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

const rx = /^[a-f0-9]{32}\+[0-9]+/;
const rootDir = {};
const streams = [];

onmessage = function(e) {
  switch (e.data[0]) {
  case 'precreatePaths':
    precreatePaths(e.data[1]);
    postMessage([ 'precreatePathsResult' ]);
    break;
  case 'parseStream':
    parseStream(e.data[1]);
    postMessage([ 'parseStreamResult' ]);
    break;
  case 'listDirectory': {
    const lst = listDirectory(rootDir, e.data[1], e.data[2]);
    postMessage([ 'listDirectoryResult', lst ])
    break; }
  default:
    throw Error('Unknown verb: ' + e.data[0]);
  }
}

function precreatePaths(paths) {
  for (let i = 0; i < paths.length; i++) {
    mkpath(rootDir, paths[i]);
  }
}

function parseStream(s) {
  if (!s) return;

  const tokens = s.split(' ');
  const streamName = unescapeName(tokens[0]);

  let n = tokens.map(t => rx.exec(t));
  n = n.indexOf(null, 1);

  let locators = tokens.slice(1, n);
  let pos = 0;
  locators = locators.map(loc => {
    const sz = parseInt(loc.split('+')[1], 10);
    return [ loc, pos, pos += sz ];
  });

  let fileTokens = tokens.slice(n);
  let lastFile = null;
  let lastPath = null;
  fileTokens.map(t => {
    let seg = t.split(':');
    seg = [ parseInt(seg[0], 10), parseInt(seg[1], 10),
      unescapeName(seg.slice(2).join(':')) ]
    const path = streamName + '/' + seg[2];
    let f;
    if (path === lastPath) {
      f = lastFile;
    } else {
      let dirName = path.split('/');
      const name = dirName[dirName.length - 1];
      dirName = dirName.slice(0, dirName.length - 1);
      const d = mkpath(rootDir, dirName);
      lastFile = f = makeFile(d, name);
      lastPath = path;
    }
    appendFile(f, streams.length, seg);
  });

  streams.push(locators);
}

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 makeFile(dir, name) {
  if (name in dir) {
    if (!(dir[name] instanceof Array))
      throw Error('Directory with the same name already exists');
    return dir[name];
  }
  const f = [[], 0];
  dir[name] = f;
  return f;
}

function appendFile(f, sidx, seg) {
  f[0].push([ sidx, seg[0], seg[1] ]);
  f[1] += seg[1];
  return f;
}

function unescapeName(name) {
  return name.replace(/(\\\\|\\[0-9]{3})/g,
    (_, $1) => ($1 === '\\\\' ? '\\' : String.fromCharCode(parseInt($1.substr(1), 8))));
}

function findDir(parent, path, lenient=false) {
  if (typeof(path) === 'string')
    path = path.split('/');
  if (path[0] !== '.')
    throw Error('Path must start with a dot (.)');
  let dir = parent;
  for (let i = 1; i < path.length; i++) {
    if (!(path[i] in dir)) {
      if (lenient)
        return {};
      else
        throw Error('Directory not found');
    }
    dir = dir[path[i]];
  }
  return dir;
}

function listDirectory(rootDir, path, lenient=false) {
  let dir = findDir(rootDir, path, lenient);
  let keys = Object.keys(dir);
  keys.sort();
  let subdirs = keys.filter(k => !(dir[k] instanceof Array));
  let files = keys.filter(k => (dir[k] instanceof Array));
  let res = subdirs.map(k => [ 'd', k, null ]);
  res = res.concat(files.map(k => [ 'f', k, dir[k][1] ]));
  return res;
}