wba/frontend/src/js/misc/wb-manifest-reader.js

function mkdir(parent, name) {
  if (name in parent && (parent[name] instanceof Array))
    throw Error('File with the same name already exists');
  if (name in parent)
    return parent[name];
  const dir = {};
  parent[name] = dir;
  return dir;
}

function mkpath(parent, path) {
  if (typeof(path) === 'string')
    path = path.split('/');
  let dir = parent;
  for (let i = 1; i < path.length; i++) {
    dir = mkdir(dir, path[i]);
  }
  return dir;
}

function appendFile(dir, name, sidx, seg) {
  if (name in dir && (!(dir[name] instanceof Array)))
    throw Error('Directory with the same name already exists');
  if (!(name in dir))
    dir[name] = [];
  const f = dir[name];
  f.push([ sidx, seg[0], seg[1] ]);
  return f;
}

function process(streams) {
  const rootDir = {};

  streams.map((s, sidx) => {
    const [ streamName, locators, segments ] = s;
    const streamDir = mkpath(rootDir, streamName);
    segments.map((seg, segidx) => {
      let name = seg[2].split('/');
      const dir = (name.length === 1 ? streamDir :
        mkpath(streamDir, ['.'].concat(name.slice(0, name.length - 1))));
      name = name[name.length - 1];
      appendFile(dir, name, sidx, seg);
    });
  });

  return rootDir;
}

function parse(manifestText) {
  const M_STREAM_NAME = 0;
  const M_LOCATORS = 1;
  const M_FILE_SEGMENTS = 2;

  let mode = M_STREAM_NAME;

  const streams = [];
  let locators = [];
  let segments = [];

  let streamName;
  let accum = '';
  let tokenStart = 0;

  for (let i = 0; i < manifestText.length; i++) {
    const c = manifestText[i];

    if (mode === M_STREAM_NAME) {
      if (c === ' ') {
        mode = M_LOCATORS;
        streamName = accum;
        accum = '';
        tokenStart = i + 1;
      } else {
        accum += c;
      }

    } else if (mode === M_LOCATORS) {
      if (c === ':') {
        mode = M_FILE_SEGMENTS;
        accum = '';
        i = tokenStart - 1;
        let pos = 0;
        locators = locators.map(loc => {
          const r = loc.concat([ pos, pos + loc[1] ]);
          pos += loc[1];
          return r;
        });
      } else if (c === ' ') {
        const sz = Number(accum.split('+')[1]);
        locators.push([accum, sz]);
        accum = '';
        tokenStart = i + 1;
      } else {
        accum += c;
      }

    } else if (mode === M_FILE_SEGMENTS) {
      if (c === ' ' || c === '\n') {
        let seg = accum.split(':');
        seg = [Number(seg[0]), Number(seg[1]), seg[2]];
        segments.push(seg);
        accum = '';
        tokenStart = i + 1;
        if (c === '\n') {
          streams.push([streamName, locators, segments]);
          locators = [];
          segments = [];
          mode = M_STREAM_NAME;
        }
      } else {
        accum += c;
      }

    }
  }

  return streams;
}

class WBManifestReader {
  constructor(manifestText) {
    this.streams = parse(manifestText);
    this.rootDir = process(this.streams);
  }
}

export default WBManifestReader;