DevTools: extract modules (with extensions)

third_party/WebKit/Source/devtools/scripts/extract_module/extract_module.js

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+'use strict';
+const fs = require('fs');
+const path = require('path');
+
+const utils = require('../utils');
+
+const FRONTEND_PATH = path.resolve(__dirname, '..', '..', 'front_end');
+const BUILD_GN_PATH = path.resolve(__dirname, '..', '..', 'BUILD.gn');
+const SPECIAL_CASE_NAMESPACES_PATH = path.resolve(__dirname, '..', 'special_case_namespaces.json');
+
+const APPLICATION_DESCRIPTORS = [
+  'inspector.json',
+  'unit_test_runner.json',
+];
+
+// Replace based on specified transformation
+
+const MODULES_TO_REMOVE = []; // ['components_lazy', 'ui_lazy'];
+
+// NOTE: Extensions-only change
+const FILES_AFFECTING_EXTENSIONS = [
+  'components_lazy/LineLevelProfile.js',
+  'components_lazy/GCActionDelegate.js',
+  'components/RequestAppBannerActionDelegate.js',
+  'ui_lazy/CommandMenu.js',
+];
+
+const JS_FILES_MAPPING = [
+  // {file: 'components_lazy/CookiesTable.js', new: 'cookie_table'},
+  // {file: 'ui/BezierEditor.js', new: 'inline_editor'},
+  // {file: 'ui/BezierUI.js', new: 'inline_editor'},
+  // {file: 'ui/ColorSwatch.js', new: 'inline_editor'},
+  // {file: 'ui/CSSShadowEditor.js', new: 'inline_editor'},
+  // {file: 'ui/SwatchPopoverHelper.js', new: 'inline_editor'},
+  // {file: 'components/Spectrum.js', new: 'color_picker'},
+  //
+  // // Cannot extract dom_ui because of cyclic dependency with components
+  // // {file: 'components/DOMPresentationUtils.js', new: 'dom_ui'},
+  // {file: 'components/ExecutionContextSelector.js', existing: 'main'},
+  // {file: 'components_lazy/FilmStripModel.js', existing: 'sdk'},
+  //
+  // {file: 'components_lazy/FilmStripView.js', new: 'perf_ui'},
+  {file: 'components_lazy/GCActionDelegate.js', existing: 'main'},
+  {file: 'components_lazy/LineLevelProfile.js', new: 'perf_ui'},
+  {file: 'components/RequestAppBannerActionDelegate.js', existing: 'main'},
+  // {file: 'components/ShortcutsScreen.js', existing: 'ui'},
+  {file: 'ui_lazy/FilteredListWidget.js', new: 'quick_open'},
+  {file: 'ui_lazy/CommandMenu.js', new: 'quick_open'},
+  // {file: 'ui_lazy/DataGrid.js', new: 'data_grid'},
+  // {file: 'ui_lazy/ViewportDataGrid.js', new: 'data_grid'},
+  // {file: 'ui_lazy/SortableDataGrid.js', new: 'data_grid'},
+  // {file: 'ui_lazy/ShowMoreDataGridNode.js', new: 'data_grid'},
+  // {file: 'ui_lazy/ChartViewport.js', new: 'perf_ui'},
+  // {file: 'ui_lazy/FlameChart.js', new: 'perf_ui'},
+  // {file: 'ui_lazy/OverviewGrid.js', new: 'perf_ui'},
+  // {file: 'ui_lazy/PieChart.js', new: 'perf_ui'},
+  // {file: 'ui_lazy/TimelineGrid.js', new: 'perf_ui'},
+  // {file: 'ui_lazy/TimelineOverviewPane.js', new: 'perf_ui'},
+  {file: 'sources/UISourceCodeFrame.js', existing: 'source_frame'},
+  {file: 'sources/SourceCodeDiff.js', existing: 'source_frame'},
+];
+
+const MODULE_MAPPING = {
+  // cookie_table: {
+  //   dependencies: ['ui', 'sdk', 'data_grid'],
+  //   dependents: ['resources', 'network'],
+  //   applications: ['inspector.json'],
+  //   autostart: false,
+  // },
+  // inline_editor: {
+  //   dependencies: ['ui'],
+  //   dependents: ['sources', 'elements', 'resources'],
+  //   applications: ['inspector.json', 'unit_test_runner.json'],
+  //   autostart: false,
+  // },
+  // color_picker: {
+  //   dependencies: ['ui', 'sdk'],
+  //   dependents: ['sources', 'elements'],
+  //   applications: ['inspector.json'],
+  //   autostart: false,
+  // },
+  perf_ui: {
+    dependencies: ['ui', 'sdk', 'bindings', 'source_frame', 'text_editor'],
+    dependents: ['network', 'timeline', 'profiler', 'layer_viewer'],
+    applications: ['inspector.json'],
+    autostart: false,
+  },
+  quick_open: {
+    dependencies: ['ui', 'diff'],
+    dependents: ['sources'],
+    applications: ['inspector.json', 'unit_test_runner.json'],
+    autostart: false,
+  },
+  // data_grid: {
+  //   dependencies: ['ui'],
+  //   dependents: ['network', 'profiler', 'resources', 'console', 'timeline'],
+  //   applications: ['inspector.json', 'unit_test_runner.json'],
+  //   autostart: false,
+  // },
+};
+
+const NEW_DEPENDENCIES_BY_EXISTING_MODULES = {
+  // resources: ['components'],
+  source_frame: ['persistence', 'diff'],
+  timeline: ['extensions'],
+  css_tracker: ['source_frame'],
+};
+
+const REMOVE_DEPENDENCIES_BY_EXISTING_MODULES = {
+  css_tracker: ['sources'],
+};
+
+const DEPENDENCIES_BY_MODULE = Object.keys(MODULE_MAPPING).reduce((acc, module) => {
+  acc[module] = MODULE_MAPPING[module].dependencies;
+  return acc;
+}, {});
+
+const APPLICATIONS_BY_MODULE = Object.keys(MODULE_MAPPING).reduce((acc, module) => {
+  acc[module] = MODULE_MAPPING[module].applications;
+  return acc;
+}, {});
+
+const DEPENDENTS_BY_MODULE = Object.keys(MODULE_MAPPING).reduce((acc, module) => {
+  acc[module] = MODULE_MAPPING[module].dependents;
+  return acc;
+}, {});
+
+function extractModule() {
+  const modules = new Set();
+  for (let fileObj of JS_FILES_MAPPING) {
+    let moduleName = fileObj.file.split('/')[0];
+    modules.add(moduleName);
+  }
+  const newModuleSet = JS_FILES_MAPPING.reduce((acc, file) => file.new ? acc.add(file.new) : acc, new Set());
+  const targetToOriginalFilesMap = JS_FILES_MAPPING.reduce((acc, f) => {
+    let components = f.file.split('/');
+    components[0] = f.new || f.existing;
+    acc.set(components.join('/'), f.file);
+    return acc;
+  }, new Map());
+
+  const cssFilesMapping = findCSSFiles();
+  const identifiersByFile = calculateIdentifiers();
+  const identifierMap = mapIdentifiers(identifiersByFile, cssFilesMapping);
+  const extensionMap = removeFromExistingModuleDescriptors(modules, identifierMap, cssFilesMapping);
+
+  // Find out which files are moving extensions
+  for (let e of extensionMap.keys()) {
+    for (let [f, identifiers] of identifiersByFile) {
+      if (identifiers.includes(e))
+        console.log(`extension: ${e} in file: ${f}`);
+    }
+  }
+
+  moveFiles(cssFilesMapping);
+  createNewModuleDescriptors(extensionMap, cssFilesMapping, identifiersByFile, targetToOriginalFilesMap);
+  updateExistingModuleDescriptors(extensionMap, cssFilesMapping, identifiersByFile, targetToOriginalFilesMap);
+  addDependenciesToDescriptors();
+  renameIdentifiers(identifierMap);
+  updateBuildGNFile(cssFilesMapping, newModuleSet);
+  for (let descriptor of APPLICATION_DESCRIPTORS)
+    updateApplicationDescriptor(descriptor, newModuleSet);
+
+  for (let m of MODULES_TO_REMOVE) {
+    utils.removeRecursive(path.resolve(FRONTEND_PATH, m));
+  }
+}
+
+String.prototype.replaceAll = function(search, replacement) {
+  let target = this;
+  return target.replace(new RegExp('\\b' + search + '\\b', 'g'), replacement);
+};
+
+Set.prototype.union = function(setB) {
+  let union = new Set(this);
+  for (let elem of setB)
+    union.add(elem);
+
+  return union;
+};
+
+function mapModuleToNamespace(module) {
+  const specialCases = require(SPECIAL_CASE_NAMESPACES_PATH);
+  return specialCases[module] || toCamelCase(module);
+
+  function toCamelCase(module) {
+    return module.split('_').map(a => a.substring(0, 1).toUpperCase() + a.substring(1)).join('');
+  }
+}
+
+function findCSSFiles() {
+  let cssFilesMapping = new Map();
+  for (let fileObj of JS_FILES_MAPPING)
+    cssFilesMapping.set(fileObj.file, scrapeCSSFile(fileObj.file));
+
+
+  function scrapeCSSFile(filePath) {
+    let cssFiles = new Set();
+    const fullPath = path.resolve(FRONTEND_PATH, filePath);
+    let content = fs.readFileSync(fullPath).toString();
+    let lines = content.split('\n');
+    for (let line of lines) {
+      let match = line.match(/'(.+\.css)'/);
+      if (!match)
+        continue;
+      let matchPath = match[1];
+      cssFiles.add(path.basename(path.resolve(FRONTEND_PATH, matchPath)));
+    }
+    return cssFiles;
+  }
+
+  return cssFilesMapping;
+}
+
+function calculateIdentifiers() {
+  const identifiersByFile = new Map();
+  for (let fileObj of JS_FILES_MAPPING) {
+    const fullPath = path.resolve(FRONTEND_PATH, fileObj.file);
+    let content = fs.readFileSync(fullPath).toString();
+    identifiersByFile.set(fileObj.file, scrapeIdentifiers(content, fileObj));
+  }
+  return identifiersByFile;
+
+  function scrapeIdentifiers(content, fileObj) {
+    let identifiers = [];
+    let lines = content.split('\n');
+    for (let line of lines) {
+      let match = line.match(new RegExp(`^([a-z_A-Z0-9\.]+)\\s=`)) || line.match(new RegExp(`^([a-z_A-Z0-9\.]+);`));
+      if (!match)
+        continue;
+      let name = match[1];
+
+      var currentModule = fileObj.file.split('/')[0];
+      if (name.split('.')[0] !== mapModuleToNamespace(currentModule))
+        console.log(`POSSIBLE ISSUE: identifier: ${name} found in ${currentModule}`);
+      else
+        identifiers.push(name);
+    }
+    return identifiers;
+  }
+}
+
+function moveFiles(cssFilesMapping) {
+  for (let fileObj of JS_FILES_MAPPING) {
+    let sourceFilePath = path.resolve(FRONTEND_PATH, fileObj.file);
+    let targetFilePath = getMappedFilePath(fileObj);
+    let moduleDir = path.resolve(targetFilePath, '..');
+    if (!fs.existsSync(moduleDir))
+      fs.mkdirSync(moduleDir);
+
+    move(sourceFilePath, targetFilePath);
+    if (cssFilesMapping.has(fileObj.file)) {
+      cssFilesMapping.get(fileObj.file).forEach((file) => {
+        let module = fileObj.new || fileObj.existing;
+        move(path.resolve(FRONTEND_PATH, fileObj.file.split('/')[0], file), path.resolve(FRONTEND_PATH, module, file));
+      });
+    }
+  }
+
+  function move(sourceFilePath, targetFilePath) {
+    try {
+      fs.writeFileSync(targetFilePath, fs.readFileSync(sourceFilePath));
+      fs.unlinkSync(sourceFilePath);
+    } catch (err) {
+      console.log(`error moving ${sourceFilePath} -> ${targetFilePath}`);
+    }
+  }
+
+  function getMappedFilePath(fileObj) {
+    let components = fileObj.file.split('/');
+    components[0] = fileObj.existing || fileObj.new;
+    return path.resolve(FRONTEND_PATH, components.join('/'));
+  }
+}
+
+function updateBuildGNFile(cssFilesMapping, newModuleSet) {
+  let content = fs.readFileSync(BUILD_GN_PATH).toString();
+  let newSourcesToAdd = [];
+  let partialPathMapping = calculatePartialPathMapping();
+  for (let module of MODULES_TO_REMOVE) {
+    partialPathMapping.set(`"front_end/${module}/module.json",\n`, '');
+    partialPathMapping.set(`"$resources_out_dir/${module}/${module}_module.js",\n`, '');
+  }
+  const newNonAutostartModules = [...newModuleSet]
+                                     .filter(module => !MODULE_MAPPING[module].autostart)
+                                     .map(module => `"$resources_out_dir/${module}/${module}_module.js",`);
+
+  let newContent = addContentToLinesInSortedOrder({
+    content,
+    startLine: '# this contains non-autostart non-remote modules only.',
+    endLine: ']',
+    linesToInsert: newNonAutostartModules,
+  });
+
+  for (let pair of partialPathMapping.entries())
+    newContent = newContent.replace(pair[0], pair[1]);
+
+  newContent = addContentToLinesInSortedOrder({
+    content: newContent,
+    startLine: 'all_devtools_files = [',
+    endLine: ']',
+    linesToInsert: newSourcesToAdd,
+  });
+
+  fs.writeFileSync(BUILD_GN_PATH, newContent);
+
+  function calculatePartialPathMapping() {
+    let partialPathMapping = new Map();
+    for (let fileObj of JS_FILES_MAPPING) {
+      let components = fileObj.file.split('/');
+      let sourceModule = components[0];
+      let targetModule = fileObj.existing || fileObj.new;
+      components[0] = targetModule;
+      partialPathMapping.set(`"front_end/${fileObj.file}",\n`, '');
+      newSourcesToAdd.push(`"front_end/${components.join('/')}",`);
+      if (cssFilesMapping.has(fileObj.file)) {
+        for (let cssFile of cssFilesMapping.get(fileObj.file)) {
+          partialPathMapping.set(`"front_end/${sourceModule}/${cssFile}",\n`, '');
+          newSourcesToAdd.push(`"front_end/${targetModule}/${cssFile}",`);
+        }
+      }
+    }
+    return partialPathMapping;
+  }
+
+  function top(array) {
+    return array[array.length - 1];
+  }
+
+  function addContentToLinesInSortedOrder({content, startLine, endLine, linesToInsert}) {
+    let lines = content.split('\n');
+    let seenStartLine = false;
+    let contentStack = linesToInsert.sort((a, b) => a.toLowerCase().localeCompare(b.toLowerCase())).reverse();
+    for (var i = 0; i < lines.length; i++) {
+      let line = lines[i].trim();
+      let nextLine = lines[i + 1].trim();
+      if (line === startLine)
+        seenStartLine = true;
+
+      if (line === endLine && seenStartLine)
+        break;
+
+      if (!seenStartLine)
+        continue;
+
+      const nextContent = top(contentStack) ? top(contentStack).toLowerCase() : '';
+      if ((line === startLine || nextContent > line.toLowerCase()) &&
+          (nextLine === endLine || nextContent < nextLine.toLowerCase()))
+        lines.splice(i + 1, 0, contentStack.pop());
+    }
+    if (contentStack.length)
+      lines.splice(i, 0, ...contentStack);
+    return lines.join('\n');
+  }
+}
+
+function mapIdentifiers(identifiersByFile, cssFilesMapping) {
+  const filesToTargetModule = new Map();
+  for (let fileObj of JS_FILES_MAPPING)
+    filesToTargetModule.set(fileObj.file, fileObj.existing || fileObj.new);
+
+
+  const map = new Map();
+  for (let [file, identifiers] of identifiersByFile) {
+    let targetModule = filesToTargetModule.get(file);
+    for (let identifier of identifiers) {
+      let components = identifier.split('.');
+      components[0] = mapModuleToNamespace(targetModule);
+      let newIdentifier = components.join('.');
+      map.set(identifier, newIdentifier);
+    }
+  }
+  for (let [jsFile, cssFiles] of cssFilesMapping) {
+    let fileObj = JS_FILES_MAPPING.filter(f => f.file === jsFile)[0];
+    let sourceModule = fileObj.file.split('/')[0];
+    let targetModule = fileObj.existing || fileObj.new;
+    for (let cssFile of cssFiles) {
+      let key = `${sourceModule}/${cssFile}`;
+      let value = `${targetModule}/${cssFile}`;
+      map.set(key, value);
+    }
+  }
+  return map;
+}
+
+function renameIdentifiers(identifierMap) {
+  walkSync('front_end', write, true);
+
+  walkSync('../../LayoutTests/http/tests/inspector', write, false);
+  walkSync('../../LayoutTests/http/tests/inspector-enabled', write, false);
+  walkSync('../../LayoutTests/http/tests/inspector-protocol', write, false);
+  walkSync('../../LayoutTests/http/tests/inspector-unit', write, false);
+  walkSync('../../LayoutTests/inspector', write, false);
+  walkSync('../../LayoutTests/inspector-enabled', write, false);
+  walkSync('../../LayoutTests/inspector-protocol', write, false);
+
+  function walkSync(currentDirPath, process, json) {
+    fs.readdirSync(currentDirPath).forEach(function(name) {
+      let filePath = path.join(currentDirPath, name);
+      let stat = fs.statSync(filePath);
+      if (stat.isFile() && (filePath.endsWith('.js') || filePath.endsWith('.html') || filePath.endsWith('.xhtml') ||
+                            filePath.endsWith('-expected.txt') || (json && filePath.endsWith('.json')))) {
+        if (filePath.includes('ExtensionAPI.js'))
+          return;
+        if (filePath.includes('externs.js'))
+          return;
+        if (filePath.includes('eslint') || filePath.includes('lighthouse-background.js') || filePath.includes('/cm/') ||
+            filePath.includes('/xterm.js/') || filePath.includes('/acorn/') || filePath.includes('/gonzales-scss'))
+          return;
+        if (filePath.includes('/cm_modes/') && !filePath.includes('DefaultCodeMirror') &&
+            !filePath.includes('module.json'))
+          return;
+        process(filePath);
+      } else if (stat.isDirectory()) {
+        walkSync(filePath, process, json);
+      }
+    });
+  }
+
+  function write(filePath) {
+    let content = fs.readFileSync(filePath).toString();
+    let newContent = content;
+    for (let key of identifierMap.keys()) {
+      let originalIdentifier = key;
+      let newIdentifier = identifierMap.get(key);
+      newContent = newContent.replaceAll(originalIdentifier, newIdentifier);
+    }
+    // one-off
+    if (filePath.includes('LayoutTests/http/tests/inspector-unit/filtered-item-selection-dialog-filtering.js'))
+      newContent = newContent.replaceAll('ui_lazy', 'quick_open');
+    // if (filePath.includes('LayoutTests/inspector/components/cookies-table.html'))
+    //   newContent = newContent.replaceAll('components_lazy', 'cookie_table');
+    // if (filePath.includes('LayoutTests/inspector/components/datagrid-autosize.html'))
+    //   newContent = newContent.replaceAll('ui_lazy', 'data_grid');
+    // if (filePath.includes('LayoutTests/inspector/components/datagrid-test.js'))
+    //   newContent = newContent.replaceAll('ui_lazy', 'data_grid');
+
+    if (content !== newContent)
+      fs.writeFileSync(filePath, newContent);
+  }
+}
+
+function removeFromExistingModuleDescriptors(modules, identifierMap, cssFilesMapping) {
+  let extensionMap = new Map();
+  let moduleFileMap = new Map();
+
+  for (let fileObj of JS_FILES_MAPPING) {
+    let components = fileObj.file.split('/');
+    let module = components[0];
+    let fileName = components[1];
+
+    if (!moduleFileMap.get(module))
+      moduleFileMap.set(module, []);
+
+    moduleFileMap.set(module, moduleFileMap.get(module).concat(fileName));
+  }
+
+  for (let module of modules) {
+    let moduleJSONPath = path.resolve(FRONTEND_PATH, module, 'module.json');
+    let content = fs.readFileSync(moduleJSONPath).toString();
+    let moduleObj = parseJSON(content);
+    let removedScripts = removeScripts(moduleObj, module);
+    removeResources(moduleObj, removedScripts);
+    removeExtensions(moduleObj);
+    fs.writeFileSync(moduleJSONPath, stringifyJSON(moduleObj));
+  }
+
+  return extensionMap;
+
+  function removeScripts(moduleObj, module) {
+    let remainingScripts = [];
+    let removedScripts = [];
+    let moduleFiles = moduleFileMap.get(module);
+    for (let script of moduleObj.scripts) {
+      if (!moduleFiles.includes(script))
+        remainingScripts.push(script);
+      else
+        removedScripts.push(module + '/' + script);
+    }
+    moduleObj.scripts = remainingScripts;
+    return removedScripts;
+  }
+
+  function removeResources(moduleObj, removedScripts) {
+    if (!moduleObj.resources)
+      return;
+    let remainingResources = [];
+    let removedResources = new Set();
+    for (let script of removedScripts)
+      removedResources = removedResources.union(cssFilesMapping.get(script));
+
+
+    for (let resource of moduleObj.resources) {
+      if (!removedResources.has(resource))
+        remainingResources.push(resource);
+    }
+    moduleObj.resources = remainingResources;
+  }
+
+  function removeExtensions(moduleObj) {
+    if (!moduleObj.extensions)
+      return;
+    let remainingExtensions = [];
+    for (let extension of moduleObj.extensions) {
+      if (!objectIncludesIdentifier(extension))
+        remainingExtensions.push(extension);
+      else
+        extensionMap.set(objectIncludesIdentifier(extension), extension);
+    }
+    moduleObj.extensions = remainingExtensions;
+  }
+
+  function objectIncludesIdentifier(object) {
+    for (let key in object) {
+      let value = object[key];
+      if (identifierMap.has(value))
+        return value;
+    }
+    return false;
+  }
+}
+
+function createNewModuleDescriptors(extensionMap, cssFilesMapping, identifiersByFile, targetToOriginalFilesMap) {
+  let filesByNewModule = getFilesByNewModule();
+
+  for (let module of filesByNewModule.keys()) {
+    let moduleObj = {};
+
+    let scripts = getModuleScripts(module);
+    let extensions = getModuleExtensions(scripts, module);
+    if (extensions.length)
+      moduleObj.extensions = extensions;
+
+    moduleObj.dependencies = DEPENDENCIES_BY_MODULE[module];
+
+    moduleObj.scripts = scripts;
+
+    let resources = getModuleResources(moduleObj.scripts, module);
+    if (resources.length)
+      moduleObj.resources = resources;
+
+    let moduleJSONPath = path.resolve(FRONTEND_PATH, module, 'module.json');
+    fs.writeFileSync(moduleJSONPath, stringifyJSON(moduleObj));
+  }
+
+  function getFilesByNewModule() {
+    let filesByNewModule = new Map();
+    for (let fileObj of JS_FILES_MAPPING) {
+      if (!fileObj.new)
+        continue;
+      if (!filesByNewModule.has(fileObj.new))
+        filesByNewModule.set(fileObj.new, []);
+
+      filesByNewModule.set(fileObj.new, filesByNewModule.get(fileObj.new).concat([fileObj.file]));
+    }
+    return filesByNewModule;
+  }
+
+  function getModuleScripts(module) {
+    return filesByNewModule.get(module).map((file) => file.split('/')[1]);
+  }
+
+  function getModuleResources(scripts, module) {
+    let resources = [];
+    scripts.map(script => module + '/' + script).forEach((script) => {
+      script = targetToOriginalFilesMap.get(script);
+      if (!cssFilesMapping.has(script))
+        return;
+
+      resources = resources.concat([...cssFilesMapping.get(script)]);
+    });
+    return resources;
+  }
+
+  function getModuleExtensions(scripts, module) {
+    let extensions = [];
+    let identifiers =
+        scripts.map(script => module + '/' + script)
+            .reduce((acc, file) => acc.concat(identifiersByFile.get(targetToOriginalFilesMap.get(file))), []);
+    for (let identifier of identifiers) {
+      if (extensionMap.has(identifier))
+        extensions.push(extensionMap.get(identifier));
+    }
+    return extensions;
+  }
+}
+
+function calculateFilesByModuleType(type) {
+  let filesByNewModule = new Map();
+  for (let fileObj of JS_FILES_MAPPING) {
+    if (!fileObj[type])
+      continue;
+    if (!filesByNewModule.has(fileObj[type]))
+      filesByNewModule.set(fileObj[type], []);
+
+    filesByNewModule.set(fileObj[type], filesByNewModule.get(fileObj[type]).concat([fileObj.file]));
+  }
+  return filesByNewModule;
+}
+
+function updateExistingModuleDescriptors(extensionMap, cssFilesMapping, identifiersByFile, targetToOriginalFilesMap) {
+  let filesByExistingModule = calculateFilesByModuleType('existing');
+  for (let module of filesByExistingModule.keys()) {
+    let moduleJSONPath = path.resolve(FRONTEND_PATH, module, 'module.json');
+    let content = fs.readFileSync(moduleJSONPath).toString();
+    let moduleObj = parseJSON(content);
+
+    let scripts = getModuleScripts(module);
+    let existingExtensions = moduleObj.extensions || [];
+    let extensions = existingExtensions.concat(getModuleExtensions(scripts, module));
+    if (extensions.length)
+      moduleObj.extensions = extensions;
+
+    moduleObj.scripts = moduleObj.scripts.concat(scripts);
+
+    let existingResources = moduleObj.resources || [];
+    let resources = existingResources.concat(getModuleResources(scripts, module));
+    if (resources.length)
+      moduleObj.resources = resources;
+
+    fs.writeFileSync(moduleJSONPath, stringifyJSON(moduleObj));
+  }
+
+
+  function getModuleScripts(module) {
+    return filesByExistingModule.get(module).map((file) => file.split('/')[1]);
+  }
+
+  function getModuleResources(scripts, module) {
+    let resources = [];
+    scripts.map(script => module + '/' + script).forEach((script) => {
+      script = targetToOriginalFilesMap.get(script);
+      if (!cssFilesMapping.has(script))
+        return;
+
+      resources = resources.concat([...cssFilesMapping.get(script)]);
+    });
+    return resources;
+  }
+
+  function getModuleExtensions(scripts, module) {
+    let extensions = [];
+    let identifiers =
+        scripts.map(script => module + '/' + script)
+            .reduce((acc, file) => acc.concat(identifiersByFile.get(targetToOriginalFilesMap.get(file))), []);
+    for (let identifier of identifiers) {
+      if (extensionMap.has(identifier))
+        extensions.push(extensionMap.get(identifier));
+    }
+    return extensions;
+  }
+}
+
+function addDependenciesToDescriptors() {
+  for (let module of getModules()) {
+    let moduleJSONPath = path.resolve(FRONTEND_PATH, module, 'module.json');
+    let content = fs.readFileSync(moduleJSONPath).toString();
+    let moduleObj = parseJSON(content);
+
+    let existingDependencies = moduleObj.dependencies || [];
+    let dependencies = existingDependencies.concat(getModuleDependencies(module))
+                           .filter((depModule) => !MODULES_TO_REMOVE.includes(depModule))
+                           .filter((depModule) => !(REMOVE_DEPENDENCIES_BY_EXISTING_MODULES[module] || []).includes(depModule));
+    let newDependenciesForExistingModule = NEW_DEPENDENCIES_BY_EXISTING_MODULES[module];
+    if (newDependenciesForExistingModule)
+      dependencies = dependencies.concat(newDependenciesForExistingModule);
+    if (dependencies.length)
+      moduleObj.dependencies = dependencies;
+    let newStringified = stringifyJSON(moduleObj);
+    if (stringifyJSON(moduleObj) !== stringifyJSON(parseJSON(content)))
+      fs.writeFileSync(moduleJSONPath, newStringified);
+  }
+
+  function getModuleDependencies(existingModule) {
+    let newDeps = [];
+    for (let newModule in DEPENDENTS_BY_MODULE) {
+      let dependents = DEPENDENTS_BY_MODULE[newModule];
+      if (dependents.includes(existingModule))
+        newDeps.push(newModule);
+    }
+    return newDeps;
+  }
+}
+
+function updateApplicationDescriptor(descriptorFileName, newModuleSet) {
+  let descriptorPath = path.join(FRONTEND_PATH, descriptorFileName);
+  let newModules = [...newModuleSet].filter(m => APPLICATIONS_BY_MODULE[m].includes(descriptorFileName));
+  let includeNewModules = (acc, line) => {
+    if (line.includes('{') && line.endsWith('}')) {
+      line += ',';
+      acc.push(line);
+      return acc.concat(newModules.map((m, i) => {
+        // Need spacing to preserve indentation
+        let string;
+        if (MODULE_MAPPING[m].autostart)
+          string = `        { "name": "${m}", "type": "autostart"}`;
+        else
+          string = `        { "name": "${m}" }`;
+        if (i !== newModules.length - 1)
+          string += ',';
+        return string;
+      }));
+    }
+    return acc.concat([line]);
+  };
+  let removeModules = (acc, line) => MODULES_TO_REMOVE.every(m => !line.includes(m)) ? acc.concat([line]) : acc;
+  let lines =
+      fs.readFileSync(descriptorPath).toString().split('\n').reduce(includeNewModules, []).reduce(removeModules, []);
+  fs.writeFileSync(descriptorPath, lines.join('\n'));
+}
+
+function getModules() {
+  return fs.readdirSync(FRONTEND_PATH).filter(function(file) {
+    return fs.statSync(path.join(FRONTEND_PATH, file)).isDirectory() &&
+        utils.isFile(path.join(FRONTEND_PATH, file, 'module.json'));
+  });
+}
+
+function parseJSON(string) {
+  return JSON.parse(string);
+}
+
+function stringifyJSON(obj) {
+  return unicodeEscape(JSON.stringify(obj, null, 4) + '\n');
+}
+
+// http://stackoverflow.com/questions/7499473/need-to-escape-non-ascii-characters-in-javascript
+function unicodeEscape(string) {
+  function padWithLeadingZeros(string) {
+    return new Array(5 - string.length).join("0") + string;
+  }
+
+  function unicodeCharEscape(charCode) {
+    return "\\u" + padWithLeadingZeros(charCode.toString(16));
+  }
+
+  return string.split("")
+    .map(function (char) {
+      var charCode = char.charCodeAt(0);
+      return charCode > 127 ? unicodeCharEscape(charCode) : char;
+    })
+    .join("");
+}
+
+if (require.main === module)
+  extractModule();