#include "bsp5.h"

typedef struct wvert_s
{
    vec_t           t;
    struct wvert_s* prev;
    struct wvert_s* next;
}
wvert_t;

typedef struct wedge_s
{
    struct wedge_s* next;
    vec3_t          dir;
    vec3_t          origin;
    wvert_t         head;
}
wedge_t;

static int      numwedges;
static int      numwverts;
static int      tjuncs;
static int      tjuncfaces;

#define MAX_WVERTS   0x40000
#define MAX_WEDGES   0x20000

static wvert_t  wverts[MAX_WVERTS];
static wedge_t  wedges[MAX_WEDGES];

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

#define	NUM_HASH	1024

wedge_t*        wedge_hash[NUM_HASH];

static vec3_t   hash_min;
static vec3_t   hash_scale;

static void     InitHash(const vec3_t mins, const vec3_t maxs)
{
    vec3_t          size;
    vec_t           volume;
    vec_t           scale;
    int             newsize[2];

    VectorCopy(mins, hash_min);
    VectorSubtract(maxs, mins, size);
    memset(wedge_hash, 0, sizeof(wedge_hash));

    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] = newsize[1];
}

static unsigned HashVec(const vec3_t vec)
{
    unsigned        h;

    h = 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;
}

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

static bool     CanonicalVector(vec3_t vec)
{
    if (VectorNormalize(vec))
    {
        if (vec[0] > NORMAL_EPSILON )
        {
            return true;
        }
        else if (vec[0] < -NORMAL_EPSILON )
        {
            VectorSubtract(vec3_origin, vec, vec);
            return true;
        }
        else
        {
            vec[0] = 0;
        }
    
        if (vec[1] > NORMAL_EPSILON )
        {
            return true;
        }
        else if (vec[1] < -NORMAL_EPSILON )
        {
            VectorSubtract(vec3_origin, vec, vec);
            return true;
        }
        else
        {
            vec[1] = 0;
        }

        if (vec[2] > NORMAL_EPSILON )
        {
            return true;
        }
        else if (vec[2] < -NORMAL_EPSILON )
        {
            VectorSubtract(vec3_origin, vec, vec);
            return true;
        }
        else
        {
            vec[2] = 0;
        }
//        hlassert(false);
        return false;
    }
//    hlassert(false);
    return false;
}

static wedge_t *FindEdge(const vec3_t p1, const vec3_t p2, vec_t* t1, vec_t* t2)
{
    vec3_t          origin;
    vec3_t          dir;
    wedge_t*        w;
    vec_t           temp;
    int             h;

    VectorSubtract(p2, p1, dir);
    if (!CanonicalVector(dir))
    {
#if _DEBUG
        Warning("CanonicalVector: degenerate @ (%4.3f %4.3f %4.3f )\n", p1[0], p1[1], p1[2]);
#endif
    }

    *t1 = DotProduct(p1, dir);
    *t2 = DotProduct(p2, dir);

    VectorMA(p1, -*t1, dir, origin);

    if (*t1 > *t2)
    {
        temp = *t1;
        *t1 = *t2;
        *t2 = temp;
    }

    h = HashVec(origin);

    for (w = wedge_hash[h]; w; w = w->next)
    {
        temp = w->origin[0] - origin[0];
        if (temp < -EQUAL_EPSILON || temp > EQUAL_EPSILON)
        {
            continue;
        }
        temp = w->origin[1] - origin[1];
        if (temp < -EQUAL_EPSILON || temp > EQUAL_EPSILON)
        {
            continue;
        }
        temp = w->origin[2] - origin[2];
        if (temp < -EQUAL_EPSILON || temp > EQUAL_EPSILON)
        {
            continue;
        }

        temp = w->dir[0] - dir[0];
        if (temp < -EQUAL_EPSILON || temp > EQUAL_EPSILON)
        {
            continue;
        }
        temp = w->dir[1] - dir[1];
        if (temp < -EQUAL_EPSILON || temp > EQUAL_EPSILON)
        {
            continue;
        }
        temp = w->dir[2] - dir[2];
        if (temp < -EQUAL_EPSILON || temp > EQUAL_EPSILON)
        {
            continue;
        }

        return w;
    }

    hlassume(numwedges < MAX_WEDGES, assume_MAX_WEDGES);
    w = &wedges[numwedges];
    numwedges++;

    w->next = wedge_hash[h];
    wedge_hash[h] = w;

    VectorCopy(origin, w->origin);
    VectorCopy(dir, w->dir);
    w->head.next = w->head.prev = &w->head;
    w->head.t = 99999;
    return w;
}

/*
 * ===============
 * AddVert
 * 
 * ===============
 */
#define T_EPSILON	ON_EPSILON

static void     AddVert(const wedge_t* const w, const vec_t t)
{
    wvert_t*        v;
    wvert_t*        newv;

    v = w->head.next;
    do
    {
        if (fabs(v->t - t) < T_EPSILON)
        {
            return;
        }
        if (v->t > t)
        {
            break;
        }
        v = v->next;
    }
    while (1);

    // insert a new wvert before v
    hlassume(numwverts < MAX_WVERTS, assume_MAX_WVERTS);

    newv = &wverts[numwverts];
    numwverts++;

    newv->t = t;
    newv->next = v;
    newv->prev = v->prev;
    v->prev->next = newv;
    v->prev = newv;
}

/*
 * ===============
 * AddEdge
 * ===============
 */
static void     AddEdge(const vec3_t p1, const vec3_t p2)
{
    wedge_t*        w;
    vec_t           t1;
    vec_t           t2;

    w = FindEdge(p1, p2, &t1, &t2);
    AddVert(w, t1);
    AddVert(w, t2);
}

/*
 * ===============
 * AddFaceEdges
 * 
 * ===============
 */
static void     AddFaceEdges(const face_t* const f)
{
    int             i, j;

    for (i = 0; i < f->numpoints; i++)
    {
        j = (i + 1) % f->numpoints;
        AddEdge(f->pts[i], f->pts[j]);
    }
}

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

static byte     superfacebuf[1024 * 16];
static face_t*  superface = (face_t*)superfacebuf;
static int      MAX_SUPERFACEEDGES = (sizeof(superfacebuf) - sizeof(face_t) + sizeof(superface->pts)) / sizeof(vec3_t);
static face_t*  newlist;

static void     SplitFaceForTjunc(face_t* f, face_t* original)
{
    int             i;
    face_t*         newface;
    face_t*         chain;
    vec3_t          dir, test;
    vec_t           v;
    int             firstcorner, lastcorner;

#ifdef _DEBUG
    static int      counter = 0;

    Log("SplitFaceForTjunc %d\n", counter++);
#endif

    chain = NULL;
    do
    {
        hlassume(f->original == NULL, assume_ValidPointer);     // "SplitFaceForTjunc: f->original"

        if (f->numpoints <= MAXPOINTS)
        {                                                  // the face is now small enough without more cutting
            // so copy it back to the original
            *original = *f;
            original->original = chain;
            original->next = newlist;
            newlist = original;
            return;
        }

        tjuncfaces++;

restart:
        // find the last corner 
        VectorSubtract(f->pts[f->numpoints - 1], f->pts[0], dir);
        VectorNormalize(dir);
        for (lastcorner = f->numpoints - 1; lastcorner > 0; lastcorner--)
        {
            VectorSubtract(f->pts[lastcorner - 1], f->pts[lastcorner], test);
            VectorNormalize(test);
            v = DotProduct(test, dir);
            if (v < 1.0 - ON_EPSILON || v > 1.0 + ON_EPSILON)
            {
                break;
            }
        }

        // find the first corner        
        VectorSubtract(f->pts[1], f->pts[0], dir);
        VectorNormalize(dir);
        for (firstcorner = 1; firstcorner < f->numpoints - 1; firstcorner++)
        {
            VectorSubtract(f->pts[firstcorner + 1], f->pts[firstcorner], test);
            VectorNormalize(test);
            v = DotProduct(test, dir);
            if (v < 1.0 - ON_EPSILON || v > 1.0 + ON_EPSILON)
            {
                break;
            }
        }

        if (firstcorner + 2 >= MAXPOINTS)
        {
            // rotate the point winding
            VectorCopy(f->pts[0], test);
            for (i = 1; i < f->numpoints; i++)
            {
                VectorCopy(f->pts[i], f->pts[i - 1]);
            }
            VectorCopy(test, f->pts[f->numpoints - 1]);
            goto restart;
        }

        // cut off as big a piece as possible, less than MAXPOINTS, and not
        // past lastcorner

        newface = NewFaceFromFace(f);

        hlassume(f->original == NULL, assume_ValidPointer);     // "SplitFaceForTjunc: f->original"

        newface->original = chain;
        chain = newface;
        newface->next = newlist;
        newlist = newface;
        if (f->numpoints - firstcorner <= MAXPOINTS)
        {
            newface->numpoints = firstcorner + 2;
        }
        else if (lastcorner + 2 < MAXPOINTS && f->numpoints - lastcorner <= MAXPOINTS)
        {
            newface->numpoints = lastcorner + 2;
        }
        else
        {
            newface->numpoints = MAXPOINTS;
        }

        for (i = 0; i < newface->numpoints; i++)
        {
            VectorCopy(f->pts[i], newface->pts[i]);
        }

        for (i = newface->numpoints - 1; i < f->numpoints; i++)
        {
            VectorCopy(f->pts[i], f->pts[i - (newface->numpoints - 2)]);
        }
        f->numpoints -= (newface->numpoints - 2);
    }
    while (1);

}

/*
 * ===============
 * FixFaceEdges
 * 
 * ===============
 */
static void     FixFaceEdges(face_t* f)
{
    int             i;
    int             j;
    int             k;
    wedge_t*        w;
    wvert_t*        v;
    vec_t           t1;
    vec_t           t2;

    *superface = *f;

restart:
    for (i = 0; i < superface->numpoints; i++)
    {
        j = (i + 1) % superface->numpoints;

        w = FindEdge(superface->pts[i], superface->pts[j], &t1, &t2);

        for (v = w->head.next; v->t < t1 + T_EPSILON; v = v->next)
        {
        }

        if (v->t < t2 - T_EPSILON)
        {
            tjuncs++;
            // insert a new vertex here
            for (k = superface->numpoints; k > j; k--)
            {
                VectorCopy(superface->pts[k - 1], superface->pts[k]);
            }
            VectorMA(w->origin, v->t, w->dir, superface->pts[j]);
            superface->numpoints++;
            hlassume(superface->numpoints < MAX_SUPERFACEEDGES, assume_MAX_SUPERFACEEDGES);
            goto restart;
        }
    }

    if (superface->numpoints <= MAXPOINTS)
    {
        *f = *superface;
        f->next = newlist;
        newlist = f;
        return;
    }

    // the face needs to be split into multiple faces because of too many edges

    SplitFaceForTjunc(superface, f);

}

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

static void     tjunc_find_r(node_t* node)
{
    face_t*         f;

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

    for (f = node->faces; f; f = f->next)
    {
        AddFaceEdges(f);
    }

    tjunc_find_r(node->children[0]);
    tjunc_find_r(node->children[1]);
}

static void     tjunc_fix_r(node_t* node)
{
    face_t*         f;
    face_t*         next;

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

    newlist = NULL;

    for (f = node->faces; f; f = next)
    {
        next = f->next;
        FixFaceEdges(f);
    }

    node->faces = newlist;

    tjunc_fix_r(node->children[0]);
    tjunc_fix_r(node->children[1]);
}

/*
 * ===========
 * tjunc
 * 
 * ===========
 */
void            tjunc(node_t* headnode)
{
    vec3_t          maxs, mins;
    int             i;

    Verbose("---- tjunc ----\n");

    if (g_notjunc)
    {
        return;
    }

    //
    // identify all points on common edges
    //

    // origin points won't allways be inside the map, so extend the hash area 
    for (i = 0; i < 3; i++)
    {
        if (fabs(headnode->maxs[i]) > fabs(headnode->mins[i]))
        {
            maxs[i] = fabs(headnode->maxs[i]);
        }
        else
        {
            maxs[i] = fabs(headnode->mins[i]);
        }
    }
    VectorSubtract(vec3_origin, maxs, mins);

    InitHash(mins, maxs);

    numwedges = numwverts = 0;

    tjunc_find_r(headnode);

    Verbose("%i world edges  %i edge points\n", numwedges, numwverts);

    //
    // add extra vertexes on edges where needed
    //
    tjuncs = tjuncfaces = 0;

    tjunc_fix_r(headnode);

    Verbose("%i edges added by tjunctions\n", tjuncs);
    Verbose("%i faces added by tjunctions\n", tjuncfaces);
}