From 75fbed4a4d841e07ce577b5b58719bf9f188c35d Mon Sep 17 00:00:00 2001
From: Noah Petherbridge <root@kirsle.net>
Date: Fri, 24 Mar 2023 22:47:58 -0700
Subject: [PATCH] YouTube link embeds

---
 pkg/expand_media.go     | 29 +++++++++++++++++++++++++++++
 pkg/handlers.go         |  3 +++
 web/static/css/chat.css |  5 +++++
 3 files changed, 37 insertions(+)
 create mode 100644 pkg/expand_media.go

diff --git a/pkg/expand_media.go b/pkg/expand_media.go
new file mode 100644
index 0000000..345a1b0
--- /dev/null
+++ b/pkg/expand_media.go
@@ -0,0 +1,29 @@
+package barertc
+
+import (
+	"fmt"
+	"regexp"
+)
+
+// Media regexps
+var (
+	ytLinkRegexp = regexp.MustCompile(`(?:youtube(?:-nocookie)?\.com/(?:[^/]+/.+/|(?:v|e(?:mbed)?)/|.*[?&]v=)|youtu\.be/)([^"&?/\s]{11})`)
+	ytIdRegexp   = regexp.MustCompile(`[0-9A-Za-z_-]{10}[048AEIMQUYcgkosw]`) // YT ID validator
+)
+
+// YT embed template
+const youtubeEmbedTemplate = `<iframe class="youtube-embed" width="560" height="315" src="https://www.youtube.com/embed/%s" title="YouTube video player" frameborder="0" allow="autoplay; encrypted-media; picture-in-picture; web-share" allowfullscreen></iframe>`
+
+// ExpandMedia detects media URLs such as YouTube videos and stylizes the message up with embeds.
+func (s *Server) ExpandMedia(message string) string {
+	// YouTube links.
+	if m := ytLinkRegexp.FindStringSubmatch(message); len(m) > 0 {
+		var ytid = m[1]
+
+		// Sanity check the ID parsed OK (e.g. multiple youtube links can throw it off)
+		if ytIdRegexp.Match([]byte(ytid)) {
+			message += fmt.Sprintf(youtubeEmbedTemplate, ytid)
+		}
+	}
+	return message
+}
diff --git a/pkg/handlers.go b/pkg/handlers.go
index b08306e..423a0ee 100644
--- a/pkg/handlers.go
+++ b/pkg/handlers.go
@@ -120,6 +120,9 @@ func (s *Server) OnMessage(sub *Subscriber, msg Message) {
 		return
 	}
 
+	// Detect and expand media such as YouTube videos.
+	markdown = s.ExpandMedia(markdown)
+
 	// Message to be echoed to the channel.
 	var message = Message{
 		Action:   ActionMessage,
diff --git a/web/static/css/chat.css b/web/static/css/chat.css
index 308f621..a62acd4 100644
--- a/web/static/css/chat.css
+++ b/web/static/css/chat.css
@@ -237,4 +237,9 @@ body {
     left: 4px;
     font-size: small;
     padding: 2px 4px;
+}
+
+/* YouTube embeds */
+.youtube-embed {
+    max-width: 100%;
 }
\ No newline at end of file