/*
 * Copyright (C) 1996-1997 Id Software, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */
// world.c -- world query functions

#include "quakedef.h"

/*
 *
 * entities never clip against themselves, or their owner line of sight checks
 * trace->crosscontent, but bullets don't
 *
 */

typedef struct {
    vec3_t        boxmins, boxmaxs;    // enclose the test object along entire move
    float        *mins, *maxs;         // size of the moving object
    vec3_t        mins2, maxs2;        // size when clipping against mosnters
    float        *start, *end;
    trace_t       trace;
    int           type;
    edict_t      *passedict;
} moveclip_t;

/*
 *
 *
 * HULL BOXES
 *
 *
 */

static hull_t box_hull;
static dclipnode_t box_clipnodes[6];
static mplane_t box_planes[6];

/*
 * SV_InitBoxHull
 *
 * Set up the planes and clipnodes so that the six floats of a bounding box can
 * just be stored out and get a proper hull_t structure.
 */
void SV_InitBoxHull (void) {
    int           i, side;

    box_hull.clipnodes = box_clipnodes;
    box_hull.planes = box_planes;
    box_hull.firstclipnode = 0;
    box_hull.lastclipnode = 5;

    for (i = 0; i < 6; i++) {
        box_clipnodes[i].planenum = i;

        side = i & 1;

        box_clipnodes[i].children[side] = CONTENTS_EMPTY;
        if (i != 5)
            box_clipnodes[i].children[side ^ 1] = i + 1;
        else
            box_clipnodes[i].children[side ^ 1] = CONTENTS_SOLID;

        box_planes[i].type = i >> 1;
        box_planes[i].normal[i >> 1] = 1;
    }
}

/*
 * SV_HullForBox
 *
 * To keep everything totally uniform, bounding boxes are turned into small BSP
 * trees instead of being compared directly.
 */
hull_t       *SV_HullForBox (vec3_t mins, vec3_t maxs) {
    box_planes[0].dist = maxs[0];
    box_planes[1].dist = mins[0];
    box_planes[2].dist = maxs[1];
    box_planes[3].dist = mins[1];
    box_planes[4].dist = maxs[2];
    box_planes[5].dist = mins[2];

    return &box_hull;
}

/*
 * SV_HullForEntity
 *
 * Returns a hull that can be used for testing or clipping an object of
 * mins/maxs size. Offset is filled in to contain the adjustment that must be
 * added to the testing object's origin to get a point to use with the returned
 * hull.
 */
hull_t       *SV_HullForEntity (edict_t * ent, vec3_t mins, vec3_t maxs, vec3_t offset) {
    model_t      *model;
    vec3_t        size, hullmins, hullmaxs;
    hull_t       *hull;

    // decide which clipping hull to use, based on the size
    if (ent->v.solid == SOLID_BSP) {   // explicit hulls in the BSP model
        if (ent->v.movetype != MOVETYPE_PUSH)
            Host_Error ("SOLID_BSP without MOVETYPE_PUSH");

        model = sv.models[(int) ent->v.modelindex];

        if (!model || model->type != mod_brush)
            Host_Error ("SOLID_BSP with a non-bsp model");

        VectorSubtract (maxs, mins, size);
        if (size[0] < 3)
            hull = &model->hulls[0];
        else if (size[0] <= 32)
            hull = &model->hulls[1];
        else
            hull = &model->hulls[2];

        // calculate an offset value to center the origin
        VectorSubtract (hull->clip_mins, mins, offset);
        VectorAdd (offset, ent->v.origin, offset);
    } else {                           // create a temp hull from bounding box sizes
        VectorSubtract (ent->v.mins, maxs, hullmins);
        VectorSubtract (ent->v.maxs, mins, hullmaxs);
        hull = SV_HullForBox (hullmins, hullmaxs);

        VectorCopy (ent->v.origin, offset);
    }

    return hull;
}

/*
 *
 *
 * ENTITY AREA CHECKING
 *
 *
 */

typedef struct areanode_s {
    int           axis;                // -1 = leaf node
    float         dist;
    struct areanode_s *children[2];
    link_t        trigger_edicts;
    link_t        solid_edicts;
} areanode_t;

#define	AREA_DEPTH	4
#define	AREA_NODES	32

static areanode_t sv_areanodes[AREA_NODES];
static int    sv_numareanodes;

/*
 * SV_CreateAreaNode
 */
areanode_t   *SV_CreateAreaNode (int depth, vec3_t mins, vec3_t maxs) {
    areanode_t   *anode;
    vec3_t        size, mins1, maxs1, mins2, maxs2;

    anode = &sv_areanodes[sv_numareanodes];
    sv_numareanodes++;

    ClearLink (&anode->trigger_edicts);
    ClearLink (&anode->solid_edicts);

    if (depth == AREA_DEPTH) {
        anode->axis = -1;
        anode->children[0] = anode->children[1] = NULL;
        return anode;
    }

    VectorSubtract (maxs, mins, size);
    anode->axis = (size[0] > size[1]) ? 0 : 1;

    anode->dist = 0.5 * (maxs[anode->axis] + mins[anode->axis]);
    VectorCopy (mins, mins1);
    VectorCopy (mins, mins2);
    VectorCopy (maxs, maxs1);
    VectorCopy (maxs, maxs2);

    maxs1[anode->axis] = mins2[anode->axis] = anode->dist;

    anode->children[0] = SV_CreateAreaNode (depth + 1, mins2, maxs2);
    anode->children[1] = SV_CreateAreaNode (depth + 1, mins1, maxs1);

    return anode;
}

/*
 * SV_ClearWorld
 */
void SV_ClearWorld (void) {
    SV_InitBoxHull ();

    memset (sv_areanodes, 0, sizeof (sv_areanodes));
    sv_numareanodes = 0;
    SV_CreateAreaNode (0, sv.worldmodel->mins, sv.worldmodel->maxs);
}

/*
 * SV_UnlinkEdict
 */
void SV_UnlinkEdict (edict_t * ent) {
    if (!ent->area.prev)
        return;                        // not linked in anywhere

    RemoveLink (&ent->area);
    ent->area.prev = ent->area.next = NULL;
}

/*
 * SV_TouchLinks
 */
void SV_TouchLinks (edict_t * ent, areanode_t * node) {
    link_t       *l, *next;
    edict_t      *touch;
    int           old_self, old_other;

    // touch linked edicts
    for (l = node->trigger_edicts.next; l != &node->trigger_edicts; l = next) {
        // e2m2 bug fix
        if (!l)
            Host_Error ("NULL area link");

        next = l->next;
        touch = EDICT_FROM_AREA (l);
        if (touch == ent)
            continue;

        if (!touch->v.touch || touch->v.solid != SOLID_TRIGGER)
            continue;

        if (ent->v.absmin[0] > touch->v.absmax[0] || ent->v.absmin[1] > touch->v.absmax[1]
            || ent->v.absmin[2] > touch->v.absmax[2] || ent->v.absmax[0] < touch->v.absmin[0]
            || ent->v.absmax[1] < touch->v.absmin[1] || ent->v.absmax[2] < touch->v.absmin[2])
            continue;

        old_self = pr_global_struct->self;
        old_other = pr_global_struct->other;

        pr_global_struct->self = EDICT_TO_PROG (touch);
        pr_global_struct->other = EDICT_TO_PROG (ent);
        pr_global_struct->time = sv.time;
        PR_ExecuteProgram (touch->v.touch);

        pr_global_struct->self = old_self;
        pr_global_struct->other = old_other;
    }

    // recurse down both sides
    if (node->axis == -1)
        return;

    if (ent->v.absmax[node->axis] > node->dist)
        SV_TouchLinks (ent, node->children[0]);
    if (ent->v.absmin[node->axis] < node->dist)
        SV_TouchLinks (ent, node->children[1]);
}

/*
 * SV_FindTouchedLeafs
 */
void SV_FindTouchedLeafs (edict_t * ent, mnode_t * node) {
    mplane_t     *splitplane;
    mleaf_t      *leaf;
    int           sides, leafnum;

    if (node->contents == CONTENTS_SOLID)
        return;

    // add an efrag if the node is a leaf
    if (node->contents < 0) {
        if (ent->num_leafs == MAX_ENT_LEAFS)
            return;

        leaf = (mleaf_t *) node;
        leafnum = leaf - sv.worldmodel->leafs - 1;

        ent->leafnums[ent->num_leafs] = leafnum;
        ent->num_leafs++;
        return;
    }
    // NODE_MIXED

    splitplane = node->plane;
    sides = BOX_ON_PLANE_SIDE (ent->v.absmin, ent->v.absmax, splitplane);

    // recurse down the contacted sides
    if (sides & 1)
        SV_FindTouchedLeafs (ent, node->children[0]);

    if (sides & 2)
        SV_FindTouchedLeafs (ent, node->children[1]);
}

/*
 * SV_LinkEdict
 */
void SV_LinkEdict (edict_t * ent, qboolean touch_triggers) {
    areanode_t   *node;

    if (ent->area.prev)
        SV_UnlinkEdict (ent);          // unlink from old position

    if (ent == sv.edicts)
        return;                        // don't add the world

    if (ent->free)
        return;

    // set the abs box
    VectorAdd (ent->v.origin, ent->v.mins, ent->v.absmin);
    VectorAdd (ent->v.origin, ent->v.maxs, ent->v.absmax);

    // to make items easier to pick up and allow them to be grabbed off of shelves, the abs sizes are expanded
    if ((int) ent->v.flags & FL_ITEM) {
        ent->v.absmin[0] -= 15;
        ent->v.absmin[1] -= 15;
        ent->v.absmax[0] += 15;
        ent->v.absmax[1] += 15;
    } else {                           // because movement is clipped an epsilon away from an actual edge,
        // we must fully check even when bounding boxes don't quite touch
        ent->v.absmin[0] -= 1;
        ent->v.absmin[1] -= 1;
        ent->v.absmin[2] -= 1;
        ent->v.absmax[0] += 1;
        ent->v.absmax[1] += 1;
        ent->v.absmax[2] += 1;
    }

    // link to PVS leafs
    ent->num_leafs = 0;
    if (ent->v.modelindex)
        SV_FindTouchedLeafs (ent, sv.worldmodel->nodes);

    if (ent->v.solid == SOLID_NOT)
        return;

    // find the first node that the ent's box crosses
    node = sv_areanodes;
    while (1) {
        if (node->axis == -1)
            break;

        if (ent->v.absmin[node->axis] > node->dist)
            node = node->children[0];
        else if (ent->v.absmax[node->axis] < node->dist)
            node = node->children[1];
        else
            break;                     // crosses the node
    }

    // link it in
    if (ent->v.solid == SOLID_TRIGGER)
        InsertLinkBefore (&ent->area, &node->trigger_edicts);
    else
        InsertLinkBefore (&ent->area, &node->solid_edicts);

    // if touch_triggers, touch all entities at this node and decend for more
    if (touch_triggers)
        SV_TouchLinks (ent, sv_areanodes);
}

/*
 *
 *
 * POINT TESTING IN HULLS
 *
 *
 */

/*
 * SV_HullPointContents
 */
int SV_HullPointContents (hull_t * hull, int num, vec3_t p) {
    float         d;
    dclipnode_t  *node;
    mplane_t     *plane;

    while (num >= 0) {
        if (num < hull->firstclipnode || num > hull->lastclipnode)
            Sys_Error ("SV_HullPointContents: bad node number");

        node = hull->clipnodes + num;
        plane = hull->planes + node->planenum;

        d = PlaneDiff (p, plane);
        num = (d < 0) ? node->children[1] : node->children[0];
    }

    return num;
}

/*
 * SV_PointContents
 */
int SV_PointContents (vec3_t p) {
    return SV_HullPointContents (&sv.worldmodel->hulls[0], 0, p);
}

// 

/*
 * SV_TestEntityPosition
 *
 * This could be a lot more efficient...
 */
edict_t      *SV_TestEntityPosition (edict_t * ent) {
    trace_t       trace;

    trace = SV_Move (ent->v.origin, ent->v.mins, ent->v.maxs, ent->v.origin, 0, ent);

    if (trace.startsolid)
        return sv.edicts;

    return NULL;
}

/*
 *
 *
 * LINE TESTING IN HULLS
 *
 *
 */

// 1/32 epsilon to keep floating point happy
#define	DIST_EPSILON	(0.03125)

/*
 * SV_RecursiveHullCheck
 */
qboolean SV_RecursiveHullCheck (hull_t * hull, int num, float p1f, float p2f, vec3_t p1, vec3_t p2, trace_t * trace) {
    int           i, side;
    float         t1, t2, frac, midf;
    vec3_t        mid;
    dclipnode_t  *node;
    mplane_t     *plane;

    // check for empty
    if (num < 0) {
        if (num != CONTENTS_SOLID) {
            trace->allsolid = false;
            if (num == CONTENTS_EMPTY)
                trace->inopen = true;
            else
                trace->inwater = true;
        } else {
            trace->startsolid = true;
        }
        return true;                   // empty
    }

    if (num < hull->firstclipnode || num > hull->lastclipnode)
        Sys_Error ("SV_RecursiveHullCheck: bad node number");

    // find the point distances
    node = hull->clipnodes + num;
    plane = hull->planes + node->planenum;

    if (plane->type < 3) {
        t1 = p1[plane->type] - plane->dist;
        t2 = p2[plane->type] - plane->dist;
    } else {
        t1 = DotProduct (plane->normal, p1) - plane->dist;
        t2 = DotProduct (plane->normal, p2) - plane->dist;
    }

    if (t1 >= 0 && t2 >= 0)
        return SV_RecursiveHullCheck (hull, node->children[0], p1f, p2f, p1, p2, trace);
    if (t1 < 0 && t2 < 0)
        return SV_RecursiveHullCheck (hull, node->children[1], p1f, p2f, p1, p2, trace);

    // put the crosspoint DIST_EPSILON pixels on the near side
    if (t1 < 0)
        frac = (t1 + DIST_EPSILON) / (t1 - t2);
    else
        frac = (t1 - DIST_EPSILON) / (t1 - t2);
    frac = bound (0, frac, 1);

    midf = p1f + (p2f - p1f) * frac;
    for (i = 0; i < 3; i++)
        mid[i] = p1[i] + frac * (p2[i] - p1[i]);

    side = (t1 < 0);

    // move up to the node
    if (!SV_RecursiveHullCheck (hull, node->children[side], p1f, midf, p1, mid, trace))
        return false;

#ifdef __PARANOID__BUGBUGBUG
    if (SV_HullPointContents (hull, mid, node->children[side]) == CONTENTS_SOLID) {
        Con_Printf ("mid PointInHullSolid\n");
        return false;
    }
#endif

    if (SV_HullPointContents (hull, node->children[side ^ 1], mid) != CONTENTS_SOLID)   // go past the node
        return SV_RecursiveHullCheck (hull, node->children[side ^ 1], midf, p2f, mid, p2, trace);

    if (trace->allsolid)
        return false;                  // never got out of the solid area

    // the other side of the node is solid, this is the impact point
    if (!side) {
        VectorCopy (plane->normal, trace->plane.normal);
        trace->plane.dist = plane->dist;
    } else {
        VectorNegate (plane->normal, trace->plane.normal);
        trace->plane.dist = -plane->dist;
    }

    while (SV_HullPointContents (hull, hull->firstclipnode, mid) == CONTENTS_SOLID) {   // shouldn't really happen, but does occasionally
        frac -= 0.1;
        if (frac < 0) {
            trace->fraction = midf;
            VectorCopy (mid, trace->endpos);
            Con_DPrintf ("backup past 0\n");
            return false;
        }
        midf = p1f + (p2f - p1f) * frac;
        for (i = 0; i < 3; i++)
            mid[i] = p1[i] + frac * (p2[i] - p1[i]);
    }

    trace->fraction = midf;
    VectorCopy (mid, trace->endpos);

    return false;
}

/*
 * SV_ClipMoveToEntity
 *
 * Handles selection or creation of a clipping hull, and offseting (and
 * eventually rotation) of the end points
 */
trace_t SV_ClipMoveToEntity (edict_t * ent, vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end) {
    trace_t       trace;
    vec3_t        offset, start_l, end_l;
    hull_t       *hull;

    // fill in a default trace
    memset (&trace, 0, sizeof (trace_t));
    trace.fraction = 1;
    trace.allsolid = true;
    VectorCopy (end, trace.endpos);

    // get the clipping hull
    hull = SV_HullForEntity (ent, mins, maxs, offset);

    VectorSubtract (start, offset, start_l);
    VectorSubtract (end, offset, end_l);

    // trace a line through the apropriate clipping hull
    SV_RecursiveHullCheck (hull, hull->firstclipnode, 0, 1, start_l, end_l, &trace);

    // fix trace up by the offset
    if (trace.fraction != 1)
        VectorAdd (trace.endpos, offset, trace.endpos);

    // did we clip the move?
    if (trace.fraction < 1 || trace.startsolid)
        trace.ent = ent;

    return trace;
}

// 

/*
 * SV_ClipToLinks
 *
 * Mins and maxs enclose the entire area swept by the move
 */
void SV_ClipToLinks (areanode_t * node, moveclip_t * clip) {
    link_t       *l, *next;
    edict_t      *touch;
    trace_t       trace;

    // touch linked edicts
    for (l = node->solid_edicts.next; l != &node->solid_edicts; l = next) {
        next = l->next;
        touch = EDICT_FROM_AREA (l);
        if (touch->v.solid == SOLID_NOT)
            continue;
        if (touch == clip->passedict)
            continue;
        if (touch->v.solid == SOLID_TRIGGER)
            Sys_Error ("Trigger in clipping list");

        if (clip->type == MOVE_NOMONSTERS && touch->v.solid != SOLID_BSP)
            continue;

        if (clip->boxmins[0] > touch->v.absmax[0] || clip->boxmins[1] > touch->v.absmax[1]
            || clip->boxmins[2] > touch->v.absmax[2] || clip->boxmaxs[0] < touch->v.absmin[0]
            || clip->boxmaxs[1] < touch->v.absmin[1] || clip->boxmaxs[2] < touch->v.absmin[2])
            continue;

        if (clip->passedict && clip->passedict->v.size[0] && !touch->v.size[0])
            continue;                  // points never interact

        // might intersect, so do an exact clip
        if (clip->trace.allsolid)
            return;
        if (clip->passedict) {
            if (PROG_TO_EDICT (touch->v.owner) == clip->passedict)
                continue;              // don't clip against own missiles
            if (PROG_TO_EDICT (clip->passedict->v.owner) == touch)
                continue;              // don't clip against owner
        }

        if ((int) touch->v.flags & FL_MONSTER)
            trace = SV_ClipMoveToEntity (touch, clip->start, clip->mins2, clip->maxs2, clip->end);
        else
            trace = SV_ClipMoveToEntity (touch, clip->start, clip->mins, clip->maxs, clip->end);
        if (trace.allsolid || trace.startsolid || trace.fraction < clip->trace.fraction) {
            trace.ent = touch;
            if (clip->trace.startsolid) {
                clip->trace = trace;
                clip->trace.startsolid = true;
            } else
                clip->trace = trace;
        } else if (trace.startsolid)
            clip->trace.startsolid = true;
    }

    // recurse down both sides
    if (node->axis == -1)
        return;

    if (clip->boxmaxs[node->axis] > node->dist)
        SV_ClipToLinks (node->children[0], clip);
    if (clip->boxmins[node->axis] < node->dist)
        SV_ClipToLinks (node->children[1], clip);
}

/*
 * SV_MoveBounds
 */
void SV_MoveBounds (vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end, vec3_t boxmins, vec3_t boxmaxs) {
#if 0
    // debug to test against everything
    boxmins[0] = boxmins[1] = boxmins[2] = -9999;
    boxmaxs[0] = boxmaxs[1] = boxmaxs[2] = 9999;
#else
    int           i;

    for (i = 0; i < 3; i++) {
        if (end[i] > start[i]) {
            boxmins[i] = start[i] + mins[i] - 1;
            boxmaxs[i] = end[i] + maxs[i] + 1;
        } else {
            boxmins[i] = end[i] + mins[i] - 1;
            boxmaxs[i] = start[i] + maxs[i] + 1;
        }
    }
#endif
}

/*
 * SV_Move
 */
trace_t SV_Move (vec3_t start, vec3_t mins, vec3_t maxs, vec3_t end, int type, edict_t * passedict) {
    moveclip_t    clip;
    int           i;

    memset (&clip, 0, sizeof (moveclip_t));

    // clip to world
    clip.trace = SV_ClipMoveToEntity (sv.edicts, start, mins, maxs, end);

    clip.start = start;
    clip.end = end;
    clip.mins = mins;
    clip.maxs = maxs;
    clip.type = type;
    clip.passedict = passedict;

    if (type == MOVE_MISSILE) {
        for (i = 0; i < 3; i++) {
            clip.mins2[i] = -15;
            clip.maxs2[i] = 15;
        }
    } else {
        VectorCopy (mins, clip.mins2);
        VectorCopy (maxs, clip.maxs2);
    }

    // create the bounding box of the entire move
    SV_MoveBounds (start, clip.mins2, clip.maxs2, end, clip.boxmins, clip.boxmaxs);

    // clip to entities
    SV_ClipToLinks (sv_areanodes, &clip);

    return clip.trace;
}
