From aec344d30fcedadc930b8214f58feb96aec31cea Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Mon, 14 Feb 2022 14:15:39 +0530
Subject: [PATCH 1/8] Add page reloading in offline.php templates

* Automatically reload the offline page once the user is back online.
---
 wp-includes/template.php | 44 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/wp-includes/template.php b/wp-includes/template.php
index fd3e859ac..a0c9c2a1e 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -171,3 +171,47 @@ function wp_service_worker_error_details_template( $output = '' ) {
 function wp_service_worker_error_message_placeholder() {
 	echo '<p><!--WP_SERVICE_WORKER_ERROR_MESSAGE--></p>';
 }
+
+/**
+ * Reload the offline page and check if user comes online.
+ *
+ * @since 0.7
+ */
+function wp_service_worker_offline_page_reload() {
+	if ( ! is_offline() ) {
+		return;
+	}
+	?>
+	<script>
+		/**
+		 * Listen to changes in the network state, reload when online.
+		 * This handles the case when the device is completely offline.
+		 */
+		window.addEventListener('online', () => {
+			window.location.reload();
+		});
+
+		/**
+		 * Check if the server is responding and reload the page if it is.
+		 * This handles the case when the device is online, but the server is offline or misbehaving.
+		 */
+		async function checkNetworkAndReload() {
+			try {
+				const response = await fetch('.', {method: 'HEAD'});
+				// Verify we get a valid response from the server
+				if (response.status >= 200 && response.status < 500) {
+					window.location.reload();
+					return;
+				}
+			} catch {
+				console.log('User is offline');
+			}
+			window.setTimeout(checkNetworkAndReload, 2500);
+		}
+		checkNetworkAndReload();
+	</script>
+	<?php
+}
+
+add_action( 'wp_footer', 'wp_service_worker_offline_page_reload' );
+add_action( 'error_footer', 'wp_service_worker_offline_page_reload' );

From 4245fa31716b77497b380529cad7bc5e5f914718 Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Tue, 15 Feb 2022 12:40:05 +0530
Subject: [PATCH 2/8] Add counter to delay reloading in each retry

---
 wp-includes/template.php | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/wp-includes/template.php b/wp-includes/template.php
index a0c9c2a1e..22bf4ee63 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -182,7 +182,7 @@ function wp_service_worker_offline_page_reload() {
 		return;
 	}
 	?>
-	<script>
+	<script type="module">
 		/**
 		 * Listen to changes in the network state, reload when online.
 		 * This handles the case when the device is completely offline.
@@ -191,6 +191,9 @@ function wp_service_worker_offline_page_reload() {
 			window.location.reload();
 		});
 
+		// Create a counter to implement exponential backoff.
+		let count = 0;
+
 		/**
 		 * Check if the server is responding and reload the page if it is.
 		 * This handles the case when the device is online, but the server is offline or misbehaving.
@@ -206,7 +209,7 @@ function wp_service_worker_offline_page_reload() {
 			} catch {
 				console.log('User is offline');
 			}
-			window.setTimeout(checkNetworkAndReload, 2500);
+			window.setTimeout(checkNetworkAndReload, Math.pow(2, count++) * 2500);
 		}
 		checkNetworkAndReload();
 	</script>

From 9f2e7c1bd0b5cdc59dcccff4b57b6784bb29dba2 Mon Sep 17 00:00:00 2001
From: Lovekesh Kumar <lpschaudhary1256@gmail.com>
Date: Tue, 15 Feb 2022 15:37:00 +0530
Subject: [PATCH 3/8] Update: Make fetch request to location.href instead of
 base origin

Making fetch requests to the base origin i.e. fetch('.') will drop the query params.

Co-authored-by: Weston Ruter <westonruter@google.com>
---
 wp-includes/template.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/wp-includes/template.php b/wp-includes/template.php
index 22bf4ee63..2ea6b08f9 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -200,7 +200,7 @@ function wp_service_worker_offline_page_reload() {
 		 */
 		async function checkNetworkAndReload() {
 			try {
-				const response = await fetch('.', {method: 'HEAD'});
+				const response = await fetch(location.href, {method: 'HEAD'});
 				// Verify we get a valid response from the server
 				if (response.status >= 200 && response.status < 500) {
 					window.location.reload();

From 3ad9e561da5020a2f6d3aedb66f046045d01978d Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Tue, 15 Feb 2022 21:01:29 +0530
Subject: [PATCH 4/8] Add reloading script in offline and 500 templates and
 allow only on GET method

---
 wp-includes/template.php | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/wp-includes/template.php b/wp-includes/template.php
index 2ea6b08f9..917ffbdf1 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -178,9 +178,14 @@ function wp_service_worker_error_message_placeholder() {
  * @since 0.7
  */
 function wp_service_worker_offline_page_reload() {
-	if ( ! is_offline() ) {
+	if ( isset( $_SERVER['REQUEST_METHOD'] ) && 'GET' !== $_SERVER['REQUEST_METHOD'] ) {
 		return;
 	}
+
+	if ( ! is_offline() && ! is_500() ) {
+		return;
+	}
+
 	?>
 	<script type="module">
 		/**
@@ -207,7 +212,7 @@ function wp_service_worker_offline_page_reload() {
 					return;
 				}
 			} catch {
-				console.log('User is offline');
+				// Unable to connect so do nothing.
 			}
 			window.setTimeout(checkNetworkAndReload, Math.pow(2, count++) * 2500);
 		}

From 19b06c99421054cb0287a6d466b98b773423b1be Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Wed, 16 Feb 2022 20:47:20 +0530
Subject: [PATCH 5/8] Add output control function

---
 wp-includes/template.php | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/wp-includes/template.php b/wp-includes/template.php
index 917ffbdf1..98f79daaf 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -186,6 +186,7 @@ function wp_service_worker_offline_page_reload() {
 		return;
 	}
 
+	ob_start();
 	?>
 	<script type="module">
 		/**
@@ -219,6 +220,7 @@ function wp_service_worker_offline_page_reload() {
 		checkNetworkAndReload();
 	</script>
 	<?php
+	return ob_get_clean();
 }
 
 add_action( 'wp_footer', 'wp_service_worker_offline_page_reload' );

From b8da05a892f7706ac8acc46ea834b9690c62b0e9 Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Wed, 16 Feb 2022 20:50:59 +0530
Subject: [PATCH 6/8] Add test for wp_service_worker_offline_page_reload

---
 tests/test-template.php | 62 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 tests/test-template.php

diff --git a/tests/test-template.php b/tests/test-template.php
new file mode 100644
index 000000000..2d3ed52d7
--- /dev/null
+++ b/tests/test-template.php
@@ -0,0 +1,62 @@
+<?php
+/**
+ * Tests for template.php
+ *
+ * @package PWA
+ */
+
+use Yoast\WPTestUtils\WPIntegration\TestCase;
+
+/**
+ * Tests for template.php
+ */
+class Test_Template extends TestCase {
+	/**
+	 * Test if function adding script on GET method, is_offline() or is_500 is true
+	 *
+	 * @covers ::wp_service_worker_offline_page_reload()
+	 */
+	public function test_wp_service_worker_offline_page_reload() {
+		$this->assertEquals( 10, has_action( 'wp_footer', 'wp_service_worker_offline_page_reload' ) );
+		$this->assertEquals( 10, has_action( 'error_footer', 'wp_service_worker_offline_page_reload' ) );
+
+		// Check when method is GET but not offline or 500.
+		$actual_script = wp_service_worker_offline_page_reload();
+		$this->assertEquals( $_SERVER['REQUEST_METHOD'], 'GET' );
+		$this->assertFalse( is_offline() );
+		$this->assertFalse( is_500() );
+		$this->assertEmpty( $actual_script );
+
+		// Check if script is added when offline.
+		$error_template_url = add_query_arg( 'wp_error_template', 'offline', home_url( '/', 'relative' ) );
+		$this->go_to( $error_template_url );
+
+		$actual_script = wp_service_worker_offline_page_reload();
+		$this->assertEquals( $_SERVER['REQUEST_METHOD'], 'GET' );
+		$this->assertTrue( is_offline() );
+		$this->assertFalse( is_500() );
+		$this->assertStringContainsString( '<script type="module">', $actual_script );
+		$this->assertStringContainsString( 'await fetch(location.href, {method: \'HEAD\'})', $actual_script );
+
+		// Check if script is added when 500.
+		$error_template_url = add_query_arg( 'wp_error_template', '500', home_url( '/', 'relative' ) );
+		$this->go_to( $error_template_url );
+
+		$actual_script = wp_service_worker_offline_page_reload();
+		$this->assertEquals( $_SERVER['REQUEST_METHOD'], 'GET' );
+		$this->assertFalse( is_offline() );
+		$this->assertTrue( is_500() );
+		$this->assertStringContainsString( '<script type="module">', $actual_script );
+		$this->assertStringContainsString( 'await fetch(location.href, {method: \'HEAD\'})', $actual_script );
+
+		$this->go_to( home_url( '/', 'relative' ) );
+
+		// Check when method is not GET.
+		$_SERVER['REQUEST_METHOD'] = 'POST';
+		$actual_script             = wp_service_worker_offline_page_reload();
+		$this->assertEquals( $_SERVER['REQUEST_METHOD'], 'POST' );
+		$this->assertFalse( is_offline() );
+		$this->assertFalse( is_500() );
+		$this->assertEmpty( $actual_script );
+	}
+}

From b80cd853df5f464a32456fcbeb7fff26b127999b Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Wed, 16 Feb 2022 22:52:18 +0530
Subject: [PATCH 7/8] Remove output control functions

---
 wp-includes/template.php | 2 --
 1 file changed, 2 deletions(-)

diff --git a/wp-includes/template.php b/wp-includes/template.php
index 98f79daaf..917ffbdf1 100644
--- a/wp-includes/template.php
+++ b/wp-includes/template.php
@@ -186,7 +186,6 @@ function wp_service_worker_offline_page_reload() {
 		return;
 	}
 
-	ob_start();
 	?>
 	<script type="module">
 		/**
@@ -220,7 +219,6 @@ function wp_service_worker_offline_page_reload() {
 		checkNetworkAndReload();
 	</script>
 	<?php
-	return ob_get_clean();
 }
 
 add_action( 'wp_footer', 'wp_service_worker_offline_page_reload' );

From 661946f5c90c3db23d3e64394b54bda8eeeaac42 Mon Sep 17 00:00:00 2001
From: thelovekesh <lovekesh.kumar@rtcamp.com>
Date: Wed, 16 Feb 2022 22:55:21 +0530
Subject: [PATCH 8/8] Update test cases by adding output control function in
 output

---
 tests/test-template.php | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tests/test-template.php b/tests/test-template.php
index 2d3ed52d7..6d81766f0 100644
--- a/tests/test-template.php
+++ b/tests/test-template.php
@@ -31,7 +31,9 @@ public function test_wp_service_worker_offline_page_reload() {
 		$error_template_url = add_query_arg( 'wp_error_template', 'offline', home_url( '/', 'relative' ) );
 		$this->go_to( $error_template_url );
 
-		$actual_script = wp_service_worker_offline_page_reload();
+		ob_start();
+		wp_service_worker_offline_page_reload();
+		$actual_script = ob_get_clean();
 		$this->assertEquals( $_SERVER['REQUEST_METHOD'], 'GET' );
 		$this->assertTrue( is_offline() );
 		$this->assertFalse( is_500() );
@@ -42,7 +44,9 @@ public function test_wp_service_worker_offline_page_reload() {
 		$error_template_url = add_query_arg( 'wp_error_template', '500', home_url( '/', 'relative' ) );
 		$this->go_to( $error_template_url );
 
-		$actual_script = wp_service_worker_offline_page_reload();
+		ob_start();
+		wp_service_worker_offline_page_reload();
+		$actual_script = ob_get_clean();
 		$this->assertEquals( $_SERVER['REQUEST_METHOD'], 'GET' );
 		$this->assertFalse( is_offline() );
 		$this->assertTrue( is_500() );