I just learned that URL unfurling is a thing, and now this chat client supports it (poorly).

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@3335 ed5197a5-7fde-0310-b194-c3ffbd925b24

packages/cory/libunfurl/libunfurl.js

@@ -0,0 +1,67 @@
+"use strict";
+
+//! {"category": "libraries", "require": ["libhttp", "libxml"], "permissions": ["network"]}
+
+let libxml = require("libxml");
+let libhttp = require("libhttp");
+
+let gEmbedIndex = 0;
+
+async function unfurl(url) {
+	let result = {href: url};
+	let response = await libhttp.get(url);
+	let parsed = libxml.StreamParser().parse(response.body);
+	let oEmbedUrl;
+	for (let node of parsed) {
+		if (node.type == "element" && node.value == "link" && node.attributes.type == "application/json+oembed") {
+			oEmbedUrl = node.attributes.href;
+			break;
+		}
+	}
+
+	if (oEmbedUrl) {
+		response = await libhttp.get(oEmbedUrl);
+		let oEmbed = JSON.parse(response.body);
+		gEmbedIndex++;
+		result = [{href: url}, "\n", {
+			name: "oEmbed" + gEmbedIndex,
+			iframe: `
+	<span style="border: 0; padding: 0; margin: 0; overflow: hidden">
+		${oEmbed.html}
+	</span>
+	<script language="javascript">
+		let gResizeMeMessage = {
+			event: "resizeMe",
+			name: "oEmbed${gEmbedIndex}",
+			width: -1,
+			height: -1,
+		};
+		setInterval(function() {
+			if (document.body.scrollHeight != gResizeMeMessage.height
+				|| document.body.scrollWidth != gResizeMeMessage.width) {
+				gResizeMeMessage.width = document.body.scrollWidth;
+				gResizeMeMessage.height = document.body.scrollHeight;
+				parent.postMessage(gResizeMeMessage, "*");
+			}
+		}, 100);
+	</script>
+`,
+			width: oEmbed.width || 320,
+			height: oEmbed.height || 120,
+			style: "margin: 0; padding: 0; border: 0; overflow: hidden",
+		}];
+	}
+
+	return result;
+}
+
+async function test() {
+	terminal.print(await unfurl("https://twitter.com/511nyAlbany/status/777221230915096576"));
+	terminal.print(await unfurl("https://www.youtube.com/watch?v=pTA0DSfrGZ0"));
+}
+
+//test().catch(terminal.print);
+
+core.register("onMessage", function(sender, message) {
+	return unfurl(message).catch(error => [message, "(error retrieving: ", error, ")"]);
+});