From 6c7259eec8b94900763e3410a9d37825e313568b Mon Sep 17 00:00:00 2001
From: David Baker <dave@matrix.org>
Date: Thu, 22 Sep 2016 17:18:12 +0100
Subject: [PATCH] Better detection of when input contains markdown

---
 src/Markdown.js                               | 99 +++++++++++++++++++
 .../views/rooms/MessageComposerInputOld.js    | 37 ++++---
 2 files changed, 121 insertions(+), 15 deletions(-)
 create mode 100644 src/Markdown.js

diff --git a/src/Markdown.js b/src/Markdown.js
new file mode 100644
index 0000000000..e4161c0b76
--- /dev/null
+++ b/src/Markdown.js
@@ -0,0 +1,99 @@
+/*
+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({}, {
+    renderer: new marked.Renderer(),
+    gfm: true,
+    tables: true,
+    breaks: true,
+    pedantic: false,
+    sanitize: true,
+    smartLists: true,
+    smartypants: false,
+}, marked.defaults);
+
+const real_parser = new marked.Parser(marked_options);
+
+/**
+ * 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 it's 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 dummyRenderer = {};
+        for (const k of Object.keys(marked.Renderer.prototype)) {
+            dummyRenderer[k] = setNotPlain;
+        }
+        // text and paragraph are just text
+        dummyRenderer.text = function(t){return t;}
+        dummyRenderer.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
+        dummyRenderer.link = function(href, title, text) {
+            if (text != href) {
+                is_plain = false;
+            }
+        }
+
+        const dummyOptions = {};
+        Object.assign(dummyOptions, marked_options, {
+            renderer: dummyRenderer,
+        });
+        const dummyParser = new marked.Parser(dummyOptions);
+        dummyParser.parse(this._copyTokens());
+
+        return is_plain;
+    }
+
+    toHTML() {
+        return real_parser.parse(this._copyTokens());
+    }
+}
diff --git a/src/components/views/rooms/MessageComposerInputOld.js b/src/components/views/rooms/MessageComposerInputOld.js
index 20b57fb246..5a1ca4e461 100644
--- a/src/components/views/rooms/MessageComposerInputOld.js
+++ b/src/components/views/rooms/MessageComposerInputOld.js
@@ -16,6 +16,18 @@
 var React = require("react");
 
 var marked = require("marked");
+
+var marked_options = {
+    renderer: new marked.Renderer(),
+    gfm: true,
+    tables: true,
+    breaks: true,
+    pedantic: false,
+    sanitize: true,
+    smartLists: true,
+    smartypants: false
+};
+
 marked.setOptions({
     renderer: new marked.Renderer(),
     gfm: true,
@@ -35,24 +47,12 @@ 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 +341,15 @@ 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);