import { Base } from "./base";
import * as json from "./json";
import { IndexedObjects, IndexedStrings } from "./types";

/**
 * Wrapper for HASHMAP Redis storage.
 * Mocks JavaScript Maps and has most of the Map's methods.
 *
 * @example
 * let human = new Hash(client, 'human', useJSON = true);
 * await human.set('alice', { isHuman: 'definitely' });
 * await human.set('damir', { isHuman: 'could be' });
 */
export class Hash<T> extends Base {
  /**
   * Get the length of the hash (keys length)
   *
   * - Redis command: [HLEN] {@link https://redis.io/commands/hlen}
   * - JavaScript analogy: [Map.prototype.size] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/size}
   */
  size(): Promise<number> {
    return this.call("HLEN")();
  }

  /**
   * Get array of keys in the hash
   *
   * - Redis command: [HKEYS] {@link https://redis.io/commands/hkeys}
   * - JavaScript analogy: [Map.prototype.keys] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/keys}
   */
  keys(): Promise<string[]> {
    return this.call("HKEYS")();
  }

  /**
   * Delete element in hash by it's key
   *
   * - Redis command: [HDEL] {@link https://redis.io/commands/hdel}
   * - JavaScript analogy: [Map.prototype.delete] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/delete}
   *
   * @param  {String}  key Name of the key to delete
   */
  delete(key: string): Promise<void> {
    return this.call("HDEL")(key);
  }

  /**
   * Check whether key exists in hash
   *
   * - Redis command: [HEXISTS] {@link https://redis.io/commands/hexists}
   * - JavaScript analogy: [Map.prototype.has] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/has}
   *
   * @param {String} key Key to check
   */
  has(key: string): Promise<boolean> {
    return this.call("HEXISTS")(key).then((e: any) => !!e);
  }

  /**
   * Set value under given key
   *
   * - Redis command: [HSET] {@link https://redis.io/commands/hset}
   * - JavaScript analogy: [Map.prototype.set] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/set}
   *
   * @param  {String}  key   Key to set
   * @param  {String}  value Value to set under given key
   */
  set(key: string, value: T): Promise<void> {
    return this.useJSON
      ? this.call("HSET")(key, json.toJSON(value))
      : this.call("HSET")(key, value);
  }

  /**
   * Get value by it's key
   *
   * - Redis command: [HGET] {@link https://redis.io/commands/hget}
   * - JavaScript analogy: [Map.prototype.get] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/get}
   *
   * @param  {String} key Key to get from hash
   */
  get(key: string): Promise<T> {
    return this.useJSON
      ? this.call("HGET")(key).then(json.parse)
      : this.call("HGET")(key);
  }

  /**
   * Get array of values from the hash
   *
   * - Redis command: [HVALS] {@link https://redis.io/commands/hvals}
   * - JavaScript analogy: [Map.prototype.values] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/values}
   */
  values(): Promise<T[]> {
    return this.useJSON
      ? this.call("HVALS")().then(json.parseArray)
      : this.call("HVALS")();
  }

  /**
   * Returns 2-dimensional array of kind:
   *
   * ```JavaScript
   * [[key1, value1], [key2, value2]]
   * ```
   * To support Object to Map transformation
   *
   * - Redis command: [HGETALL] {@link https://redis.io/commands/hgetall}
   * - JavaScript analogy: [Map.prototype.entries] {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/entries}
   *
   */
  entries(): Promise<[string, T][]> {
    return this.getAll().then(function(obj) {
      if (obj === null) {
        return [];
      }

      return Object.keys(obj).map(function(key) {
        return [key, obj[key]];
      });
    });
  }

  /**
   * Get multiple keys by passing an array of keys
   * This command has no analogy in JS
   *
   * - Redis command: [HMGET] {@link https://redis.io/commands/hmget}
   * - JavaScript analogy: none
   *
   * @param {String[]} keys Keys to get values for
   */
  getMul(keys: string[]): Promise<T[]> {
    return this.useJSON
      ? this.call("HMGET")(keys).then(json.parseArray)
      : this.call("HMGET")(keys);
  }

  /**
   * Returns object representing hash structure
   * This command has no analogy in JS
   *
   * - Redis command: [HGETALL] {@link https://redis.io/commands/hgetall}
   * - JavaScript analogy: none
   */
  getAll(): Promise<{ [key: string]: T }> {
    return this.useJSON
      ? this.call("HGETALL")().then(json.parseObjectValues)
      : this.call("HGETALL")();
  }

  /**
   * Set multiple keys by passing an object with key-value structure
   * This command has no analogy in JS
   *
   * - Redis command: [HMSET] {@link https://redis.io/commands/hmset}
   * - JavaScript analogy: none
   *
   * @param   {Object}  valuesObj Object with key-value pairs to set
   * @returns {Promise}
   */
  setMul(valuesObj: { [key: string]: T }) {
    return this.useJSON
      ? this.call("HMSET")(json.stringifyObjectValues(valuesObj))
      : this.call("HMSET")(valuesObj);
  }
}