/*
    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/qbsp.hh>
#include <map>
#include <list>

/*
===============
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;
    qbsp_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);
            
            // ericw -- reverted this, was causing https://github.com/ericwa/ericw-tools/issues/160
//            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;
            plane.dist = (mins + subdiv - 16) / 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;
}

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

// This is a kludge.   Should be pEdgeFaces[2].
static std::map<int, const face_t *> pEdgeFaces0;
static std::map<int, const face_t *> pEdgeFaces1;

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

using vertidx_t = int;
using edgeidx_t = int;
static std::map<std::pair<vertidx_t, vertidx_t>, std::list<edgeidx_t>> hashedges;
static std::map<std::tuple<int,int,int>, std::list<hashvert_t>> hashverts;

static void
InitHash(void)
{
    pEdgeFaces0.clear();
    pEdgeFaces1.clear();
    hashverts.clear();
    hashedges.clear();
}

static void
AddHashEdge(int v1, int v2, int i)
{
    hashedges[std::make_pair(v1, v2)].push_front(i);
}

static std::tuple<int,int,int>
HashVec(const vec3_t vec)
{
    return std::make_tuple(static_cast<int>(floor(vec[0])),
                           static_cast<int>(floor(vec[1])),
                           static_cast<int>(floor(vec[2])));
}

static void
AddHashVert(const vec3_t vert, const int global_vert_num)
{
    hashvert_t hv;
    VectorCopy(vert, hv.point);
    hv.num = global_vert_num;
    
    // insert each vert at floor(pos[axis]) and floor(pos[axis]) + 1 (for each axis)
    // so e.g. a vert at (0.99, 0.99, 0.99) shows up if we search at (1.01, 1.01, 1.01)
    // this is a bit wasteful, since it inserts 8 copies of each vert.
    
    for (int x=0; x<=1; x++) {
        for (int y=0; y<=1; y++) {
            for (int z=0; z<=1; z++) {
                const auto h = std::make_tuple(static_cast<int>(floor(vert[0])) + x,
                                               static_cast<int>(floor(vert[1])) + y,
                                               static_cast<int>(floor(vert[2])) + z);
                hashverts[h].push_front(hv);
            }
        }
    }
}

/*
=============
GetVertex
=============
*/
static int
GetVertex(mapentity_t *entity, const vec3_t in)
{
    int i;
    vec3_t vert;
    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];
    }

    const auto h = HashVec(vert);
    auto it = hashverts.find(h);
    if (it != hashverts.end()) {
        for (hashvert_t &hv : it->second) {
            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) {

                return hv.num;
            }
        }
    }

    const int global_vert_num = static_cast<int>(map.exported_vertexes.size());

    AddHashVert(vert, global_vert_num);
    
    /* emit a vertex */
    map.exported_vertexes.push_back({});
    dvertex = &map.exported_vertexes.at(global_vert_num);
    dvertex->point[0] = vert[0];
    dvertex->point[1] = vert[1];
    dvertex->point[2] = vert[2];

    return global_vert_num;
}

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

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

Don't allow four way edges (FIXME: What is this?)
 
Returns a global edge number, possibly negative to indicate a backwards edge.
==================
*/
static int
GetEdge(mapentity_t *entity, const vec3_t p1, const vec3_t p2,
        const face_t *face)
{
    int v1, v2;
    int i;

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

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

    // search for an existing edge from v2->v1
    const std::pair<int,int> edge_hash_key = std::make_pair(v2, v1);

    {
        bsp29_dedge_t *edge;

        auto it = hashedges.find(edge_hash_key);
        if (it != hashedges.end()) {
            for (const int i : it->second) {
                edge = &map.exported_edges.at(i);
                if (pEdgeFaces1[i] == NULL
                    && pEdgeFaces0[i]->contents[0] == face->contents[0]) {
                    pEdgeFaces1[i] = face;
                    return -i;
                }
            }
        }

        /* emit an edge */
        i = static_cast<int>(map.exported_edges.size());
        map.exported_edges.push_back({});
        edge = &map.exported_edges.at(i);
        edge->v[0] = v1;
        edge->v[1] = v2;
    }

    AddHashEdge(v1, v2, i);

    pEdgeFaces0[i] = face;
    return i;
}


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

    if (map.mtexinfos.at(face->texinfo).flags & (TEX_SKIP | TEX_HINT))
        return;
    
    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) {
        FindFaceEdges(entity, f);
    }

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

    return progress;
}

/*
==============
EmitFace
==============
*/
static void
EmitFace(mapentity_t *entity, face_t *face)
{
    bsp29_dface_t *out;
    int i;

    if (map.mtexinfos.at(face->texinfo).flags & (TEX_SKIP | TEX_HINT))
        return;
    
    // emit a region
    Q_assert(face->outputnumber == -1);
    face->outputnumber = static_cast<int>(map.exported_faces.size());
    map.exported_faces.push_back({});

    // emit lmshift
    map.exported_lmshifts.push_back(face->lmshift[1]);
    Q_assert(map.exported_faces.size() == map.exported_lmshifts.size());
    
    out = &map.exported_faces.at(face->outputnumber);
    out->planenum = ExportMapPlane(face->planenum);
    out->side = face->planeside;
    out->texinfo = ExportMapTexinfo(face->texinfo);
    for (i = 0; i < MAXLIGHTMAPS; i++)
        out->styles[i] = 255;
    out->lightofs = -1;
    
    // emit surfedges
    out->firstedge = static_cast<int>(map.exported_surfedges.size());
    for (i = 0; i < face->w.numpoints; i++) {
        map.exported_surfedges.push_back(face->edges[i]);
    }
    FreeMem(face->edges, OTHER, face->w.numpoints * sizeof(int));
    
    out->numedges = static_cast<int>(map.exported_surfedges.size()) - out->firstedge;
}

/*
==============
GrowNodeRegion
==============
*/
static void
GrowNodeRegion(mapentity_t *entity, node_t *node)
{
    if (node->planenum == PLANENUM_LEAF)
        return;

    node->firstface = static_cast<int>(map.exported_faces.size());

    for (face_t *face = node->faces; face; face = face->next) {
        Q_assert(face->planenum == node->planenum);
        
        // emit a region
        EmitFace(entity, face);
    }

    node->numfaces = static_cast<int>(map.exported_faces.size()) - node->firstface;

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

static void
CountFace(mapentity_t *entity, face_t *f, int *facesCount, int *vertexesCount)
{
    if (map.mtexinfos.at(f->texinfo).flags & (TEX_SKIP | TEX_HINT))
        return;
    
    if (f->lmshift[1] != 4)
        map.needslmshifts = true;

    (*facesCount)++;
    (*vertexesCount) += f->w.numpoints;
}

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

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

    for (f = node->faces; f; f = f->next) {
        CountFace(entity, f, facesCount, vertexesCount);
    }

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

/*
================
MakeFaceEdges
================
*/
int
MakeFaceEdges(mapentity_t *entity, node_t *headnode)
{
    int i, firstface;

    Message(msgProgress, "MakeFaceEdges");

    Q_assert(entity->firstoutputfacenumber == -1);
    entity->firstoutputfacenumber = static_cast<int>(map.exported_faces.size());

    int facesCount = 0;
    int vertexesCount = 0;
    CountData_r(entity, headnode, &facesCount, &vertexesCount);

    // Accessory data
    InitHash();

    firstface = static_cast<int>(map.exported_faces.size());
    MakeFaceEdges_r(entity, headnode, 0);

    pEdgeFaces0.clear();
    pEdgeFaces1.clear();

    Message(msgProgress, "GrowRegions");
    GrowNodeRegion(entity, headnode);
    
    return firstface;
}