/******************************************************************************
 *
 *  Copyright (C) 2014 Google, Inc.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at:
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 ******************************************************************************/

#include <assert.h>

#include "osi/include/allocator.h"
#include "osi/include/hash_map.h"
#include "osi/include/list.h"
#include "osi/include/osi.h"

struct hash_map_t;

typedef struct hash_map_bucket_t {
  list_t *list;
} hash_map_bucket_t;

typedef struct hash_map_t {
  hash_map_bucket_t *bucket;
  size_t num_bucket;
  size_t hash_size;
  hash_index_fn hash_fn;
  key_free_fn key_fn;
  data_free_fn data_fn;
  const allocator_t *allocator;
  key_equality_fn keys_are_equal;
} hash_map_t;

// Hidden constructor for list, only to be used by us.
list_t *list_new_internal(list_free_cb callback, const allocator_t *zeroed_allocator);

static void bucket_free_(void *data);
static bool default_key_equality(const void *x, const void *y);
static hash_map_entry_t *find_bucket_entry_(list_t *hash_bucket_list,
    const void *key);

// Hidden constructor, only to be used by the allocation tracker. Behaves the same as
// |hash_map_new|, except you get to specify the allocator.
hash_map_t *hash_map_new_internal(
    size_t num_bucket,
    hash_index_fn hash_fn,
    key_free_fn key_fn,
    data_free_fn data_fn,
    key_equality_fn equality_fn,
    const allocator_t *zeroed_allocator) {
  assert(hash_fn != NULL);
  assert(num_bucket > 0);
  assert(zeroed_allocator != NULL);

  hash_map_t *hash_map = zeroed_allocator->alloc(sizeof(hash_map_t));
  if (hash_map == NULL)
    return NULL;

  hash_map->hash_fn = hash_fn;
  hash_map->key_fn = key_fn;
  hash_map->data_fn = data_fn;
  hash_map->allocator = zeroed_allocator;
  hash_map->keys_are_equal = equality_fn ? equality_fn : default_key_equality;

  hash_map->num_bucket = num_bucket;
  hash_map->bucket = zeroed_allocator->alloc(sizeof(hash_map_bucket_t) * num_bucket);
  if (hash_map->bucket == NULL) {
    zeroed_allocator->free(hash_map);
    return NULL;
  }
  return hash_map;
}

hash_map_t *hash_map_new(
    size_t num_bucket,
    hash_index_fn hash_fn,
    key_free_fn key_fn,
    data_free_fn data_fn,
    key_equality_fn equality_fn) {
  return hash_map_new_internal(num_bucket, hash_fn, key_fn, data_fn, equality_fn, &allocator_calloc);
}

void hash_map_free(hash_map_t *hash_map) {
  if (hash_map == NULL)
    return;
  hash_map_clear(hash_map);
  hash_map->allocator->free(hash_map->bucket);
  hash_map->allocator->free(hash_map);
}

bool hash_map_is_empty(const hash_map_t *hash_map) {
  assert(hash_map != NULL);
  return (hash_map->hash_size == 0);
}

size_t hash_map_size(const hash_map_t *hash_map) {
  assert(hash_map != NULL);
  return hash_map->hash_size;
}

size_t hash_map_num_buckets(const hash_map_t *hash_map) {
  assert(hash_map != NULL);
  return hash_map->num_bucket;
}

bool hash_map_has_key(const hash_map_t *hash_map, const void *key) {
  assert(hash_map != NULL);

  hash_index_t hash_key = hash_map->hash_fn(key) % hash_map->num_bucket;
  list_t *hash_bucket_list = hash_map->bucket[hash_key].list;

  hash_map_entry_t *hash_map_entry = find_bucket_entry_(hash_bucket_list, key);
  return (hash_map_entry != NULL);
}

bool hash_map_set(hash_map_t *hash_map, const void *key, void *data) {
  assert(hash_map != NULL);
  assert(data != NULL);

  hash_index_t hash_key = hash_map->hash_fn(key) % hash_map->num_bucket;

  if (hash_map->bucket[hash_key].list == NULL) {
    hash_map->bucket[hash_key].list = list_new_internal(bucket_free_, hash_map->allocator);
    if (hash_map->bucket[hash_key].list == NULL)
        return false;
  }
  list_t *hash_bucket_list = hash_map->bucket[hash_key].list;

  hash_map_entry_t *hash_map_entry = find_bucket_entry_(hash_bucket_list, key);

  if (hash_map_entry) {
    // Calls hash_map callback to delete the hash_map_entry.
    UNUSED_ATTR bool rc = list_remove(hash_bucket_list, hash_map_entry);
    assert(rc == true);
  } else {
    hash_map->hash_size++;
  }
  hash_map_entry = hash_map->allocator->alloc(sizeof(hash_map_entry_t));
  if (hash_map_entry == NULL)
    return false;

  hash_map_entry->key = key;
  hash_map_entry->data = data;
  hash_map_entry->hash_map = hash_map;

  return list_append(hash_bucket_list, hash_map_entry);
}

bool hash_map_erase(hash_map_t *hash_map, const void *key) {
  assert(hash_map != NULL);

  hash_index_t hash_key = hash_map->hash_fn(key) % hash_map->num_bucket;
  list_t *hash_bucket_list = hash_map->bucket[hash_key].list;

  hash_map_entry_t *hash_map_entry = find_bucket_entry_(hash_bucket_list, key);
  if (hash_map_entry == NULL) {
    return false;
  }

  hash_map->hash_size--;

  return list_remove(hash_bucket_list, hash_map_entry);
}

void *hash_map_get(const hash_map_t *hash_map, const void *key) {
  assert(hash_map != NULL);

  hash_index_t hash_key = hash_map->hash_fn(key) % hash_map->num_bucket;
  list_t *hash_bucket_list = hash_map->bucket[hash_key].list;

  hash_map_entry_t *hash_map_entry = find_bucket_entry_(hash_bucket_list, key);
  if (hash_map_entry != NULL)
    return hash_map_entry->data;

  return NULL;
}

void hash_map_clear(hash_map_t *hash_map) {
  assert(hash_map != NULL);

  for (hash_index_t i = 0; i < hash_map->num_bucket; i++){
    if (hash_map->bucket[i].list == NULL)
      continue;
    list_free(hash_map->bucket[i].list);
    hash_map->bucket[i].list = NULL;
  }
}

void hash_map_foreach(hash_map_t *hash_map, hash_map_iter_cb callback, void *context) {
  assert(hash_map != NULL);
  assert(callback != NULL);

  for (hash_index_t i = 0; i < hash_map->num_bucket; ++i){
    if (hash_map->bucket[i].list == NULL)
      continue;
    for (const list_node_t *iter = list_begin(hash_map->bucket[i].list);
        iter != list_end(hash_map->bucket[i].list);
        iter = list_next(iter)) {
       hash_map_entry_t *hash_map_entry = (hash_map_entry_t *)list_node(iter);
       if (!callback(hash_map_entry, context))
        return;
    }
  }
}

static void bucket_free_(void *data) {
  assert(data != NULL);
  hash_map_entry_t *hash_map_entry = (hash_map_entry_t *)data;
  const hash_map_t *hash_map = hash_map_entry->hash_map;

  if (hash_map->key_fn)
    hash_map->key_fn((void *)hash_map_entry->key);
  if (hash_map->data_fn)
    hash_map->data_fn(hash_map_entry->data);
  hash_map->allocator->free(hash_map_entry);
}

static hash_map_entry_t * find_bucket_entry_(list_t *hash_bucket_list,
    const void *key) {

  if (hash_bucket_list == NULL)
    return NULL;

  for (const list_node_t *iter = list_begin(hash_bucket_list);
      iter != list_end(hash_bucket_list);
      iter = list_next(iter)) {
    hash_map_entry_t *hash_map_entry = (hash_map_entry_t *)list_node(iter);
    if (hash_map_entry->hash_map->keys_are_equal(hash_map_entry->key, key)) {
      return hash_map_entry;
    }
  }
  return NULL;
}

static bool default_key_equality(const void *x, const void *y) {
  return x == y;
}
