<?php
/**
 * HPCT Import integration for WP Data Optimizer.
 *
 * @package WP_Data_Optimizer
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * HPCT Import — reads hp-custom-tables' feature flags and migration records,
 * maps them to WPDO's 7-state lifecycle, and copies progress data.
 *
 * After import, WPDO takes ownership of all 9 HPCT modules and their
 * corresponding hpct_* tables. The user is advised to deactivate hp-custom-tables.
 *
 * Usage:
 *   - Admin UI: Tools > WP Data Optimizer > HPCT Import tab
 *   - CLI:      wp wpdo import-hpct
 */
class TMDO_HPCT_Import {

	/** Option key that marks import as completed. */
	public const IMPORTED_OPTION = 'wpdo_hpct_imported';

	/**
	 * Check if HPCT import has already been completed.
	 */
	public static function is_imported(): bool {
		return (bool) get_option( self::IMPORTED_OPTION, false );
	}

	/**
	 * Check if hp-custom-tables is active and has data to import.
	 */
	public static function can_import(): bool {
		if ( self::is_imported() ) {
			return false;
		}

		return TMDO_Compatibility::is_hpct_active();
	}

	/**
	 * Preview: return what will be imported without actually doing it.
	 *
	 * @return array{modules: array, migration_records: int, has_data: bool}
	 */
	public static function preview(): array {
		$hpct_features = get_option( 'hpct_features', array() );
		if ( ! is_array( $hpct_features ) ) {
			$hpct_features = array();
		}

		$modules = array();
		foreach ( TMDO_Feature_Flags::HPCT_MODULES as $module ) {
			$hpct_status = $hpct_features[ $module ] ?? 'disabled';
			$wpdo_state  = TMDO_Feature_Flags::map_hpct_status( $hpct_status );

			$modules[] = array(
				'module'      => $module,
				'hpct_status' => $hpct_status,
				'wpdo_state'  => $wpdo_state,
			);
		}

		// Count HPCT migration records.
		global $wpdb;
		$hpct_migrations_table = $wpdb->prefix . 'hpct_migrations';
		$migration_count       = 0;

		// Check if hpct_migrations table exists.
		if ( TMDO_IS_SQLITE ) {
			$table_exists = $wpdb->get_var(
				$wpdb->prepare(
					"SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = %s",
					$hpct_migrations_table
				)
			);
		} else {
			$table_exists = $wpdb->get_var(
				$wpdb->prepare(
					'SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = DATABASE() AND table_name = %s',
					$hpct_migrations_table
				)
			);
		}

		if ( $table_exists ) {
			$migration_count = (int) $wpdb->get_var( "SELECT COUNT(*) FROM `{$hpct_migrations_table}`" ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name is $wpdb->prefix . 'hpct_migrations'.
		}

		return array(
			'modules'           => $modules,
			'migration_records' => $migration_count,
			'has_data'          => ! empty( $hpct_features ),
		);
	}

	/**
	 * Execute the import.
	 *
	 * @return array{success: bool, message: string, imported: array}
	 */
	public static function run(): array {
		if ( self::is_imported() ) {
			return array(
				'success'  => false,
				'message'  => 'HPCT import has already been completed.',
				'imported' => array(),
			);
		}

		// Step 1: Read HPCT feature flags.
		$hpct_features = get_option( 'hpct_features', array() );
		if ( ! is_array( $hpct_features ) ) {
			$hpct_features = array();
		}

		$imported = array();

		// Step 2: Map each HPCT module state to WPDO state.
		foreach ( TMDO_Feature_Flags::HPCT_MODULES as $module ) {
			$hpct_status = $hpct_features[ $module ] ?? 'disabled';
			$wpdo_state  = TMDO_Feature_Flags::map_hpct_status( $hpct_status );

			TMDO_Feature_Flags::set( $module, $wpdo_state );

			$imported[] = array(
				'module'      => $module,
				'hpct_status' => $hpct_status,
				'wpdo_state'  => $wpdo_state,
			);
		}

		// Step 3: Copy HPCT migration records to WPDO.
		self::copy_migration_records();

		// Step 4: Mark import as completed.
		update_option( self::IMPORTED_OPTION, true );

		return array(
			'success'  => true,
			'message'  => sprintf(
				'Successfully imported %d HPCT modules. You can now deactivate hp-custom-tables.',
				count( $imported )
			),
			'imported' => $imported,
		);
	}

	/**
	 * Copy HPCT migration progress records to wpdo_migrations.
	 */
	private static function copy_migration_records(): void {
		global $wpdb;

		$hpct_table = $wpdb->prefix . 'hpct_migrations';
		$wpdo_table = TMDO_DB::table( 'wpdo_migrations' );
		$now        = TMDO_DB::now();

		// Check if hpct_migrations table exists.
		$exists = false;
		if ( TMDO_IS_SQLITE ) {
			$exists = (bool) $wpdb->get_var(
				$wpdb->prepare(
					"SELECT COUNT(*) FROM sqlite_master WHERE type = 'table' AND name = %s",
					$hpct_table
				)
			);
		} else {
			$exists = (bool) $wpdb->get_var(
				$wpdb->prepare(
					'SELECT COUNT(*) FROM information_schema.tables WHERE table_schema = DATABASE() AND table_name = %s',
					$hpct_table
				)
			);
		}

		if ( ! $exists ) {
			return;
		}

		$hpct_records = $wpdb->get_results( "SELECT * FROM `{$hpct_table}`", ARRAY_A ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name is $wpdb->prefix . 'hpct_migrations'.
		if ( ! $hpct_records ) {
			return;
		}

		foreach ( $hpct_records as $record ) {
			$module = $record['module'] ?? '';
			if ( ! $module ) {
				continue;
			}

			// Map HPCT status to WPDO state.
			$hpct_status = $record['status'] ?? 'pending';
			$state       = self::map_migration_status( $hpct_status );

			// Check if WPDO already has a record for this module.
			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from TMDO_DB::table().
			$existing = $wpdb->get_var(
				$wpdb->prepare(
					"SELECT id FROM `{$wpdo_table}` WHERE module = %s",
					$module
				)
			);
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared

			$data = array(
				'module'         => $module,
				'zone'           => '',
				'state'          => $state,
				'total_rows'     => (int) ( $record['total_rows'] ?? 0 ),
				'processed_rows' => (int) ( $record['processed_rows'] ?? 0 ),
				'last_offset'    => (int) ( $record['last_offset'] ?? 0 ),
				'error_count'    => (int) ( $record['error_count'] ?? 0 ),
				'started_at'     => $record['started_at'] ?? null,
				'completed_at'   => $record['completed_at'] ?? null,
				'updated_at'     => $now,
			);

			if ( $existing ) {
				$wpdb->update( $wpdo_table, $data, array( 'id' => (int) $existing ) );
			} else {
				$data['created_at'] = $now;
				$wpdb->insert( $wpdo_table, $data );
			}
		}
	}

	/**
	 * Map HPCT migration record status to WPDO migration state.
	 *
	 * @param string $hpct_status HPCT migration status string.
	 * @return string Corresponding WPDO migration state.
	 */
	private static function map_migration_status( string $hpct_status ): string {
		return match ( $hpct_status ) {
			'pending'   => 'idle',
			'running'   => 'backfill',
			'completed' => 'verify',
			'failed'    => 'idle',
			default     => 'idle',
		};
	}
}