/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright 2011 Blender Foundation. All rights reserved. */

/** \file
 * \ingroup bke
 */

#undef DEBUG_MESSAGES

#include <cstdlib> /* for qsort */
#include <memory.h>
#include <mutex>

#include "MEM_CacheLimiterC-Api.h"
#include "MEM_guardedalloc.h"

#include "BLI_ghash.h"
#include "BLI_mempool.h"
#include "BLI_string.h"
#include "BLI_threads.h"
#include "BLI_utildefines.h"

#include "IMB_moviecache.h"

#include "IMB_imbuf.h"
#include "IMB_imbuf_types.h"

#ifdef DEBUG_MESSAGES
#  if defined __GNUC__
#    define PRINT(format, args...) printf(format, ##args)
#  else
#    define PRINT(format, ...) printf(__VA_ARGS__)
#  endif
#else
#  define PRINT(format, ...)
#endif

static MEM_CacheLimiterC *limitor = nullptr;

/* Image buffers managed by a moviecache might be using their own movie caches (used by color
 * management). In practice this means that, for example, freeing MovieCache used by MovieClip
 * will request freeing MovieCache owned by ImBuf. Freeing MovieCache needs to be thread-safe,
 * so regular mutex will not work here, hence the recursive lock. */
static std::recursive_mutex limitor_lock;

struct MovieCache {
  char name[64];

  GHash *hash;
  GHashHashFP hashfp;
  GHashCmpFP cmpfp;
  MovieCacheGetKeyDataFP getdatafp;

  MovieCacheGetPriorityDataFP getprioritydatafp;
  MovieCacheGetItemPriorityFP getitempriorityfp;
  MovieCachePriorityDeleterFP prioritydeleterfp;

  struct BLI_mempool *keys_pool;
  struct BLI_mempool *items_pool;
  struct BLI_mempool *userkeys_pool;

  int keysize;

  void *last_userkey;

  int totseg, *points, proxy, render_flags; /* for visual statistics optimization */
  int pad;
};

struct MovieCacheKey {
  MovieCache *cache_owner;
  void *userkey;
};

struct MovieCacheItem {
  MovieCache *cache_owner;
  ImBuf *ibuf;
  MEM_CacheLimiterHandleC *c_handle;
  void *priority_data;
  /* Indicates that #ibuf is null, because there was an error during load. */
  bool added_empty;
};

static unsigned int moviecache_hashhash(const void *keyv)
{
  const MovieCacheKey *key = (const MovieCacheKey *)keyv;

  return key->cache_owner->hashfp(key->userkey);
}

static bool moviecache_hashcmp(const void *av, const void *bv)
{
  const MovieCacheKey *a = (const MovieCacheKey *)av;
  const MovieCacheKey *b = (const MovieCacheKey *)bv;

  return a->cache_owner->cmpfp(a->userkey, b->userkey);
}

static void moviecache_keyfree(void *val)
{
  MovieCacheKey *key = (MovieCacheKey *)val;

  BLI_mempool_free(key->cache_owner->userkeys_pool, key->userkey);

  BLI_mempool_free(key->cache_owner->keys_pool, key);
}

static void moviecache_valfree(void *val)
{
  MovieCacheItem *item = (MovieCacheItem *)val;
  MovieCache *cache = item->cache_owner;

  PRINT("%s: cache '%s' free item %p buffer %p\n", __func__, cache->name, item, item->ibuf);

  if (item->c_handle) {
    limitor_lock.lock();
    MEM_CacheLimiter_unmanage(item->c_handle);
    limitor_lock.unlock();
  }

  if (item->ibuf) {
    IMB_freeImBuf(item->ibuf);
  }

  if (item->priority_data && cache->prioritydeleterfp) {
    cache->prioritydeleterfp(item->priority_data);
  }

  BLI_mempool_free(item->cache_owner->items_pool, item);
}

static void check_unused_keys(MovieCache *cache)
{
  GHashIterator gh_iter;

  BLI_ghashIterator_init(&gh_iter, cache->hash);

  while (!BLI_ghashIterator_done(&gh_iter)) {
    const MovieCacheKey *key = (const MovieCacheKey *)BLI_ghashIterator_getKey(&gh_iter);
    const MovieCacheItem *item = (const MovieCacheItem *)BLI_ghashIterator_getValue(&gh_iter);

    BLI_ghashIterator_step(&gh_iter);

    if (item->added_empty) {
      /* Don't remove entries that have been added empty. Those indicate that the image couldn't be
       * loaded correctly. */
      continue;
    }

    bool remove = !item->ibuf;

    if (remove) {
      PRINT("%s: cache '%s' remove item %p without buffer\n", __func__, cache->name, item);
    }

    if (remove) {
      BLI_ghash_remove(cache->hash, key, moviecache_keyfree, moviecache_valfree);
    }
  }
}

static int compare_int(const void *av, const void *bv)
{
  const int *a = (int *)av;
  const int *b = (int *)bv;
  return *a - *b;
}

static void moviecache_destructor(void *p)
{
  MovieCacheItem *item = (MovieCacheItem *)p;

  if (item && item->ibuf) {
    MovieCache *cache = item->cache_owner;

    PRINT("%s: cache '%s' destroy item %p buffer %p\n", __func__, cache->name, item, item->ibuf);

    IMB_freeImBuf(item->ibuf);

    item->ibuf = nullptr;
    item->c_handle = nullptr;

    /* force cached segments to be updated */
    MEM_SAFE_FREE(cache->points);
  }
}

static size_t get_size_in_memory(ImBuf *ibuf)
{
  /* Keep textures in the memory to avoid constant file reload on viewport update. */
  if (ibuf->userflags & IB_PERSISTENT) {
    return 0;
  }

  return IMB_get_size_in_memory(ibuf);
}
static size_t get_item_size(void *p)
{
  size_t size = sizeof(MovieCacheItem);
  MovieCacheItem *item = (MovieCacheItem *)p;

  if (item->ibuf) {
    size += get_size_in_memory(item->ibuf);
  }

  return size;
}

static int get_item_priority(void *item_v, int default_priority)
{
  MovieCacheItem *item = (MovieCacheItem *)item_v;
  MovieCache *cache = item->cache_owner;
  int priority;

  if (!cache->getitempriorityfp) {
    PRINT("%s: cache '%s' item %p use default priority %d\n",
          __func__,
          cache->name,
          item,
          default_priority);

    return default_priority;
  }

  priority = cache->getitempriorityfp(cache->last_userkey, item->priority_data);

  PRINT("%s: cache '%s' item %p priority %d\n", __func__, cache->name, item, priority);

  return priority;
}

static bool get_item_destroyable(void *item_v)
{
  MovieCacheItem *item = (MovieCacheItem *)item_v;
  if (item->ibuf == nullptr) {
    return true;
  }
  /* IB_BITMAPDIRTY means image was modified from inside blender and
   * changes are not saved to disk.
   *
   * Such buffers are never to be freed.
   */
  if ((item->ibuf->userflags & IB_BITMAPDIRTY) || (item->ibuf->userflags & IB_PERSISTENT)) {
    return false;
  }
  return true;
}

void IMB_moviecache_init(void)
{
  limitor = new_MEM_CacheLimiter(moviecache_destructor, get_item_size);

  MEM_CacheLimiter_ItemPriority_Func_set(limitor, get_item_priority);
  MEM_CacheLimiter_ItemDestroyable_Func_set(limitor, get_item_destroyable);
}

void IMB_moviecache_destruct(void)
{
  if (limitor) {
    delete_MEM_CacheLimiter(limitor);
    limitor = nullptr;
  }
}

MovieCache *IMB_moviecache_create(const char *name,
                                  int keysize,
                                  GHashHashFP hashfp,
                                  GHashCmpFP cmpfp)
{
  MovieCache *cache;

  PRINT("%s: cache '%s' create\n", __func__, name);

  cache = (MovieCache *)MEM_callocN(sizeof(MovieCache), "MovieCache");

  BLI_strncpy(cache->name, name, sizeof(cache->name));

  cache->keys_pool = BLI_mempool_create(sizeof(MovieCacheKey), 0, 64, BLI_MEMPOOL_NOP);
  cache->items_pool = BLI_mempool_create(sizeof(MovieCacheItem), 0, 64, BLI_MEMPOOL_NOP);
  cache->userkeys_pool = BLI_mempool_create(keysize, 0, 64, BLI_MEMPOOL_NOP);
  cache->hash = BLI_ghash_new(
      moviecache_hashhash, moviecache_hashcmp, "MovieClip ImBuf cache hash");

  cache->keysize = keysize;
  cache->hashfp = hashfp;
  cache->cmpfp = cmpfp;
  cache->proxy = -1;

  return cache;
}

void IMB_moviecache_set_getdata_callback(MovieCache *cache, MovieCacheGetKeyDataFP getdatafp)
{
  cache->getdatafp = getdatafp;
}

void IMB_moviecache_set_priority_callback(struct MovieCache *cache,
                                          MovieCacheGetPriorityDataFP getprioritydatafp,
                                          MovieCacheGetItemPriorityFP getitempriorityfp,
                                          MovieCachePriorityDeleterFP prioritydeleterfp)
{
  cache->last_userkey = MEM_mallocN(cache->keysize, "movie cache last user key");

  cache->getprioritydatafp = getprioritydatafp;
  cache->getitempriorityfp = getitempriorityfp;
  cache->prioritydeleterfp = prioritydeleterfp;
}

static void do_moviecache_put(MovieCache *cache, void *userkey, ImBuf *ibuf, bool need_lock)
{
  MovieCacheKey *key;
  MovieCacheItem *item;

  if (!limitor) {
    IMB_moviecache_init();
  }

  if (ibuf != nullptr) {
    IMB_refImBuf(ibuf);
  }

  key = (MovieCacheKey *)BLI_mempool_alloc(cache->keys_pool);
  key->cache_owner = cache;
  key->userkey = BLI_mempool_alloc(cache->userkeys_pool);
  memcpy(key->userkey, userkey, cache->keysize);

  item = (MovieCacheItem *)BLI_mempool_alloc(cache->items_pool);

  PRINT("%s: cache '%s' put %p, item %p\n", __func__, cache->name, ibuf, item);

  item->ibuf = ibuf;
  item->cache_owner = cache;
  item->c_handle = nullptr;
  item->priority_data = nullptr;
  item->added_empty = ibuf == nullptr;

  if (cache->getprioritydatafp) {
    item->priority_data = cache->getprioritydatafp(userkey);
  }

  BLI_ghash_reinsert(cache->hash, key, item, moviecache_keyfree, moviecache_valfree);

  if (cache->last_userkey) {
    memcpy(cache->last_userkey, userkey, cache->keysize);
  }

  if (need_lock) {
    limitor_lock.lock();
  }

  item->c_handle = MEM_CacheLimiter_insert(limitor, item);

  MEM_CacheLimiter_ref(item->c_handle);
  MEM_CacheLimiter_enforce_limits(limitor);
  MEM_CacheLimiter_unref(item->c_handle);

  if (need_lock) {
    limitor_lock.unlock();
  }

  /* cache limiter can't remove unused keys which points to destroyed values */
  check_unused_keys(cache);

  MEM_SAFE_FREE(cache->points);
}

void IMB_moviecache_put(MovieCache *cache, void *userkey, ImBuf *ibuf)
{
  do_moviecache_put(cache, userkey, ibuf, true);
}

bool IMB_moviecache_put_if_possible(MovieCache *cache, void *userkey, ImBuf *ibuf)
{
  size_t mem_in_use, mem_limit, elem_size;
  bool result = false;

  elem_size = (ibuf == nullptr) ? 0 : get_size_in_memory(ibuf);
  mem_limit = MEM_CacheLimiter_get_maximum();

  limitor_lock.lock();
  mem_in_use = MEM_CacheLimiter_get_memory_in_use(limitor);

  if (mem_in_use + elem_size <= mem_limit) {
    do_moviecache_put(cache, userkey, ibuf, false);
    result = true;
  }

  limitor_lock.unlock();

  return result;
}

void IMB_moviecache_remove(MovieCache *cache, void *userkey)
{
  MovieCacheKey key;
  key.cache_owner = cache;
  key.userkey = userkey;
  BLI_ghash_remove(cache->hash, &key, moviecache_keyfree, moviecache_valfree);
}

ImBuf *IMB_moviecache_get(MovieCache *cache, void *userkey, bool *r_is_cached_empty)
{
  MovieCacheKey key;
  MovieCacheItem *item;

  key.cache_owner = cache;
  key.userkey = userkey;
  item = (MovieCacheItem *)BLI_ghash_lookup(cache->hash, &key);

  if (r_is_cached_empty) {
    *r_is_cached_empty = false;
  }

  if (item) {
    if (item->ibuf) {
      limitor_lock.lock();
      MEM_CacheLimiter_touch(item->c_handle);
      limitor_lock.unlock();

      IMB_refImBuf(item->ibuf);

      return item->ibuf;
    }
    if (r_is_cached_empty) {
      *r_is_cached_empty = true;
    }
  }

  return nullptr;
}

bool IMB_moviecache_has_frame(MovieCache *cache, void *userkey)
{
  MovieCacheKey key;
  MovieCacheItem *item;

  key.cache_owner = cache;
  key.userkey = userkey;
  item = (MovieCacheItem *)BLI_ghash_lookup(cache->hash, &key);

  return item != nullptr;
}

void IMB_moviecache_free(MovieCache *cache)
{
  PRINT("%s: cache '%s' free\n", __func__, cache->name);

  BLI_ghash_free(cache->hash, moviecache_keyfree, moviecache_valfree);

  BLI_mempool_destroy(cache->keys_pool);
  BLI_mempool_destroy(cache->items_pool);
  BLI_mempool_destroy(cache->userkeys_pool);

  if (cache->points) {
    MEM_freeN(cache->points);
  }

  if (cache->last_userkey) {
    MEM_freeN(cache->last_userkey);
  }

  MEM_freeN(cache);
}

void IMB_moviecache_cleanup(MovieCache *cache,
                            bool(cleanup_check_cb)(ImBuf *ibuf, void *userkey, void *userdata),
                            void *userdata)
{
  GHashIterator gh_iter;

  check_unused_keys(cache);

  BLI_ghashIterator_init(&gh_iter, cache->hash);

  while (!BLI_ghashIterator_done(&gh_iter)) {
    MovieCacheKey *key = (MovieCacheKey *)BLI_ghashIterator_getKey(&gh_iter);
    MovieCacheItem *item = (MovieCacheItem *)BLI_ghashIterator_getValue(&gh_iter);

    BLI_ghashIterator_step(&gh_iter);

    if (cleanup_check_cb(item->ibuf, key->userkey, userdata)) {
      PRINT("%s: cache '%s' remove item %p\n", __func__, cache->name, item);

      BLI_ghash_remove(cache->hash, key, moviecache_keyfree, moviecache_valfree);
    }
  }
}

void IMB_moviecache_get_cache_segments(
    MovieCache *cache, int proxy, int render_flags, int *r_totseg, int **r_points)
{
  *r_totseg = 0;
  *r_points = nullptr;

  if (!cache->getdatafp) {
    return;
  }

  if (cache->proxy != proxy || cache->render_flags != render_flags) {
    MEM_SAFE_FREE(cache->points);
  }

  if (cache->points) {
    *r_totseg = cache->totseg;
    *r_points = cache->points;
  }
  else {
    int totframe = BLI_ghash_len(cache->hash);
    int *frames = (int *)MEM_callocN(totframe * sizeof(int), "movieclip cache frames");
    int a, totseg = 0;
    GHashIterator gh_iter;

    a = 0;
    GHASH_ITER (gh_iter, cache->hash) {
      MovieCacheKey *key = (MovieCacheKey *)BLI_ghashIterator_getKey(&gh_iter);
      MovieCacheItem *item = (MovieCacheItem *)BLI_ghashIterator_getValue(&gh_iter);
      int framenr, curproxy, curflags;

      if (item->ibuf) {
        cache->getdatafp(key->userkey, &framenr, &curproxy, &curflags);

        if (curproxy == proxy && curflags == render_flags) {
          frames[a++] = framenr;
        }
      }
    }

    qsort(frames, totframe, sizeof(int), compare_int);

    /* count */
    for (a = 0; a < totframe; a++) {
      if (a && frames[a] - frames[a - 1] != 1) {
        totseg++;
      }

      if (a == totframe - 1) {
        totseg++;
      }
    }

    if (totseg) {
      int b, *points;

      points = (int *)MEM_callocN(sizeof(int[2]) * totseg, "movieclip cache segments");

      /* fill */
      for (a = 0, b = 0; a < totframe; a++) {
        if (a == 0) {
          points[b++] = frames[a];
        }

        if (a && frames[a] - frames[a - 1] != 1) {
          points[b++] = frames[a - 1];
          points[b++] = frames[a];
        }

        if (a == totframe - 1) {
          points[b++] = frames[a];
        }
      }

      *r_totseg = totseg;
      *r_points = points;

      cache->totseg = totseg;
      cache->points = points;
      cache->proxy = proxy;
      cache->render_flags = render_flags;
    }

    MEM_freeN(frames);
  }
}

struct MovieCacheIter *IMB_moviecacheIter_new(MovieCache *cache)
{
  GHashIterator *iter;

  check_unused_keys(cache);
  iter = BLI_ghashIterator_new(cache->hash);

  return (struct MovieCacheIter *)iter;
}

void IMB_moviecacheIter_free(struct MovieCacheIter *iter)
{
  BLI_ghashIterator_free((GHashIterator *)iter);
}

bool IMB_moviecacheIter_done(struct MovieCacheIter *iter)
{
  return BLI_ghashIterator_done((GHashIterator *)iter);
}

void IMB_moviecacheIter_step(struct MovieCacheIter *iter)
{
  BLI_ghashIterator_step((GHashIterator *)iter);
}

ImBuf *IMB_moviecacheIter_getImBuf(struct MovieCacheIter *iter)
{
  MovieCacheItem *item = (MovieCacheItem *)BLI_ghashIterator_getValue((GHashIterator *)iter);
  return item->ibuf;
}

void *IMB_moviecacheIter_getUserKey(struct MovieCacheIter *iter)
{
  MovieCacheKey *key = (MovieCacheKey *)BLI_ghashIterator_getKey((GHashIterator *)iter);
  return key->userkey;
}