/* -*- indent-tabs-mode: nil; js-indent-level: 2; fill-column: 80 -*- */
/* vim:set ts=2 sw=2 sts=2 et tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

"use strict";

const {
  EXPAND_TAB,
  TAB_SIZE,
  DETECT_INDENT,
  getIndentationFromIteration
} = require("devtools/shared/indentation");

const ENABLE_CODE_FOLDING = "devtools.editor.enableCodeFolding";
const KEYMAP = "devtools.editor.keymap";
const AUTO_CLOSE = "devtools.editor.autoclosebrackets";
const AUTOCOMPLETE = "devtools.editor.autocomplete";
const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
const VALID_KEYMAPS = new Set(["emacs", "vim", "sublime"]);

// Maximum allowed margin (in number of lines) from top or bottom of the editor
// while shifting to a line which was initially out of view.
const MAX_VERTICAL_OFFSET = 3;

// Match @Scratchpad/N:LINE[:COLUMN] or (LINE[:COLUMN]) anywhere at an end of
// line in text selection.
const RE_SCRATCHPAD_ERROR = /(?:@Scratchpad\/\d+:|\()(\d+):?(\d+)?(?:\)|\n)/;
const RE_JUMP_TO_LINE = /^(\d+):?(\d+)?/;

const Services = require("Services");
const promise = require("promise");
const events = require("devtools/shared/event-emitter");
const { PrefObserver } = require("devtools/client/styleeditor/utils");
const { getClientCssProperties } = require("devtools/shared/fronts/css-properties");
const {KeyShortcuts} = require("devtools/client/shared/key-shortcuts");

const {LocalizationHelper} = require("devtools/shared/l10n");
const L10N = new LocalizationHelper("devtools/client/locales/sourceeditor.properties");

const { OS } = Services.appinfo;

// CM_STYLES, CM_SCRIPTS and CM_IFRAME represent the HTML,
// JavaScript and CSS that is injected into an iframe in
// order to initialize a CodeMirror instance.

const CM_STYLES = [
  "chrome://devtools/content/sourceeditor/codemirror/lib/codemirror.css",
  "chrome://devtools/content/sourceeditor/codemirror/addon/dialog/dialog.css",
  "chrome://devtools/content/sourceeditor/codemirror/mozilla.css"
];

const CM_SCRIPTS = [
  "chrome://devtools/content/sourceeditor/codemirror/codemirror.bundle.js",
];

const CM_IFRAME =
  "data:text/html;charset=utf8,<!DOCTYPE html>" +
  "<html dir='ltr'>" +
  "  <head>" +
  "    <style>" +
  "      html, body { height: 100%; }" +
  "      body { margin: 0; overflow: hidden; }" +
  "      .CodeMirror { width: 100% !important; line-height: 1.25 !important; }" +
  "    </style>" +
  CM_STYLES.map(style => "<link rel='stylesheet' href='" + style + "'>").join("\n") +
  "  </head>" +
  "  <body class='theme-body devtools-monospace'></body>" +
  "</html>";

const CM_MAPPING = [
  "focus",
  "hasFocus",
  "lineCount",
  "somethingSelected",
  "getCursor",
  "setSelection",
  "getSelection",
  "replaceSelection",
  "extendSelection",
  "undo",
  "redo",
  "clearHistory",
  "openDialog",
  "refresh",
  "getScrollInfo",
  "getViewport"
];

const editors = new WeakMap();

Editor.modes = {
  text: { name: "text" },
  html: { name: "htmlmixed" },
  css: { name: "css" },
  wasm: { name: "wasm" },
  js: { name: "javascript" },
  vs: { name: "x-shader/x-vertex" },
  fs: { name: "x-shader/x-fragment" }
};

/**
 * A very thin wrapper around CodeMirror. Provides a number
 * of helper methods to make our use of CodeMirror easier and
 * another method, appendTo, to actually create and append
 * the CodeMirror instance.
 *
 * Note that Editor doesn't expose CodeMirror instance to the
 * outside world.
 *
 * Constructor accepts one argument, config. It is very
 * similar to the CodeMirror configuration object so for most
 * properties go to CodeMirror's documentation (see below).
 *
 * Other than that, it accepts one additional and optional
 * property contextMenu. This property should be an element, or
 * an ID of an element that we can use as a context menu.
 *
 * This object is also an event emitter.
 *
 * CodeMirror docs: http://codemirror.net/doc/manual.html
 */
function Editor(config) {
  const tabSize = Services.prefs.getIntPref(TAB_SIZE);
  const useTabs = !Services.prefs.getBoolPref(EXPAND_TAB);
  const useAutoClose = Services.prefs.getBoolPref(AUTO_CLOSE);

  this.version = null;
  this.config = {
    value: "",
    mode: Editor.modes.text,
    indentUnit: tabSize,
    tabSize: tabSize,
    contextMenu: null,
    matchBrackets: true,
    extraKeys: {},
    indentWithTabs: useTabs,
    inputStyle: "textarea",
    styleActiveLine: true,
    autoCloseBrackets: "()[]{}''\"\"``",
    autoCloseEnabled: useAutoClose,
    theme: "mozilla",
    themeSwitching: true,
    autocomplete: false,
    autocompleteOpts: {}
  };

  // Additional shortcuts.
  this.config.extraKeys[Editor.keyFor("jumpToLine")] = () => this.jumpToLine();
  this.config.extraKeys[Editor.keyFor("moveLineUp", { noaccel: true })] =
    () => this.moveLineUp();
  this.config.extraKeys[Editor.keyFor("moveLineDown", { noaccel: true })] =
    () => this.moveLineDown();
  this.config.extraKeys[Editor.keyFor("toggleComment")] = "toggleComment";

  // Disable ctrl-[ and ctrl-] because toolbox uses those shortcuts.
  this.config.extraKeys[Editor.keyFor("indentLess")] = false;
  this.config.extraKeys[Editor.keyFor("indentMore")] = false;

  // Overwrite default config with user-provided, if needed.
  Object.keys(config).forEach(k => {
    if (k != "extraKeys") {
      this.config[k] = config[k];
      return;
    }

    if (!config.extraKeys) {
      return;
    }

    Object.keys(config.extraKeys).forEach(key => {
      this.config.extraKeys[key] = config.extraKeys[key];
    });
  });

  if (!this.config.gutters) {
    this.config.gutters = [];
  }
  if (this.config.lineNumbers
      && this.config.gutters.indexOf("CodeMirror-linenumbers") === -1) {
    this.config.gutters.push("CodeMirror-linenumbers");
  }

  // Remember the initial value of autoCloseBrackets.
  this.config.autoCloseBracketsSaved = this.config.autoCloseBrackets;

  // Overwrite default tab behavior. If something is selected,
  // indent those lines. If nothing is selected and we're
  // indenting with tabs, insert one tab. Otherwise insert N
  // whitespaces where N == indentUnit option.
  this.config.extraKeys.Tab = cm => {
    if (cm.somethingSelected()) {
      cm.indentSelection("add");
      return;
    }

    if (this.config.indentWithTabs) {
      cm.replaceSelection("\t", "end", "+input");
      return;
    }

    let num = cm.getOption("indentUnit");
    if (cm.getCursor().ch !== 0) {
      num -= 1;
    }
    cm.replaceSelection(" ".repeat(num), "end", "+input");
  };

  // Allow add-ons to inject scripts for their editor instances
  if (!this.config.externalScripts) {
    this.config.externalScripts = [];
  }

  if (this.config.cssProperties) {
    // Ensure that autocompletion has cssProperties if it's passed in via the options.
    this.config.autocompleteOpts.cssProperties = this.config.cssProperties;
  } else {
    // Use a static client-side database of CSS values if none is provided.
    this.config.cssProperties = getClientCssProperties();
  }

  events.decorate(this);
}

Editor.prototype = {
  container: null,
  version: null,
  config: null,
  Doc: null,

  /**
   * Exposes the CodeMirror instance. We want to get away from trying to
   * abstract away the API entirely, and this makes it easier to integrate in
   * various environments and do complex things.
   */
  get codeMirror() {
    if (!editors.has(this)) {
      throw new Error(
        "CodeMirror instance does not exist. You must wait " +
          "for it to be appended to the DOM."
      );
    }
    return editors.get(this);
  },

  /**
   * Appends the current Editor instance to the element specified by
   * 'el'. You can also provide your won iframe to host the editor as
   * an optional second parameter. This method actually creates and
   * loads CodeMirror and all its dependencies.
   *
   * This method is asynchronous and returns a promise.
   */
  appendTo: function (el, env) {
    let def = promise.defer();
    let cm = editors.get(this);

    if (!env) {
      env = el.ownerDocument.createElementNS(XUL_NS, "iframe");
    }

    env.flex = 1;

    if (cm) {
      throw new Error("You can append an editor only once.");
    }

    let onLoad = () => {
      let win = env.contentWindow.wrappedJSObject;

      if (!this.config.themeSwitching) {
        win.document.documentElement.setAttribute("force-theme", "light");
      }

      Services.scriptloader.loadSubScript(
        "chrome://devtools/content/shared/theme-switching.js",
        win, "utf8"
      );
      this.container = env;
      this._setup(win.document.body, el.ownerDocument);
      env.removeEventListener("load", onLoad, true);

      def.resolve();
    };

    env.addEventListener("load", onLoad, true);
    env.setAttribute("src", CM_IFRAME);
    el.appendChild(env);

    this.once("destroy", () => el.removeChild(env));
    return def.promise;
  },

  appendToLocalElement: function (el) {
    this._setup(el);
  },

  /**
   * Do the actual appending and configuring of the CodeMirror instance. This is
   * used by both append functions above, and does all the hard work to
   * configure CodeMirror with all the right options/modes/etc.
   */
  _setup: function (el, doc) {
    doc = doc || el.ownerDocument;
    let win = el.ownerDocument.defaultView;

    let scriptsToInject = CM_SCRIPTS.concat(this.config.externalScripts);
    scriptsToInject.forEach(url => {
      if (url.startsWith("chrome://")) {
        Services.scriptloader.loadSubScript(url, win, "utf8");
      }
    });

    // Replace the propertyKeywords, colorKeywords and valueKeywords
    // properties of the CSS MIME type with the values provided by the CSS properties
    // database.
    const {
      propertyKeywords,
      colorKeywords,
      valueKeywords
    } = getCSSKeywords(this.config.cssProperties);

    let cssSpec = win.CodeMirror.resolveMode("text/css");
    cssSpec.propertyKeywords = propertyKeywords;
    cssSpec.colorKeywords = colorKeywords;
    cssSpec.valueKeywords = valueKeywords;
    win.CodeMirror.defineMIME("text/css", cssSpec);

    let scssSpec = win.CodeMirror.resolveMode("text/x-scss");
    scssSpec.propertyKeywords = propertyKeywords;
    scssSpec.colorKeywords = colorKeywords;
    scssSpec.valueKeywords = valueKeywords;
    win.CodeMirror.defineMIME("text/x-scss", scssSpec);

    win.CodeMirror.commands.save = () => this.emit("saveRequested");

    // Create a CodeMirror instance add support for context menus,
    // overwrite the default controller (otherwise items in the top and
    // context menus won't work).

    let cm = win.CodeMirror(el, this.config);
    this.Doc = win.CodeMirror.Doc;

    // Disable APZ for source editors. It currently causes the line numbers to
    // "tear off" and swim around on top of the content. Bug 1160601 tracks
    // finding a solution that allows APZ to work with CodeMirror.
    cm.getScrollerElement().addEventListener("wheel", ev => {
      // By handling the wheel events ourselves, we force the platform to
      // scroll synchronously, like it did before APZ. However, we lose smooth
      // scrolling for users with mouse wheels. This seems acceptible vs.
      // doing nothing and letting the gutter slide around.
      ev.preventDefault();

      let { deltaX, deltaY } = ev;

      if (ev.deltaMode == ev.DOM_DELTA_LINE) {
        deltaX *= cm.defaultCharWidth();
        deltaY *= cm.defaultTextHeight();
      } else if (ev.deltaMode == ev.DOM_DELTA_PAGE) {
        deltaX *= cm.getWrapperElement().clientWidth;
        deltaY *= cm.getWrapperElement().clientHeight;
      }

      cm.getScrollerElement().scrollBy(deltaX, deltaY);
    });

    cm.getWrapperElement().addEventListener("contextmenu", ev => {
      ev.preventDefault();

      if (!this.config.contextMenu) {
        return;
      }

      let popup = this.config.contextMenu;
      if (typeof popup == "string") {
        popup = doc.getElementById(this.config.contextMenu);
      }

      this.emit("popupOpen", ev, popup);
      popup.openPopupAtScreen(ev.screenX, ev.screenY, true);
    }, false);

    cm.on("focus", () => this.emit("focus"));
    cm.on("scroll", () => this.emit("scroll"));
    cm.on("change", () => {
      this.emit("change");
      if (!this._lastDirty) {
        this._lastDirty = true;
        this.emit("dirty-change");
      }
    });
    cm.on("cursorActivity", () => this.emit("cursorActivity"));

    cm.on("gutterClick", (cmArg, line, gutter, ev) => {
      let head = { line: line, ch: 0 };
      let tail = { line: line, ch: this.getText(line).length };

      // Shift-click on a gutter selects the whole line.
      if (ev.shiftKey) {
        cmArg.setSelection(head, tail);
        return;
      }

      this.emit("gutterClick", line, ev.button);
    });

    win.CodeMirror.defineExtension("l10n", (name) => {
      return L10N.getStr(name);
    });

    this._initShortcuts(win);

    editors.set(this, cm);

    this.reloadPreferences = this.reloadPreferences.bind(this);
    this._prefObserver = new PrefObserver("devtools.editor.");
    this._prefObserver.on(TAB_SIZE, this.reloadPreferences);
    this._prefObserver.on(EXPAND_TAB, this.reloadPreferences);
    this._prefObserver.on(KEYMAP, this.reloadPreferences);
    this._prefObserver.on(AUTO_CLOSE, this.reloadPreferences);
    this._prefObserver.on(AUTOCOMPLETE, this.reloadPreferences);
    this._prefObserver.on(DETECT_INDENT, this.reloadPreferences);
    this._prefObserver.on(ENABLE_CODE_FOLDING, this.reloadPreferences);

    this.reloadPreferences();

    win.editor = this;
    let editorReadyEvent = new win.CustomEvent("editorReady");
    win.dispatchEvent(editorReadyEvent);
  },

  /**
   * Returns a boolean indicating whether the editor is ready to
   * use. Use appendTo(el).then(() => {}) for most cases
   */
  isAppended: function () {
    return editors.has(this);
  },

  /**
   * Returns the currently active highlighting mode.
   * See Editor.modes for the list of all suppoert modes.
   */
  getMode: function () {
    return this.getOption("mode");
  },

  /**
   * Loads a script into editor's containing window.
   */
  loadScript: function (url) {
    if (!this.container) {
      throw new Error("Can't load a script until the editor is loaded.");
    }
    let win = this.container.contentWindow.wrappedJSObject;
    Services.scriptloader.loadSubScript(url, win, "utf8");
  },

  /**
   * Creates a CodeMirror Document
   * @returns CodeMirror.Doc
   */
  createDocument: function () {
    return new this.Doc("");
  },

  /**
   * Replaces the current document with a new source document
   */
  replaceDocument: function (doc) {
    let cm = editors.get(this);
    cm.swapDoc(doc);
  },

  /**
   * Changes the value of a currently used highlighting mode.
   * See Editor.modes for the list of all supported modes.
   */
  setMode: function (value) {
    this.setOption("mode", value);

    // If autocomplete was set up and the mode is changing, then
    // turn it off and back on again so the proper mode can be used.
    if (this.config.autocomplete) {
      this.setOption("autocomplete", false);
      this.setOption("autocomplete", true);
    }
  },

  /**
   * The source editor can expose several commands linked from system and context menus.
   * Kept for backward compatibility with scratchpad and styleeditor.
   */
  insertCommandsController: function () {
    const { insertCommandsController } =
      require("devtools/client/sourceeditor/editor-commands-controller");
    insertCommandsController(this);
  },

  /**
   * Returns text from the text area. If line argument is provided
   * the method returns only that line.
   */
  getText: function (line) {
    let cm = editors.get(this);

    if (line == null) {
      return cm.getValue();
    }

    let info = cm.lineInfo(line);
    return info ? cm.lineInfo(line).text : "";
  },

  /**
   * Replaces whatever is in the text area with the contents of
   * the 'value' argument.
   */
  setText: function (value) {
    let cm = editors.get(this);
    cm.setValue(value);

    this.resetIndentUnit();
  },

  /**
   * Reloads the state of the editor based on all current preferences.
   * This is called automatically when any of the relevant preferences
   * change.
   */
  reloadPreferences: function () {
    // Restore the saved autoCloseBrackets value if it is preffed on.
    let useAutoClose = Services.prefs.getBoolPref(AUTO_CLOSE);
    this.setOption("autoCloseBrackets",
      useAutoClose ? this.config.autoCloseBracketsSaved : false);

    // If alternative keymap is provided, use it.
    const keyMap = Services.prefs.getCharPref(KEYMAP);
    if (VALID_KEYMAPS.has(keyMap)) {
      this.setOption("keyMap", keyMap);
    } else {
      this.setOption("keyMap", "default");
    }
    this.updateCodeFoldingGutter();

    this.resetIndentUnit();
    this.setupAutoCompletion();
  },

  /**
   * Sets the editor's indentation based on the current prefs and
   * re-detect indentation if we should.
   */
  resetIndentUnit: function () {
    let cm = editors.get(this);

    let iterFn = function (start, end, callback) {
      cm.eachLine(start, end, (line) => {
        return callback(line.text);
      });
    };

    let {indentUnit, indentWithTabs} = getIndentationFromIteration(iterFn);

    cm.setOption("tabSize", indentUnit);
    cm.setOption("indentUnit", indentUnit);
    cm.setOption("indentWithTabs", indentWithTabs);
  },

  /**
   * Replaces contents of a text area within the from/to {line, ch}
   * range. If neither `from` nor `to` arguments are provided works
   * exactly like setText. If only `from` object is provided, inserts
   * text at that point, *overwriting* as many characters as needed.
   */
  replaceText: function (value, from, to) {
    let cm = editors.get(this);

    if (!from) {
      this.setText(value);
      return;
    }

    if (!to) {
      let text = cm.getRange({ line: 0, ch: 0 }, from);
      this.setText(text + value);
      return;
    }

    cm.replaceRange(value, from, to);
  },

  /**
   * Inserts text at the specified {line, ch} position, shifting existing
   * contents as necessary.
   */
  insertText: function (value, at) {
    let cm = editors.get(this);
    cm.replaceRange(value, at, at);
  },

  /**
   * Deselects contents of the text area.
   */
  dropSelection: function () {
    if (!this.somethingSelected()) {
      return;
    }

    this.setCursor(this.getCursor());
  },

  /**
   * Returns true if there is more than one selection in the editor.
   */
  hasMultipleSelections: function () {
    let cm = editors.get(this);
    return cm.listSelections().length > 1;
  },

  /**
   * Gets the first visible line number in the editor.
   */
  getFirstVisibleLine: function () {
    let cm = editors.get(this);
    return cm.lineAtHeight(0, "local");
  },

  /**
   * Scrolls the view such that the given line number is the first visible line.
   */
  setFirstVisibleLine: function (line) {
    let cm = editors.get(this);
    let { top } = cm.charCoords({line: line, ch: 0}, "local");
    cm.scrollTo(0, top);
  },

  /**
   * Sets the cursor to the specified {line, ch} position with an additional
   * option to align the line at the "top", "center" or "bottom" of the editor
   * with "top" being default value.
   */
  setCursor: function ({line, ch}, align) {
    let cm = editors.get(this);
    this.alignLine(line, align);
    cm.setCursor({line: line, ch: ch});
    this.emit("cursorActivity");
  },

  /**
   * Aligns the provided line to either "top", "center" or "bottom" of the
   * editor view with a maximum margin of MAX_VERTICAL_OFFSET lines from top or
   * bottom.
   */
  alignLine: function (line, align) {
    let cm = editors.get(this);
    let from = cm.lineAtHeight(0, "page");
    let to = cm.lineAtHeight(cm.getWrapperElement().clientHeight, "page");
    let linesVisible = to - from;
    let halfVisible = Math.round(linesVisible / 2);

    // If the target line is in view, skip the vertical alignment part.
    if (line <= to && line >= from) {
      return;
    }

    // Setting the offset so that the line always falls in the upper half
    // of visible lines (lower half for bottom aligned).
    // MAX_VERTICAL_OFFSET is the maximum allowed value.
    let offset = Math.min(halfVisible, MAX_VERTICAL_OFFSET);

    let topLine = {
      "center": Math.max(line - halfVisible, 0),
      "bottom": Math.max(line - linesVisible + offset, 0),
      "top": Math.max(line - offset, 0)
    }[align || "top"] || offset;

    // Bringing down the topLine to total lines in the editor if exceeding.
    topLine = Math.min(topLine, this.lineCount());
    this.setFirstVisibleLine(topLine);
  },

  /**
   * Returns whether a marker of a specified class exists in a line's gutter.
   */
  hasMarker: function (line, gutterName, markerClass) {
    let marker = this.getMarker(line, gutterName);
    if (!marker) {
      return false;
    }

    return marker.classList.contains(markerClass);
  },

  /**
   * Adds a marker with a specified class to a line's gutter. If another marker
   * exists on that line, the new marker class is added to its class list.
   */
  addMarker: function (line, gutterName, markerClass) {
    let cm = editors.get(this);
    let info = cm.lineInfo(line);
    if (!info) {
      return;
    }

    let gutterMarkers = info.gutterMarkers;
    let marker;
    if (gutterMarkers) {
      marker = gutterMarkers[gutterName];
      if (marker) {
        marker.classList.add(markerClass);
        return;
      }
    }

    marker = cm.getWrapperElement().ownerDocument.createElement("div");
    marker.className = markerClass;
    cm.setGutterMarker(info.line, gutterName, marker);
  },

  /**
   * The reverse of addMarker. Removes a marker of a specified class from a
   * line's gutter.
   */
  removeMarker: function (line, gutterName, markerClass) {
    if (!this.hasMarker(line, gutterName, markerClass)) {
      return;
    }

    let cm = editors.get(this);
    cm.lineInfo(line).gutterMarkers[gutterName].classList.remove(markerClass);
  },

  /**
   * Adds a marker with a specified class and an HTML content to a line's
   * gutter. If another marker exists on that line, it is overwritten by a new
   * marker.
   */
  addContentMarker: function (line, gutterName, markerClass, content) {
    let cm = editors.get(this);
    let info = cm.lineInfo(line);
    if (!info) {
      return;
    }

    let marker = cm.getWrapperElement().ownerDocument.createElement("div");
    marker.className = markerClass;
    marker.innerHTML = content;
    cm.setGutterMarker(info.line, gutterName, marker);
  },

  /**
   * The reverse of addContentMarker. Removes any line's markers in the
   * specified gutter.
   */
  removeContentMarker: function (line, gutterName) {
    let cm = editors.get(this);
    let info = cm.lineInfo(line);
    if (!info) {
      return;
    }

    cm.setGutterMarker(info.line, gutterName, null);
  },

  getMarker: function (line, gutterName) {
    let cm = editors.get(this);
    let info = cm.lineInfo(line);
    if (!info) {
      return null;
    }

    let gutterMarkers = info.gutterMarkers;
    if (!gutterMarkers) {
      return null;
    }

    return gutterMarkers[gutterName];
  },

  /**
   * Removes all gutter markers in the gutter with the given name.
   */
  removeAllMarkers: function (gutterName) {
    let cm = editors.get(this);
    cm.clearGutter(gutterName);
  },

  /**
   * Handles attaching a set of events listeners on a marker. They should
   * be passed as an object literal with keys as event names and values as
   * function listeners. The line number, marker node and optional data
   * will be passed as arguments to the function listener.
   *
   * You don't need to worry about removing these event listeners.
   * They're automatically orphaned when clearing markers.
   */
  setMarkerListeners: function (line, gutterName, markerClass, eventsArg, data) {
    if (!this.hasMarker(line, gutterName, markerClass)) {
      return;
    }

    let cm = editors.get(this);
    let marker = cm.lineInfo(line).gutterMarkers[gutterName];

    for (let name in eventsArg) {
      let listener = eventsArg[name].bind(this, line, marker, data);
      marker.addEventListener(name, listener);
    }
  },

  /**
   * Returns whether a line is decorated using the specified class name.
   */
  hasLineClass: function (line, className) {
    let cm = editors.get(this);
    let info = cm.lineInfo(line);

    if (!info || !info.wrapClass) {
      return false;
    }

    return info.wrapClass.split(" ").indexOf(className) != -1;
  },

  /**
   * Sets a CSS class name for the given line, including the text and gutter.
   */
  addLineClass: function (line, className) {
    let cm = editors.get(this);
    cm.addLineClass(line, "wrap", className);
  },

  /**
   * The reverse of addLineClass.
   */
  removeLineClass: function (line, className) {
    let cm = editors.get(this);
    cm.removeLineClass(line, "wrap", className);
  },

  /**
   * Mark a range of text inside the two {line, ch} bounds. Since the range may
   * be modified, for example, when typing text, this method returns a function
   * that can be used to remove the mark.
   */
  markText: function (from, to, className = "marked-text") {
    let cm = editors.get(this);
    let text = cm.getRange(from, to);
    let span = cm.getWrapperElement().ownerDocument.createElement("span");
    span.className = className;
    span.textContent = text;

    let mark = cm.markText(from, to, { replacedWith: span });
    return {
      anchor: span,
      clear: () => mark.clear()
    };
  },

  /**
   * Calculates and returns one or more {line, ch} objects for
   * a zero-based index who's value is relative to the start of
   * the editor's text.
   *
   * If only one argument is given, this method returns a single
   * {line,ch} object. Otherwise it returns an array.
   */
  getPosition: function (...args) {
    let cm = editors.get(this);
    let res = args.map((ind) => cm.posFromIndex(ind));
    return args.length === 1 ? res[0] : res;
  },

  /**
   * The reverse of getPosition. Similarly to getPosition this
   * method returns a single value if only one argument was given
   * and an array otherwise.
   */
  getOffset: function (...args) {
    let cm = editors.get(this);
    let res = args.map((pos) => cm.indexFromPos(pos));
    return args.length > 1 ? res : res[0];
  },

  /**
   * Returns a {line, ch} object that corresponds to the
   * left, top coordinates.
   */
  getPositionFromCoords: function ({left, top}) {
    let cm = editors.get(this);
    return cm.coordsChar({ left: left, top: top });
  },

  /**
   * The reverse of getPositionFromCoords. Similarly, returns a {left, top}
   * object that corresponds to the specified line and character number.
   */
  getCoordsFromPosition: function ({line, ch}) {
    let cm = editors.get(this);
    return cm.charCoords({ line: ~~line, ch: ~~ch });
  },

  /**
   * Returns true if there's something to undo and false otherwise.
   */
  canUndo: function () {
    let cm = editors.get(this);
    return cm.historySize().undo > 0;
  },

  /**
   * Returns true if there's something to redo and false otherwise.
   */
  canRedo: function () {
    let cm = editors.get(this);
    return cm.historySize().redo > 0;
  },

  /**
   * Marks the contents as clean and returns the current
   * version number.
   */
  setClean: function () {
    let cm = editors.get(this);
    this.version = cm.changeGeneration();
    this._lastDirty = false;
    this.emit("dirty-change");
    return this.version;
  },

  /**
   * Returns true if contents of the text area are
   * clean i.e. no changes were made since the last version.
   */
  isClean: function () {
    let cm = editors.get(this);
    return cm.isClean(this.version);
  },

  /**
   * This method opens an in-editor dialog asking for a line to
   * jump to. Once given, it changes cursor to that line.
   */
  jumpToLine: function () {
    let doc = editors.get(this).getWrapperElement().ownerDocument;
    let div = doc.createElement("div");
    let inp = doc.createElement("input");
    let txt = doc.createTextNode(L10N.getStr("gotoLineCmd.promptTitle"));

    inp.type = "text";
    inp.style.width = "10em";
    inp.style.marginInlineStart = "1em";

    div.appendChild(txt);
    div.appendChild(inp);

    if (!this.hasMultipleSelections()) {
      let cm = editors.get(this);
      let sel = cm.getSelection();
      // Scratchpad inserts and selects a comment after an error happens:
      // "@Scratchpad/1:10:2". Parse this to get the line and column.
      // In the string above this is line 10, column 2.
      let match = sel.match(RE_SCRATCHPAD_ERROR);
      if (match) {
        let [, line, column ] = match;
        inp.value = column ? line + ":" + column : line;
        inp.selectionStart = inp.selectionEnd = inp.value.length;
      }
    }

    this.openDialog(div, (line) => {
      // Handle LINE:COLUMN as well as LINE
      let match = line.toString().match(RE_JUMP_TO_LINE);
      if (match) {
        let [, matchLine, column ] = match;
        this.setCursor({line: matchLine - 1, ch: column ? column - 1 : 0 });
      }
    });
  },

  /**
   * Moves the content of the current line or the lines selected up a line.
   */
  moveLineUp: function () {
    let cm = editors.get(this);
    let start = cm.getCursor("start");
    let end = cm.getCursor("end");

    if (start.line === 0) {
      return;
    }

    // Get the text in the lines selected or the current line of the cursor
    // and append the text of the previous line.
    let value;
    if (start.line !== end.line) {
      value = cm.getRange({ line: start.line, ch: 0 },
        { line: end.line, ch: cm.getLine(end.line).length }) + "\n";
    } else {
      value = cm.getLine(start.line) + "\n";
    }
    value += cm.getLine(start.line - 1);

    // Replace the previous line and the currently selected lines with the new
    // value and maintain the selection of the text.
    cm.replaceRange(value, { line: start.line - 1, ch: 0 },
      { line: end.line, ch: cm.getLine(end.line).length });
    cm.setSelection({ line: start.line - 1, ch: start.ch },
      { line: end.line - 1, ch: end.ch });
  },

  /**
   * Moves the content of the current line or the lines selected down a line.
   */
  moveLineDown: function () {
    let cm = editors.get(this);
    let start = cm.getCursor("start");
    let end = cm.getCursor("end");

    if (end.line + 1 === cm.lineCount()) {
      return;
    }

    // Get the text of next line and append the text in the lines selected
    // or the current line of the cursor.
    let value = cm.getLine(end.line + 1) + "\n";
    if (start.line !== end.line) {
      value += cm.getRange({ line: start.line, ch: 0 },
        { line: end.line, ch: cm.getLine(end.line).length });
    } else {
      value += cm.getLine(start.line);
    }

    // Replace the currently selected lines and the next line with the new
    // value and maintain the selection of the text.
    cm.replaceRange(value, { line: start.line, ch: 0 },
      { line: end.line + 1, ch: cm.getLine(end.line + 1).length});
    cm.setSelection({ line: start.line + 1, ch: start.ch },
      { line: end.line + 1, ch: end.ch });
  },

  /**
   * Intercept CodeMirror's Find and replace key shortcut to select the search input
   */
  findOrReplace: function (node, isReplaceAll) {
    let cm = editors.get(this);
    let isInput = node.tagName === "INPUT";
    let isSearchInput = isInput && node.type === "search";
    // replace box is a different input instance than search, and it is
    // located in a code mirror dialog
    let isDialogInput = isInput &&
        node.parentNode &&
        node.parentNode.classList.contains("CodeMirror-dialog");
    if (!(isSearchInput || isDialogInput)) {
      return;
    }

    if (isSearchInput || isReplaceAll) {
      // select the search input
      // it's the precise reason why we reimplement these key shortcuts
      node.select();
    }

    // need to call it since we prevent the propagation of the event and
    // cancel codemirror's key handling
    cm.execCommand("find");
  },

  /**
   * Intercept CodeMirror's findNext and findPrev key shortcut to allow
   * immediately search for next occurance after typing a word to search.
   */
  findNextOrPrev: function (node, isFindPrev) {
    let cm = editors.get(this);
    let isInput = node.tagName === "INPUT";
    let isSearchInput = isInput && node.type === "search";
    if (!isSearchInput) {
      return;
    }
    let query = node.value;
    // cm.state.search allows to automatically start searching for the next occurance
    // it's the precise reason why we reimplement these key shortcuts
    if (!cm.state.search || cm.state.search.query !== query) {
      cm.state.search = {
        posFrom: null,
        posTo: null,
        overlay: null,
        query
      };
    }

    // need to call it since we prevent the propagation of the event and
    // cancel codemirror's key handling
    if (isFindPrev) {
      cm.execCommand("findPrev");
    } else {
      cm.execCommand("findNext");
    }
  },

  /**
   * Returns current font size for the editor area, in pixels.
   */
  getFontSize: function () {
    let cm = editors.get(this);
    let el = cm.getWrapperElement();
    let win = el.ownerDocument.defaultView;

    return parseInt(win.getComputedStyle(el).getPropertyValue("font-size"), 10);
  },

  /**
   * Sets font size for the editor area.
   */
  setFontSize: function (size) {
    let cm = editors.get(this);
    cm.getWrapperElement().style.fontSize = parseInt(size, 10) + "px";
    cm.refresh();
  },

  /**
   * Sets an option for the editor.  For most options it just defers to
   * CodeMirror.setOption, but certain ones are maintained within the editor
   * instance.
   */
  setOption: function (o, v) {
    let cm = editors.get(this);

    // Save the state of a valid autoCloseBrackets string, so we can reset
    // it if it gets preffed off and back on.
    if (o === "autoCloseBrackets" && v) {
      this.config.autoCloseBracketsSaved = v;
    }

    if (o === "autocomplete") {
      this.config.autocomplete = v;
      this.setupAutoCompletion();
    } else {
      cm.setOption(o, v);
      this.config[o] = v;
    }

    if (o === "enableCodeFolding") {
      // The new value maybe explicitly force foldGUtter on or off, ignoring
      // the prefs service.
      this.updateCodeFoldingGutter();
    }
  },

  /**
   * Gets an option for the editor.  For most options it just defers to
   * CodeMirror.getOption, but certain ones are maintained within the editor
   * instance.
   */
  getOption: function (o) {
    let cm = editors.get(this);
    if (o === "autocomplete") {
      return this.config.autocomplete;
    }

    return cm.getOption(o);
  },

  /**
   * Sets up autocompletion for the editor. Lazily imports the required
   * dependencies because they vary by editor mode.
   *
   * Autocompletion is special, because we don't want to automatically use
   * it just because it is preffed on (it still needs to be requested by the
   * editor), but we do want to always disable it if it is preffed off.
   */
  setupAutoCompletion: function () {
    // The autocomplete module will overwrite this.initializeAutoCompletion
    // with a mode specific autocompletion handler.
    if (!this.initializeAutoCompletion) {
      this.extend(require("./autocomplete"));
    }

    if (this.config.autocomplete && Services.prefs.getBoolPref(AUTOCOMPLETE)) {
      this.initializeAutoCompletion(this.config.autocompleteOpts);
    } else {
      this.destroyAutoCompletion();
    }
  },

  /**
   * Extends an instance of the Editor object with additional
   * functions. Each function will be called with context as
   * the first argument. Context is a {ed, cm} object where
   * 'ed' is an instance of the Editor object and 'cm' is an
   * instance of the CodeMirror object. Example:
   *
   * function hello(ctx, name) {
   *   let { cm, ed } = ctx;
   *   cm;   // CodeMirror instance
   *   ed;   // Editor instance
   *   name; // 'Mozilla'
   * }
   *
   * editor.extend({ hello: hello });
   * editor.hello('Mozilla');
   */
  extend: function (funcs) {
    Object.keys(funcs).forEach(name => {
      let cm = editors.get(this);
      let ctx = { ed: this, cm: cm, Editor: Editor};

      if (name === "initialize") {
        funcs[name](ctx);
        return;
      }

      this[name] = funcs[name].bind(null, ctx);
    });
  },

  destroy: function () {
    this.container = null;
    this.config = null;
    this.version = null;

    if (this._prefObserver) {
      this._prefObserver.off(TAB_SIZE, this.reloadPreferences);
      this._prefObserver.off(EXPAND_TAB, this.reloadPreferences);
      this._prefObserver.off(KEYMAP, this.reloadPreferences);
      this._prefObserver.off(AUTO_CLOSE, this.reloadPreferences);
      this._prefObserver.off(AUTOCOMPLETE, this.reloadPreferences);
      this._prefObserver.off(DETECT_INDENT, this.reloadPreferences);
      this._prefObserver.off(ENABLE_CODE_FOLDING, this.reloadPreferences);
      this._prefObserver.destroy();
    }

    this.emit("destroy");
  },

  updateCodeFoldingGutter: function () {
    let shouldFoldGutter = this.config.enableCodeFolding;
    let foldGutterIndex = this.config.gutters.indexOf("CodeMirror-foldgutter");
    let cm = editors.get(this);

    if (shouldFoldGutter === undefined) {
      shouldFoldGutter = Services.prefs.getBoolPref(ENABLE_CODE_FOLDING);
    }

    if (shouldFoldGutter) {
      // Add the gutter before enabling foldGutter
      if (foldGutterIndex === -1) {
        let gutters = this.config.gutters.slice();
        gutters.push("CodeMirror-foldgutter");
        this.setOption("gutters", gutters);
      }

      this.setOption("foldGutter", true);
    } else {
      // No code should remain folded when folding is off.
      if (cm) {
        cm.execCommand("unfoldAll");
      }

      // Remove the gutter so it doesn't take up space
      if (foldGutterIndex !== -1) {
        let gutters = this.config.gutters.slice();
        gutters.splice(foldGutterIndex, 1);
        this.setOption("gutters", gutters);
      }

      this.setOption("foldGutter", false);
    }
  },

  /**
   * Register all key shortcuts.
   */
  _initShortcuts: function (win) {
    let shortcuts = new KeyShortcuts({
      window: win
    });
    this._onShortcut = this._onShortcut.bind(this);
    let keys = [
      "find.key",
      "findNext.key",
      "findPrev.key"
    ];

    if (OS === "Darwin") {
      keys.push("replaceAllMac.key");
    } else {
      keys.push("replaceAll.key");
    }
    // Process generic keys:
    keys.forEach(name => {
      let key = L10N.getStr(name);
      shortcuts.on(key, (_, event) => this._onShortcut(name, event));
    });
  },
    /**
   * Key shortcut listener.
   */
  _onShortcut: function (name, event) {
    if (!this._isInputOrTextarea(event.target)) {
      return;
    }
    let node = event.originalTarget;

    switch (name) {
      // replaceAll.key is Alt + find.key
      case "replaceAllMac.key":
        this.findOrReplace(node, true);
        break;
      // replaceAll.key is Shift + find.key
      case "replaceAll.key":
        this.findOrReplace(node, true);
        break;
      case "find.key":
        this.findOrReplace(node, false);
        break;
      // findPrev.key is Shift + findNext.key
      case "findPrev.key":
        this.findNextOrPrev(node, true);
        break;
      case "findNext.key":
        this.findNextOrPrev(node, false);
        break;
      default:
        console.error("Unexpected editor key shortcut", name);
        return;
    }
    // Prevent default for this action
    event.stopPropagation();
    event.preventDefault();
  },

  /**
   * Check if a node is an input or textarea
   */
  _isInputOrTextarea: function (element) {
    let name = element.tagName.toLowerCase();
    return name === "input" || name === "textarea";
  }
};

// Since Editor is a thin layer over CodeMirror some methods
// are mapped directly—without any changes.

CM_MAPPING.forEach(name => {
  Editor.prototype[name] = function (...args) {
    let cm = editors.get(this);
    return cm[name].apply(cm, args);
  };
});

// Static methods on the Editor object itself.

/**
 * Returns a string representation of a shortcut 'key' with
 * a OS specific modifier. Cmd- for Macs, Ctrl- for other
 * platforms. Useful with extraKeys configuration option.
 *
 * CodeMirror defines all keys with modifiers in the following
 * order: Shift - Ctrl/Cmd - Alt - Key
 */
Editor.accel = function (key, modifiers = {}) {
  return (modifiers.shift ? "Shift-" : "") +
         (Services.appinfo.OS == "Darwin" ? "Cmd-" : "Ctrl-") +
         (modifiers.alt ? "Alt-" : "") + key;
};

/**
 * Returns a string representation of a shortcut for a
 * specified command 'cmd'. Append Cmd- for macs, Ctrl- for other
 * platforms unless noaccel is specified in the options. Useful when overwriting
 * or disabling default shortcuts.
 */
Editor.keyFor = function (cmd, opts = { noaccel: false }) {
  let key = L10N.getStr(cmd + ".commandkey");
  return opts.noaccel ? key : Editor.accel(key);
};

/**
 * We compute the CSS property names, values, and color names to be used with
 * CodeMirror to more closely reflect what is supported by the target platform.
 * The database is used to replace the values used in CodeMirror while initiating
 * an editor object. This is done here instead of the file codemirror/css.js so
 * as to leave that file untouched and easily upgradable.
 */
function getCSSKeywords(cssProperties) {
  function keySet(array) {
    let keys = {};
    for (let i = 0; i < array.length; ++i) {
      keys[array[i]] = true;
    }
    return keys;
  }

  let propertyKeywords = cssProperties.getNames();
  let colorKeywords = {};
  let valueKeywords = {};

  propertyKeywords.forEach(property => {
    if (property.includes("color")) {
      cssProperties.getValues(property).forEach(value => {
        colorKeywords[value] = true;
      });
    } else {
      cssProperties.getValues(property).forEach(value => {
        valueKeywords[value] = true;
      });
    }
  });

  return {
    propertyKeywords: keySet(propertyKeywords),
    colorKeywords: colorKeywords,
    valueKeywords: valueKeywords
  };
}

module.exports = Editor;
