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

#include "common.h"
#include "env.h"
#include "hashtable.h"

#define ENV_TABLE_CAP (1 << 8)

static unsigned long str_hash(char *str)
{      
    unsigned long hash = 5381;
    int c;

    while ((c = *str++))
        hash = ((hash << 5) + hash) + c; /* hash * 33 + c */

    return hash;
}

static size_t hash(void *key)
{
    return str_hash((char*)key);
}

static bool equal(void *key1, void *key2)
{
    if(strcmp((char *)key1, (char*)key2) == 0) {
        return true;
    }

    return false;
}

static void env_add_ref(env_t env);

env_t env_create(env_t parent, env_destroy_func destroy_func)
{
    env_t env = malloc(sizeof(*env));
    env->destroy_func = destroy_func;
    env->parent = parent;
    env->refs = 0;
    
    env_add_ref(env);

    ERR_Z(env->table = hashtable_create(ENV_TABLE_CAP, hash, equal),
          env_destroy(env));
    
    return env;
}

void env_destroy(env_t env)
{
    if(!env) return;
    
    env->refs--;
    env_destroy(env->parent);
    
    if(env->refs > 0) return;


    hashtable_for_each_item(env->table, item, i) {
        env->destroy_func((char *)item->key, (value_t)item->data);
    }

    hashtable_destroy(env->table);
    free(env);
}


static void env_add_ref(env_t env)
{
    env->refs++;
    
    if(env->parent) {
        env_add_ref(env->parent);
    }
}