From 67747b43e24c6e1cf73bc022e620491d33891f65 Mon Sep 17 00:00:00 2001
From: Ari Stathopoulos <aristath@gmail.com>
Date: Thu, 7 Nov 2024 10:39:50 +0200
Subject: [PATCH 1/2] WIP migration script

---
 admin-page.php                |   4 +
 load.php                      |   1 +
 mysql-to-sqlite-migration.php | 142 ++++++++++++++++++++++++++++++++++
 3 files changed, 147 insertions(+)
 create mode 100644 mysql-to-sqlite-migration.php

diff --git a/admin-page.php b/admin-page.php
index 6a44c0e7..dace6d37 100644
--- a/admin-page.php
+++ b/admin-page.php
@@ -111,9 +111,13 @@ function sqlite_integration_admin_screen() {
 				<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>
+				<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-mysql-migration=1' ), 'sqlite-confirm-mysql-migration' ) ); ?>"><?php esc_html_e( 'Migrate database from MySQL to SQLite', 'sqlite-database-integration' ); ?></a>
 			<?php endif; ?>
 		<?php endif; ?>
 	</div>
+	<?php if ( isset( $_GET['confirm-mysql-migration'] ) ) : ?>
+		<span id="sqlite-migration-status"></span>
+	<?php endif; ?>
 	<?php
 }
 
diff --git a/load.php b/load.php
index 73f89a69..9b668625 100644
--- a/load.php
+++ b/load.php
@@ -20,3 +20,4 @@
 require_once __DIR__ . '/deactivate.php';
 require_once __DIR__ . '/admin-notices.php';
 require_once __DIR__ . '/health-check.php';
+require_once __DIR__ . '/mysql-to-sqlite-migration.php';
diff --git a/mysql-to-sqlite-migration.php b/mysql-to-sqlite-migration.php
new file mode 100644
index 00000000..4f2cce59
--- /dev/null
+++ b/mysql-to-sqlite-migration.php
@@ -0,0 +1,142 @@
+<?php
+
+require_once __DIR__ . '/constants.php';
+require_once __DIR__ . '/wp-includes/sqlite/class-wp-sqlite-lexer.php';
+require_once __DIR__ . '/wp-includes/sqlite/class-wp-sqlite-query-rewriter.php';
+require_once __DIR__ . '/wp-includes/sqlite/class-wp-sqlite-translator.php';
+require_once __DIR__ . '/wp-includes/sqlite/class-wp-sqlite-token.php';
+require_once __DIR__ . '/wp-includes/sqlite/class-wp-sqlite-pdo-user-defined-functions.php';
+require_once __DIR__ . '/wp-includes/sqlite/class-wp-sqlite-db.php';
+require_once __DIR__ . '/wp-includes/sqlite/install-functions.php';
+
+global $sqlite_db;
+$sqlite_db = new WP_SQLite_DB();
+
+/**
+ * Get an array of the tables names from the MySQL database.
+ *
+ * @return array
+ */
+function sqlite_integration_get_mysql_tables_names() {
+	global $wpdb;
+	return array_map( function ( $table ) {
+		return array_values( (array) $table )[0];
+	}, $wpdb->get_results( 'SHOW TABLES' ) );
+}
+
+/**
+ * Create a table in the SQLite database.
+ *
+ * @param string $table_name The name of the table to create.
+ * @param string $create_table_query The CREATE TABLE query to execute.
+ */
+function sqlite_integration_create_table( $table_name ) {
+	global $wpdb, $sqlite_db;
+	// Get the table structure.
+	$table_structure = $wpdb->get_results( "SHOW CREATE TABLE $table_name" );
+	// Execute the CREATE TABLE query.
+	$sqlite_db->query( $table_structure[0]->{'Create Table'} );
+}
+
+/**
+ * Migrate data for a single table.
+ *
+ * @param string $table_name The name of the table to migrate data for.
+ */
+function sqlite_integration_migrate_table( $table_name ) {
+	global $wpdb, $sqlite_db;
+	// Get the data from the MySQL table, and insert it into the SQLite table.
+	$data = $wpdb->get_results( "SELECT * FROM $table_name" );
+	foreach ( $data as $row ) {
+		$sqlite_db->insert( $table_name, (array) $row );
+	}
+}
+
+/**
+ * Run AJAX action to migrate a table.
+ */
+function sqlite_integration_migrate_table_ajax() {
+	if ( ! isset( $_POST['table_name'] ) ) {
+		wp_send_json_error( 'Table name is required' );
+	}
+	$table_name = sanitize_text_field( $_POST['table_name'] );
+	sqlite_integration_create_table( $table_name );
+	sqlite_integration_migrate_table( $table_name );
+	wp_send_json_success( 'Table migrated' );
+}
+add_action( 'wp_ajax_sqlite_integration_migrate_table', 'sqlite_integration_migrate_table_ajax' );
+
+/**
+ * Run AJAX action to add the db.php file.
+ */
+function sqlite_integration_add_db_php_file_ajax() {
+	// Check if the sqlite_plugin_copy_db_file function exists.
+	if ( ! function_exists( 'sqlite_plugin_copy_db_file' ) ) {
+		require_once __DIR__ . '/activate.php';
+	}
+	sqlite_plugin_copy_db_file();
+	wp_send_json_success( 'db.php file added' );
+}
+add_action( 'wp_ajax_sqlite_integration_add_db_php_file', 'sqlite_integration_add_db_php_file_ajax' );
+
+/**
+ * Add a script to the admin page to handle the migration process.
+ */
+function sqlite_integration_add_admin_script() {
+	?>
+	<script>
+		const databaseTables = <?php echo json_encode( sqlite_integration_get_mysql_tables_names() ); ?>;
+		const sqliteMigrateTable = ( tableName ) => {
+			jQuery( '#sqlite-migration-status' ).text( 'Migrating ' + tableName + ' table...' );
+			jQuery.ajax( {
+				url: ajaxurl,
+				type: 'POST',
+				data: {
+					action: 'sqlite_integration_migrate_table',
+					_wpnonce: '<?php echo wp_create_nonce( 'sqlite-confirm-mysql-migration' ); ?>',
+					table_name: tableName
+				},
+				success: function( response ) {
+					// Check if there is a next table to migrate.
+					if ( databaseTables.indexOf( tableName ) + 1 >= databaseTables.length ) {
+						jQuery( '#sqlite-migration-status' ).text( 'Database migrated. Adding the db.php file in your wp-content folder...' );
+						jQuery.ajax( {
+							url: ajaxurl,
+							type: 'POST',
+							data: {
+								action: 'sqlite_integration_add_db_php_file',
+								_wpnonce: '<?php echo wp_create_nonce( 'sqlite-confirm-mysql-migration' ); ?>',
+							},
+							success: function( response ) {
+								jQuery( '#sqlite-migration-status' ).text( 'Database migrated. Refreshing the page...' );
+								setTimeout( () => {
+									// Remove the confirm-mysql-migration query arg from the URL.
+									window.location.href = window.location.href.replace( '&confirm-mysql-migration=1', '' );
+								}, 1000 );
+							}
+						} );
+						return;
+					}
+					// Get the next table name.
+					const nextTableName = databaseTables[ databaseTables.indexOf( tableName ) + 1 ];
+
+					// Wait half a second, then migrate the next table.
+					setTimeout( () => {
+						sqliteMigrateTable( nextTableName );
+					}, 500 );
+				},
+				error: function( response ) {
+
+				}
+			} );
+		};
+		jQuery( document ).ready( function() {
+			let tableName = databaseTables[0];
+			sqliteMigrateTable( tableName );
+		} );
+	</script>
+	<?php
+}
+if ( isset( $_GET['confirm-mysql-migration'] ) ) {
+	add_action( 'admin_footer', 'sqlite_integration_add_admin_script' );
+}

From a99216a9a85a0a43873e1370899abbafb11c9d1a Mon Sep 17 00:00:00 2001
From: Ari Stathopoulos <aristath@gmail.com>
Date: Thu, 7 Nov 2024 13:05:03 +0200
Subject: [PATCH 2/2] minor refactor

---
 activate.php                 | 26 ++----------------------
 admin-notices.php            |  8 ++++----
 admin-page.php               | 39 ++++++++----------------------------
 constants.php                |  9 +--------
 deactivate.php               |  2 +-
 db.copy => wp-content/db.php | 20 ++++++++----------
 6 files changed, 24 insertions(+), 80 deletions(-)
 rename db.copy => wp-content/db.php (57%)

diff --git a/activate.php b/activate.php
index e91e1819..2f1bb65f 100644
--- a/activate.php
+++ b/activate.php
@@ -84,29 +84,7 @@ function sqlite_plugin_copy_db_file() {
 
 	// 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 ) ) {
-		// Init the filesystem to allow copying the file.
-		global $wp_filesystem;
-
-		require_once ABSPATH . '/wp-admin/includes/file.php';
-
-		// Init the filesystem if needed, then copy the file, replacing contents as needed.
-		if ( ( $wp_filesystem || WP_Filesystem() ) && $wp_filesystem->touch( $destination ) ) {
-
-			// Get the db.copy.php file contents, replace placeholders and write it to the destination.
-			$file_contents = str_replace(
-				array(
-					'{SQLITE_IMPLEMENTATION_FOLDER_PATH}',
-					'{SQLITE_PLUGIN}',
-				),
-				array(
-					__DIR__,
-					str_replace( WP_PLUGIN_DIR . '/', '', SQLITE_MAIN_FILE ),
-				),
-				file_get_contents( __DIR__ . '/db.copy' )
-			);
-
-			$wp_filesystem->put_contents( $destination, $file_contents );
-		}
+	if ( ! defined( 'SQLITE_DROPIN' ) && ! file_exists( $destination ) ) {
+		@symlink( __DIR__ . '/wp-content/db.php', $destination ); // phpcs:ignore
 	}
 }
diff --git a/admin-notices.php b/admin-notices.php
index 8eaf2531..7f5e273a 100644
--- a/admin-notices.php
+++ b/admin-notices.php
@@ -29,18 +29,18 @@ function sqlite_plugin_admin_notice() {
 	}
 
 	/*
-	 * If the SQLITE_DB_DROPIN_VERSION constant is not defined
+	 * If the SQLITE_DROPIN constant is not defined
 	 * but there's a db.php file in the wp-content directory, then the module can't be activated.
 	 * The module should not have been activated in the first place
 	 * (there's a check in the can-load.php file), but this is a fallback check.
 	 */
-	if ( file_exists( WP_CONTENT_DIR . '/db.php' ) && ! defined( 'SQLITE_DB_DROPIN_VERSION' ) ) {
+	if ( file_exists( WP_CONTENT_DIR . '/db.php' ) && ! defined( 'SQLITE_DROPIN' ) ) {
 		printf(
 			'<div class="notice notice-error"><p>%s</p></div>',
 			sprintf(
-				/* translators: 1: SQLITE_DB_DROPIN_VERSION constant, 2: db.php drop-in path */
+				/* translators: 1: SQLITE_DROPIN constant, 2: db.php drop-in path */
 				__( 'The SQLite Integration module is active, but the %1$s constant is missing. It appears you already have another %2$s file present on your site. ', 'sqlite-database-integration' ),
-				'<code>SQLITE_DB_DROPIN_VERSION</code>',
+				'<code>SQLITE_DROPIN</code>',
 				'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
 			)
 		);
diff --git a/admin-page.php b/admin-page.php
index dace6d37..c6816498 100644
--- a/admin-page.php
+++ b/admin-page.php
@@ -32,7 +32,7 @@ function sqlite_integration_admin_screen() {
 	</div>
 	<!-- Set the wrapper width to 50em, to improve readability. -->
 	<div style="max-width:50em;">
-		<?php if ( defined( 'SQLITE_DB_DROPIN_VERSION' ) ) : ?>
+		<?php if ( defined( 'SQLITE_DROPIN' ) ) : ?>
 			<div class="notice notice-success">
 				<p><?php esc_html_e( 'SQLite is enabled.', 'sqlite-database-integration' ); ?></p>
 			</div>
@@ -55,41 +55,18 @@ 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 if ( defined( 'PERFLAB_SQLITE_DB_DROPIN_VERSION' ) ) : ?>
-					<div class="notice notice-warning">
-						<p>
-							<?php
-							printf(
-								/* translators: %s: db.php drop-in path */
-								esc_html__( 'An older %s file was detected. Please click the button below to update the file.', 'sqlite-database-integration' ),
-								'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
-							);
-							?>
-						</p>
-					</div>
-					<a class="button button-primary" href="<?php echo esc_url( wp_nonce_url( admin_url( 'admin.php?page=sqlite-integration&confirm-install&upgrade-from-pl' ), 'sqlite-install' ) ); ?>">
+			<?php elseif ( file_exists( WP_CONTENT_DIR . '/db.php' ) && ! defined( 'SQLITE_DROPIN' ) ) : ?>
+				<div class="notice notice-error">
+					<p>
 						<?php
 						printf(
 							/* translators: %s: db.php drop-in path */
-							esc_html__( 'Update %s file', 'sqlite-database-integration' ),
+							esc_html__( 'The SQLite plugin cannot be activated because a different %s drop-in already exists.', 'sqlite-database-integration' ),
 							'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
 						);
 						?>
-					</a>
-				<?php else : ?>
-					<div class="notice notice-error">
-						<p>
-							<?php
-							printf(
-								/* translators: %s: db.php drop-in path */
-								esc_html__( 'The SQLite plugin cannot be activated because a different %s drop-in already exists.', 'sqlite-database-integration' ),
-								'<code>' . esc_html( basename( WP_CONTENT_DIR ) ) . '/db.php</code>'
-							);
-							?>
-						</p>
-					</div>
-				<?php endif; ?>
+					</p>
+				</div>
 			<?php elseif ( ! is_writable( WP_CONTENT_DIR ) ) : ?>
 				<div class="notice notice-error">
 					<p>
@@ -133,7 +110,7 @@ function sqlite_integration_admin_screen() {
 function sqlite_plugin_adminbar_item( $admin_bar ) {
 	global $wpdb;
 
-	if ( defined( 'SQLITE_DB_DROPIN_VERSION' ) && defined( 'DB_ENGINE' ) && 'sqlite' === DB_ENGINE ) {
+	if ( defined( 'SQLITE_DROPIN' ) && SQLITE_DROPIN && defined( 'DB_ENGINE' ) && 'sqlite' === DB_ENGINE ) {
 		$title = '<span style="color:#46B450;">' . __( 'Database: SQLite', 'sqlite-database-integration' ) . '</span>';
 	} elseif ( stripos( $wpdb->db_server_info(), 'maria' ) !== false ) {
 		$title = '<span style="color:#DC3232;">' . __( 'Database: MariaDB', 'sqlite-database-integration' ) . '</span>';
diff --git a/constants.php b/constants.php
index 15e6772a..ce88d557 100644
--- a/constants.php
+++ b/constants.php
@@ -8,14 +8,7 @@
 
 // Temporary - This will be in wp-config.php once SQLite is merged in Core.
 if ( ! defined( 'DB_ENGINE' ) ) {
-	if ( defined( 'SQLITE_DB_DROPIN_VERSION' ) ) {
-		define( 'DB_ENGINE', 'sqlite' );
-	} elseif ( defined( 'DATABASE_ENGINE' ) ) {
-		// backwards compatibility with previous versions of the plugin.
-		define( 'DB_ENGINE', DATABASE_ENGINE );
-	} else {
-		define( 'DB_ENGINE', 'mysql' );
-	}
+	define( 'DB_ENGINE', 'mysql' );
 }
 
 /**
diff --git a/deactivate.php b/deactivate.php
index 2b79d9a3..d9284bee 100644
--- a/deactivate.php
+++ b/deactivate.php
@@ -12,7 +12,7 @@
  * When the plugin gets merged in wp-core, this is not to be ported.
  */
 function sqlite_plugin_remove_db_file() {
-	if ( ! defined( 'SQLITE_DB_DROPIN_VERSION' ) || ! file_exists( WP_CONTENT_DIR . '/db.php' ) ) {
+	if ( ! defined( 'SQLITE_DROPIN' ) || ! SQLITE_DROPIN || ! file_exists( WP_CONTENT_DIR . '/db.php' ) ) {
 		return;
 	}
 
diff --git a/db.copy b/wp-content/db.php
similarity index 57%
rename from db.copy
rename to wp-content/db.php
index 0b0797e8..416a4bdf 100644
--- a/db.copy
+++ b/wp-content/db.php
@@ -11,17 +11,12 @@
  * @package wp-sqlite-integration
  */
 
-define( 'SQLITE_DB_DROPIN_VERSION', '1.8.0' );
-
-// Tweak to allow copy-pasting the file without having to run string-replacements.
-$sqlite_plugin_implementation_folder_path = '{SQLITE_IMPLEMENTATION_FOLDER_PATH}';
-if ( ! file_exists( $sqlite_plugin_implementation_folder_path ) ) { // Check that the folder exists.
-	$sqlite_plugin_implementation_folder_path = realpath( __DIR__ . '/plugins/sqlite-database-integration' );
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
 }
 
-// Bail early if the SQLite implementation was not located in the plugin.
-if ( ! $sqlite_plugin_implementation_folder_path || ! file_exists( $sqlite_plugin_implementation_folder_path . '/wp-includes/sqlite/db.php' ) ) {
-	return;
+if ( ! defined( 'SQLITE_DROPIN' ) ) {
+	define( 'SQLITE_DROPIN', true );
 }
 
 // Constant for backward compatibility.
@@ -34,7 +29,7 @@
 }
 
 // Require the implementation from the plugin.
-require_once $sqlite_plugin_implementation_folder_path . '/wp-includes/sqlite/db.php';
+require_once dirname( __DIR__ ) . '/wp-includes/sqlite/db.php';
 
 // Activate the performance-lab plugin if it is not already activated.
 add_action(
@@ -46,11 +41,12 @@ function() {
 		if ( ! function_exists( 'activate_plugin' ) ) {
 			require_once ABSPATH . 'wp-admin/includes/plugin.php';
 		}
-		if ( is_plugin_inactive( '{SQLITE_PLUGIN}' ) ) {
+		$plugin_file = str_replace( WP_PLUGIN_DIR . '/', '', SQLITE_MAIN_FILE );
+		if ( is_plugin_inactive( $plugin_file ) ) {
 			// If `activate_plugin()` returns a value other than null (like WP_Error),
 			// the plugin could not be found. Try with a hardcoded string,
 			// because that probably means the file was directly copy-pasted.
-			if ( null !== activate_plugin( '{SQLITE_PLUGIN}', '', false, true ) ) {
+			if ( null !== activate_plugin( $plugin_file, '', false, true ) ) {
 				activate_plugin( 'sqlite-database-integration/load.php', '', false, true );
 			}
 		}