From 16293ba57cea96e0f7f3eca12b0e6aef8f3b2f8e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adam=20Zieli=C5=84ski?= <adam@adamziel.com>
Date: Fri, 17 May 2024 16:57:56 +0200
Subject: [PATCH] Remote.html: Preload the SQLite database plugin, but only
 execute it if there's no custom db.php inside wp-content

---
 .../remote/src/lib/worker-thread.ts           | 20 ++++++++++++++-
 packages/playground/wordpress/src/index.ts    | 25 +++++++++++++++++--
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/packages/playground/remote/src/lib/worker-thread.ts b/packages/playground/remote/src/lib/worker-thread.ts
index a29a099e84..cf56ceca62 100644
--- a/packages/playground/remote/src/lib/worker-thread.ts
+++ b/packages/playground/remote/src/lib/worker-thread.ts
@@ -6,8 +6,12 @@ import {
 	getWordPressModuleDetails,
 	LatestSupportedWordPressVersion,
 	SupportedWordPressVersions,
+	sqliteDatabaseIntegration,
 } from '@wp-playground/wordpress-builds';
-import { wordPressRewriteRules } from '@wp-playground/wordpress';
+import {
+	preloadSqliteIntegration,
+	wordPressRewriteRules,
+} from '@wp-playground/wordpress';
 import { PHPRequestHandler } from '@php-wasm/universal';
 import {
 	SyncProgressCallback,
@@ -57,6 +61,14 @@ if (
 	wordPressAvailableInOPFS = await playgroundAvailableInOpfs(virtualOpfsDir!);
 }
 
+// The SQLite integration must always be downloaded, even when using OPFS or Native FS,
+// because it can't be assumed to exist in WordPress document root. Instead, it's installed
+// in the /internal directory to avoid polluting the mounted directory structure.
+downloadMonitor.expectAssets({
+	[sqliteDatabaseIntegration.url]: sqliteDatabaseIntegration.size,
+});
+const sqliteIntegrationRequest = monitoredFetch(sqliteDatabaseIntegration.url);
+
 // Start downloading WordPress if needed
 let wordPressRequest = null;
 if (!wordPressAvailableInOPFS) {
@@ -210,6 +222,12 @@ try {
 		});
 	}
 
+	const sqliteIntegrationZip = await (await sqliteIntegrationRequest).blob();
+	await preloadSqliteIntegration(
+		primaryPhp,
+		new File([sqliteIntegrationZip], 'sqlite.zip')
+	);
+
 	// Always setup the current site URL.
 	await defineSiteUrl(primaryPhp, {
 		siteUrl: scopedSiteUrl,
diff --git a/packages/playground/wordpress/src/index.ts b/packages/playground/wordpress/src/index.ts
index 7160af09c8..c20212c13f 100644
--- a/packages/playground/wordpress/src/index.ts
+++ b/packages/playground/wordpress/src/index.ts
@@ -202,12 +202,21 @@ export async function preloadSqliteIntegration(
 			"'{SQLITE_PLUGIN}'",
 			phpVar(joinPaths(SQLITE_PLUGIN_FOLDER, 'load.php'))
 		);
+	const dbPhpPath = joinPaths(await php.documentRoot, 'wp-content/db.php');
+	const stopIfDbPhpExists = `<?php
+	// Do not preload this if WordPress comes with a custom db.php file.
+	if(file_exists(${phpVar(dbPhpPath)})) {
+		return;
+	}
+	?>`;
 	const SQLITE_MUPLUGIN_PATH =
 		'/internal/shared/mu-plugins/sqlite-database-integration.php';
-	await php.writeFile(SQLITE_MUPLUGIN_PATH, dbPhp);
+	await php.writeFile(SQLITE_MUPLUGIN_PATH, stopIfDbPhpExists + dbPhp);
 	await php.writeFile(
 		`/internal/shared/preload/0-sqlite.php`,
-		`<?php
+		stopIfDbPhpExists +
+			`<?php
+
 /**
  * Loads the SQLite integration plugin before WordPress is loaded
  * and without creating a drop-in "db.php" file. 
@@ -260,6 +269,18 @@ class Playground_SQLite_Integration_Loader {
     }
 }
 $wpdb = $GLOBALS['wpdb'] = new Playground_SQLite_Integration_Loader();
+
+/**
+ * WordPress is capable of using a preloaded global $wpdb. However, if
+ * it cannot find the drop-in db.php plugin it still checks whether
+ * the mysqli_connect() function exists even though it's not used.
+ *
+ * What WordPress demands, Playground shall provide.
+ */
+if(!function_exists('mysqli_connect')) {
+	function mysqli_connect() {}
+}
+
 		`
 	);
 	/**