githubmirror/markdown-here

src/common/markdown-here.js
530 строк18 KB
Adam Pritchard
Added check for 'WebKit' prefixed MutationObserver. So now the lose-modifications prompt will work with Safari 6 and older Chrome.
18 окт 2013, 06:41
18 окт 2013, 06:41707499d
/*
 * Copyright Adam Pritchard 2012
 * MIT License : http://adampritchard.mit-license.org/
 */

/*
 * This file is the heart of Markdown Here. It decides whether we're rendering
 * or reverting; whether we're doing a selection or the whole thing; and
 * actually does it (calling out for the final render).
 */

;(function() {

"use strict";
/*global module:false*/

// In Firefox/Thunderbird, Utils won't already exist.
if (typeof(Utils) === 'undefined') {
  Components.utils.import('resource://markdown_here_common/utils.js');
}

// For debugging purposes. An external service is required to log with Firefox.
var mylog = function() {};

// Finds and returns the page element that currently has focus. Drills down into
// iframes if necessary.
function findFocusedElem(document) {
  var focusedElem = document.activeElement;

  // If the focus is within an iframe, we'll have to drill down to get to the
  // actual element.
  while (focusedElem && focusedElem.contentDocument) {
    focusedElem = focusedElem.contentDocument.activeElement;
  }

  // There's a bug in Firefox/Thunderbird that we need to work around. For
  // details see https://github.com/adam-p/markdown-here/issues/31
  // The short version: Sometimes we'll get the <html> element instead of <body>.
  if (focusedElem instanceof document.defaultView.HTMLHtmlElement) {
    focusedElem = focusedElem.ownerDocument.body;
  }

  return focusedElem;
}

// Returns true if the given element can be properly rendered (i.e., if it's
// a rich-edit compose element).
function elementCanBeRendered(elem) {
  // See here for more info about what we're checking:
  // http://stackoverflow.com/a/3333679/729729
  return (elem.contentEditable === true || elem.contentEditable === 'true' ||
          elem.contenteditable === true || elem.contenteditable === 'true' ||
          (elem.ownerDocument && elem.ownerDocument.designMode === 'on'));
}

// Get the currectly selected range. If there is no selected range (i.e., it is
// collapsed), then contents of the currently focused element will be selected.
// Returns null if no range is selected nor can be selected.
function getOperationalRange(focusedElem) {
  var selection, range, sig;

  selection = focusedElem.ownerDocument.getSelection();

  // For some reason Postbox requires window.getSelection() rather than
  // document.getSelection(). It doesn't fail, but there's a deprecation
  // warning, and then selection.getRangeAt() fails as undefined.
  if (typeof(selection.getRangeAt) === 'undefined') {
    selection = focusedElem.ownerDocument.defaultView.getSelection();
  }

  if (selection.rangeCount < 1) {
    return null;
  }

  range = selection.getRangeAt(0);

  // We're going to work around some weird OSX+Chrome/Safari behaviour where if you
  // right-click on a word it gets selected, which then causes us to render just
  // that one word and look dumb and be wrong.
  // Also, in OSX+Safari, right-clicking in empty space will cause a selection
  // that isn't collapsed, but has no content. Also ignore that.
  if ((range.toString().length === 0) ||
      ((typeof(chrome) !== 'undefined' || typeof(safari) !== 'undefined') &&
       typeof(navigator) !== 'undefined' &&
       navigator.userAgent.indexOf('OS X') >= 0 &&
       range.toString().match(/^\b\w+\b$/))) {
    range.collapse(true);
  }

  if (range.collapsed) {
    // If there's no actual selection, select the contents of the focused element.
    range.selectNodeContents(focusedElem);
  }

  // Does our range include a signature? If so, remove it.
  sig = findSignatureStart(focusedElem);
  if (sig) {
    // If the sig is an element node, set a class indicating that it's a sig.
    // This gives us (or the user) the option of styling differently.
    if (sig.nodeType === sig.ELEMENT_NODE) {
      sig.classList.add('markdown-here-signature');
    }

    if (range.isPointInRange(sig, 0)) {
      range.setEndBefore(sig);
    }
  }

  return range;
}

// A signature is indicated by the last `'-- '` text node (or something like it).
// Returns the sig start element, or null if one is not found.
// NOTE: I would really prefer that this be in markdown-render.js with the other
// exclusion code. But I'm not sure how to find the sig as well without being
// able to traverse the DOM. (Surely with regexes and parsing... someday.)
function findSignatureStart(startElem) {
  var i, child, recurseReturn, sig;

  sig = null;

  for (i = 0; i < startElem.childNodes.length; i++) {
    child = startElem.childNodes[i];
    if (child.nodeType === child.TEXT_NODE) {
      // Thunderbird wraps the sig in a `<pre>`, so there's a newline.
      // Hand-written sigs (including Hotmail and Yahoo) are `'--&nbsp;'` (aka \u00a0).
      // Gmail auto-inserted sigs are `'-- '` (plain space).
      if (child.nodeValue.search(/^--[\s\u00a0]+(\n|$)/) === 0) {

        // Assume that the entire parent element belongs to the sig only if the
        // `'--'` bit is the at the very start of the parent.
        if (startElem.firstChild === child) {
          sig = startElem;
        }
        else {
          sig = child;
        }
      }
    }
    else if (['BLOCKQUOTE'].indexOf(child.nodeName) < 0) {
      recurseReturn = findSignatureStart(child, true);

      // Did the recursive call find it?
      if (recurseReturn) {
        sig = recurseReturn;
      }
    }
  }

  return sig;
}

// Replaces the contents of `range` with the HTML string in `html`.
// Returns the element that is created from `html`.
function replaceRange(range, html) {
  var documentFragment, newElement;

  range.deleteContents();

  // Create a DocumentFragment to insert and populate it with HTML
  documentFragment = range.createContextualFragment(html);

  documentFragment = Utils.sanitizeDocumentFragment(documentFragment);

  // After inserting the node contents, the node is empty. So we need to save a
  // reference to the element that we need to return.
  newElement = documentFragment.firstChild;

  range.insertNode(documentFragment);

  // Make sure the replacement is selected. This isn't strictly necessary, but
  // in order to make Chrome and Firefox consistent, we either need to remove
  // the selection in Chrome, or set it in Firefox. We'll do the latter.
  range.selectNode(newElement);

  return newElement;
}

// Returns the stylesheet for our styles.
function getMarkdownStylesheet(elem, css) {
  var styleElem, stylesheet, i;

  // We have to actually create a style element in the document, then pull the
  // stylesheet out of it (and remove the element).

  // Create a style element
  styleElem = elem.ownerDocument.createElement('style');
  styleElem.setAttribute('title', 'markdown-here-styles');

  // Set the CSS in the style element
  styleElem.appendChild(elem.ownerDocument.createTextNode(css));

  // Put the style element in the DOM under `elem`
  elem.appendChild(styleElem);

  // Find the stylesheet that we just created
  for (i = 0; i < elem.ownerDocument.styleSheets.length; i++) {
    if (elem.ownerDocument.styleSheets[i].title === 'markdown-here-styles') {
      stylesheet = elem.ownerDocument.styleSheets[i];
      break;
    }
  }

  if (!stylesheet) {
    throw 'Markdown Here stylesheet not found!';
  }

  // Take the stylesheet element out of the DOM
  elem.removeChild(styleElem);

  return stylesheet;
}

// Applies our styling explicitly to the elements under `wrapperElem`.
function makeStylesExplicit(wrapperElem, css) {
  var stylesheet, rule, selectorMatches, i, j, styleAttr, elem;

  stylesheet = getMarkdownStylesheet(wrapperElem, css);

  for (i = 0; i < stylesheet.cssRules.length; i++) {
    rule = stylesheet.cssRules[i];

    // Note that the CSS should not have any rules that use "body" or "html".

    // We're starting our search one level above the wrapper, which means we
    // might match stuff outside of our wrapper. We'll have to double-check below.
    selectorMatches = wrapperElem.parentNode.querySelectorAll(rule.selectorText);

    for (j = 0; j < selectorMatches.length; j++) {
      elem = selectorMatches[j];

      // Make sure the element is inside our wrapper (or is our wrapper).
      if (elem !== wrapperElem &&
          !Utils.isElementDescendant(wrapperElem, elem)) {
        continue;
      }

      // Make sure the selector match isn't inside an exclusion block.
      // The check for `elem.classList` stop us if we hit a non-element node
      // while going up through the parents.
      while (elem && (typeof(elem.classList) !== 'undefined')) {
        if (elem.classList.contains('markdown-here-exclude')) {
          elem = 'excluded';
          break;
        }
        elem = elem.parentNode;
      }
      if (elem === 'excluded') {
        // Don't style this element.
        continue;
      }

      // Get the existing styles for the element.
      styleAttr = selectorMatches[j].getAttribute('style') || '';

      // Append the new styles to the end of the existing styles. This will
      // give the new ones precedence if any are the same as existing ones.

      // Make sure existing styles end with a semicolon.
      if (styleAttr && styleAttr.search(/;[\s]*$/) < 0) {
        styleAttr += '; ';
      }

      styleAttr += rule.style.cssText;

      // Set the styles back.
      selectorMatches[j].setAttribute('style', styleAttr);
    }
  }
}

function hasParentElementOfTagName(element, tagName) {
  var parent;

  tagName = tagName.toUpperCase();

  parent = element.parentNode;
  while (parent) {
    if (parent.nodeName === tagName) {
      return true;
    }

    parent = parent.parentNode;
  }

  return false;
}

// Find the wrapper element that's above the current cursor position and returns
// it. Returns falsy if there is no wrapper.
function findMarkdownHereWrapper(focusedElem) {
  var selection, range, wrapper = null;

  selection = focusedElem.ownerDocument.getSelection();

  // For some reason Postbox requires window.getSelection() rather than
  // document.getSelection(). It doesn't fail, but there's a deprecation
  // warning, and then selection.getRangeAt() fails as undefined.
  if (typeof(selection.getRangeAt) === 'undefined') {
    selection = focusedElem.ownerDocument.defaultView.getSelection();
  }

  if (selection.rangeCount < 1) {
    return null;
  }

  range = selection.getRangeAt(0);

  wrapper = range.commonAncestorContainer;
  while (wrapper) {
    // Skip all wrappers that are in a `blockquote`. We don't want to revert
    // Markdown that was sent to us.
    if (wrapper.classList && wrapper.classList.contains('markdown-here-wrapper') &&
        wrapper.attributes && wrapper.attributes.getNamedItem('data-md-original') &&
        !hasParentElementOfTagName(wrapper, 'BLOCKQUOTE')) {
      break;
    }

    wrapper = wrapper.parentNode;
  }

  return wrapper;
}

// Finds all Markdown Here wrappers in the given range. Returns an array of the
// wrapper elements, or null if no wrappers found.
function findMarkdownHereWrappersInRange(range) {
  var documentFragment, cloneWrappers, wrappers, selection, i;

  // Finding elements in a range isn't very simple...

  // Clone the contents of the range.
  documentFragment = range.cloneContents();

  // Find all wrappers. Require the presence of the `data-md-original` attribute.
  cloneWrappers = documentFragment.querySelectorAll('.markdown-here-wrapper[data-md-original]');

  if (cloneWrappers && cloneWrappers.length > 0) {
    // Now we have an array of *copies* of the wrappers in the DOM. Find them in
    // the DOM from their IDs. This is why we need unique IDs for our wrappers.

    wrappers = [];

    for (i = 0; i < cloneWrappers.length; i++) {

      // Require that the `data-md-original` attribute actually have content.
      if (!cloneWrappers[i].attributes.getNamedItem('data-md-original')) {
        continue;
      }

      // Skip all wrappers that are in a `blockquote`. We don't want to revert
      // Markdown that was sent to us.
      if (hasParentElementOfTagName(cloneWrappers[i], 'BLOCKQUOTE')) {
        continue;
      }

      wrappers.push(range.commonAncestorContainer.ownerDocument.getElementById(cloneWrappers[i].id));
    }

    return wrappers;
  }
  else {
    return null;
  }
}

// Converts the Markdown in the user's compose element to HTML and replaces it.
// If `selectedRange` is null, then the entire email is being rendered.
function renderMarkdown(focusedElem, selectedRange, markdownRenderer, renderComplete) {
  var originalHtml = Utils.getDocumentFragmentHTML(selectedRange.cloneContents());

  // Call to the extension main code to actually do the md->html conversion.
  markdownRenderer(focusedElem, selectedRange, function(mdHtml, mdCss) {
    var wrapper;

    // Wrap our pretty HTML in a <div> wrapper.
    // We'll use the wrapper as a marker to indicate that we're in a rendered state.
    mdHtml =
      '<div class="markdown-here-wrapper" ' +
           'data-md-url="' + Utils.getTopURL(focusedElem.ownerDocument.defaultView, true) + '" ' +
           'id="markdown-here-wrapper-' + Math.floor(Math.random()*1000000) + '">' +
        mdHtml +
      '</div>';

    // Store the original Markdown-in-HTML to a data attribute on the wrapper
    // element. We'll use this later if we need to unrender back to Markdown.
    wrapper = replaceRange(selectedRange, mdHtml);
    wrapper.setAttribute('data-md-original', encodeURIComponent(originalHtml));

    // Some webmail (Gmail) strips off any external style block. So we need to go
    // through our styles, explicitly applying them to matching elements.
    makeStylesExplicit(wrapper, mdCss);

    // Monitor for changes to the content of the rendered MD. This will help us
    // prevent the user from silently losing changes later.
    // We're going to set this up after a short timeout, to help prevent false
    // detections based on automatic chagnes by the host site.
    wrapper.ownerDocument.defaultView.setTimeout(function addMutationObserver() {
      var SupportedMutationObserver =
            wrapper.ownerDocument.defaultView.MutationObserver ||
            wrapper.ownerDocument.defaultView.WebKitMutationObserver;
      if (typeof(SupportedMutationObserver) !== 'undefined') {
        var observer = new SupportedMutationObserver(function(mutations) {
          wrapper.setAttribute('markdown-here-wrapper-content-modified', true);
          observer.disconnect();
        });
        observer.observe(wrapper, { childList: true, characterData: true, subtree: true });
      }
    }, 100);

    renderComplete();
  });
}

// Revert the rendered Markdown wrapperElem back to its original form.
function unrenderMarkdown(wrapperElem) {
  var originalMdHtml = decodeURIComponent(wrapperElem.getAttribute('data-md-original'));
  Utils.saferSetOuterHTML(wrapperElem, originalMdHtml);
}

// Exported function.
// The context menu handler. Does the rendering or unrendering, depending on the
// state of the email compose element and the current selection.
// @param `document`  The document object containing the email compose element.
//        (Actually, it can be any document above the compose element. We'll
//        drill down to find the correct element and document.)
// @param `markdownRenderer`  The function that provides raw-Markdown-in-HTML
//                            to pretty-Markdown-in-HTML rendering service.
// @param `logger`  A function that can be used for logging debug messages. May
//                  be null.
// @param `renderComplete`  Callback that will be called when a render or unrender
//                          has completed. Passed two arguments: `elem`
//                          (the element de/rendered) and `rendered` (boolean,
//                          true if rendered, false if derendered).
// @returns True if successful, otherwise an error message that should be shown
//          to the user.
function markdownHere(document, markdownRenderer, logger, renderComplete) {

  if (logger) {
    mylog = logger;
  }

  // If the cursor (or current selection) is in a Markdown Here wrapper, then
  // we're reverting that wrapper back to Markdown. If there's a selection that
  // contains one or more wrappers, then we're reverting those wrappers back to
  // Markdown.
  // Otherwise, we're rendering. If there's a selection, then we're rendering
  // the selection. If not, then we're rendering the whole email.

  var wrappers, outerWrapper, focusedElem, range, i;

  focusedElem = findFocusedElem(document);
  if (!focusedElem || !focusedElem.ownerDocument) {
    return 'Could not find focused element';
  }

  // Look for existing rendered-Markdown wrapper to revert.
  outerWrapper = findMarkdownHereWrapper(focusedElem);
  if (outerWrapper) {
    // There's a wrapper above us.
    wrappers = [outerWrapper];
  }
  else {
    // Are there wrappers in our selection?

    range = getOperationalRange(focusedElem);

    if (!range) {
      return 'Nothing found to render or revert';
    }

    // Look for wrappers in the range under consideration.
    wrappers = findMarkdownHereWrappersInRange(range);
  }

  // If we've found wrappers, then we're reverting.
  // Otherwise, we're rendering.
  if (wrappers && wrappers.length > 0) {
    var yesToAll = false;
    for (i = 0; i < wrappers.length; i++) {
      // Has the content been modified by the user since rendering
      if (wrappers[i].getAttribute('markdown-here-wrapper-content-modified') &&
          !yesToAll) {

          if (wrappers[i].ownerDocument.defaultView.confirm('The rendered Markdown appears to have been modifed.\nIf you unrender it, your changes since rendering will be lost.\n\nAre you sure you wish to unrender?')) {
            yesToAll = true;
          }
          else {
            break;
          }
      }

      unrenderMarkdown(wrappers[i]);
    }

    if (renderComplete) {
      renderComplete(focusedElem, false);
    }
  }
  else {
    renderMarkdown(
      focusedElem,
      range,
      markdownRenderer,
      function() {
        if (renderComplete) {
          renderComplete(focusedElem, true);
        }
      });
  }

  return true;
}

// We also export a couple of utility functions
markdownHere.findFocusedElem = findFocusedElem;
markdownHere.elementCanBeRendered = elementCanBeRendered;

var EXPORTED_SYMBOLS = ['markdownHere'];

if (typeof module !== 'undefined') {
  module.exports = markdownHere;
} else {
  this.markdownHere = markdownHere;
  this.EXPORTED_SYMBOLS = EXPORTED_SYMBOLS;
}

}).call(function() {
  return this || (typeof window !== 'undefined' ? window : global);
}());