chapterAssembler.js

module.exports = (bookCode, chapterCode, lang, shallAddChapterNumber) => {
  const { readFile } = require("./fileSystemOperator");
  const {
    getTextArrayFormatted,
    addChapterNumber,
  } = require("./textManipulator");
  const { isOdd } = require("./mathUtils");
  const generateVoiceFile = require("./voiceGenerator");
  const combineVoiceFiles = require("./audioFilesCombinator");

  const {
    INPUT_FOLDER,
    SONGS_FOLDER,
    OUTPUT_FOLDER,
    AUDIO_EXTENSION,
    getVoices,
    getTextDelimiter,
  } = require("./constants");
  let VOICES = getVoices(lang);
  let DELIMITERS = getTextDelimiter(lang);

  const filename = `${bookCode}/${bookCode}_${chapterCode}`;

  readFile(filename, (text) => {
    console.log(`${filename} read succesfully.`);

    const getSongPath = (name) =>
      `${INPUT_FOLDER}/${bookCode}/${SONGS_FOLDER}/${name}.${AUDIO_EXTENSION}`;
    const openingSong = getSongPath("opening");
    const closureSong = getSongPath("closure");

    let segmentsFilenames = [openingSong];

    if (shallAddChapterNumber) {
      text = addChapterNumber(filename, text, DELIMITERS.CHAPTER_TITLE);
    }

    let currentVoiceIndex = 0;
    const formattedTextArray = getTextArrayFormatted(text).reduce(
      (accumulator, item) => {
        if (item.trim().length > 0) {
          let voice = VOICES.NARRATOR;
          const length = item.length;
          const firstLetter = item[0];
          const dialogueStartDelimiter = /(?<= )\-/;

          const startsWith = (word) =>
            length > word.length && item.substring(0, word.length) === word;

          if (
            firstLetter === "*" ||
            startsWith(DELIMITERS.AUTHORS) ||
            startsWith(DELIMITERS.CHAPTER_TITLE) ||
            startsWith(DELIMITERS.BOOK_TITLE)
          ) {
            voice = VOICES.INTRO;
          } else if (firstLetter === "-" || dialogueStartDelimiter.test(item)) {
            voice = VOICES.DIALOGUE[currentVoiceIndex];
            currentVoiceIndex = currentVoiceIndex === 0 ? 1 : 0;
          }

          const subSegmentArray = item.split("-");

          subSegmentArray.forEach((subSegmentItem, index) => {
            if (subSegmentItem.trim().length > 0) {
              accumulator.push({
                text: subSegmentItem,
                voice:
                  subSegmentArray.length === 1 || isOdd(index)
                    ? voice
                    : VOICES.NARRATOR,
              });
            }
          });
        }

        return accumulator;
      },
      []
    );

    let formattedTextIndex = 0;

    const iterate = () => {
      const callback = () => {
        formattedTextIndex++;

        if (formattedTextIndex < formattedTextArray.length) {
          iterate();
        } else {
          // End of iteration
          segmentsFilenames.push(closureSong);

          combineVoiceFiles(
            bookCode,
            segmentsFilenames,
            `${OUTPUT_FOLDER}/${filename}.${AUDIO_EXTENSION}`
          );
        }
      };

      const segment = formattedTextArray[formattedTextIndex];
      const segmentFilename = `${filename}_${formattedTextIndex}`;
      const segmentFilePath = `${OUTPUT_FOLDER}/${segmentFilename}.${AUDIO_EXTENSION}`;
      segmentsFilenames.push(segmentFilePath);

      generateVoiceFile(segment.text, segmentFilePath, segment.voice, callback);
    };

    iterate();
  });
};