/*
 *   Sweet is a small library for basic math and small matrix operations.
 *   Copyright 2014 Luc Girod.
 *
 * This library is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation, either
 * version 3 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <math.h>
#include "sweet_types.h"
#include "sweet_math.h"

/* Definition of chain list for faces */

struct face_item
{
    unsigned int v[3];
    struct face_item * next;
    struct face_item * prev;
};

static struct face_item *
face_add (struct face_item * root, unsigned int v1, unsigned int v2, unsigned int v3)
{
    struct face_item * n = malloc (sizeof (struct face_item));
    if (n == NULL) { return root; }
    n->next = root;
    n->prev = NULL;
    n->v[0] = v1;
    n->v[1] = v2;
    n->v[2] = v3;

    if (root != NULL) { root->prev = n; }
    return n;
}

static struct face_item *
face_rm (struct face_item * root, struct face_item * f)
{
    struct face_item * next;
    struct face_item * prev;

    if (f == NULL) { return root; }

    next = f->next;
    prev = f->prev;
    f->next = NULL;
    f->prev = NULL;

    /* If it's not at one "edge" */
    if (next != NULL && prev != NULL)
    {
        prev->next = next;
        next->prev = prev;
    } /* if f is at the end */
    else if (prev != NULL)
    {
        prev->next = NULL;

    } /* if f is at the start */
    else if (next != NULL)
    {
        next->prev = NULL;
        return next;
    }
    else
    {
        return NULL;
    }
    return root;
}

static void
face_free (struct face_item * root)
{
    while (root != NULL)
    {
        struct face_item * item = root;
        root = root->next;
        free (item);
    }
}


/* Definition of map */

struct item
{
    struct item * next;
    unsigned int a;
    unsigned int b;
    unsigned int id;
};

#define MAP_SIZE    8192
struct map
{
    struct item * items[MAP_SIZE];
    unsigned int count_item;
};

static void
map_init (struct map * map)
{
    int i;
    for (i = 0; i < MAP_SIZE; i++)
    {
        map->items[i] = NULL;
    }
    map->count_item = 0;
}

static void
map_free (struct map * map)
{
    int i;
    for (i = 0; i < MAP_SIZE; i++)
    {
        struct item * item = map->items[i];
        while (item != NULL)
        {
            struct item * tmp = item;
            item = item->next;
            free (tmp);
        }
        map->items[i] = NULL;
    }
    map->count_item = 0;
}

static struct item *
map_get_item (struct map * map, unsigned int hash, unsigned int a, unsigned int b)
{
    unsigned int tmp;
    struct item * item;
    tmp = a;
    a = tmp > b ? tmp : b;
    b = tmp > b ? b : tmp;

    item = map->items[hash % MAP_SIZE];
    while (item != NULL && item->a != a && item->b != b) { item = item->next; }
    return item;
}

static int
map_add_item (struct map * map, unsigned int hash, unsigned int a, unsigned int b, int id)
{
    struct item * next;
    struct item * item;
    if (map_get_item (map, hash, a, b) != NULL) { return 0; }

    next = map->items[hash % MAP_SIZE];
    item = malloc (sizeof (struct item));
    if (item == NULL) { return -1; }

    item->a = a > b ? a : b;
    item->b = a < b ? a : b;
    item->next = next;
    item->id = id;

    map->count_item++;
    map->items[hash % MAP_SIZE] = item;
    return 1;
}

static unsigned int
hash_2_int (unsigned int a, unsigned int b)
{
    return a > b ? a * a + a + b : b * b + b + a;
}


/* helper structure */

struct vertex_array
{
    vec3 * vertices;
    size_t buffer;
    unsigned int nb_vertices;
};

struct tcoord_array
{
    vec2 * uv;
    size_t buffer;
    unsigned int nb_uv;
};


/* Utils */
static unsigned int
middle_point_v (struct map * map, int * state,
                struct vertex_array * v,
                unsigned int a, unsigned int b)
{
    unsigned int hash;
    struct item * item;
    unsigned int id;
    vec3 middle;

    hash = hash_2_int (a, b);
    item = map_get_item (map, hash, a, b);
    id = v->nb_vertices;

    if (item != NULL) { *state = 0; return item->id; }
    
    if (map_add_item (map, hash, a, b, id) == -1) { *state = -1; return 0; }
    
    *state = 1;
    middle = sweet_vector_middle3 (v->vertices[a], v->vertices[b]);

    v->vertices[v->nb_vertices++] = sweet_vector_normalize3 (middle);
    return id;
}

static unsigned int
middle_point_vt (struct map * map, int * state,
                 struct vertex_array * v, struct tcoord_array * t,
                 unsigned int a, unsigned int b)
{
    unsigned int id = middle_point_v (map, state, v, a, b);
    
    if (*state == 1)
    {
        t->uv[t->nb_uv++] = sweet_vector_middle2 (t->uv[a], t->uv[b]);
    }
    return id;
}

static struct face_item *
first_iteration (struct vertex_array * v,
                 unsigned int nb_indices, unsigned int * indices,
                 unsigned int nb_vertices, float * vertices)
{
    struct face_item * root;
    unsigned int i;
    unsigned int j;

    v->nb_vertices = nb_vertices;
    for (i = 0, j = 0; i < v->nb_vertices; i++, j += 3)
    {
        v->vertices[i] = sweet_vector_normalize3 (sweet_vector_new3 (vertices[j], vertices[j+1], vertices[j+2]));
    }

    root = NULL;
    for (i = 0; i < nb_indices; i += 3)
    {
        root = face_add (root, indices[i], indices[i+1], indices[i+2]);
    }

    return root;
}

static struct face_item *
first_iteration_vt (struct vertex_array * v, struct tcoord_array * t,
                    unsigned int nb_indices, unsigned int * indices,
                    unsigned int nb_vertices, float * vertices, float * tcoord)
{
    unsigned int i;
    unsigned int j;

    t->nb_uv = nb_vertices;
    for (i = 0, j = 0; i < t->nb_uv; i++, j += 2)
    {
        t->uv[i] = sweet_vector_new2 (tcoord[j], tcoord[j+1]);
    }

    return first_iteration (v, nb_indices, indices, nb_vertices, vertices);
}

static void
free_all (struct map * map, struct vertex_array * v, struct tcoord_array * t, struct face_item * root, void * a1, void * a2, void * a3)
{
    map_free (map);
    if (v != NULL && v->vertices != NULL) { free (v->vertices); }
    if (t != NULL && t->uv != NULL) { free (t->uv); }
    face_free (root);
    if (a1 != NULL) { free (a1); }
    if (a2 != NULL) { free (a2); }
    if (a3 != NULL) { free (a3); }
}

static void
copy_indices (unsigned int * mesh_indices, struct face_item * root)
{    
    unsigned int i;
    struct face_item * f;
    for (f = root, i = 0; f != NULL; i += 3)
    {
        mesh_indices[i] = f->v[0];
        mesh_indices[i+1] = f->v[1];
        mesh_indices[i+2] = f->v[2];
        f = f->next;
    }
}

static void
copy_vertices (float * mesh_vertices, struct vertex_array * v, float scale)
{
    unsigned int i;
    unsigned int j;
    for (i = 0, j = 0; i < v->nb_vertices; i++, j += 3)
    {
        mesh_vertices[j]   = v->vertices[i].x * scale;
        mesh_vertices[j+1] = v->vertices[i].y * scale;
        mesh_vertices[j+2] = v->vertices[i].z * scale;
    }
}

static struct face_item *
iterate (struct map * map, struct vertex_array * v, struct tcoord_array * t, struct face_item * root,
         unsigned int * nb_faces, unsigned int nb_iterations)
{
    unsigned int i;
    for (i = 0; i < nb_iterations; i++)
    {
        struct face_item * face = root;
        while (face != NULL)
        {
            int r1;
            int r2;
            int r3;
            unsigned int a;
            unsigned int b;
            unsigned int c;

            if (t != NULL)
            {
                a = middle_point_vt (map, &r1, v, t, face->v[0], face->v[1]);
                b = middle_point_vt (map, &r2, v, t, face->v[1], face->v[2]);
                c = middle_point_vt (map, &r3, v, t, face->v[2], face->v[0]);
            }
            else
            {
                a = middle_point_v (map, &r1, v, face->v[0], face->v[1]);
                b = middle_point_v (map, &r2, v, face->v[1], face->v[2]);
                c = middle_point_v (map, &r3, v, face->v[2], face->v[0]);
            }

            if (r1 == -1 || r2 == -1 || r3 == -1)
            {
                free_all (map, v, t, root, NULL, NULL, NULL);
                return 0;
            }

            r1 = face->v[1];
            r2 = face->v[2];
            face->v[1] = a;
            face->v[2] = c;

            root = face_add (root, r1, b, a);
            root = face_add (root, r2, c, b);
            root = face_add (root, a, b, c);
            
            *nb_faces += 3;

            face = face->next;
        }
    }
    return root;
}

int
sweet_geometry_subdivide_mesh_vt (unsigned int nb_iterations, float scale,
                                  unsigned int nb_indices, unsigned int * indices,
                                  unsigned int nb_vertices, float * vcoord, float * tcoord,
                                  unsigned int * count_indices, unsigned int ** mesh_indices,
                                  unsigned int * count_vertices, float ** mesh_vertices, float ** mesh_tcoord)
{
    struct face_item * root;
    unsigned int nb_faces;
    struct map map;
    struct vertex_array v;
    struct tcoord_array t;

    unsigned int i;
    unsigned int j;

    map_init (&map);
    *count_vertices = 0;
    *count_indices = 0;
    nb_faces = nb_indices / 3;

    v.buffer = nb_vertices * sizeof (vec3) * pow (4, nb_iterations); 
    v.vertices = malloc (v.buffer);
    if (v.vertices == NULL) { return 0; }

    t.buffer = nb_vertices * sizeof (vec2) * pow (4, nb_iterations);
    t.uv = malloc (t.buffer);
    if (t.uv == NULL) { free (v.vertices); return 0; }

    root = first_iteration_vt (&v, &t, nb_indices, indices, nb_vertices, vcoord, tcoord);
    root = iterate (&map, &v, &t, root, &nb_faces, nb_iterations);

    (*mesh_indices) = malloc (nb_faces * 3 * sizeof (unsigned int));
    (*mesh_vertices) = malloc (v.nb_vertices * sizeof (float) * 3);
    (*mesh_tcoord) = malloc (t.nb_uv * sizeof (float) * 2);

    if ((*mesh_indices) == NULL || (*mesh_vertices) == NULL || (*mesh_tcoord) == NULL)
    {
        free_all (&map, &v, &t, root, *mesh_vertices, *mesh_indices, *mesh_tcoord);
        return 0;
    }

    copy_indices (*mesh_indices, root);
    copy_vertices (*mesh_vertices, &v, scale);

    for (i = 0, j = 0; i < v.nb_vertices; i++, j += 2)
    {
        (*mesh_tcoord)[j] = t.uv[i].x;
        (*mesh_tcoord)[j+1] = t.uv[i].y;
    }

    free_all (&map, &v, &t, root, NULL, NULL, NULL);
    
    (*count_indices) = nb_faces * 3;
    (*count_vertices) = v.nb_vertices;
    return nb_faces;
}

int
sweet_geometry_subdivide_mesh_v (unsigned int nb_iterations, float scale,
                                 unsigned int nb_indices, unsigned int * indices,
                                 unsigned int nb_vertices, float * vcoord,
                                 unsigned int * count_indices, unsigned int ** mesh_indices,
                                 unsigned int * count_vertices, float ** mesh_vertices)
{
    struct face_item * root;
    unsigned int nb_faces;
    struct map map;
    struct vertex_array v;

    map_init (&map);
    *count_vertices = 0;
    *count_indices = 0;
    nb_faces = nb_indices / 3;

    v.buffer = nb_vertices * sizeof (vec3) * pow (4, nb_iterations); 
    v.vertices = malloc (v.buffer);
    if (v.vertices == NULL) { return 0; }

    root = first_iteration (&v, nb_indices, indices, nb_vertices, vcoord);

    root = iterate (&map, &v, NULL, root, &nb_faces, nb_iterations);

    (*mesh_indices) = malloc (nb_faces * 3 * sizeof (unsigned int));
    (*mesh_vertices) = malloc (v.nb_vertices * sizeof (float) * 3);

    if ((*mesh_indices) == NULL || (*mesh_vertices) == NULL)
    {
        free_all (&map, &v, NULL, root, *mesh_vertices, *mesh_indices, NULL);
        return 0;
    }

    copy_indices (*mesh_indices, root);
    copy_vertices (*mesh_vertices, &v, scale);

    free_all (&map, &v, NULL, root, NULL, NULL, NULL);

    (*count_indices) = nb_faces * 3;
    (*count_vertices) = v.nb_vertices;

    return nb_faces;
}

/* Icosphere */

#define NB_INDICES  60
#define NB_VERTICES 12

static float icosphere_vertices_v[36] = {
    -1,  SWEET_GOLDEN_RATIO,  0,
     1,  SWEET_GOLDEN_RATIO,  0,
    -1, -SWEET_GOLDEN_RATIO,  0,
     1, -SWEET_GOLDEN_RATIO,  0,
                              
     0, -1,  SWEET_GOLDEN_RATIO,
     0,  1,  SWEET_GOLDEN_RATIO,
     0, -1, -SWEET_GOLDEN_RATIO,
     0,  1, -SWEET_GOLDEN_RATIO,
                              
     SWEET_GOLDEN_RATIO,  0, -1,
     SWEET_GOLDEN_RATIO,  0,  1,
    -SWEET_GOLDEN_RATIO,  0, -1,
    -SWEET_GOLDEN_RATIO,  0,  1
};

static unsigned int icosphere_indices_v[NB_INDICES] = {
     0, 11,  5,
     0,  5,  1,
     0,  1,  7,
     0,  7, 10,
     0, 10, 11,

     1,  5,  9,
     5, 11,  4,
    11, 10,  2,
    10,  7,  6,
     7,  1,  8,

     3,  9,  4,
     3,  4,  2,
     3,  2,  6,
     3,  6,  8,
     3,  8,  9,

     4,  9,  5,
     2,  4, 11,
     6,  2, 10,
     8,  6,  7,
     9,  8,  1
};


int
sweet_geometry_icosphere (unsigned int nb_iterations, float scale,
                          unsigned int * count_indices, unsigned int ** mesh_indices,
                          unsigned int * count_vertices, float ** mesh_vertices)
{
    return sweet_geometry_subdivide_mesh_v (nb_iterations, scale,
                                            NB_INDICES, icosphere_indices_v, NB_VERTICES, icosphere_vertices_v,
                                            count_indices, mesh_indices, count_vertices, mesh_vertices);
}
#undef NB_INDICES 
#undef NB_VERTICES

#define NB_INDICES  36
#define NB_VERTICES 8

static float cube_vertices_v[24] = {
    -0.5, -0.5, -0.5,
     0.5, -0.5, -0.5,
     0.5, -0.5,  0.5,
    -0.5, -0.5,  0.5,
    -0.5,  0.5, -0.5,
     0.5,  0.5, -0.5,
     0.5,  0.5,  0.5,
    -0.5,  0.5,  0.5
};

static unsigned int cube_indices_v[NB_INDICES] = {
    2, 3, 0,
    0, 1, 2,
    4, 7, 6,
    6, 5, 4,
    0, 3, 7,
    7, 4, 0,
    6, 2, 1,
    1, 5, 6,
    0, 4, 1,
    1, 4, 5,
    3, 2, 6,
    6, 7, 3
};


int
sweet_geometry_cube (float scale,
                     unsigned int * count_indices, unsigned int ** mesh_indices,
                     unsigned int * count_vertices, float ** mesh_vertices)
{
    int i;
    
    *mesh_vertices = NULL;
    *mesh_indices = NULL;
    *count_indices = NB_INDICES;
    *count_vertices = NB_VERTICES;
    
    *mesh_vertices = malloc (NB_VERTICES * 3 * sizeof (float));
    if (*mesh_vertices == NULL) { return 0; }
    *mesh_indices = malloc (NB_INDICES * sizeof (unsigned int));
    if (*mesh_indices == NULL) { return 0; }

    for (i = 0; i < NB_VERTICES * 3; i++)
    {
        (*mesh_vertices)[i] = cube_vertices_v[i] * scale;
    }

    for (i = 0; i < NB_INDICES; i++)
    {
        (*mesh_indices)[i] = cube_indices_v[i];
    }

    return 6;
}