai_goal_priority_compare);

}

//      Scan the list of goals at aip->goals.
//      Remove obsolete goals.
//      objnum  Object of interest.  Redundant with *aip.
//      *aip            contains goals at aip->goals.
void validate_mission_goals(int objnum, ai_info *aip)
{
        int     i;
        
        // loop through all of the goals to determine which goal should be followed.
        // This determination will be based on priority, and the time at which it was issued.
        for ( i = 0; i < MAX_AI_GOALS; i++ ) {
                int             state;
                ai_goal *aigp;

                aigp = &aip->goals[i];

                // quick check to see if this goal is valid or not, or if we are trying to process the
                // current goal
                if (aigp->ai_mode == AI_GOAL_NONE)
                        continue;

                // purge any goals which should get purged
                if ( aigp->flags & AIGF_PURGE ) {
                        ai_remove_ship_goal( aip, i );
                        continue;
                }

                state = ai_mission_goal_achievable( objnum, aigp );

                // if this order is no longer a valid one, remove it
                if ( (state == AI_GOAL_NOT_ACHIEVABLE) || (state == AI_GOAL_SATISFIED) ) {
                        ai_remove_ship_goal( aip, i );
                        continue;
                }

                // if the status is achievable, and the on_hold flag is set, clear the flagb
                if ( (state == AI_GOAL_ACHIEVABLE) && (aigp->flags & AIGF_GOAL_ON_HOLD) )
                        aigp->flags &= ~AIGF_GOAL_ON_HOLD;

                // if the goal is not known, then set the ON_HOLD flag so that it doesn't get counted as
                // a goal to be pursued
                if ( state == AI_GOAL_NOT_KNOWN )
                        aigp->flags |= AIGF_GOAL_ON_HOLD;               // put this goal on hold until it becomes true
        }

        // if we had an active goal, and that goal is now in hold, make the mode AIM_NONE.  If a new valid
        // goal is produced after prioritizing, then the mode will get reset immediately.  Otherwise, setting
        // the mode to none will force ship to do default behavior.
        if ( (aip->goals[0].ai_mode != AI_GOAL_NONE) && (aip->goals[0].flags & AIGF_GOAL_ON_HOLD) )
                aip->mode = AIM_NONE;

        // if the active goal is a rearm/repair goal, the put all other valid goals (which are not repair goals)
        // on hold
        if ( (aip->goals[0].ai_mode == AI_GOAL_REARM_REPAIR) && (aip->ai_flags & AIF_DOCKED) ) {
                for ( i = 1; i < MAX_AI_GOALS; i++ ) {
                        if ( (aip->goals[i].ai_mode == AI_GOAL_NONE) || (aip->goals[i].ai_mode == AI_GOAL_REARM_REPAIR) )
                                continue;
                        aip->goals[i].flags |= AIGF_GOAL_ON_HOLD;
                }
        }
}

//XSTR:OFF
/* Not used, debugging stuff
static char *Goal_text[5] = {
"EVENT_SHIP",
"EVENT_WING",
"PLAYER_SHIP",
"PLAYER_WING",
"DYNAMIC",
};
*/
//XSTR:ON

extern char *Mode_text[MAX_AI_BEHAVIORS];

// code to process ai "orders".  Orders include those determined from the mission file and those
// given by the player to a ship that is under his control.  This function gets called for every
// AI object every N seconds through the ai loop.
void ai_process_mission_orders( int objnum, ai_info *aip )
{
        object  *objp = &Objects[objnum];
        object  *other_obj;
        ai_goal *current_goal;
        int             wingnum, shipnum;
        int             original_signature;

/*      if (!SDL_strcasecmp(Ships[objp->instance].ship_name, "gtt comet")) {
                for (int i=0; i<MAX_AI_GOALS; i++) {
                        if (aip->goals[i].signature != -1) {
                                nprintf(("AI", "%6.1f: mode=%s, type=%s, ship=%s\n", f2fl(Missiontime), Mode_text[aip->goals[i].ai_mode], Goal_text[aip->goals[i].type], aip->goals[i].ship_name));
                        }
                }
                nprintf(("AI", "\n"));
        }
*/

        // AL 12-12-97: If a ship is entering/leaving a docking bay, wait until path
        //                                       following is finished before pursuing goals.
        if ( aip->mode == AIM_BAY_EMERGE || aip->mode == AIM_BAY_DEPART ) {
                return;
        }

        //      Goal #0 is always the active goal, as we maintain a sorted list.
        //      Get the signature to see if sorting it again changes it.
        original_signature = aip->goals[0].signature;

        validate_mission_goals(objnum, aip);

        //      Sort the goal array by priority and other factors.
        prioritize_goals(objnum, aip);

        //      Make sure there's a goal to pursue, else return.
        if (aip->goals[0].signature == -1) {
                if (aip->mode == AIM_NONE)
                        ai_do_default_behavior(objp);
                return;
        }

        //      If goal didn't change, return.
        if ((aip->active_goal != -1) && (aip->goals[0].signature == original_signature))
                return;

        // if the first goal in the list has the ON_HOLD flag, set, there is no current valid goal
        // to pursue.
        if ( aip->goals[0].flags & AIGF_GOAL_ON_HOLD )
                return;

        //      Kind of a hack for now.  active_goal means the goal currently being pursued.
        //      It will always be #0 since the list is prioritized.
        aip->active_goal = 0;

        //nprintf(("AI", "New goal for %s = %i\n", Ships[objp->instance].ship_name, aip->goals[0].ai_mode));

        current_goal = &aip->goals[0];

        if ( MULTIPLAYER_MASTER ){
                send_ai_info_update_packet( objp, AI_UPDATE_ORDERS );
        }

        // if this object was flying in formation off of another object, remove the flag that tells him
        // to do this.  The form-on-my-wing command is removed from the goal list as soon as it is called, so
        // we are safe removing this bit here.
        aip->ai_flags &= ~AIF_FORMATION_OBJECT;

        // AL 3-7-98: If this is a player ship, and the goal is not a formation goal, then do a quick out
        if ( (objp->flags & OF_PLAYER_SHIP) && (current_goal->ai_mode != AI_GOAL_FORM_ON_WING) ) {
                return;
        }       

        switch ( current_goal->ai_mode ) {

        case AI_GOAL_CHASE:
                if ( current_goal->ship_name ) {
                        shipnum = ship_name_lookup( current_goal->ship_name );
                        SDL_assert (shipnum != -1 );                    // shouldn't get here if this is false!!!!
                        other_obj = &Objects[Ships[shipnum].objnum];
                } else
                        other_obj = NULL;                                               // we get this case when we tell ship to engage enemy!

                //      Mike -- debug code!
                //      If a ship has a subobject on it, attack that instead of the main ship!
                ai_attack_object( objp, other_obj, current_goal->priority, NULL);
                break;

        case AI_GOAL_CHASE_WEAPON:
                SDL_assert( Weapons[current_goal->wp_index].objnum != -1 );
                other_obj = &Objects[Weapons[current_goal->wp_index].objnum];
                ai_attack_object( objp, other_obj, current_goal->priority, NULL );
                break;

        case AI_GOAL_GUARD:
                shipnum = ship_name_lookup( current_goal->ship_name );
                SDL_assert (shipnum != -1 );                    // shouldn't get here if this is false!!!!
                other_obj = &Objects[Ships[shipnum].objnum];
                // shipnum and other_obj are the shipnumber and object pointer of the object that you should
                // guard.
                if (objp != other_obj) {
                        ai_set_guard_object(objp, other_obj);
                        aip->submode_start_time = Missiontime;
                } else {
                        mprintf(("Warning: Ship %s told to guard itself.  Goal ignored.\n", Ships[objp->instance].ship_name));
                }
                // -- What the hell is this doing here?? -- MK, 7/30/97 -- ai_do_default_behavior( objp );
                break;

        case AI_GOAL_GUARD_WING:
                wingnum = wing_name_lookup( current_goal->ship_name );
                SDL_assert (wingnum != -1 );                    // shouldn't get here if this is false!!!!
                ai_set_guard_wing(objp, wingnum);
                aip->submode_start_time = Missiontime;
                break;

        case AI_GOAL_WAYPOINTS:                         // do nothing for waypoints
        case AI_GOAL_WAYPOINTS_ONCE: {
                int flags = 0;

                if ( current_goal->ai_mode == AI_GOAL_WAYPOINTS)
                        flags |= WPF_REPEAT;
                ai_start_waypoints(objp, current_goal->wp_index, flags);
                break;
        }

        case AI_GOAL_DOCK: {
                shipnum = ship_name_lookup( current_goal->ship_name );
                SDL_assert (shipnum != -1 );                    // shouldn't get here if this is false!!!!
                other_obj = &Objects[Ships[shipnum].objnum];

                // be sure that we have indices for docking points here!  If we ever had names, they should
                // get fixed up in goal_achievable so that the points can be checked there for validity
                SDL_assert ( !(current_goal->flags & AIGF_DOCKER_NAME_VALID) );
                SDL_assert ( !(current_goal->flags & AIGF_DOCKEE_NAME_VALID) );
                ai_dock_with_object( objp, other_obj, current_goal->priority, AIDO_DOCK, current_goal->docker.index, current_goal->dockee.index );
                aip->submode_start_time = Missiontime;
                break;
        }

        case AI_GOAL_UNDOCK:
                // try to find the object which which this object is docked with.  Use that object as the
                // "other object" for the undocking proceedure.  If "other object" isn't found, then the undock
                // goal cannot continue.  Spit out a warning and remove the goal.
                other_obj = ai_find_docked_object( objp );
                if ( other_obj == NULL ) {
                        //Int3();
                        // assume that the guy he was docked with doesn't exist anymore.  (i.e. a cargo containuer
                        // can get destroyed while docked with a freighter.)  We should just remove this goal and
                        // let this ship pick up it's next goal.
                        ai_mission_goal_complete( aip );                // mark as complete, so we can remove it and move on!!!
                        break;
                }
                ai_dock_with_object( objp, other_obj, current_goal->priority, AIDO_UNDOCK, 0, 0 );
                aip->submode_start_time = Missiontime;
                break;


                // when destroying a subsystem, we can destroy a specific instance of a subsystem
                // or all instances of a type of subsystem (i.e. a specific engine or all engines).
                // the ai_submode value is > 0 for a specific instance of subsystem and < 0 for all
                // instances of a specific type
        case AI_GOAL_DESTROY_SUBSYSTEM:
        case AI_GOAL_DISABLE_SHIP:
        case AI_GOAL_DISARM_SHIP: {
                shipnum = ship_name_lookup( current_goal->ship_name );
                other_obj = &Objects[Ships[shipnum].objnum];
                ai_attack_object( objp, other_obj, current_goal->priority, NULL);
                ai_set_attack_subsystem( objp, current_goal->ai_submode );              // submode stored the subsystem type
                if (current_goal->ai_mode != AI_GOAL_DESTROY_SUBSYSTEM) {
                        if (aip->target_objnum != -1) {
                                //      Only protect if _not_ a capital ship.  We don't want the Lucifer accidentally getting protected.
                                if (!(Ship_info[Ships[shipnum].ship_info_index].flags & SIF_HUGE_SHIP))
                                        Objects[aip->target_objnum].flags |= OF_PROTECTED;
                        }
                } else  //      Just in case this ship had been protected, unprotect it.
                        if (aip->target_objnum != -1)
                                Objects[aip->target_objnum].flags &= ~OF_PROTECTED;

                break;
                                                                          }

        case AI_GOAL_CHASE_WING:
                wingnum = wing_name_lookup( current_goal->ship_name );
                ai_attack_wing(objp, wingnum, current_goal->priority);
                break;

        case AI_GOAL_CHASE_ANY:
                ai_attack_object( objp, NULL, current_goal->priority, NULL );
                break;

        case AI_GOAL_WARP: {
                ai_set_mode_warp_out( objp, aip );
                break;
        }

        case AI_GOAL_EVADE_SHIP:
                shipnum = ship_name_lookup( current_goal->ship_name );
                other_obj = &Objects[Ships[shipnum].objnum];
                ai_evade_object( objp, other_obj, current_goal->priority );
                break;

        case AI_GOAL_STAY_STILL:
                // for now, ignore any other parameters!!!!
                // clear out the object's goals.  Seems to me that if a ship is staying still for a purpose
                // then we need to clear everything out since there is not a real way to get rid of this goal
                // clearing out goals is okay here since we are now what mode to set this AI object to.
                ai_clear_ship_goals( aip );
                ai_stay_still( objp, NULL );
                break;

        case AI_GOAL_PLAY_DEAD:
                // if a ship is playing dead, MWA says that it shouldn't try to do anything else.
                // clearing out goals is okay here since we are now what mode to set this AI object to.
                ai_clear_ship_goals( aip );
                aip->mode = AIM_PLAY_DEAD;
                aip->submode = -1;
                break;

        case AI_GOAL_FORM_ON_WING:
                // for form on wing, we need to clear out all goals for this ship, and then call the form
                // on wing AI code
                // clearing out goals is okay here since we are now what mode to set this AI object to.
                ai_clear_ship_goals( aip );
                shipnum = ship_name_lookup( current_goal->ship_name );
                other_obj = &Objects[Ships[shipnum].objnum];
                ai_form_on_wing( objp, other_obj );
                break;

// labels for support ship commands

        case AI_GOAL_STAY_NEAR_SHIP: {
                shipnum = ship_name_lookup( current_goal->ship_name );
                other_obj = &Objects[Ships[shipnum].objnum];
                // todo MK:  hook to keep support ship near other_obj -- other_obj could be the player object!!!
                float   dist = 300.0f;          //      How far away to stay from ship.  Should be set in SEXP?
                ai_do_stay_near(objp, other_obj, dist);
                break;
                                                                                  }

        case AI_GOAL_KEEP_SAFE_DISTANCE:
                // todo MK: hook to keep support ship at a safe distance
                break;

        case AI_GOAL_REARM_REPAIR:
                shipnum = ship_name_lookup( current_goal->ship_name );
                other_obj = &Objects[Ships[shipnum].objnum];
                ai_rearm_repair( objp, other_obj, current_goal->priority, current_goal->docker.index, current_goal->dockee.index );
                break;

        default:
                Int3();
                break;
        }

}

void ai_update_goal_references(ai_goal *goals, int type, const char *old_name, char *new_name)
{
        int i, mode, flag, dummy;

        for (i=0; i<MAX_AI_GOALS; i++)  // loop through all the goals in the Ai_info entry
        {
                mode = goals[i].ai_mode;
                flag = 0;
                switch (type)
                {
                        case REF_TYPE_SHIP:
                        case REF_TYPE_PLAYER:
                                switch (mode)
                                {
                                        case AI_GOAL_CHASE:
                                        case AI_GOAL_DOCK:
                                        case AI_GOAL_DESTROY_SUBSYSTEM:
                                        case AI_GOAL_GUARD:
                                        case AI_GOAL_DISABLE_SHIP:
                                        case AI_GOAL_DISARM_SHIP:
                                        case AI_GOAL_IGNORE:
                                        case AI_GOAL_EVADE_SHIP:
                                        case AI_GOAL_STAY_NEAR_SHIP:
                                                flag = 1;
                                }
                                break;

                        case REF_TYPE_WING:
                                switch (mode)
                                {
                                        case AI_GOAL_CHASE_WING:
                                        case AI_GOAL_GUARD_WING:
                                                flag = 1;
                                }
                                break;

                        case REF_TYPE_WAYPOINT:
                                switch (mode)
                                {
                                        case AI_GOAL_WAYPOINTS:
                                        case AI_GOAL_WAYPOINTS_ONCE:
                                                flag = 1;
                                }
                                break;

                        case REF_TYPE_PATH:
                                switch (mode)
                                {
                                        case AI_GOAL_WAYPOINTS:
                                        case AI_GOAL_WAYPOINTS_ONCE:
                                        
                                                flag = 1;
                                }
                                break;
                }

                if (flag)  // is this a valid goal to parse for this conversion?
                        if (!SDL_strcasecmp(goals[i].ship_name, old_name)) {
                                if (*new_name == '<')  // target was just deleted..
                                        goals[i].ai_mode = AI_GOAL_NONE;
                                else
                                        goals[i].ship_name = ai_get_goal_ship_name(new_name, &dummy);
                        }
        }
}

int query_referenced_in_ai_goals(ai_goal *goals, int type, const char *name)
{
        int i, mode, flag;

        for (i=0; i<MAX_AI_GOALS; i++)  // loop through all the goals in the Ai_info entry
        {
                mode = goals[i].ai_mode;
                flag = 0;
                switch (type)
                {
                        case REF_TYPE_SHIP:
                                switch (mode)
                                {
                                        case AI_GOAL_CHASE:
                                        case AI_GOAL_DOCK:
                                        case AI_GOAL_DESTROY_SUBSYSTEM:
                                        case AI_GOAL_GUARD:
                                        case AI_GOAL_DISABLE_SHIP:
                                        case AI_GOAL_DISARM_SHIP:
                                        case AI_GOAL_IGNORE:
                                        case AI_GOAL_EVADE_SHIP:
                                        case AI_GOAL_STAY_NEAR_SHIP:
                                                flag = 1;
                                }
                                break;

                        case REF_TYPE_WING:
                                switch (mode)
                                {
                                        case AI_GOAL_CHASE_WING:
                                        case AI_GOAL_GUARD_WING:
                                                flag = 1;
                                }
                                break;

                        case REF_TYPE_WAYPOINT:
                                switch (mode)
                                {
                                        case AI_GOAL_WAYPOINTS:
                                        case AI_GOAL_WAYPOINTS_ONCE:
                                                flag = 1;
                                }
                                break;

                        case REF_TYPE_PATH:
                                switch (mode)
                                {
                                        case AI_GOAL_WAYPOINTS:
                                        case AI_GOAL_WAYPOINTS_ONCE:
                                                flag = 1;
                                }
                                break;
                }

                if (flag)  // is this a valid goal to parse for this conversion?
                {
                        if (!SDL_strcasecmp(goals[i].ship_name, name))
                                return 1;
                }
        }

        return 0;
}

char *ai_add_dock_name(const char *str)
{
        char *ptr;
        int i;

        SDL_assert(strlen(str) < NAME_LENGTH - 1);
        for (i=0; i<Num_ai_dock_names; i++)
                if (!SDL_strcasecmp(Ai_dock_names[i], str))
                        return Ai_dock_names[i];

        SDL_assert(Num_ai_dock_names < MAX_AI_DOCK_NAMES);
        ptr = Ai_dock_names[Num_ai_dock_names++];
        SDL_strlcpy(ptr, str, NAME_LENGTH);
        return ptr;
}