#include <stdlib.h>
#include <string.h>

#include <hexagram/dict.h>
#include <hexagram/hash.h>

hexagram_dict *hexagram_dict_new() {
    hexagram_dict *dict;

    if ((dict = malloc(sizeof(*dict))) == NULL) {
        goto error_malloc_dict;
    }

    memset(dict, 0x00, sizeof(*dict));

    if ((dict->bucket = malloc(sizeof(*dict->bucket))) == NULL) {
        goto error_malloc_dict_bucket;
    }

    memset(dict->bucket, 0x00, sizeof(*dict->bucket));

    return dict;

error_malloc_dict_bucket:
    free(dict);

error_malloc_dict:
    return NULL;
}

static void bucket_destroy(hexagram_dict *dict, hexagram_dict_bucket *bucket) {
    int i;

    for (i=0; i<HEXAGRAM_DICT_BUCKET_SLOTS; i++) {
        hexagram_dict_slot *slot = &bucket->slots[i];

        if (slot->next_bucket) {
            bucket_destroy(dict, (hexagram_dict_bucket *)slot->next_bucket);
        }

        if (slot->key) {
            slot->key = NULL;
        }

        if (slot->value) {
            slot->value = NULL;
        }
    }

    free(bucket);
}

void hexagram_dict_destroy(hexagram_dict *dict) {
    bucket_destroy(dict, dict->bucket);

    free(dict);
}

static hexagram_dict_slot *slot_find_readable(hexagram_dict *dict, uint32_t hash) {
    hexagram_dict_bucket *bucket = dict->bucket;

    int collisions;

    for (collisions = 0; collisions < HEXAGRAM_DICT_BUCKET_DEPTH; collisions++) {
        uint32_t mask  = 0x0f << (4 * collisions);
        uint8_t  index = (hash & mask) >> (4 * collisions);

        hexagram_dict_slot *slot = &bucket->slots[index];

        if (slot->hash == 0x00000000) {
            /*
             * In this case, we have determined that there is no value in the
             * dict for the given hash.
             */
            return NULL;
        } else if (slot->hash == hash) {
            /*
             * We have found the desired slot, so return that.
             */
            return slot;
        }

        /*
         * Otherwise, look for the next bucket, if present.
         */
        bucket = (hexagram_dict_bucket *)slot->next_bucket;

        /*
         * If there is no next bucket available, then return null.
         */
        if (bucket == NULL) {
            return NULL;
        }
    }

    return NULL;
}

static hexagram_dict_slot *slot_find_writable(hexagram_dict *dict, uint32_t hash) {
    hexagram_dict_bucket *bucket = dict->bucket;

    int collisions;

    for (collisions = 0; collisions < HEXAGRAM_DICT_BUCKET_DEPTH; collisions++) {
        uint32_t mask  = 0x0f << (4 * collisions);
        uint8_t  index = (hash & mask) >> (4 * collisions);

        hexagram_dict_slot *slot = &bucket->slots[index];

        if ((slot->hash == 0x00 && slot->key == NULL) || slot->hash == hash) {
            /*
             * We have found a suitable slot, so let's return that.
             */
            return slot;
        }

        /*
         * Take a look to see if there is a next bucket in the chain.
         */
        bucket = (hexagram_dict_bucket *)slot->next_bucket;

        /*
         * If there is no next bucket available, then create one.
         */
        if (bucket == NULL) {
            if ((bucket = malloc(sizeof(*bucket))) == NULL) {
                goto error_malloc_bucket;
            }

            memset(bucket, 0x00, sizeof(*bucket));

            slot->next_bucket = (hexagram_dict_slot *)bucket;
        }
    }

    return NULL;

error_malloc_bucket:
    return NULL;
}

static int bucket_each_slot(hexagram_dict *dict,
                            int level,
                            hexagram_dict_bucket *bucket,
                            hexagram_dict_callback *callback,
                            void *ctx) {
    int i;

    if (level > HEXAGRAM_DICT_BUCKET_DEPTH) {
        return 0;
    }

    for (i=0; i<HEXAGRAM_DICT_BUCKET_SLOTS; i++) {
        hexagram_dict_slot *slot = &bucket->slots[i];

        if (slot->next_bucket) {
            return bucket_each_slot(dict,
                                    level+1,
                                    (hexagram_dict_bucket *)slot->next_bucket,
                                    callback,
                                    ctx);
        }

        if (slot->key) {
            if (callback(dict, slot, ctx) < 0) {
                goto error_callback;
            }
        }
    }

    return 0;

error_callback:
    return -1;
}

int hexagram_dict_each(hexagram_dict *dict,
                      hexagram_dict_callback *callback,
                      void *ctx) {
    return bucket_each_slot(dict, 0, dict->bucket, callback, ctx);
}

void *hexagram_dict_get(hexagram_dict *dict,
                        void *key,
                        size_t keysz) {
    hexagram_dict_slot *slot;
    uint32_t hash;

    if (hexagram_hash(key, keysz, &hash) < 0) {
        goto error_hash;
    }

    if ((slot = slot_find_readable(dict, hash)) == NULL) {
        goto error_slot_find_readable;
    }

    return slot->value;

error_slot_find_readable:
error_hash:
    return NULL;
}

void *hexagram_dict_get_s(hexagram_dict *dict, const char *key) {
    return hexagram_dict_get(dict, (void *)key, strlen(key));
}

int hexagram_dict_delete(hexagram_dict *dict, void *key, size_t keysz) {
    hexagram_dict_slot *slot;
    uint32_t hash;

    if (hexagram_hash(key, keysz, &hash) < 0) {
        goto error_hash;
    }

    if ((slot = slot_find_readable(dict, hash)) == NULL) {
        goto error_slot_find_readable;
    }

    if (slot->key) {
        slot->key = NULL;
    }

    if (slot->value) {
        slot->value = NULL;
    }

    return 0;

error_hash:
error_slot_find_readable:
    return -1;
}

int hexagram_dict_delete_s(hexagram_dict *dict, const char *key) {
    return hexagram_dict_delete(dict, (void*)key, strlen(key));
}

void *hexagram_dict_set_with_hash(hexagram_dict *dict,
                                  void *key,
                                  void *value,
                                  uint32_t hash) {
    hexagram_dict_slot *slot;

    if ((slot = slot_find_writable(dict, hash)) == NULL) {
        goto error_slot_find_writable;
    }

    slot->hash = hash;
    slot->key  = key;

    return slot->value = value;

error_slot_find_writable:
    return NULL;
}

void *hexagram_dict_set(hexagram_dict *dict,
                        void *key,
                        size_t keysz,
                        void *value) {
    uint32_t hash;

    if (hexagram_hash(key, keysz, &hash) < 0) {
        goto error_hash;
    }

    return hexagram_dict_set_with_hash(dict, key, value, hash);

error_hash:
    return NULL;
}

void *hexagram_dict_set_s(hexagram_dict *dict, const char *key, void *value) {
    return hexagram_dict_set(dict, (void *)key, strlen(key), value);
}