Remove old PR preview HTML files and add redirects to new preview mod…

…als (#2081)

## Motivation for the change, related issues

This PR removes old PR preview pages, adds relevant redirects, and
updates old PR preview redirects.

Fixes #1969

## Implementation details

In addition to the removals and redirects, this PR:
- Removes some more complicated redirect-related logic because it is
awkward and no longer needed.
- Adjust old UI links to wordpress.html to link to the new modal instead

## Testing Instructions (or ideally a Blueprint)

- Tested manually on a staging site.
- Use `php -l` to ensure there are no syntax errors in
custom-redirects-lib.php
- Deploy and confirm the following paths redirect to the new PR preview
modals
  - /wordpress
  - /wordpress.html
  - /gutenberg
  - /gutenberg.html

packages/playground/website-deployment/custom-redirects-lib.php

@@ -57,29 +57,10 @@ function playground_handle_request() {
 		// Note: Using the header `Vary: Referer` does not seem to affect cacheability.
 		$may_edge_cache = false;
 
-		if ( isset( $redirect['internal' ] ) && $redirect['internal'] ) {
-			$requested_path = $redirect['location'];
-		} else {
-			$should_redirect = true;
-			if ( isset( $redirect['condition']['referers'] ) ) {
-				$should_redirect = false;
-				if ( isset( $_SERVER['HTTP_REFERER'] ) ) {
-					foreach ( $redirect['condition']['referers'] as $referer ) {
-						if ( str_starts_with( $_SERVER['HTTP_REFERER'], $referer ) ) {
-							$should_redirect = true;
-							break;
-						}
-					}
-				}
-			}
-
-			if ( $should_redirect ) {
-				$log( "Redirecting to '{$redirect['location']}' with status '{$redirect['status']}'" );
-				header( "Location: {$redirect['location']}" );
-				http_response_code( $redirect['status'] );
-				die();
-			}
-		}
+		$log( "Redirecting to '{$redirect['location']}' with status '{$redirect['status']}'" );
+		header( "Location: {$redirect['location']}" );
+		http_response_code( $redirect['status'] );
+		die();
 	}
 
 	//
@@ -207,20 +188,6 @@ function playground_maybe_redirect( $requested_path ) {
 		);
 	}
 
-	if ( str_ends_with( $requested_path, '/wordpress' ) ) {
-		return array(
-			'location' => 'wordpress.html',
-			'status' => 301
-		);
-	}
-
-	if ( str_ends_with( $requested_path, '/gutenberg' ) ) {
-		return array(
-			'location' => 'gutenberg.html',
-			'status' => 301
-		);
-	}
-
 	if ( str_ends_with( $requested_path, '/proxy' ) ) {
 		return array(
 			'location' => 'https://github-proxy.com/',
@@ -249,19 +216,41 @@ function playground_maybe_redirect( $requested_path ) {
 		);
 	}
 
-	if ( str_ends_with( $requested_path, '/wordpress.html' ) ) {
+	if (
+		str_ends_with( $requested_path, '/wordpress.html' ) &&
+		isset( $_SERVER['HTTP_REFERER'] ) &&
+		(
+			str_starts_with( $_SERVER['HTTP_REFERER'], 'https://developer.wordpress.org/') ||
+			str_starts_with( $_SERVER['HTTP_REFERER'], 'https://wordpress.org/')
+		)
+	) {
 		return array(
-			'condition' => array(
-				'referers' => array(
-					'https://developer.wordpress.org/',
-					'https://wordpress.org/',
-				),
-			),
 			'location' => '/index.html',
 			'status' => 302,
 		);
 	}
 
+	if (
+		str_ends_with( $requested_path, '/wordpress' ) ||
+		str_ends_with( $requested_path, '/wordpress.html' )
+	) {
+		error_log( 'redir wp' );
+		return array(
+			'location' => '/?modal=preview-pr-wordpress',
+			'status' => 301
+		);
+	}
+
+	if (
+		str_ends_with( $requested_path, '/gutenberg' ) ||
+		str_ends_with( $requested_path, '/gutenberg.html' )
+	) {
+		return array(
+			'location' => '/?modal=preview-pr-gutenberg',
+			'status' => 301
+		);
+	}
+
 	return false;
 }
 

packages/playground/website/demos/index.html

@@ -67,7 +67,7 @@ <h2>WordPress Playground demos</h2>
 			<a href="time-traveling.html" target="_blank">Time Travel</a>
 		</li>
 		<li>
-			<a href="../wordpress.html" target="_blank"
+			<a href="../?modal=preview-pr-wordpress" target="_blank"
 				>WordPress Pull Request Previewer</a
 			>
 		</li>