/**
 * Copyright 2015 CANAL+ Group
 *
 * 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.
 */

import { concat, itobe4, itobe8 } from "../../../utils/byte_parsing";
import { strToUtf8 } from "../../../utils/string_parsing";
import { MAX_32_BIT_INT } from "./constants";

/**
 * Speed up string to bytes conversion by memorizing the result
 *
 * The keys here are ISOBMFF box names. The values are the corresponding
 * bytes conversion for putting as an ISOBMFF boxes.
 *
 * Used by the boxName method.
 * @type {Object}
 */
const boxNamesMem: { [boxName: string]: Uint8Array } = {};

/**
 * Convert the string name of an ISOBMFF box into the corresponding bytes.
 * Has a memorization mechanism to speed-up if you want to translate the
 * same string multiple times.
 * @param {string} str
 * @returns {Uint8Array}
 */
function boxName(str: string): Uint8Array {
  if (boxNamesMem[str] !== undefined) {
    return boxNamesMem[str];
  }

  const nameInBytes = strToUtf8(str);
  boxNamesMem[str] = nameInBytes;
  return nameInBytes;
}

/**
 * Create a new ISOBMFF "box" with the given name.
 * @param {string} name - name of the box you want to create, must always
 * be 4 characters (uuid boxes not supported)
 * @param {Uint8Array} buff - content of the box
 * @returns {Uint8Array} - The entire ISOBMFF box (length+name+content)
 */
function createBox(name: string, buff: Uint8Array): Uint8Array {
  const len = buff.length + 8;
  return len <= MAX_32_BIT_INT
    ? concat(itobe4(len), boxName(name), buff)
    : concat(itobe4(1), boxName(name), itobe8(len + 8), buff);
}

/**
 * @param {string} name
 * @param {Array.<Uint8Array>} children
 * @returns {Uint8Array}
 */
function createBoxWithChildren(name: string, children: Uint8Array[]): Uint8Array {
  return createBox(name, concat(...children));
}

export { createBox, createBoxWithChildren };