text: // Copyright 2012 The Closure Library Authors. All Rights Reserved.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //      http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS-IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  /**
   * @fileoverview A plugin to enable the First Strong Bidi algorithm.  The First
   * Strong algorithm as a heuristic used to automatically set paragraph direction
   * depending on its content.
   *
   * In the documentation below, a 'paragraph' is the local element which we
   * evaluate as a whole for purposes of determining directionality. It may be a
   * block-level element (e.g. &lt;div&gt;) or a whole list (e.g. &lt;ul&gt;).
   *
   * This implementation is based on, but is not identical to, the original
   * First Strong algorithm defined in Unicode
   * @see http://www.unicode.org/reports/tr9/
   * The central difference from the original First Strong algorithm is that this
   * implementation decides the paragraph direction based on the first strong
   * character that is <em>typed</em> into the paragraph, regardless of its
   * location in the paragraph, as opposed to the original algorithm where it is
   * the first character in the paragraph <em>by location</em>, regardless of
   * whether other strong characters already appear in the paragraph, further its
   * start.
   *
   * <em>Please note</em> that this plugin does not perform the direction change
   * itself. Rather, it fires editor commands upon the key up event when a
   * direction change needs to be performed; {@code goog.editor.Command.DIR_RTL}
   * or {@code goog.editor.Command.DIR_RTL}.
   *
   */
  
  goog.provide('goog.editor.plugins.FirstStrong');
  
  goog.require('goog.dom.NodeType');
  goog.require('goog.dom.TagIterator');
  goog.require('goog.dom.TagName');
  goog.require('goog.editor.Command');
  goog.require('goog.editor.Plugin');
  goog.require('goog.editor.node');
  goog.require('goog.editor.range');
  goog.require('goog.i18n.bidi');
  goog.require('goog.i18n.uChar');
  goog.require('goog.iter');
  goog.require('goog.userAgent');
  
  
  
  /**
   * First Strong plugin.
   * @constructor
   * @extends {goog.editor.Plugin}
   */
  goog.editor.plugins.FirstStrong = function() {
    goog.base(this);
  
    /**
     * Indicates whether or not the cursor is in a paragraph we have not yet
     * finished evaluating for directionality. This is set to true whenever the
     * cursor is moved, and set to false after seeing a strong character in the
     * paragraph the cursor is currently in.
     *
     * @type {boolean}
     * @private
     */
    this.isNewBlock_ = true;
  
    /**
     * Indicates whether or not the current paragraph the cursor is in should be
     * set to Right-To-Left directionality.
     *
     * @type {boolean}
     * @private
     */
    this.switchToRtl_ = false;
  
    /**
     * Indicates whether or not the current paragraph the cursor is in should be
     * set to Left-To-Right directionality.
     *
     * @type {boolean}
     * @private
     */
    this.switchToLtr_ = false;
  };
  goog.inherits(goog.editor.plugins.FirstStrong, goog.editor.Plugin);
  
  
  /** @override */
  goog.editor.plugins.FirstStrong.prototype.getTrogClassId = function() {
    return 'FirstStrong';
  };
  
  
  /** @override */
  goog.editor.plugins.FirstStrong.prototype.queryCommandValue =
      function(command) {
    return false;
  };
  
  
  /** @override */
  goog.editor.plugins.FirstStrong.prototype.handleSelectionChange =
      function(e, node) {
    this.isNewBlock_ = true;
    return false;
  };
  
  
  /**
   * The name of the attribute which records the input text.
   *
   * @type {string}
   * @const
   */
  goog.editor.plugins.FirstStrong.INPUT_ATTRIBUTE = 'fs-input';
  
  
  /** @override */
  goog.editor.plugins.FirstStrong.prototype.handleKeyPress = function(e) {
    if (!this.isNewBlock_) {
      return false;  // We've already determined this paragraph's direction.
    }
    // Ignore non-character key press events.
    if (e.ctrlKey || e.metaKey) {
      return false;
    }
    var newInput = goog.i18n.uChar.fromCharCode(e.charCode);
  
    // IME's may return 0 for the charCode, which is a legitimate, non-Strong
    // charCode, or they may return an illegal charCode (for which newInput will
    // be false).
    if (!newInput || !e.charCode) {
      var browserEvent = e.getBrowserEvent();
      if (browserEvent) {
        if (goog.userAgent.IE && browserEvent['getAttribute']) {
          newInput = browserEvent['getAttribute'](
              goog.editor.plugins.FirstStrong.INPUT_ATTRIBUTE);
        } else {
          newInput = browserEvent[
              goog.editor.plugins.FirstStrong.INPUT_ATTRIBUTE];
        }
      }
    }
  
    if (!newInput) {
      return false;  // Unrecognized key.
    }
  
    var isLtr = goog.i18n.bidi.isLtrChar(newInput);
    var isRtl = !isLtr && goog.i18n.bidi.isRtlChar(newInput);
    if (!isLtr && !isRtl) {
      return false;  // This character cannot change anything (it is not Strong).
    }
    // This character is Strongly LTR or Strongly RTL. We might switch direction
    // on it now, but in any case we do not need to check any more characters in
    // this paragraph after it.
    this.isNewBlock_ = false;
  
    // Are there no Strong characters already in the paragraph?
    if (this.isNeutralBlock_()) {
      this.switchToRtl_ = isRtl;
      this.switchToLtr_ = isLtr;
    }
    return false;
  };
  
  
  /**
   * Calls the flip directionality commands.  This is done here so things go into
   * the redo-undo stack at the expected order; fist enter the input, then flip
   * directionality.
   * @override
   */
  goog.editor.plugins.FirstStrong.prototype.handleKeyUp = function(e) {
    if (this.switchToRtl_) {
      var field = this.getFieldObject();
      field.dispatchChange(true);
      field.execCommand(goog.editor.Command.DIR_RTL);
      this.switchToRtl_ = false;
    } else if (this.switchToLtr_) {
      var field = this.getFieldObject();
      field.dispatchChange(true);
      field.execCommand(goog.editor.Command.DIR_LTR);
      this.switchToLtr_ = false;
    }
    return false;
  };
  
  
  /**
   * @return {Element} The lowest Block element ancestor of the node where the
   *     next character will be placed.
   * @private
   */
  goog.editor.plugins.FirstStrong.prototype.getBlockAncestor_ = function() {
    var start = this.getFieldObject().getRange().getStartNode();
    // Go up in the DOM until we reach a Block element.
    while (!goog.editor.plugins.FirstStrong.isBlock_(start)) {
      start = start.parentNode;
    }
    return /** @type {Element} */ (start);
  };
  
  
  /**
   * @return {boolean} Whether the paragraph where the next character will be
   *     entered contains only non-Strong characters.
   * @private
   */
  goog.editor.plugins.FirstStrong.prototype.isNeutralBlock_ = function() {
    var root = this.getBlockAncestor_();
    // The exact node with the cursor location. Simply calling getStartNode() on
    // the range only returns the containing block node.
    var cursor = goog.editor.range.getDeepEndPoint(
        this.getFieldObject().getRange(), false).node;
  
    // In FireFox the BR tag also represents a change in paragraph if not inside a
    // list. So we need special handling to only look at the sub-block between
    // BR elements.
    var blockFunction = (goog.userAgent.GECKO &&
        !this.isList_(root)) ?
            goog.editor.plugins.FirstStrong.isGeckoBlock_ :
            goog.editor.plugins.FirstStrong.isBlock_;
    var paragraph = this.getTextAround_(root, cursor,
        blockFunction);
    // Not using {@code goog.i18n.bidi.isNeutralText} as it contains additional,
    // unwanted checks to the content.
    return !goog.i18n.bidi.hasAnyLtr(paragraph) &&
        !goog.i18n.bidi.hasAnyRtl(paragraph);
  };
  
  
  /**
   * Checks if an element is a list element ('UL' or 'OL').
   *
   * @param {Element} element The element to test.
   * @return {boolean} Whether the element is a list element ('UL' or 'OL').
   * @private
   */
  goog.editor.plugins.FirstStrong.prototype.isList_ = function(element) {
    if (!element) {
      return false;
    }
    var tagName = element.tagName;
    return tagName == goog.dom.TagName.UL || tagName == goog.dom.TagName.OL;
  };
  
  
  /**
   * Returns the text within the local paragraph around the cursor.
   * Notice that for GECKO a BR represents a pargraph change despite not being a
   * block element.
   *
   * @param {Element} root The first block element ancestor of the node the cursor
   *     is in.
   * @param {Node} cursorLocation Node where the cursor currently is, marking the
   *     paragraph whose text we will return.
   * @param {function(Node): boolean} isParagraphBoundary The function to
   *     determine if a node represents the start or end of the paragraph.
   * @return {string} the text in the paragraph around the cursor location.
   * @private
   */
  goog.editor.plugins.FirstStrong.prototype.getTextAround_ = function(root,
      cursorLocation, isParagraphBoundary) {
    // The buffer where we're collecting the text.
    var buffer = [];
    // Have we reached the cursor yet, or are we still before it?
    var pastCursorLocation = false;
  
    if (root && cursorLocation) {
      goog.iter.some(new goog.dom.TagIterator(root), function(node) {
        if (node == cursorLocation) {
          pastCursorLocation = true;
        } else if (isParagraphBoundary(node)) {
          if (pastCursorLocation) {
            // This is the end of the paragraph containing the cursor. We're done.
            return true;
          } else {
            // All we collected so far does not count; it was in a previous
            // paragraph that did not contain the cursor.
            buffer = [];
          }
        }
        if (node.nodeType == goog.dom.NodeType.TEXT) {
          buffer.push(node.nodeValue);
        }
        return false;  // Keep going.
      });
    }
    return buffer.join('');
  };
  
  
  /**
   * @param {Node} node Node to check.
   * @return {boolean} Does the given node represent a Block element? Notice we do
   *     not consider list items as Block elements in the algorithm.
   * @private
   */
  goog.editor.plugins.FirstStrong.isBlock_ = function(node) {
    return !!node && goog.editor.node.isBlockTag(node) &&
        node.tagName != goog.dom.TagName.LI;
  };
  
  
  /**
   * @param {Node} node Node to check.
   * @return {boolean} Does the given node represent a Block element from the
   *     point of view of FireFox? Notice we do not consider list items as Block
   *     elements in the algorithm.
   * @private
   */
  goog.editor.plugins.FirstStrong.isGeckoBlock_ = function(node) {
    return !!node && (node.tagName == goog.dom.TagName.BR ||
        goog.editor.plugins.FirstStrong.isBlock_(node));
  };
  