From 7da1555c847edfc5a1d75b1ed26362901d3f9609 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Sat, 21 Apr 2018 20:19:43 +0300
Subject: [PATCH] Improve Markdown rendering

* Remove paragraphs from output HTML
* Remove mention link wrapper from text (leaving only mention name)
---
 lib/bfhtml/doc.go  |  2 ++
 lib/bfhtml/html.go | 34 ++++++++++++++++++++++++++++++++++
 matrix/matrix.go   | 35 ++++++++++++++++++++++++++++++++++-
 ui/room-view.go    |  5 +----
 4 files changed, 71 insertions(+), 5 deletions(-)
 create mode 100644 lib/bfhtml/doc.go
 create mode 100644 lib/bfhtml/html.go

diff --git a/lib/bfhtml/doc.go b/lib/bfhtml/doc.go
new file mode 100644
index 0000000..4881087
--- /dev/null
+++ b/lib/bfhtml/doc.go
@@ -0,0 +1,2 @@
+// Package bfhtml contains an extension to the Blackfriday HTML renderer to disable paragraph tags.
+package bfhtml
diff --git a/lib/bfhtml/html.go b/lib/bfhtml/html.go
new file mode 100644
index 0000000..14076ee
--- /dev/null
+++ b/lib/bfhtml/html.go
@@ -0,0 +1,34 @@
+// gomuks - A terminal Matrix client written in Go.
+// Copyright (C) 2018 Tulir Asokan
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package bfhtml
+
+import (
+	"io"
+
+	bf "gopkg.in/russross/blackfriday.v2"
+)
+
+type HTMLRenderer struct {
+	*bf.HTMLRenderer
+}
+
+func (r *HTMLRenderer) RenderNode(w io.Writer, node *bf.Node, entering bool) bf.WalkStatus {
+	if node.Type == bf.Paragraph {
+		return bf.GoToNext
+	}
+	return r.HTMLRenderer.RenderNode(w, node, entering)
+}
diff --git a/matrix/matrix.go b/matrix/matrix.go
index a38b439..eb0eea5 100644
--- a/matrix/matrix.go
+++ b/matrix/matrix.go
@@ -36,6 +36,7 @@ import (
 	"maunium.net/go/gomuks/config"
 	"maunium.net/go/gomuks/debug"
 	"maunium.net/go/gomuks/interface"
+	"maunium.net/go/gomuks/lib/bfhtml"
 	"maunium.net/go/gomuks/matrix/pushrules"
 	"maunium.net/go/gomuks/matrix/rooms"
 )
@@ -327,14 +328,46 @@ func (c *Container) SendMessage(roomID, msgtype, text string) (string, error) {
 	return resp.EventID, nil
 }
 
+func (c *Container) RenderMarkdown(text string) string {
+	parser := blackfriday.New(
+		blackfriday.WithExtensions(blackfriday.NoIntraEmphasis |
+			blackfriday.Tables |
+			blackfriday.FencedCode |
+			blackfriday.Strikethrough |
+			blackfriday.SpaceHeadings |
+			blackfriday.DefinitionLists))
+	ast := parser.Parse([]byte(text))
+
+	renderer := bfhtml.HTMLRenderer{
+		HTMLRenderer: blackfriday.NewHTMLRenderer(blackfriday.HTMLRendererParameters{
+			Flags: blackfriday.UseXHTML,
+		}),
+	}
+
+	var buf strings.Builder
+	renderer.RenderHeader(&buf, ast)
+	ast.Walk(func(node *blackfriday.Node, entering bool) blackfriday.WalkStatus {
+		return renderer.RenderNode(&buf, node, entering)
+	})
+	renderer.RenderFooter(&buf, ast)
+	return buf.String()
+}
+
+var mentionRegex = regexp.MustCompile("\\[(.+?)]\\(https://matrix.to/#/@.+?:.+?\\)")
+var roomRegex = regexp.MustCompile("\\[.+?]\\(https://matrix.to/#/(#.+?:[^/]+?)\\)")
+
 func (c *Container) SendMarkdownMessage(roomID, msgtype, text string) (string, error) {
 	defer debug.Recover()
 
-	html := string(blackfriday.Run([]byte(text)))
+	html := c.RenderMarkdown(text)
 	if html == text {
 		return c.SendMessage(roomID, msgtype, text)
 	}
 
+	// Remove markdown link stuff from plaintext mentions and room links
+	text = mentionRegex.ReplaceAllString(text, "$1")
+	text = roomRegex.ReplaceAllString(text, "$1")
+
 	c.SendTyping(roomID, false)
 	resp, err := c.client.SendMessageEvent(roomID, "m.room.message",
 		map[string]interface{}{
diff --git a/ui/room-view.go b/ui/room-view.go
index 332605b..a66b0ee 100644
--- a/ui/room-view.go
+++ b/ui/room-view.go
@@ -242,10 +242,7 @@ type completion struct {
 }
 
 func (view *RoomView) AutocompleteUser(existingText string) (completions []completion) {
-	textWithoutPrefix := existingText
-	if strings.HasPrefix(existingText, "@") {
-		textWithoutPrefix = existingText[1:]
-	}
+	textWithoutPrefix := strings.TrimPrefix(existingText, "@")
 	for _, user := range view.Room.GetMembers() {
 		if user.DisplayName == textWithoutPrefix || user.UserID == existingText {
 			// Exact match, return that.