From 6e4e0f9b86f1a0be5a60799281333bcd56ed8f03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adam=20Zieli=C5=84ski?= <adam@adamziel.com>
Date: Fri, 13 Sep 2024 22:13:21 +0200
Subject: [PATCH] Website: Preview the PR specified by the referer header

Enables easy linking to Playground PRs from WordPress and Gutenberg
GitHub PRs without interpolating the PR number in the link.

This PR adds a https://playground.wordpress.net/preview-referrer-pr.php script
that looks at the Referer header, extracts the repo and the PR number
from it, and redirects to the relevant PR previewer.

 ## Testing instructions

1. Run the script on a HTTPS domain (or use my link: https://adamadam.blog/referer.php)
2. Link to that script from a WordPress develop and a Gutenberg PR
3. Click those links
4. Confirm you were redirected to /wordpress.html or /gutenberg.html
   with a proper `?pr=` query parameter

Props to @gziolo for the idea
---
 .../website/public/preview-referrer-pr.php     | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 packages/playground/website/public/preview-referrer-pr.php

diff --git a/packages/playground/website/public/preview-referrer-pr.php b/packages/playground/website/public/preview-referrer-pr.php
new file mode 100644
index 0000000000..08ee3af3af
--- /dev/null
+++ b/packages/playground/website/public/preview-referrer-pr.php
@@ -0,0 +1,18 @@
+<?php
+
+$referrer = $_SERVER['HTTP_REFERER'];
+$prNumber = null;
+
+if (preg_match('/github\.com\/WordPress\/gutenberg\/pull\/(?<prNumber>\d+)/i', $referrer, $matches)) {
+    $prNumber = $matches['prNumber'];
+    header('Location: ./gutenberg.html?pr=' . $prNumber);
+    exit;
+} else if (preg_match('/github\.com\/WordPress\/wordpress-develop\/pull\/(?<prNumber>\d+)/i', $referrer, $matches)) {
+    $prNumber = $matches['prNumber'];
+    header('Location: ./wordpress.html?pr=' . $prNumber);
+    exit;
+} else {
+    header('HTTP/1.1 403 Forbidden');
+    echo 'Invalid referrer';
+    exit;
+}