3 files changed, 102 insertions(+), 2 deletions(-)

A lib/link_preview.dart
M lib/linkify.dart
M lib/page/buffer.dart

@@ 0,0 1,58 @@
+import 'dart:io';
+
+import 'package:linkify/linkify.dart' as lnk;
+
+import 'linkify.dart';
+
+const maxPhotoSize = 10 * 1024 * 1024;
+
+class LinkPreviewer {
+	final HttpClient client = HttpClient();
+
+	void dispose() {
+		client.close();
+	}
+
+	Future<PhotoPreview?> previewUrl(Uri url) async {
+		if (url.scheme != 'https') {
+			return null;
+		}
+
+		var req = await client.headUrl(url);
+		var resp = await req.close();
+		if (resp.statusCode ~/ 100 != 2) {
+			throw Exception('HTTP error fetching $url: ${resp.statusCode}');
+		}
+
+		if (resp.headers.contentType?.primaryType != 'image') {
+			return null;
+		}
+		if (resp.headers.contentLength > maxPhotoSize) {
+			return null;
+		}
+
+		return PhotoPreview(url);
+	}
+
+	Future<List<PhotoPreview>> previewText(String text) async {
+		var links = extractLinks(text);
+
+		List<PhotoPreview> previews = [];
+		await Future.wait(links.map((link) async {
+			if (link is lnk.UrlElement) {
+				var preview = await previewUrl(Uri.parse(link.url));
+				if (preview != null) {
+					previews.add(preview);
+				}
+			}
+		}));
+
+		return previews;
+	}
+}
+
+class PhotoPreview {
+	final Uri url;
+
+	PhotoPreview(this.url);
+}

@@ 3,11 3,15 @@ import 'package:flutter_linkify/flutter_linkify.dart';
 import 'package:linkify/linkify.dart' as lnk;
 import 'package:url_launcher/url_launcher.dart';
 
-TextSpan linkify(String text, { required TextStyle textStyle, required TextStyle linkStyle }) {
-	var elements = lnk.linkify(text, options: lnk.LinkifyOptions(
+List<LinkifyElement> extractLinks(String text) {
+	return lnk.linkify(text, options: lnk.LinkifyOptions(
 		humanize: false,
 		defaultToHttps: true,
 	));
+}
+
+TextSpan linkify(String text, { required TextStyle textStyle, required TextStyle linkStyle }) {
+	var elements = extractLinks(text);
 	return buildTextSpan(
 		elements,
 		onOpen: (link) async {

@@ 3,6 3,7 @@ import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:flutter_typeahead/flutter_typeahead.dart';
 import 'package:provider/provider.dart';
+import 'package:url_launcher/url_launcher.dart';
 
 import '../ansi.dart';
 import '../client.dart';


@@ 10,6 11,7 @@ import '../client_controller.dart';
 import '../database.dart';
 import '../irc.dart';
 import '../linkify.dart';
+import '../link_preview.dart';
 import '../models.dart';
 import '../notification_controller.dart';
 import '../prefs.dart';


@@ 636,6 638,8 @@ class _CompactMessageItem extends StatelessWidget {
 	}
 }
 
+var linkPreviewer = LinkPreviewer();
+
 class _MessageItem extends StatelessWidget {
 	final MessageModel msg;
 	final MessageModel? prevMsg, nextMsg;


@@ 651,6 655,36 @@ class _MessageItem extends StatelessWidget {
 		this.onSwipe
 	}) : super(key: key);
 
+	Widget _buildLinkPreview(String text) {
+		return FutureBuilder<List<PhotoPreview>>(
+			future: linkPreviewer.previewText(text),
+			builder: (context, snapshot) {
+				var previews = snapshot.data;
+				if (previews == null || previews.isEmpty) {
+					return Container();
+				}
+				var preview = previews.first;
+				return Container(
+					margin: EdgeInsets.all(10),
+					child: ClipRRect(
+						borderRadius: BorderRadius.circular(10),
+						child: InkWell(
+							onTap: () {
+								launchUrl(preview.url, mode: LaunchMode.externalApplication);
+							},
+							child: Image.network(
+								preview.url.toString(),
+								width: 250,
+								height: 250,
+								fit: BoxFit.cover,
+							),
+						),
+					),
+				);
+			},
+		);
+	}
+
 	@override
 	Widget build(BuildContext context) {
 		var client = context.read<Client>();


@@ 717,6 751,7 @@ class _MessageItem extends StatelessWidget {
 		var linkStyle = textStyle.apply(decoration: TextDecoration.underline);
 
 		List<InlineSpan> content;
+		Widget? linkPreview;
 		if (isAction) {
 			// isAction can only ever be true if we have a ctcp
 			var actionText = stripAnsiFormatting(ctcp!.param ?? '');


@@ 744,6 779,8 @@ class _MessageItem extends StatelessWidget {
 				if (isFirstInGroup) TextSpan(text: '\n'),
 				linkify(body, textStyle: textStyle, linkStyle: linkStyle),
 			];
+
+			linkPreview = _buildLinkPreview(body);
 		}
 
 		Widget inner = RichText(text: TextSpan(


@@ 829,6 866,7 @@ class _MessageItem extends StatelessWidget {
 				margin: EdgeInsets.only(left: margin, right: margin, top: marginTop, bottom: marginBottom),
 				child: decoratedMessage,
 			),
+			if (linkPreview != null) linkPreview,
 		]);
 	}
 }