/* EINA - EFL data type library
 * Copyright (C) 2010 Cedric Bail
 *
 * 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 2.1 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/>.
 */

/**
 * @page tutorial_quadtree_page QuadTree Tutorial
 *
 * to be written...
 *
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdlib.h>
#include <stdio.h>

#include "eina_quadtree.h"
#include "eina_magic.h"
#include "eina_mempool.h"
#include "eina_list.h"
#include "eina_inlist.h"
#include "eina_trash.h"
#include "eina_log.h"
#include "eina_rectangle.h"

#include "eina_private.h"

typedef struct _Eina_QuadTree_Root Eina_QuadTree_Root;

static const char EINA_MAGIC_QUADTREE_STR[] = "Eina QuadTree";
static const char EINA_MAGIC_QUADTREE_ROOT_STR[] = "Eina QuadTree Root";
static const char EINA_MAGIC_QUADTREE_ITEM_STR[] = "Eina QuadTree Item";

#define EINA_MAGIC_CHECK_QUADTREE(d, ...)               \
   do {                                                  \
        if (!EINA_MAGIC_CHECK(d, EINA_MAGIC_QUADTREE))     \
          {                                                \
             EINA_MAGIC_FAIL(d, EINA_MAGIC_QUADTREE);      \
             return __VA_ARGS__;                           \
          }                                                \
     } while(0);

#define EINA_MAGIC_CHECK_QUADTREE_ROOT(d, ...)                  \
   do {                                                          \
        if (!EINA_MAGIC_CHECK(d, EINA_MAGIC_QUADTREE_ROOT))        \
          {                                                        \
             EINA_MAGIC_FAIL(d, EINA_MAGIC_QUADTREE_ROOT);         \
             return __VA_ARGS__;                                   \
          }                                                        \
     } while(0);

#define EINA_MAGIC_CHECK_QUADTREE_ITEM(d, ...)                  \
   do {                                                          \
        if (!EINA_MAGIC_CHECK(d, EINA_MAGIC_QUADTREE_ITEM))        \
          {                                                        \
             EINA_MAGIC_FAIL(d, EINA_MAGIC_QUADTREE_ITEM);         \
             return __VA_ARGS__;                                   \
          }                                                        \
     } while(0);

struct _Eina_QuadTree
{
   Eina_QuadTree_Root *root;

   Eina_List *hidden;

   size_t root_count;
   size_t items_count;

   Eina_Trash *items_trash;
   Eina_Trash *root_trash;

   Eina_Inlist *change;
   Eina_Inlist *cached;
   Eina_Rectangle target;

   size_t index;

   struct
   {
      Eina_Quad_Callback v;
      Eina_Quad_Callback h;
   } func;

   struct
   {
      size_t w;
      size_t h;
   } geom;

   Eina_Bool resize : 1;
   Eina_Bool lost : 1;

   EINA_MAGIC
};

struct _Eina_QuadTree_Root
{
   Eina_QuadTree_Root *parent;
   Eina_QuadTree_Root *left;
   Eina_QuadTree_Root *right;

   Eina_List *both;

   Eina_Bool sorted : 1;

   EINA_MAGIC
};

struct _Eina_QuadTree_Item
{
   EINA_INLIST;

   Eina_QuadTree *quad;
   Eina_QuadTree_Root *root;

   const void *object;

   size_t index;

   Eina_Bool change : 1;
   Eina_Bool delete_me : 1;
   Eina_Bool visible : 1;
   Eina_Bool hidden : 1;

   EINA_MAGIC
};

static int _eina_quadtree_log_dom = -1;
static Eina_Mempool *eina_quadtree_root_mp = NULL;
static Eina_Mempool *_eina_quadtree_items_mp = NULL;

#ifdef ERR
#undef ERR
#endif
#define ERR(...) EINA_LOG_DOM_ERR(_eina_quadtree_log_dom, __VA_ARGS__)

#ifdef DBG
#undef DBG
#endif
#define DBG(...) EINA_LOG_DOM_DBG(_eina_quadtree_log_dom, __VA_ARGS__)


static int
_eina_quadtree_item_cmp(const void *a, const void *b)
{
   const Eina_QuadTree_Item *i = a;
   const Eina_QuadTree_Item *j = b;

   if (i->index == j->index) return 0;
   if (i->index > j->index) return 1;
   return -1;
}

static Eina_QuadTree_Root *
eina_quadtree_root_free(Eina_QuadTree *q, Eina_QuadTree_Root *root)
{
   Eina_QuadTree_Item *item;

   if (!root)
      return NULL;

   EINA_MAGIC_CHECK_QUADTREE_ROOT(root, NULL);

   EINA_LIST_FREE(root->both, item)
   eina_mempool_free(_eina_quadtree_items_mp, item);

   root->left = eina_quadtree_root_free(q, root->left);
   root->right = eina_quadtree_root_free(q, root->right);

   EINA_MAGIC_SET(root, 0);
   eina_mempool_free(eina_quadtree_root_mp, root);

   return NULL;
}

static Eina_QuadTree_Root *
eina_quadtree_root_rebuild_pre(Eina_QuadTree *q,
                               Eina_Inlist **change,
                               Eina_QuadTree_Root *root)
{
   Eina_QuadTree_Item *item;

   if (!root)
      return NULL;

   EINA_LIST_FREE(root->both, item)
   {
      if (item->visible)
         *change = eina_inlist_append(*change, EINA_INLIST_GET(item));
      else if (!item->hidden)
        {
           q->hidden = eina_list_append(q->hidden, item);
           item->hidden = EINA_TRUE;
           item->root = NULL;
        }
   }

   root->left = eina_quadtree_root_rebuild_pre(q, change, root->left);
   root->right = eina_quadtree_root_rebuild_pre(q, change, root->right);

   EINA_MAGIC_SET(root, 0);
   if (q->root_count > 50)
      eina_mempool_free(eina_quadtree_root_mp, root);
   else
     {
        eina_trash_push(&q->root_trash, root);
        q->root_count++;
     }

   return NULL;
}

static size_t
_eina_quadtree_split(Eina_Inlist *objects,
                     Eina_QuadTree_Root *root,
                     Eina_Inlist **left,
                     Eina_Inlist **right,
                     Eina_Quad_Callback func,
                     int border,
                     int middle)
{
   Eina_QuadTree_Item *object;

   middle /= 2;

   if (middle <= 4)
      while (objects)
        {
           object = EINA_INLIST_CONTAINER_GET(objects, Eina_QuadTree_Item);
           objects = objects->next;

           object->change = EINA_FALSE;
           if (!object->visible)
             {
                if (!object->hidden)
                  {
                     object->hidden = EINA_TRUE;
                     object->quad->hidden = eina_list_append(
                           object->quad->hidden,
                           object);
                  }

                continue;
             }

           if (object->hidden)
             {
                object->hidden = EINA_FALSE;
                object->quad->hidden = eina_list_remove(object->quad->hidden,
                                                        object);
             }

           if (!object->delete_me)
             {
                if (root->sorted)
                   root->both = eina_list_sorted_insert(root->both,
                                                        _eina_quadtree_item_cmp,
                                                        object);
                else
                   root->both = eina_list_append(root->both, object);

                object->root = root;
             }
           else
              eina_quadtree_del(object);
        }
   else
      while (objects)
        {
           object = EINA_INLIST_CONTAINER_GET(objects, Eina_QuadTree_Item);
           objects = objects->next;

           object->change = EINA_FALSE;
           if (!object->visible)
             {
                if (!object->hidden)
                  {
                     object->hidden = EINA_TRUE;
                     object->quad->hidden = eina_list_append(
                           object->quad->hidden,
                           object);
                  }

                continue;
             }

           if (object->hidden)
             {
                object->hidden = EINA_FALSE;
                object->quad->hidden = eina_list_remove(object->quad->hidden,
                                                        object);
             }

           if (!object->delete_me)
             {
                switch (func(object->object, border + middle))
                  {
                   case EINA_QUAD_LEFT:
                      *left = eina_inlist_append(*left, EINA_INLIST_GET(object));
                      break;

                   case EINA_QUAD_RIGHT:
                      *right =
                         eina_inlist_append(*right, EINA_INLIST_GET(object));
                      break;

                   case EINA_QUAD_BOTH:
                      root->both = eina_list_append(root->both, object);
                      object->root = root;
                      break;

                   default:
                      abort();
                  }
             }
           else
              eina_quadtree_del(object);
        }

   return middle;
}


static Eina_QuadTree_Root *
_eina_quadtree_update(Eina_QuadTree *q, Eina_QuadTree_Root *parent,
                      Eina_QuadTree_Root *root, Eina_Inlist *objects,
                      Eina_Bool direction, Eina_Rectangle *size)
{
   Eina_Inlist *right = NULL;
   Eina_Inlist *left = NULL;
   size_t w2;
   size_t h2;

   if (!objects)
      return root;

   if (!root)
     {
        root = eina_trash_pop(&q->root_trash);
        if (!root)
           root = eina_mempool_malloc(eina_quadtree_root_mp, sizeof (Eina_QuadTree_Root));
        else
           q->root_count--;

        if (!root)
           /* FIXME: NOT GOOD TIMING, WE ARE GOING TO LEAK MORE MEMORY */
           return NULL;

        root->parent = parent;
        root->both = NULL;
        root->left = NULL;
        root->right = NULL;
        root->sorted = EINA_TRUE;

        EINA_MAGIC_SET(root, EINA_MAGIC_QUADTREE_ROOT);
     }

   w2 = 0;
   h2 = 0;

   if (direction)
      w2 = _eina_quadtree_split(objects, root,
                                &left, &right,
                                q->func.h, size->x, size->w);
   else
      h2 = _eina_quadtree_split(objects, root,
                                &left, &right,
                                q->func.v, size->y, size->h);

   size->w -= w2; size->h -= h2;
   root->left = _eina_quadtree_update(q, root,
                                      root->left, left,
                                      !direction, size);
   size->x += w2; size->y += h2;
   root->right = _eina_quadtree_update(q, root,
                                       root->right, right,
                                       !direction, size);
   size->x -= w2; size->y -= h2;
   size->w += w2; size->h += h2;

   return root;
}

static Eina_Inlist *
_eina_quadtree_merge(Eina_Inlist *result,
                     Eina_List *both)
{
   Eina_QuadTree_Item *item;
   Eina_QuadTree_Item *b;
   Eina_Inlist *moving;

   if (!both)
      return result;

   if (!result)
     {
        Eina_List *l;

        EINA_LIST_FOREACH(both, l, item)
        if (item->visible)
           result = eina_inlist_append(result, EINA_INLIST_GET(item));

        return result;
     }

   moving = result;

   item = EINA_INLIST_CONTAINER_GET(moving, Eina_QuadTree_Item);
   b = eina_list_data_get(both);

   while (both && moving)
     {
        if (!b->visible)
          {
             both = eina_list_next(both);
             b = eina_list_data_get(both);
             continue;
          }

        if (_eina_quadtree_item_cmp(item, b) < 0)
          {
             /* moving is still lower than item, so we can continue to the next one. */
             moving = moving->next;
             item = EINA_INLIST_CONTAINER_GET(moving, Eina_QuadTree_Item);
          }
        else
          {
             /* we just get above the limit of both, so insert it */
             result = eina_inlist_prepend_relative(result,
                                                   EINA_INLIST_GET(b),
                                                   moving);
             both = eina_list_next(both);
             b = eina_list_data_get(both);
          }
     }

   item = EINA_INLIST_CONTAINER_GET(result->last, Eina_QuadTree_Item);

   while (both)
     {
        b = eina_list_data_get(both);
        if (b->visible)
          {
             if (_eina_quadtree_item_cmp(item, b) < 0)
                break;

             result = eina_inlist_prepend_relative(result,
                                                   EINA_INLIST_GET(b),
                                                   result->last);
          }

        both = eina_list_next(both);
     }

   while (both)
     {
        b = eina_list_data_get(both);
        if (b->visible)
           result = eina_inlist_append(result, EINA_INLIST_GET(b));

        both = eina_list_next(both);
     }

   return result;
}

static Eina_Inlist *
_eina_quadtree_collide(Eina_Inlist *result,
                       Eina_QuadTree_Root *root,
                       Eina_Bool direction, Eina_Rectangle *size,
                       Eina_Rectangle *target)
{
   if (!root)
      return result;

   if (!root->sorted)
     {
        root->both = eina_list_sort(root->both, -1, _eina_quadtree_item_cmp);
        root->sorted = EINA_TRUE;
     }

   result = _eina_quadtree_merge(result, root->both);
   DBG("%p: %i in both for (%i, %i - %i, %i)",
       root, eina_list_count(root->both),
       size->x, size->y, size->w, size->h);

   if (direction)
     {
        int middle = size->w / 2;

        size->w -= middle;
        if (eina_spans_intersect(size->x, size->w, target->x, target->w))
           result = _eina_quadtree_collide(result, root->left,
                                           !direction, size,
                                           target);

        size->x += middle;
        if (eina_spans_intersect(size->x, size->w, target->x, target->w))
           result = _eina_quadtree_collide(result, root->right,
                                           !direction, size,
                                           target);

        size->x -= middle;
        size->w += middle;
     }
   else
     {
        int middle = size->h / 2;

        size->h -= middle;
        if (eina_spans_intersect(size->y, size->h, target->y, target->h))
           result = _eina_quadtree_collide(result, root->left,
                                           !direction, size,
                                           target);

        size->y += middle;
        if (eina_spans_intersect(size->y, size->h, target->y, target->h))
           result = _eina_quadtree_collide(result, root->right,
                                           !direction, size,
                                           target);

        size->y -= middle;
        size->h += middle;
     }

   return result;
}

static void
_eina_quadtree_remove(Eina_QuadTree_Item *object)
{
   if (!object->root)
      return;

   object->root->both = eina_list_remove(object->root->both, object);
   if (object->root->both)
      goto end;

   if (object->root->left)
      goto end;

   if (object->root->right)
      goto end;

   /* The root is not useful anymore... */
   if (object->root->parent)
     {
        if (object->root->parent->left == object->root)
           object->root->parent->left = NULL;
        else
           object->root->parent->right = NULL;

        object->root->parent = NULL;
     }
   else
      object->quad->root = NULL;

   if (object->quad->root_count > 50)
      eina_mempool_free(eina_quadtree_root_mp, object->root);
   else
     {
        eina_trash_push(&object->quad->root_trash, object->root);
        object->quad->root_count++;
     }

end:
   object->root = NULL;
}

EAPI Eina_QuadTree *
eina_quadtree_new(size_t w, size_t h,
                  Eina_Quad_Callback vertical, Eina_Quad_Callback horizontal)
{
   Eina_QuadTree *result;

   if (!vertical || !horizontal || h == 0 || w == 0)
      return NULL;

   result = calloc(1, sizeof (Eina_QuadTree));
   if (!result)
      return NULL;

   result->func.v = vertical;
   result->func.h = horizontal;

   result->geom.w = w;
   result->geom.h = h;

   result->change = NULL;

   result->lost = EINA_TRUE;

   EINA_MAGIC_SET(result, EINA_MAGIC_QUADTREE);

   return result;
}

EAPI void
eina_quadtree_free(Eina_QuadTree *q)
{
   Eina_QuadTree_Item *item;

   if (!q)
      return;

   EINA_MAGIC_CHECK_QUADTREE(q);

   while (q->change)
     {
        item = EINA_INLIST_CONTAINER_GET(q->change, Eina_QuadTree_Item);
        q->change = q->change->next;
        if (!item->hidden)
           eina_mempool_free(_eina_quadtree_items_mp, item);
     }

   EINA_LIST_FREE(q->hidden, item)
   eina_mempool_free(_eina_quadtree_items_mp, item);

   eina_quadtree_root_free(q, q->root);

   while (q->items_trash)
     {
        item = eina_trash_pop(&q->items_trash);
        eina_mempool_free(_eina_quadtree_items_mp, item);
     }

   while (q->root_trash)
     {
        Eina_QuadTree_Root *root;

        root = eina_trash_pop(&q->root_trash);
        eina_mempool_free(eina_quadtree_root_mp, root);
     }

        EINA_MAGIC_SET(q, 0);
   free(q);
}

EAPI Eina_QuadTree_Item *
eina_quadtree_add(Eina_QuadTree *q, const void *object)
{
   Eina_QuadTree_Item *result;

   EINA_MAGIC_CHECK_QUADTREE(q, NULL);

   if (!object)
      return NULL;

   result = eina_trash_pop(&q->items_trash);
   if (!result)
      result = eina_mempool_malloc(_eina_quadtree_items_mp, sizeof (Eina_QuadTree_Item));
   else
      q->items_count--;

   if (!result)
      return NULL;

   result->quad = q;
   result->root = NULL;
   result->object = object;

   result->index = q->index++;

   result->change = EINA_TRUE;
   result->delete_me = EINA_FALSE;
   result->visible = EINA_TRUE;
   result->hidden = EINA_FALSE;

   EINA_MAGIC_SET(result, EINA_MAGIC_QUADTREE_ITEM);

   /* Insertion is delayed until we really need to use it */
   q->change = eina_inlist_append(q->change, EINA_INLIST_GET(result));

   return result;
}

EAPI Eina_Bool
eina_quadtree_del(Eina_QuadTree_Item *object)
{
   if (!object)
      return EINA_FALSE;

   EINA_MAGIC_CHECK_QUADTREE_ITEM(object, EINA_FALSE);

   _eina_quadtree_remove(object);

   if (object->change)
     {
        /* This object is still in the update array, delaying it's removal !*/
        object->delete_me = EINA_TRUE;
        object->visible = EINA_TRUE;
        return EINA_TRUE;
     }

   if (object->hidden)
     {
        object->quad->hidden = eina_list_remove(object->quad->hidden, object);
        object->hidden = EINA_TRUE;
     }

   /* This object is not anymore inside the tree, we can remove it now !*/
   EINA_MAGIC_SET(object, 0);
   if (object->quad->items_count > 256)
      eina_mempool_free(_eina_quadtree_items_mp, object);
   else
     {
        object->quad->items_count++;
        eina_trash_push(&object->quad->items_trash, object);
     }

   return EINA_TRUE;
}

EAPI Eina_Bool
eina_quadtree_change(Eina_QuadTree_Item *object)
{
   EINA_MAGIC_CHECK_QUADTREE_ITEM(object, EINA_FALSE);

   if (object->delete_me || !object->visible)
      return EINA_FALSE;

   if (object->quad->resize)
      return EINA_TRUE;

   /* Delaying change until needed */
   if (!object->change)
      object->quad->change = eina_inlist_append(object->quad->change,
                                                EINA_INLIST_GET(object));

   object->change = EINA_TRUE;

   _eina_quadtree_remove(object);

   return EINA_TRUE;
}

EAPI Eina_Bool
eina_quadtree_hide(Eina_QuadTree_Item *object)
{
   EINA_MAGIC_CHECK_QUADTREE_ITEM(object, EINA_FALSE);

   object->visible = EINA_FALSE;

   return EINA_TRUE;
}

EAPI Eina_Bool
eina_quadtree_show(Eina_QuadTree_Item *object)
{
   EINA_MAGIC_CHECK_QUADTREE_ITEM(object, EINA_FALSE);

   object->quad->lost = EINA_TRUE;

   if (object->visible)
      return EINA_TRUE;

   object->visible = EINA_TRUE;
   if (!object->change)
      return eina_quadtree_change(object);

   return EINA_TRUE;
}

EAPI Eina_Inlist *
eina_quadtree_collide(Eina_QuadTree *q, int x, int y, int w, int h)
{
   Eina_Rectangle canvas;

   EINA_MAGIC_CHECK_QUADTREE(q, NULL);

   /* Now we need the tree to be up to date, so it's time */
   if (q->resize) /* Full rebuild needed ! */
     {
        DBG("resizing quadtree");
        q->root = eina_quadtree_root_rebuild_pre(q, &q->change, q->root);
        q->resize = EINA_FALSE;
     }

   EINA_RECTANGLE_SET(&canvas, 0, 0, q->geom.w, q->geom.h);

   if (q->change)
     {
        DBG("updating quadtree content");
        q->root = _eina_quadtree_update(q, NULL, q->root, q->change,
                                        EINA_FALSE, &canvas);
        q->change = NULL;
        q->lost = EINA_TRUE;
     }

   if (q->target.x != x
       || q->target.y != y
       || q->target.w != w
       || q->target.h != h)
     {
        DBG("new target");
        EINA_RECTANGLE_SET(&q->target, x, y, w, h);
        q->lost = EINA_TRUE;
     }

   if (q->lost)
     {
        DBG("computing collide");
        q->cached = _eina_quadtree_collide(NULL, q->root,
                                           EINA_FALSE, &canvas,
                                           &q->target);
        q->lost = EINA_FALSE;
     }

   return q->cached;
}

EAPI void *
eina_quadtree_object(Eina_Inlist *item)
{
   Eina_QuadTree_Item *qi;

   if (!item)
      return NULL;

   qi = EINA_INLIST_CONTAINER_GET(item, Eina_QuadTree_Item);
   if (!qi)
      return NULL;

   EINA_MAGIC_CHECK_QUADTREE_ITEM(qi, NULL);

   if (!qi->visible)
      return NULL;

   return (void *)qi->object;
}

EAPI void
eina_quadtree_resize(Eina_QuadTree *q, size_t w, size_t h)
{
   EINA_MAGIC_CHECK_QUADTREE(q);

   if (q->geom.w == w
       && q->geom.h == h)
      return;

   q->resize = EINA_TRUE;
   q->geom.w = w;
   q->geom.h = h;
}

EAPI void
eina_quadtree_cycle(Eina_QuadTree *q)
{
   EINA_MAGIC_CHECK_QUADTREE(q);

   q->index = 0;
}

EAPI void
eina_quadtree_increase(Eina_QuadTree_Item *object)
{
   size_t tmp;

   EINA_MAGIC_CHECK_QUADTREE_ITEM(object);

   tmp = object->quad->index++;
   if (object->index == tmp)
      return;

   object->index = tmp;
   if (object->root)
      object->root->sorted = EINA_FALSE;
}

Eina_Bool
eina_quadtree_init(void)
{
   const char *choice, *tmp;

   _eina_quadtree_log_dom = eina_log_domain_register("eina_quadtree",
                                                     EINA_LOG_COLOR_DEFAULT);
   if (_eina_quadtree_log_dom < 0)
     {
        EINA_LOG_ERR("Could not register log domain: eina_quadtree");
        return EINA_FALSE;
     }

#define EMS(n) eina_magic_string_static_set(n, n ## _STR)
   EMS(EINA_MAGIC_QUADTREE);
   EMS(EINA_MAGIC_QUADTREE_ROOT);
   EMS(EINA_MAGIC_QUADTREE_ITEM);
#undef EMS

#ifdef EINA_DEFAULT_MEMPOOL
   choice = "pass_through";
#else
   choice = "chained_mempool";
#endif
   tmp = getenv("EINA_MEMPOOL");
   if (tmp && tmp[0])
      choice = tmp;

   _eina_quadtree_items_mp = eina_mempool_add(choice, "QuadTree Item", NULL,
                                              sizeof (Eina_QuadTree_Item), 32);
   eina_quadtree_root_mp = eina_mempool_add(choice, "QuadTree Root", NULL,
                                            sizeof (Eina_QuadTree_Root), 8);

   return EINA_TRUE;
}

Eina_Bool
eina_quadtree_shutdown(void)
{
   eina_mempool_del(eina_quadtree_root_mp);
   eina_mempool_del(_eina_quadtree_items_mp);

   eina_log_domain_unregister(_eina_quadtree_log_dom);
   _eina_quadtree_log_dom = -1;
   return EINA_TRUE;
}