Enable overriding Query Monitor's "wp-content/db.php" file

Author: JanJakes

activate.php

@@ -82,6 +82,28 @@ function sqlite_plugin_copy_db_file() {
 
 	$destination = WP_CONTENT_DIR . '/db.php';
 
+	/*
+	 * When an existing "db.php" drop-in is detected, let's check if it's a known
+	 * plugin that we can continue supporting even when we override the drop-in.
+	 */
+	$override_db_dropin = false;
+	if ( file_exists( $destination ) ) {
+		// Check for the Query Monitor plugin.
+		// When "QM_DB" exists, it must have been loaded via the "db.php" file.
+		if ( class_exists( 'QM_DB', false ) ) {
+			$override_db_dropin = true;
+		}
+
+		if ( $override_db_dropin ) {
+			require_once ABSPATH . '/wp-admin/includes/file.php';
+			global $wp_filesystem;
+			if ( ! $wp_filesystem ) {
+				WP_Filesystem();
+			}
+			$wp_filesystem->delete( $destination );
+		}
+	}
+
 	// Place database drop-in if not present yet, except in case there is
 	// another database drop-in present already.
 	if ( ! defined( 'SQLITE_DB_DROPIN_VERSION' ) && ! file_exists( $destination ) ) {

admin-page.php

@@ -26,6 +26,21 @@ function sqlite_add_admin_menu() {
  * The admin page contents.
  */
 function sqlite_integration_admin_screen() {
+	$db_dropin_path = WP_CONTENT_DIR . '/db.php';
+
+	/*
+	 * When an existing "db.php" drop-in is detected, let's check if it's a known
+	 * plugin that we can continue supporting even when we override the drop-in.
+	 */
+	$override_db_dropin = false;
+	if ( file_exists( $db_dropin_path ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) ) {
+		// Check for the Query Monitor plugin.
+		// When "QM_DB" exists, it must have been loaded via the "db.php" file.
+		if ( class_exists( 'QM_DB', false ) ) {
+			$override_db_dropin = true;
+		}
+	}
+
 	?>
 	<div class="wrap">
 		<h1><?php esc_html_e( 'SQLite integration.', 'sqlite-database-integration' ); ?></h1>
@@ -50,7 +65,7 @@ function sqlite_integration_admin_screen() {
 			<div class="notice notice-error">
 				<p><?php esc_html_e( 'We detected that the PDO SQLite driver is missing from your server (the pdo_sqlite extension is not loaded). Please make sure that SQLite is enabled in your PHP installation before proceeding.', 'sqlite-database-integration' ); ?></p>
 			</div>
-		<?php elseif ( file_exists( WP_CONTENT_DIR . '/db.php' ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) ) : ?>
+		<?php elseif ( file_exists( $db_dropin_path ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) && ! $override_db_dropin ) : ?>
 			<?php if ( defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) : ?>
 				<div class="notice notice-warning">
 					<p>
@@ -103,6 +118,22 @@ function sqlite_integration_admin_screen() {
 			</div>
 			<h2><?php esc_html_e( 'Important note', 'sqlite-database-integration' ); ?></h2>
 			<p><?php esc_html_e( 'This plugin will switch to a separate database and install WordPress in it. You will need to reconfigure your site, and start with a fresh site. Disabling the plugin you will get back to your previous MySQL database, with all your previous data intact.', 'sqlite-database-integration' ); ?></p>
+
+			<?php if ( $override_db_dropin ) : ?>
+				<p>
+					<strong>NOTE:</strong>
+					<?php
+					printf(
+						/* translators: %s: db.php drop-in path */
+						esc_html__( 'We’ve detected an existing database drop-in file at %s, created by the Query Monitor plugin.', 'sqlite-database-integration' ),
+						'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
+					);
+					?>
+					<?php esc_html_e( 'To enable SQLite support, this file will need to be replaced.', 'sqlite-database-integration' ); ?>
+					<?php esc_html_e( 'The Query Monitor plugin will continue to function correctly after the change. You can safely proceed with the installation.', 'sqlite-database-integration' ); ?>
+				</p>
+			<?php endif; ?>
+
 			<p><?php esc_html_e( 'By clicking the button below, you will be redirected to the WordPress installation screen to setup your new database', 'sqlite-database-integration' ); ?></p>
 
 			<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-install' ), 'sqlite-install' ) ); ?>"><?php esc_html_e( 'Install SQLite database', 'sqlite-database-integration' ); ?></a>