Make markdown less aggressive

src/Markdown.js

@@ -0,0 +1,128 @@
+/*
+Copyright 2016 OpenMarket Ltd
+
+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.
+*/
+
+import marked from 'marked';
+
+// marked only applies the default options on the high
+// level marked() interface, so we do it here.
+const marked_options = Object.assign({}, marked.defaults, {
+    gfm: true,
+    tables: true,
+    breaks: true,
+    pedantic: false,
+    sanitize: true,
+    smartLists: true,
+    smartypants: false,
+    xhtml: true, // return self closing tags (ie. <br /> not <br>)
+});
+
+/**
+ * Class that wraps marked, adding the ability to see whether
+ * a given message actually uses any markdown syntax or whether
+ * it's plain text.
+ */
+export default class Markdown {
+    constructor(input) {
+        const lexer = new marked.Lexer(marked_options);
+        this.tokens = lexer.lex(input);
+    }
+
+    _copyTokens() {
+        // copy tokens (the parser modifies its input arg)
+        const tokens_copy = this.tokens.slice();
+        // it also has a 'links' property, because this is javascript
+        // and why wouldn't you have an array that also has properties?
+        return Object.assign(tokens_copy, this.tokens);
+    }
+
+    isPlainText() {
+        // we determine if the message requires markdown by
+        // running the parser on the tokens with a dummy
+        // rendered and seeing if any of the renderer's
+        // functions are called other than those noted below.
+        // In case you were wondering, no we can't just examine
+        // the tokens because the tokens we have are only the
+        // output of the *first* tokenizer: any line-based
+        // markdown is processed by marked within Parser by
+        // the 'inline lexer'...
+        let is_plain = true;
+
+        function setNotPlain() {
+            is_plain = false;
+        }
+
+        const dummy_renderer = {};
+        for (const k of Object.keys(marked.Renderer.prototype)) {
+            dummy_renderer[k] = setNotPlain;
+        }
+        // text and paragraph are just text
+        dummy_renderer.text = function(t){return t;}
+        dummy_renderer.paragraph = function(t){return t;}
+
+        // ignore links where text is just the url:
+        // this ignores plain URLs that markdown has
+        // detected whilst preserving markdown syntax links
+        dummy_renderer.link = function(href, title, text) {
+            if (text != href) {
+                is_plain = false;
+            }
+        }
+
+        const dummy_options = Object.assign({}, marked_options, {
+            renderer: dummy_renderer,
+        });
+        const dummy_parser = new marked.Parser(dummy_options);
+        dummy_parser.parse(this._copyTokens());
+
+        return is_plain;
+    }
+
+    toHTML() {
+        const real_renderer = new marked.Renderer();
+        real_renderer.link = function(href, title, text) {
+            // prevent marked from turning plain URLs
+            // into links, because its algorithm is fairly
+            // poor. Let's send plain URLs rather than
+            // badly linkified ones (the linkifier Vector
+            // uses on message display is way better, eg.
+            // handles URLs with closing parens at the end).
+            if (text == href) {
+                return href;
+            }
+            return marked.Renderer.prototype.apply(this, arguments);
+        }
+
+        real_renderer.paragraph = (text) => {
+            // The tokens at the top level are the 'blocks', so if we
+            // have more than one, there are multiple 'paragraphs'.
+            // If there is only one top level token, just return the
+            // bare text: it's a single line of text and so should be
+            // 'inline', rather than necessarily wrapped in its own
+            // p tag. If, however, we have multiple tokens, each gets
+            // its own p tag to keep them as separate paragraphs.
+            if (this.tokens.length == 1) {
+                return text;
+            }
+            return '<p>' + text + '</p>';
+        }
+
+        const real_options = Object.assign({}, marked_options, {
+            renderer: real_renderer,
+        });
+        const real_parser = new marked.Parser(real_options);
+        return real_parser.parse(this._copyTokens());
+    }
+}

src/components/views/rooms/MessageComposerInputOld.js

@@ -15,18 +15,6 @@
  */
 var React = require("react");
 
-var marked = require("marked");
-marked.setOptions({
-    renderer: new marked.Renderer(),
-    gfm: true,
-    tables: true,
-    breaks: true,
-    pedantic: false,
-    sanitize: true,
-    smartLists: true,
-    smartypants: false
-});
-
 var MatrixClientPeg = require("../../../MatrixClientPeg");
 var SlashCommands = require("../../../SlashCommands");
 var Modal = require("../../../Modal");
@@ -35,24 +23,12 @@ var sdk = require('../../../index');
 
 var dis = require("../../../dispatcher");
 var KeyCode = require("../../../KeyCode");
+var Markdown = require("../../../Markdown");
 
 var TYPING_USER_TIMEOUT = 10000;
 var TYPING_SERVER_TIMEOUT = 30000;
 var MARKDOWN_ENABLED = true;
 
-function mdownToHtml(mdown) {
-    var html = marked(mdown) || "";
-    html = html.trim();
-    // strip start and end <p> tags else you get 'orrible spacing
-    if (html.indexOf("<p>") === 0) {
-        html = html.substring("<p>".length);
-    }
-    if (html.lastIndexOf("</p>") === (html.length - "</p>".length)) {
-        html = html.substring(0, html.length - "</p>".length);
-    }
-    return html;
-}
-
 /*
  * The textInput part of the MessageComposer
  */
@@ -341,8 +317,15 @@ module.exports = React.createClass({
             contentText = contentText.substring(1);
         }
 
-        var htmlText;
-        if (this.markdownEnabled && (htmlText = mdownToHtml(contentText)) !== contentText) {
+        let send_markdown = false;
+        let mdown;
+        if (this.markdownEnabled) {
+            mdown = new Markdown(contentText);
+            send_markdown = !mdown.isPlainText();
+        }
+
+        if (send_markdown) {
+            const htmlText = mdown.toHTML();
             sendMessagePromise = isEmote ?
                 MatrixClientPeg.get().sendHtmlEmote(this.props.room.roomId, contentText, htmlText) :
                 MatrixClientPeg.get().sendHtmlMessage(this.props.room.roomId, contentText, htmlText);