/*
    Copyright (C) 1996-1997  Id Software, Inc.
    Copyright (C) 1997       Greg Lewis

    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

    See file, 'COPYING', for details.
*/

#include "qbsp.hh"

static hashvert_t *pHashverts;
static int needlmshifts;

/*
===============
SubdivideFace

If the face is >256 in either texture direction, carve a valid sized
piece off and insert the remainder in the next link
===============
*/
void
SubdivideFace(face_t *f, face_t **prevptr)
{
    vec_t mins, maxs;
    vec_t v;
    int axis, i;
    plane_t plane;
    face_t *front, *back, *next;
    const mtexinfo_t *tex;
    vec3_t tmp;
    vec_t subdiv;
    vec_t extent;
    int lmshift;

    /* special (non-surface cached) faces don't need subdivision */
    tex = &map.mtexinfos.at(f->texinfo);
    if (tex->flags & (TEX_SPECIAL | TEX_SKIP | TEX_HINT))
        return;

//subdivision is pretty much pointless other than because of lightmap block limits
//one lightmap block will always be added at the end, for smooth interpolation

    //engines that do support scaling will support 256*256 blocks (at whatever scale).
    lmshift = f->lmshift[0];
    if (lmshift > 4)
        lmshift = 4;    //no bugging out with legacy lighting
    subdiv = 255<<lmshift;

//legacy engines support 18*18 max blocks (at 1:16 scale).
//the 18*18 limit can be relaxed in certain engines, and doing so will generally give a performance boost.
    if (subdiv >= options.dxSubdivide)
        subdiv = options.dxSubdivide;

//      subdiv += 8;

//floating point precision from clipping means we should err on the low side
//the bsp is possibly going to be used in both engines that support scaling and those that do not. this means we always over-estimate by 16 rathern than 1<<lmscale

    for (axis = 0; axis < 2; axis++) {
        while (1) {
            mins = VECT_MAX;
            maxs = -VECT_MAX;

            tmp[0] = tex->vecs[axis][0];
            tmp[1] = tex->vecs[axis][1];
            tmp[2] = tex->vecs[axis][2];

            for (i = 0; i < f->w.numpoints; i++) {
                v = DotProduct(f->w.points[i], tmp);
                if (v < mins)
                    mins = v;
                if (v > maxs)
                    maxs = v;
            }

            extent = ceil(maxs) - floor(mins);
//          extent = maxs - mins;
            if (extent <= subdiv)
                break;

            // split it
            VectorCopy(tmp, plane.normal);
            v = VectorLength(plane.normal);
            VectorNormalize(plane.normal);
            if (subdiv > extent/2)      /* if we're near a boundary, just split the difference, this should balance the load slightly */
                plane.dist = (mins + subdiv/2) / v;
            else
                plane.dist = (mins + subdiv) / v;
            next = f->next;
            SplitFace(f, &plane, &front, &back);
            if (!front || !back)
            {
                printf("didn't split\n");
                break;
//              Error("Didn't split the polygon (%s)", __func__);
            }
            *prevptr = back;
            back->next = front;
            front->next = next;
            f = back;
        }
    }
}


/*
=============================================================================
GatherNodeFaces

Frees the current node tree and returns a new chain of the surfaces that
have inside faces.
=============================================================================
*/

static void
GatherNodeFaces_r(node_t *node, std::map<int, face_t *> &planefaces)
{
    face_t *f, *next;

    if (node->planenum != PLANENUM_LEAF) {
        // decision node
        for (f = node->faces; f; f = next) {
            next = f->next;
            if (!f->w.numpoints) {      // face was removed outside
                FreeMem(f, FACE, 1);
            } else {
                f->next = planefaces[f->planenum];
                planefaces[f->planenum] = f;
            }
        }
        GatherNodeFaces_r(node->children[0], planefaces);
        GatherNodeFaces_r(node->children[1], planefaces);
    }
    FreeMem(node, NODE, 1);
}

/*
================
GatherNodeFaces
================
*/
surface_t *
GatherNodeFaces(node_t *headnode)
{
    surface_t *surfaces;

    std::map<int, face_t *> planefaces;
    GatherNodeFaces_r(headnode, planefaces);
    surfaces = BuildSurfaces(planefaces);

    return surfaces;
}

//===========================================================================

static hashvert_t *hvert_p;

// This is a kludge.   Should be pEdgeFaces[2].
static const face_t **pEdgeFaces0;
static const face_t **pEdgeFaces1;
static int cStartEdge;

//============================================================================

#define NUM_HASH        4096

static hashvert_t *hashverts[NUM_HASH];
static vec3_t hash_min, hash_scale;

typedef struct hashedge_s {
    unsigned i;
    struct hashedge_s *next;
} hashedge_t;

static hashedge_t *hashedges[NUM_HASH];

static void
InitHash(void)
{
    vec3_t size;
    vec_t volume;
    vec_t scale;
    int newsize[2];
    int i;

    memset(hashverts, 0, sizeof(hashverts));

    for (i = 0; i < 3; i++) {
        hash_min[i] = -8000;
        size[i] = 16000;
    }

    volume = size[0] * size[1];

    scale = sqrt(volume / NUM_HASH);

    newsize[0] = size[0] / scale;
    newsize[1] = size[1] / scale;

    hash_scale[0] = newsize[0] / size[0];
    hash_scale[1] = newsize[1] / size[1];
    hash_scale[2] = (vec_t)newsize[1];

    hvert_p = pHashverts;
    
    /* edges hash table */
    for (i=0; i<NUM_HASH; i++) {
        hashedge_t *he;
        for (he = hashedges[i]; he; )
        {
            hashedge_t *to_free = he;
            he = he->next;
            FreeMem(to_free, OTHER, sizeof(hashedge_t));
        }
    }
    memset(hashedges, 0, sizeof(hashedges));
}

static unsigned
HashEdge(unsigned v1, unsigned v2)
{
    return (v1 + v2) % NUM_HASH;
}

static void
AddHashEdge(unsigned v1, unsigned v2, unsigned i)
{
    hashedge_t *he = (hashedge_t *)AllocMem(OTHER, sizeof(hashedge_t), true);
    unsigned slot = HashEdge(v1, v2);
    
    he->i = i;
    he->next = hashedges[slot];
    hashedges[slot] = he;
}

static unsigned
HashVec(vec3_t vec)
{
    unsigned h;

    h = (unsigned)(hash_scale[0] * (vec[0] - hash_min[0]) * hash_scale[2] +
                   hash_scale[1] * (vec[1] - hash_min[1]));
    if (h >= NUM_HASH)
        return NUM_HASH - 1;
    return h;
}


/*
=============
GetVertex
=============
*/
static int
GetVertex(mapentity_t *entity, const vec3_t in)
{
    int h;
    int i;
    hashvert_t *hv;
    vec3_t vert;
    struct lumpdata *vertices = &entity->lumps[LUMP_VERTEXES];
    dvertex_t *dvertex;

    for (i = 0; i < 3; i++) {
        if (fabs(in[i] - Q_rint(in[i])) < ZERO_EPSILON)
            vert[i] = Q_rint(in[i]);
        else
            vert[i] = in[i];
    }

    h = HashVec(vert);
    for (hv = hashverts[h]; hv; hv = hv->next) {
        if (fabs(hv->point[0] - vert[0]) < POINT_EPSILON &&
            fabs(hv->point[1] - vert[1]) < POINT_EPSILON &&
            fabs(hv->point[2] - vert[2]) < POINT_EPSILON) {
            hv->numedges++;
            return hv->num;
        }
    }

    hv = hvert_p++;
    hv->num = map.cTotal[LUMP_VERTEXES]++;
    hv->numedges = 1;
    hv->next = hashverts[h];
    hashverts[h] = hv;
    VectorCopy(vert, hv->point);

    if (vertices->index == vertices->count)
        Error("Internal error: didn't allocate enough vertices?");

    /* emit a vertex */
    dvertex = (dvertex_t *)vertices->data + vertices->index;
    dvertex->point[0] = vert[0];
    dvertex->point[1] = vert[1];
    dvertex->point[2] = vert[2];
    vertices->index++;

    return hv->num;
}

//===========================================================================

/*
==================
GetEdge

Don't allow four way edges
==================
*/
static int
GetEdge(mapentity_t *entity, const vec3_t p1, const vec3_t p2,
        const face_t *face)
{
    struct lumpdata *edges = &entity->lumps[LUMP_EDGES];
    int v1, v2;
    int i;
    unsigned edge_hash_key;
    hashedge_t *he;

    if (!face->contents[0])
        Error("Face with 0 contents (%s)", __func__);

    v1 = GetVertex(entity, p1);
    v2 = GetVertex(entity, p2);

    edge_hash_key = HashEdge(v1, v2);

    if (options.BSPVersion == BSPVERSION) {
        bsp29_dedge_t *edge;

        for (he = hashedges[edge_hash_key]; he; he = he->next) {
            i = he->i;
            edge = (bsp29_dedge_t *)edges->data + i;
            if (v1 == edge->v[1] && v2 == edge->v[0]
                && pEdgeFaces1[i] == NULL
                && pEdgeFaces0[i]->contents[0] == face->contents[0]) {
                pEdgeFaces1[i] = face;
                return -(i + cStartEdge);
            }
        }

        /* emit an edge */
        i = edges->index;
        edge = (bsp29_dedge_t *)edges->data + i;
        if (edges->index >= edges->count)
            Error("Internal error: didn't allocate enough edges?");
        edge->v[0] = v1;
        edge->v[1] = v2;
    } else {
        bsp2_dedge_t *edge = (bsp2_dedge_t *)edges->data;

        for (he = hashedges[edge_hash_key]; he; he = he->next) {
            i = he->i;
            edge = (bsp2_dedge_t *)edges->data + i;
            if (v1 == edge->v[1] && v2 == edge->v[0]
                && pEdgeFaces1[i] == NULL
                && pEdgeFaces0[i]->contents[0] == face->contents[0]) {
                pEdgeFaces1[i] = face;
                return -(i + cStartEdge);
            }
        }

        /* emit an edge */
        i = edges->index;
        edge = (bsp2_dedge_t *)edges->data + i;
        if (edges->index >= edges->count)
            Error("Internal error: didn't allocate enough edges?");
        edge->v[0] = v1;
        edge->v[1] = v2;
    }

    AddHashEdge(v1, v2, edges->index);

    edges->index++;
    map.cTotal[LUMP_EDGES]++;
    pEdgeFaces0[i] = face;
    return i + cStartEdge;
}


/*
==================
FindFaceEdges
==================
*/
static void
FindFaceEdges(mapentity_t *entity, face_t *face)
{
    int i, memsize;

    face->outputnumber = -1;
    if (face->w.numpoints > MAXEDGES)
        Error("Internal error: face->numpoints > MAXEDGES (%s)", __func__);

    memsize = face->w.numpoints * sizeof(face->edges[0]);
    face->edges = (int *)AllocMem(OTHER, memsize, true);
    for (i = 0; i < face->w.numpoints; i++) {
        const vec_t *p1 = face->w.points[i];
        const vec_t *p2 = face->w.points[(i + 1) % face->w.numpoints];
        face->edges[i] = GetEdge(entity, p1, p2, face);
    }
}


/*
================
MakeFaceEdges_r
================
*/
static int
MakeFaceEdges_r(mapentity_t *entity, node_t *node, int progress)
{
    face_t *f;

    if (node->planenum == PLANENUM_LEAF)
        return progress;

    for (f = node->faces; f; f = f->next) {
        if (map.mtexinfos.at(f->texinfo).flags & (TEX_SKIP | TEX_HINT))
            continue;
        FindFaceEdges(entity, f);
    }

    Message(msgPercent, ++progress, splitnodes);
    progress = MakeFaceEdges_r(entity, node->children[0], progress);
    progress = MakeFaceEdges_r(entity, node->children[1], progress);

    return progress;
}

/*
==============
GrowNodeRegion
==============
*/
static void
GrowNodeRegion_BSP29(mapentity_t *entity, node_t *node)
{
    struct lumpdata *surfedges = &entity->lumps[LUMP_SURFEDGES];
    struct lumpdata *faces = &entity->lumps[LUMP_FACES];
    struct lumpdata *lmshifts = &entity->lumps[BSPX_LMSHIFT];
    bsp29_dface_t *out;
    face_t *face;
    int i;

    if (node->planenum == PLANENUM_LEAF)
        return;

    node->firstface = map.cTotal[LUMP_FACES];

    for (face = node->faces; face; face = face->next) {
        if (map.mtexinfos.at(face->texinfo).flags & (TEX_SKIP | TEX_HINT))
            continue;

        // emit a region
        face->outputnumber = map.cTotal[LUMP_FACES];
        if (lmshifts->data)
            ((unsigned char*)lmshifts->data)[faces->index] = face->lmshift[1];
        out = (bsp29_dface_t *)faces->data + faces->index;
        out->planenum = node->outputplanenum;
        out->side = face->planeside;
        out->texinfo = face->texinfo;
        for (i = 0; i < MAXLIGHTMAPS; i++)
            out->styles[i] = 255;
        out->lightofs = -1;

        out->firstedge = map.cTotal[LUMP_SURFEDGES];
        for (i = 0; i < face->w.numpoints; i++) {
            ((int *)surfedges->data)[surfedges->index] = face->edges[i];
            surfedges->index++;
            map.cTotal[LUMP_SURFEDGES]++;
        }
        FreeMem(face->edges, OTHER, face->w.numpoints * sizeof(int));

        out->numedges = map.cTotal[LUMP_SURFEDGES] - out->firstedge;

        map.cTotal[LUMP_FACES]++;
        faces->index++;
    }

    node->numfaces = map.cTotal[LUMP_FACES] - node->firstface;

    GrowNodeRegion_BSP29(entity, node->children[0]);
    GrowNodeRegion_BSP29(entity, node->children[1]);
}

static void
GrowNodeRegion_BSP2(mapentity_t *entity, node_t *node)
{
    struct lumpdata *surfedges = &entity->lumps[LUMP_SURFEDGES];
    struct lumpdata *faces = &entity->lumps[LUMP_FACES];
    struct lumpdata *lmshifts = &entity->lumps[BSPX_LMSHIFT];
    bsp2_dface_t *out;
    face_t *face;
    int i;

    if (node->planenum == PLANENUM_LEAF)
        return;

    node->firstface = map.cTotal[LUMP_FACES];

    for (face = node->faces; face; face = face->next) {
        if (map.mtexinfos.at(face->texinfo).flags & (TEX_SKIP | TEX_HINT))
            continue;

        // emit a region
        face->outputnumber = map.cTotal[LUMP_FACES];
        if (lmshifts->data)
            ((unsigned char*)lmshifts->data)[faces->index] = face->lmshift[1];
        out = (bsp2_dface_t *)faces->data + faces->index;
        out->planenum = node->outputplanenum;
        out->side = face->planeside;
        out->texinfo = face->texinfo;
        for (i = 0; i < MAXLIGHTMAPS; i++)
            out->styles[i] = 255;
        out->lightofs = -1;

        out->firstedge = map.cTotal[LUMP_SURFEDGES];
        for (i = 0; i < face->w.numpoints; i++) {
            ((int *)surfedges->data)[surfedges->index] = face->edges[i];
            surfedges->index++;
            map.cTotal[LUMP_SURFEDGES]++;
        }
        FreeMem(face->edges, OTHER, face->w.numpoints * sizeof(int));

        out->numedges = map.cTotal[LUMP_SURFEDGES] - out->firstedge;

        map.cTotal[LUMP_FACES]++;
        faces->index++;
    }

    node->numfaces = map.cTotal[LUMP_FACES] - node->firstface;

    GrowNodeRegion_BSP2(entity, node->children[0]);
    GrowNodeRegion_BSP2(entity, node->children[1]);
}

/*
==============
CountData_r
==============
*/
static void
CountData_r(mapentity_t *entity, node_t *node)
{
    face_t *f;

    if (node->planenum == PLANENUM_LEAF)
        return;

    for (f = node->faces; f; f = f->next) {
        if (map.mtexinfos.at(f->texinfo).flags & (TEX_SKIP | TEX_HINT))
            continue;

        if (f->lmshift[1] != 4)
                needlmshifts = true;
        entity->lumps[LUMP_FACES].count++;
        entity->lumps[LUMP_VERTEXES].count += f->w.numpoints;
    }

    CountData_r(entity, node->children[0]);
    CountData_r(entity, node->children[1]);
}


/*
================
MakeFaceEdges
================
*/
int
MakeFaceEdges(mapentity_t *entity, node_t *headnode)
{
    int i, firstface;
    struct lumpdata *surfedges = &entity->lumps[LUMP_SURFEDGES];
    struct lumpdata *edges = &entity->lumps[LUMP_EDGES];
    struct lumpdata *vertices = &entity->lumps[LUMP_VERTEXES];
    struct lumpdata *faces = &entity->lumps[LUMP_FACES];
    struct lumpdata *lmshifts = &entity->lumps[BSPX_LMSHIFT];

    Message(msgProgress, "MakeFaceEdges");

    needlmshifts = false;
    cStartEdge = 0;
    const int entnum = entity - &map.entities.at(0);
    for (i = 0; i < entnum; i++)
        cStartEdge += map.entities.at(i).lumps[LUMP_EDGES].count;

    CountData_r(entity, headnode);

    /*
     * Remember edges are +1 in BeginBSPFile.  Often less than half
     * the vertices actually are unique, although heavy use of skip
     * faces will break that assumption.  2/3 should be safe most of
     * the time without wasting too much memory...
     */
    surfedges->count = vertices->count;
    edges->count += surfedges->count;

    vertices->data = AllocMem(BSP_VERTEX, vertices->count, true);
    edges->data = AllocMem(BSP_EDGE, edges->count, true);

    // Accessory data
    pHashverts = (hashvert_t *)AllocMem(HASHVERT, vertices->count, true);
    pEdgeFaces0 = (const face_t **)AllocMem(OTHER, sizeof(face_t *) * edges->count, true);
    pEdgeFaces1 = (const face_t **)AllocMem(OTHER, sizeof(face_t *) * edges->count, true);

    InitHash();

    firstface = map.cTotal[LUMP_FACES];
    MakeFaceEdges_r(entity, headnode, 0);

    FreeMem(pHashverts, HASHVERT, vertices->count);
    FreeMem(pEdgeFaces0, OTHER, sizeof(face_t *) * edges->count);
    FreeMem(pEdgeFaces1, OTHER, sizeof(face_t *) * edges->count);

    /* Free any excess allocated memory */
    if (vertices->index < vertices->count) {
        dvertex_t *temp = (dvertex_t *)AllocMem(BSP_VERTEX, vertices->index, true);
        memcpy(temp, vertices->data, sizeof(*temp) * vertices->index);
        FreeMem(vertices->data, BSP_VERTEX, vertices->count);
        vertices->data = temp;
        vertices->count = vertices->index;
    }
    if (edges->index < edges->count) {
        void *temp = AllocMem(BSP_EDGE, edges->index, true);
        memcpy(temp, edges->data, MemSize[BSP_EDGE] * edges->index);
        FreeMem(edges->data, BSP_EDGE, edges->count);
        edges->data = temp;
        edges->count = edges->index;
    }

    if (map.cTotal[LUMP_VERTEXES] > 65535 && options.BSPVersion == BSPVERSION)
        Error("Too many vertices (%d > 65535). Recompile with the \"-bsp2\" flag to lift this restriction.", map.cTotal[LUMP_VERTEXES]);

    surfedges->data = AllocMem(BSP_SURFEDGE, surfedges->count, true);
    faces->data = AllocMem(BSP_FACE, faces->count, true);

    lmshifts->count = needlmshifts?faces->count:0;
    lmshifts->data = needlmshifts?AllocMem(OTHER, sizeof(byte) * lmshifts->count, true):NULL;

    Message(msgProgress, "GrowRegions");

    if (options.BSPVersion == BSPVERSION)
        GrowNodeRegion_BSP29(entity, headnode);
    else
        GrowNodeRegion_BSP2(entity, headnode);

    return firstface;
}