//
// Copyright (C) Stanislaw Adaszewski, 2020
// Contact: s.adaszewski@gmail.com
// Website: https://adared.ch/wba
// License: GNU Affero General Public License, Version 3
//

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; }
    case 'getData':
      postMessage([ 'getDataResult', rootDir, streams ]);
      break;
    case 'getFile':
      postMessage([ 'getFileResult', getFile(rootDir, streams, e.data[1]) ]);
      break;
    default: {
      const err = Error('Unknown verb: ' + e.data[0]);
      postMessage([ 'error', err.message ]);
      throw err; }
  }
}

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;
}

function getFile(rootDir, streams, path) {
  if (typeof(path) === 'string')
    path = path.split('/');

  if (path.length < 2)
    throw Error('Invalid file path');

  const name = path[path.length - 1];

  const dir = findDir(rootDir, path.slice(0, path.length - 1));

  if (!(name in dir))
    throw Error('File not found');

  if (!(dir[name] instanceof Array))
    throw Error('Path points to a directory not a file');

  let file = dir[name];
  file = [ file[0].map(seg => {
    const stm = streams[seg[0]];
    const used = stm.map(loc => !( loc[2] <= seg[1] || loc[1] >= seg[1] + seg[2] ) );
    const start = used.indexOf(true);
    const end = used.lastIndexOf(true) + 1;
    if (start === -1)
      return [];
    const res = [];
    for (let i = start; i < end; i++) {
      const loc = stm[i];
      res.push([ loc[0], Math.max(0, seg[1] - loc[1]),
        Math.min(loc[2] - loc[1], seg[1] + seg[2] - loc[1]) ]);
    }
    return res;
  }), file[1] ];
  file[0] = file[0].reduce((a, b) => a.concat(b));

  return file;
}