/**
 * @license
 * Copyright 2021 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @fileoverview Bootstrap code to load Blockly, typically in
 *     uncompressed mode.
 *
 *     Load this file in a <script> tag in a web page to use the
 *     Closure Library debug module loader to load Blockly in
 *     uncompressed mode.
 *
 *     You must use a <script src=> tag to load this script first
 *     (after setting BLOCKLY_BOOTSTRAP_OPTIONS in a preceeding
 *     <script> tag, if desired - see below), then import
 *     bootstrap_done.mjs in a <script type=module> to wait for
 *     bootstrapping to finish.
 *
 *     See tests/playground.html for example usage.
 *
 *     Exception: for speed and compatibility reasons, if this is
 *     script is loaded in Internet Explorer or from a host other than
 *     localhost, blockly_compressed.js (et al.) will be loaded
 *     instead.  IE 11 doesn't understand modern JavaScript, and
 *     because of the sequential, non-parallel module loading carried
 *     out by thedeubg module loader can be painfully tedious over a
 *     slow network connection.  (This can be overridden by the page
 *     if desired.)
 *
 *     (Note also that this file eschews certain modern JS constructs,
 *     like template literals, for compatibility with IE 11.)
 *
 *     The bootstrap code will consult a BLOCKLY_BOOTSTRAP_OPTIONS
 *     global variable to determine what to load.  This must be set
 *     before loading this script.  See documentation inline below.
 *
 */
'use strict';

(function() {
  // Values used to compute default bootstrap options.
  const isIe = navigator.userAgent.indexOf('MSIE') !== -1 ||
      navigator.appVersion.indexOf('Trident/') > -1;
  const localhosts = ['localhost', '127.0.0.1', '[::1]'];
  const isLocalhost = localhosts.includes(location.hostname);
  const isFileUrl = location.origin === 'file://';

  // Default bootstrap options.  These can be overridden by setting
  // the same property on BLOCKLY_BOOTSTRAP_OPTIONS.
  const options = {
    // Decide whether to use compressed mode or not.  Please see issue
    // #5557 for more information.
    loadCompressed: isIe || !(isLocalhost || isFileUrl),

    // URL of the blockly repository.  This is needed for a few reasons:
    //
    // - We need an absolute path instead of relative path because the
    //   advanced_playground and the regular playground are in
    //   different folders.
    // - We need to get the root directory for blockly because it is
    //   different for github.io, appspot and local.
    //
    // Default value will work so long as top-level page is loaded
    // from somewhere in tests/.
    root: window.location.href.replace(/\/tests\/.*$/, '/'),

    // List of deps files to load.  Paths relative to root.
    depsFiles: [
      'build/deps.js',
    ],
    
    // List of goog.modules to goog.require.
    requires: [
      'Blockly',
      'Blockly.libraryBlocks',
      'Blockly.Dart.all',
      'Blockly.JavaScript.all',
      'Blockly.Lua.all',
      'Blockly.PHP.all',
      'Blockly.Python.all',
    ],

    // List of scripts to load in compressed mode, instead of
    // requires.  Paths relative to root.
    compressedScripts: [
      'blockly_compressed.js',
      'blocks_compressed.js',
      'dart_compressed.js',
      'javascript_compressed.js',
      'lua_compressed.js',
      'php_compressed.js',
      'python_compressed.js',
    ],

    // Additional scripts to be loaded after Blockly is loaded,
    // whether Blockly is loaded from compressed or uncompressed.
    // Paths relative to root.
    additionalScripts: [
      'msg/messages.js',
    ],
  };
  if (typeof window.BLOCKLY_BOOTSTRAP_OPTIONS === 'object') {
    Object.assign(options, window.BLOCKLY_BOOTSTRAP_OPTIONS);
  }

  /* eslint-disable-next-line no-undef */
  if (typeof module === 'object' && typeof module.exports === 'object') {
    // Running in node.js.  Maybe we wish to support this.
    // blockly_uncompressed formerly did, though it appears that the
    // code had not been working for some time (at least since PR
    // #5718 back in December 2021.  For now just throw an error.
    throw new Error('Bootstrapping in node.js not implemented.');
  }

  // Create a global variable to remember some state that will be
  // needed by later scripts.
  window.bootstrapInfo = {
    /** boolean */ compressed: options.loadCompressed,
    /** ?Array<string> */ requires: null,
    /** ?Promise */ done: null,
  };

  if (!options.loadCompressed) {
    // We can load Blockly in uncompressed mode.  Note that this section
    // needs to parse in IE11 (mostly ES5.1, but allowing e.g. const),
    // but it does not need to be _executable_ in IE11 - it is safe to
    // use ES6 builtins.

    // Disable loading of closure/goog/deps.js (which doesn't exist).
    window.CLOSURE_NO_DEPS = true;
    // Load the Closure Library's base.js (the only part of the
    // libary we use, mainly for goog.require / goog.provide /
    // goog.module).
    document.write(
        '<script src="' + options.root + '/closure/goog/base.js"></script>');

    // Prevent spurious transpilation warnings.
    document.write('<script>goog.TRANSPILE = "never";</script>');

    // Load dependency graph info from the specified deps files -
    // typically just build/deps.js.  To update deps after changing
    // any module's goog.requires / imports, run `npm run build:deps`.
    for (let i = 0; i < options.depsFiles.length; i++) {
      document.write(
          '<script src="' + options.root + options.depsFiles[i] + '">' +
              '</script>');
    }

    // Record require targets for bootstrap_helper.js.
    window.bootstrapInfo.requires = options.requires;

    // Assemble a list of module targets to bootstrap.
    //
    // The first group of targets are those listed in
    // options.requires.
    //
    // The next target is a fake one that will load
    // bootstrap_helper.js.  We generate a call to goog.addDependency
    // to tell the debug module loader that it can be loaded via a
    // fake module name, and that it depends on all the targets in the
    // first group (and indeed bootstrap_helper.js will make a call to
    // goog.require for each one).
    //
    // We then create another target for each of
    // options.additionalScripts, again generating calls to
    // goog.addDependency for each one making it dependent on the
    // previous one.
    let requires = options.requires.slice();
    const scripts =
        ['tests/bootstrap_helper.js'].concat(options.additionalScripts);
    const scriptDeps = [];
    for (let script, i = 0; script = scripts[i]; i++) {
      const fakeModuleName = 'script.' + script.replace(/[./]/g, "-");
      scriptDeps.push('  goog.addDependency(' +
          quote('../../' + script) + ', [' + quote(fakeModuleName) +
          '], [' + requires.map(quote).join() + "], {'lang': 'es6'});\n");
      requires = [fakeModuleName];
    }

    // Finally, write out a script containing the generated
    // goog.addDependency calls and a call to goog.bootstrap
    // requesting the loading of the final target, which will cause
    // all the previous ones to be loaded recursively.  Wrap this in a
    // promise and save it so it can be awaited in bootstrap_done.mjs.
    document.write(
        '<script>\n' + scriptDeps.join('') +
        '  window.bootstrapInfo.done = new Promise((resolve, reject) => {\n' +
        '    goog.bootstrap([' + requires.map(quote).join() + '], resolve);\n' +
        '  });\n' +
        '</script>\n');
  } else {
    // We need to load Blockly in compressed mode.  Load
    // blockly_compressed.js et al. using <script> tags.
    const scripts =
        options.compressedScripts.concat(options.additionalScripts);
    for (let i = 0; i < scripts.length; i++) {
      document.write(
          '<script src="' + options.root + scripts[i] + '"></script>');
    }
  }

  return;  // All done.  Only helper functions after this point.

  /**
   * Convert a string into a string literal.  Strictly speaking we
   * only need to escape backslash, \r, \n, \u2028 (line separator),
   * \u2029 (paragraph separator) and whichever quote character we're
   * using, but for simplicity we escape all the control characters.
   *
   * Based on https://github.com/google/CodeCity/blob/master/server/code.js
   *
   * @param {string} str The string to convert.
   * @return {string} The value s as a eval-able string literal.
   */
  function quote(str) {
    /* eslint-disable no-control-regex, no-multi-spaces */
    /** Regexp for characters to be escaped in a single-quoted string. */
    const singleRE = /[\x00-\x1f\\\u2028\u2029']/g;

    /** Map of control character replacements. */
    const replacements = {
      '\x00': '\\0',   '\x01': '\\x01', '\x02': '\\x02', '\x03': '\\x03',
      '\x04': '\\x04', '\x05': '\\x05', '\x06': '\\x06', '\x07': '\\x07',
      '\x08': '\\b',   '\x09': '\\t',   '\x0a': '\\n',   '\x0b': '\\v',
      '\x0c': '\\f',   '\x0d': '\\r',   '\x0e': '\\x0e', '\x0f': '\\x0f',
      '"': '\\"', "'": "\\'", '\\': '\\\\',
      '\u2028': '\\u2028', '\u2029': '\\u2029',
    };
    /* eslint-enable no-control-regex, no-multi-spaces */

    /**
     * Replacer function.
     * @param {string} c Single UTF-16 code unit ("character") string to
     *     be replaced.
     * @return {string} Multi-character string containing escaped
     *     representation of c.
     */
    function replace(c) {
      return replacements[c];
    }

    return "'" + str.replace(singleRE, replace) + "'";
  }
})();