<?php
/**
 * MultilingualPress 2 detection service.
 *
 * Detects whether MultilingualPress 2 is installed (active or inactive),
 * reads its plugin metadata, and identifies its database tables and schema.
 *
 * Note: MLP2 does not need to be active for migration. Only its database
 * tables need to exist. See docs/ROADMAP.md — Background section.
 *
 * @package Robotstxt_Mlp2_Mlp5
 */

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

/**
 * Class Robotstxt_Mlp2_Mlp5_Detector_Mlp2
 *
 * Instantiate once to detect MLP2; all detection results are cached in
 * instance properties to avoid repeated file or database reads.
 *
 * Usage:
 *   $mlp2 = new Robotstxt_Mlp2_Mlp5_Detector_Mlp2();
 *   if ( $mlp2->get_site_relations_table() !== '' ) { ... }
 */
class Robotstxt_Mlp2_Mlp5_Detector_Mlp2 {

	/**
	 * Known plugin basename for MultilingualPress 2 (WordPress.org slug).
	 *
	 * @var string
	 */
	const PLUGIN_BASENAME = 'multilingual-press/multilingual-press.php';

	/**
	 * Resolved MLP2 plugin basename, or empty string if not found on disk.
	 *
	 * @var string
	 */
	private string $plugin_file;

	/**
	 * Plugin header data from get_plugin_data(), or empty array if unavailable.
	 *
	 * @var array
	 */
	private array $plugin_data;

	/**
	 * Constructor. Locates the MLP2 plugin file and loads its header data.
	 */
	public function __construct() {
		$this->plugin_file = $this->find_plugin_file();
		$this->plugin_data = $this->plugin_file ? $this->load_plugin_data() : array();
	}

	/**
	 * Whether MultilingualPress 2 is currently network-active.
	 *
	 * Informational only. MLP2 may be deactivated or uninstalled while its
	 * database tables still exist. Table presence is the migration gate, not
	 * plugin activity.
	 *
	 * @return bool
	 */
	public function is_active(): bool {
		if ( ! function_exists( 'is_plugin_active_for_network' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php';
		}

		return '' !== $this->plugin_file && is_plugin_active_for_network( $this->plugin_file );
	}

	/**
	 * Return the MLP2 version string, or empty string if unavailable.
	 *
	 * @return string
	 */
	public function get_version(): string {
		return isset( $this->plugin_data['Version'] ) ? (string) $this->plugin_data['Version'] : '';
	}

	/**
	 * Return the resolved MLP2 plugin basename, or empty string if not on disk.
	 *
	 * @return string
	 */
	public function get_plugin_file(): string {
		return $this->plugin_file;
	}

	/**
	 * Check whether a given table exists in the database.
	 *
	 * @param string $table Full table name (including prefix).
	 * @return bool
	 */
	public function table_exists( string $table ): bool {
		global $wpdb;

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
		return (string) $wpdb->get_var( $wpdb->prepare( 'SHOW TABLES LIKE %s', $table ) ) === $table;
	}

	/**
	 * Return the full MLP2 site relations table name, or empty string if absent.
	 *
	 * Checks the original name first. If the original has been renamed by the
	 * Table_Preparer, returns the backup name instead so that later phases can
	 * read the data regardless of whether preparation has run.
	 *
	 * @return string
	 */
	public function get_site_relations_table(): string {
		global $wpdb;

		$table  = $wpdb->base_prefix . 'mlp_site_relations';
		$backup = Robotstxt_Mlp2_Mlp5_Table_Preparer::backup_name( $table );

		// Check backup first: after preparation the original name belongs to MLP5.
		if ( '' !== $backup && $this->table_exists( $backup ) ) {
			return $backup;
		}

		// Fall back to original only when no backup tables exist (preparation not done yet).
		if ( ! Robotstxt_Mlp2_Mlp5_Table_Preparer::has_backup_tables() && $this->table_exists( $table ) ) {
			return $table;
		}

		return '';
	}

	/**
	 * Return the full MLP2 content relations table name, or empty string if absent.
	 *
	 * MLP2 uses `mlp_relationships` in older minor versions,
	 * `mlp_content_relations` in newer ones, and `multilingual_linked` in some
	 * installations (table name lacks the mlp_ prefix and is never renamed by
	 * the Table_Preparer). All three are checked. If the original table has been
	 * renamed by the Table_Preparer, its backup name is returned.
	 *
	 * @return string
	 */
	public function get_content_relations_table(): string {
		global $wpdb;

		// After preparation, original names belong to MLP5; only look at backups.
		$preparation_done = Robotstxt_Mlp2_Mlp5_Table_Preparer::has_backup_tables();

		foreach ( array( 'mlp_relationships', 'mlp_content_relations' ) as $candidate ) {
			$table  = $wpdb->base_prefix . $candidate;
			$backup = Robotstxt_Mlp2_Mlp5_Table_Preparer::backup_name( $table );

			if ( '' !== $backup && $this->table_exists( $backup ) ) {
				return $backup;
			}

			// Fall back to original only when preparation has not run yet.
			if ( ! $preparation_done && $this->table_exists( $table ) ) {
				return $table;
			}
		}

		// Some MLP2 installations store content relations in `multilingual_linked`
		// (no mlp_ prefix). This table is never touched by Table_Preparer, so it
		// remains accessible regardless of whether preparation has run.
		$linked = $wpdb->base_prefix . 'multilingual_linked';
		if ( $this->table_exists( $linked ) ) {
			return $linked;
		}

		return '';
	}

	/**
	 * Return all tables in the database that match the MLP table prefix pattern.
	 *
	 * This may include tables belonging to MLP5 if it uses the same prefix.
	 * Use get_site_relations_table() and get_content_relations_table() for
	 * precise MLP2-specific detection.
	 *
	 * @return string[] Array of full table names.
	 */
	public function get_all_tables(): array {
		global $wpdb;

		$like = $wpdb->esc_like( $wpdb->base_prefix . 'mlp_' ) . '%';

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
		$tables = $wpdb->get_col( $wpdb->prepare( 'SHOW TABLES LIKE %s', $like ) );

		return is_array( $tables ) ? $tables : array();
	}

	/**
	 * Return column definitions for a table.
	 *
	 * @param string $table Full table name (must start with the DB base prefix).
	 * @return array Associative array keyed by column name (Field), or empty array
	 *               if the table does not exist or the name fails validation.
	 */
	public function describe_table( string $table ): array {
		global $wpdb;

		// Validate: table name must start with the base prefix.
		if ( ! str_starts_with( $table, $wpdb->base_prefix ) ) {
			return array();
		}

		if ( ! $this->table_exists( $table ) ) {
			return array();
		}

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		$columns = $wpdb->get_results( "SHOW COLUMNS FROM {$table}", ARRAY_A );

		if ( empty( $columns ) || ! is_array( $columns ) ) {
			return array();
		}

		$result = array();
		foreach ( $columns as $column ) {
			if ( isset( $column['Field'] ) ) {
				$result[ $column['Field'] ] = $column;
			}
		}

		return $result;
	}

	/**
	 * Locate the MLP2 plugin file on disk.
	 *
	 * Checks the known canonical basename first. If not found, scans all
	 * installed plugins for a plugin named "MultilingualPress" with a
	 * version below 3.0.0 (which marks the MLP3+ series).
	 *
	 * @return string Plugin basename, or empty string if not found.
	 */
	private function find_plugin_file(): string {
		if ( file_exists( WP_PLUGIN_DIR . '/' . self::PLUGIN_BASENAME ) ) {
			return self::PLUGIN_BASENAME;
		}

		if ( ! function_exists( 'get_plugins' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php';
		}

		foreach ( get_plugins() as $basename => $data ) {
			if (
				isset( $data['Name'], $data['Version'] ) &&
				'MultilingualPress' === $data['Name'] &&
				version_compare( (string) $data['Version'], '3.0.0', '<' )
			) {
				return $basename;
			}
		}

		return '';
	}

	/**
	 * Load plugin header data from the MLP2 main file.
	 *
	 * @return array Plugin data from get_plugin_data(), or empty array on failure.
	 */
	private function load_plugin_data(): array {
		if ( ! function_exists( 'get_plugin_data' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php';
		}

		$path = WP_PLUGIN_DIR . '/' . $this->plugin_file;

		if ( ! file_exists( $path ) ) {
			return array();
		}

		return get_plugin_data( $path, false, false );
	}
}