From 30f40ee448cf6df8a991218d7ff41fec2bb66a5a Mon Sep 17 00:00:00 2001
From: Pavel Djundik <github@xpaw.me>
Date: Fri, 21 Jul 2017 13:22:59 +0300
Subject: [PATCH] Fix remaining issues with link previews

Fixes #1357
---
 client/js/renderPreview.js             | 19 +++++++++++++++----
 client/js/socket-events/msg_preview.js |  2 --
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/client/js/renderPreview.js b/client/js/renderPreview.js
index e88c563e..46bb54e6 100644
--- a/client/js/renderPreview.js
+++ b/client/js/renderPreview.js
@@ -12,6 +12,18 @@ function renderPreview(preview, msg) {
 		return;
 	}
 
+	const escapedLink = preview.link.replace(/["\\]/g, "\\$&");
+	const previewContainer = msg.find(`.preview[data-url="${escapedLink}"]`);
+
+	// This is to fix a very rare case of rendering a preview twice
+	// This happens when a very large amount of messages is being sent to the client
+	// and they get queued, so the `preview` object on the server has time to load before
+	// it actually gets sent to the server, which makes the loaded preview sent twice,
+	// once in `msg` and another in `msg:preview`
+	if (!previewContainer.is(":empty")) {
+		return;
+	}
+
 	preview.shown = options.shouldOpenMessagePreview(preview.type);
 
 	const container = msg.closest(".chat");
@@ -20,12 +32,11 @@ function renderPreview(preview, msg) {
 		bottom = container.isScrollBottom();
 	}
 
-	msg.find(`.text a[href="${preview.link}"]`)
+	msg.find(`.text a[href="${escapedLink}"]`)
 		.first()
-		.after(templates.msg_preview_toggle({preview: preview}));
+		.after(templates.msg_preview_toggle({preview: preview}).trim());
 
-	msg.find(`.preview[data-url="${preview.link}"]`)
-		.first()
+	previewContainer
 		.append(templates.msg_preview({preview: preview}));
 
 	if (preview.shown && bottom) {
diff --git a/client/js/socket-events/msg_preview.js b/client/js/socket-events/msg_preview.js
index 81a3d617..42972d61 100644
--- a/client/js/socket-events/msg_preview.js
+++ b/client/js/socket-events/msg_preview.js
@@ -1,13 +1,11 @@
 "use strict";
 
 const $ = require("jquery");
-const Handlebars = require("handlebars/runtime");
 const renderPreview = require("../renderPreview");
 const socket = require("../socket");
 
 socket.on("msg:preview", function(data) {
 	const msg = $("#msg-" + data.id);
 
-	data.link = Handlebars.Utils.escapeExpression(data.link);
 	renderPreview(data.preview, msg);
 });