rochars / wavefile

 * Copyright (c) 2017-2019 Rafael da Silva Rocha.

 *

 * Permission is hereby granted, free of charge, to any person obtaining

 * a copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sublicense, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice shall be

 * included in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 *

 */

/**

 * @fileoverview The WaveFileTagEditor class.

 * @see https://github.com/rochars/wavefile

 */

import { WaveFileCreator } from './wavefile-creator';

/**

 * A class to edit meta information in wav files.

 * @extends WaveFileCreator

 * @ignore

 */

export class WaveFileTagEditor extends WaveFileCreator {

  /**

   * Return the value of a RIFF tag in the INFO chunk.

   * @param {string} tag The tag name.

   * @return {?string} The value if the tag is found, null otherwise.

   */

  getTag(tag) {

    /** @type {!Object} */

    let index = this.getTagIndex_(tag);

    if (index.TAG !== null) {

      return this.LIST[index.LIST].subChunks[index.TAG].value;

    }

    return null;

  }

  /**

   * Write a RIFF tag in the INFO chunk. If the tag do not exist,

   * then it is created. It if exists, it is overwritten.

   * @param {string} tag The tag name.

   * @param {string} value The tag value.

   * @throws {Error} If the tag name is not valid.

   */

  setTag(tag, value) {

    tag = fixRIFFTag_(tag);

    /** @type {!Object} */

    let index = this.getTagIndex_(tag);

    if (index.TAG !== null) {

      this.LIST[index.LIST].subChunks[index.TAG].chunkSize =

        value.length + 1;

      this.LIST[index.LIST].subChunks[index.TAG].value = value;

    } else if (index.LIST !== null) {

      this.LIST[index.LIST].subChunks.push({

        chunkId: tag,

        chunkSize: value.length + 1,

        value: value});

    } else {

      this.LIST.push({

        chunkId: 'LIST',

        chunkSize: 8 + value.length + 1,

        format: 'INFO',

        subChunks: []});

      this.LIST[this.LIST.length - 1].subChunks.push({

        chunkId: tag,

        chunkSize: value.length + 1,

        value: value});

    }

  }

  /**

   * Remove a RIFF tag from the INFO chunk.

   * @param {string} tag The tag name.

   * @return {boolean} True if a tag was deleted.

   */

  deleteTag(tag) {

    /** @type {!Object} */

    let index = this.getTagIndex_(tag);

    if (index.TAG !== null) {

      this.LIST[index.LIST].subChunks.splice(index.TAG, 1);

      return true;

    }

    return false;

  }

  /**

   * Return a Object<tag, value> with the RIFF tags in the file.

   * @return {!Object<string, string>} The file tags.

   */

  listTags() {

    /** @type {?number} */

    let index = this.getLISTIndex('INFO');

    /** @type {!Object} */

    let tags = {};

    if (index !== null) {

      for (let i = 0, len = this.LIST[index].subChunks.length; i < len; i++) {

        tags[this.LIST[index].subChunks[i].chunkId] =

          this.LIST[index].subChunks[i].value;

      }

    }

    return tags;

  }

  /**

   * Return the index of a list by its type.

   * @param {string} listType The list type ('adtl', 'INFO')

   * @return {?number}

   * @protected

   */

  /**

   * Return the index of a tag in a FILE chunk.

   * @param {string} tag The tag name.

   * @return {!Object<string, ?number>}

   *    Object.LIST is the INFO index in LIST

   *    Object.TAG is the tag index in the INFO

   * @private

   */

  getTagIndex_(tag) {

    /** @type {!Object<string, ?number>} */

    let index = {LIST: null, TAG: null};

    for (let i = 0, len = this.LIST.length; i < len; i++) {

      if (this.LIST[i].format == 'INFO') {

        index.LIST = i;

        for (let j=0, subLen = this.LIST[i].subChunks.length; j < subLen; j++) {

          if (this.LIST[i].subChunks[j].chunkId == tag) {

            index.TAG = j;

            break;

          }

        }

        break;

      }

    }

    return index;

  }

}

/**

 * Fix a RIFF tag format if possible, throw an error otherwise.

 * @param {string} tag The tag name.

 * @return {string} The tag name in proper fourCC format.

 * @private

 */

function fixRIFFTag_(tag) {

  if (tag.constructor !== String) {

    throw new Error('Invalid tag name.');

  } else if (tag.length < 4) {

    for (let i = 0, len = 4 - tag.length; i < len; i++) {

      tag += ' ';

    }

  }

  return tag;

}