From 2352eb406a46c5e7b15e1e7defdcdddb1f833c91 Mon Sep 17 00:00:00 2001
From: Sorunome <mail@sorunome.de>
Date: Sat, 9 May 2020 14:00:46 +0000
Subject: [PATCH] add markdown parsing

---
 lib/src/room.dart           | 42 +++++++++++++---
 lib/src/utils/markdown.dart | 99 +++++++++++++++++++++++++++++++++++++
 pubspec.lock                | 14 ++++++
 pubspec.yaml                |  2 +
 test/markdown_test.dart     | 42 ++++++++++++++++
 5 files changed, 193 insertions(+), 6 deletions(-)
 create mode 100644 lib/src/utils/markdown.dart
 create mode 100644 test/markdown_test.dart

diff --git a/lib/src/room.dart b/lib/src/room.dart
index b91664d..097d728 100644
--- a/lib/src/room.dart
+++ b/lib/src/room.dart
@@ -37,11 +37,13 @@ import 'package:image/image.dart';
 import 'package:matrix_file_e2ee/matrix_file_e2ee.dart';
 import 'package:mime_type/mime_type.dart';
 import 'package:olm/olm.dart' as olm;
+import 'package:html_unescape/html_unescape.dart';
 
 import './user.dart';
 import 'timeline.dart';
 import 'utils/matrix_localizations.dart';
 import 'utils/states_map.dart';
+import './utils/markdown.dart';
 
 enum PushRuleState { notify, mentions_only, dont_notify }
 enum JoinRules { public, knock, invite, private }
@@ -478,14 +480,42 @@ class Room {
 
   /// Sends a normal text message to this room. Returns the event ID generated
   /// by the server for this message.
-  Future<String> sendTextEvent(String message, {String txid, Event inReplyTo}) {
-    var type = 'm.text';
+  Future<String> sendTextEvent(String message, {String txid, Event inReplyTo, bool parseMarkdown = true}) {
+    final event = <String, dynamic>{
+      'msgtype': 'm.text',
+      'body': message,
+    };
     if (message.startsWith('/me ')) {
-      type = 'm.emote';
-      message = message.substring(4);
+      event['type'] = 'm.emote';
+      event['body'] = message.substring(4);
     }
-    return sendEvent({'msgtype': type, 'body': message},
-        txid: txid, inReplyTo: inReplyTo);
+    if (parseMarkdown) {
+      // load the emote packs
+      final emotePacks = <String, Map<String, String>>{};
+      final addEmotePack = (String packName, Map<String, dynamic> content) {
+        emotePacks[packName] = <String, String>{};
+        content.forEach((key, value) {
+          if (key is String && value is String && value.startsWith('mxc://')) {
+            emotePacks[packName][key] = value;
+          }
+        });
+      };
+      final roomEmotes = getState('im.ponies.room_emotes');
+      final userEmotes = client.accountData['im.ponies.user_emotes'];
+      if (roomEmotes != null && roomEmotes.content['short'] is Map) {
+        addEmotePack('room', roomEmotes.content['short']);
+      }
+      if (userEmotes != null && userEmotes.content['short'] is Map) {
+        addEmotePack('user', userEmotes.content['short']);
+      }
+      final html = markdown(event['body'], emotePacks);
+      // if the decoded html is the same as the body, there is no need in sending a formatted message
+      if (HtmlUnescape().convert(html) != event['body']) {
+        event['format'] = 'org.matrix.custom.html';
+        event['formatted_body'] = html;
+      }
+    }
+    return sendEvent(event, txid: txid, inReplyTo: inReplyTo);
   }
 
   /// Sends a [file] to this room after uploading it. The [msgType] is optional
diff --git a/lib/src/utils/markdown.dart b/lib/src/utils/markdown.dart
new file mode 100644
index 0000000..f0577d2
--- /dev/null
+++ b/lib/src/utils/markdown.dart
@@ -0,0 +1,99 @@
+import 'package:markdown/markdown.dart';
+import 'dart:convert';
+
+class LinebreakSyntax extends InlineSyntax {
+  LinebreakSyntax() : super(r'\n');
+
+  @override
+  bool onMatch(InlineParser parser, Match match) {
+    parser.addNode(Element.empty('br'));
+    return true;
+  }
+}
+
+class SpoilerSyntax extends TagSyntax {
+  Map<String, String> reasonMap = <String, String>{};
+  SpoilerSyntax() : super(
+    r'\|\|(?:([^\|]+)\|(?!\|))?',
+    requiresDelimiterRun: true,
+    end: r'\|\|',
+  );
+
+  @override
+  bool onMatch(InlineParser parser, Match match) {
+    if (super.onMatch(parser, match)) {
+      reasonMap[match.input] = match[1];
+      return true;
+    }
+    return false;
+  }
+
+  @override
+  bool onMatchEnd(InlineParser parser, Match match, TagState state) {
+    final element = Element('span', state.children);
+    element.attributes['data-mx-spoiler'] = htmlEscape.convert(reasonMap[match.input] ?? '');
+    parser.addNode(element);
+    return true;
+  }
+}
+
+class EmoteSyntax extends InlineSyntax {
+  final Map<String, Map<String, String>> emotePacks;
+  EmoteSyntax(this.emotePacks) : super(r':(?:([-\w]+)~)?([-\w]+):');
+
+  @override
+  bool onMatch(InlineParser parser, Match match) {
+    final pack = match[1] ?? '';
+    final emote = ':${match[2]}:';
+    String mxc;
+    if (pack.isEmpty) {
+      // search all packs
+      for (final emotePack in emotePacks.values) {
+        mxc = emotePack[emote];
+        if (mxc != null) {
+          break;
+        }
+      }
+    } else {
+      mxc = emotePacks[pack] != null ? emotePacks[pack][emote] : null;
+    }
+    if (mxc == null) {
+      // emote not found. Insert the whole thing as plain text
+      parser.addNode(Text(match[0]));
+      return true;
+    }
+    final element = Element.empty('img');
+    element.attributes['src'] = htmlEscape.convert(mxc);
+    element.attributes['alt'] = htmlEscape.convert(emote);
+    element.attributes['title'] = htmlEscape.convert(emote);
+    element.attributes['height'] = '32';
+    element.attributes['vertical-align'] = 'middle';
+    parser.addNode(element);
+    return true;
+  }
+}
+
+
+String markdown(String text, [Map<String, Map<String, String>> emotePacks]) {
+  emotePacks ??= <String, Map<String, String>>{};
+  var ret = markdownToHtml(text,
+    extensionSet: ExtensionSet.commonMark,
+    inlineSyntaxes: [StrikethroughSyntax(), LinebreakSyntax(), SpoilerSyntax(), EmoteSyntax(emotePacks)],
+  );
+    
+  var stripPTags = '<p>'.allMatches(ret).length <= 1;
+  if (stripPTags) {
+    final otherBlockTags = ['table', 'pre', 'ol', 'ul', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote'];
+    for (final tag in otherBlockTags) {
+      // we check for the close tag as the opening one might have attributes
+      if (ret.contains('</${tag}>')) {
+        stripPTags = false;
+        break;
+      }
+    }
+  }
+  if (stripPTags) {
+    ret = ret.replaceAll('<p>', '').replaceAll('</p>', '');
+  }
+  return ret.trim().replaceAll(RegExp(r'(<br />)+$'), '');
+}
diff --git a/pubspec.lock b/pubspec.lock
index bcd7fd7..b8efd9f 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -197,6 +197,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.14.0+2"
+  html_unescape:
+    dependency: "direct main"
+    description:
+      name: html_unescape
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.1+3"
   http:
     dependency: "direct main"
     description:
@@ -260,6 +267,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.11.3+2"
+  markdown:
+    dependency: "direct main"
+    description:
+      name: markdown
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.3"
   matcher:
     dependency: transitive
     description:
diff --git a/pubspec.yaml b/pubspec.yaml
index 74664bc..ea95e73 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -12,6 +12,8 @@ dependencies:
   mime_type: ^0.3.0
   canonical_json: ^1.0.0
   image: ^2.1.4
+  markdown: ^2.1.3
+  html_unescape: ^1.0.1+3
 
   olm:
     git:
diff --git a/test/markdown_test.dart b/test/markdown_test.dart
new file mode 100644
index 0000000..f11af69
--- /dev/null
+++ b/test/markdown_test.dart
@@ -0,0 +1,42 @@
+import 'package:famedlysdk/src/utils/markdown.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('markdown', () {
+    final emotePacks = {
+      'room': {
+        ':fox:': 'mxc://roomfox',
+        ':bunny:': 'mxc://roombunny',
+      },
+      'user': {
+        ':fox:': 'mxc://userfox',
+        ':bunny:': 'mxc://userbunny',
+        ':raccoon:': 'mxc://raccoon',
+      },
+    };
+    test('simple markdown', () {
+      expect(markdown('hey *there* how are **you** doing?'), 'hey <em>there</em> how are <strong>you</strong> doing?');
+      expect(markdown('wha ~~strike~~ works!'), 'wha <del>strike</del> works!');
+    });
+    test('spoilers', () {
+      expect(markdown('Snape killed ||Dumbledoor||'), 'Snape killed <span data-mx-spoiler="">Dumbledoor</span>');
+      expect(markdown('Snape killed ||Story|Dumbledoor||'), 'Snape killed <span data-mx-spoiler="Story">Dumbledoor</span>');
+    });
+    test('multiple paragraphs', () {
+      expect(markdown('Heya!\n\nBeep'), '<p>Heya!</p>\n<p>Beep</p>');
+    });
+    test('Other block elements', () {
+      expect(markdown('# blah\n\nblubb'), '<h1>blah</h1>\n<p>blubb</p>');
+    });
+    test('linebreaks', () {
+      expect(markdown('foxies\ncute'), 'foxies<br />\ncute');
+    });
+    test('emotes', () {
+      expect(markdown(':fox:', emotePacks), '<img src="mxc:&#47;&#47;roomfox" alt=":fox:" title=":fox:" height="32" vertical-align="middle" />');
+      expect(markdown(':user~fox:', emotePacks), '<img src="mxc:&#47;&#47;userfox" alt=":fox:" title=":fox:" height="32" vertical-align="middle" />');
+      expect(markdown(':raccoon:', emotePacks), '<img src="mxc:&#47;&#47;raccoon" alt=":raccoon:" title=":raccoon:" height="32" vertical-align="middle" />');
+      expect(markdown(':invalid:', emotePacks), ':invalid:');
+      expect(markdown(':room~invalid:', emotePacks), ':room~invalid:');
+    });
+  });
+}