<?php
/**
 * Migration log manager.
 *
 * Handles creation, insertion, retrieval, truncation, and CSV export
 * of the migration log table.
 *
 * @package Robotstxt_Mlp2_Mlp5
 */

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

/**
 * Class Robotstxt_Mlp2_Mlp5_Logger
 *
 * All queries in this class are intentionally direct — the log table is
 * write-once per operation and must never be read from an object cache.
 * Per-line DirectDatabaseQuery suppressions are applied throughout.
 */
class Robotstxt_Mlp2_Mlp5_Logger {

	/**
	 * Sitemeta key used to track the installed DB schema version.
	 *
	 * @var string
	 */
	const DB_VERSION_KEY = 'mlp_migrator_db_version';

	/**
	 * Return the fully qualified log table name.
	 *
	 * @return string
	 */
	public static function table_name(): string {
		global $wpdb;
		return $wpdb->base_prefix . 'mlp_migrator_log';
	}

	/**
	 * Create (or update) the log table via dbDelta().
	 *
	 * Safe to call multiple times — dbDelta() is idempotent and only alters
	 * the table when the schema has changed. The DB upgrader is responsible
	 * for calling this method and for updating the stored schema version.
	 */
	public static function create_table(): void {
		global $wpdb;

		$table           = self::table_name();
		$charset_collate = $wpdb->get_charset_collate();

		// Note: dbDelta() requires two spaces before PRIMARY KEY.
		$sql = "CREATE TABLE {$table} (
  id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  created_at datetime NOT NULL,
  type varchar(20) NOT NULL,
  context varchar(50) NOT NULL,
  source_id bigint(20) unsigned DEFAULT NULL,
  target_id bigint(20) unsigned DEFAULT NULL,
  message text NOT NULL,
  metadata longtext DEFAULT NULL,
  PRIMARY KEY  (id),
  KEY type (type),
  KEY context (context)
) {$charset_collate};";

		require_once ABSPATH . 'wp-admin/includes/upgrade.php';
		dbDelta( $sql );
	}

	/**
	 * Drop the log table and remove the schema version option.
	 *
	 * Only called from uninstall.php when the user has explicitly opted in
	 * to data deletion via the plugin settings.
	 */
	public static function drop_table(): void {
		global $wpdb;

		$table = self::table_name();

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.DirectDatabaseQuery.SchemaChange, WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		$wpdb->query( "DROP TABLE IF EXISTS {$table}" );

		delete_site_option( self::DB_VERSION_KEY );
	}

	/**
	 * Insert a log entry.
	 *
	 * @param string   $type      Entry type: 'success', 'skipped', or 'error'.
	 * @param string   $context   Operation context: 'site_relation', 'post_relation', 'term_relation', or 'cleanup'.
	 * @param int|null $source_id Source content or site ID, or null if not applicable.
	 * @param int|null $target_id Target content or site ID, or null if not applicable.
	 * @param string   $message   Human-readable description of the operation result.
	 * @param array    $metadata  Optional additional structured data (stored as JSON).
	 *
	 * @return int Inserted row ID, or 0 on failure.
	 */
	public static function log(
		string $type,
		string $context,
		?int $source_id,
		?int $target_id,
		string $message,
		array $metadata = array()
	): int {
		global $wpdb;

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber
		$inserted = $wpdb->insert(
			self::table_name(),
			array(
				'created_at' => current_time( 'mysql', true ),
				'type'       => $type,
				'context'    => $context,
				'source_id'  => $source_id,
				'target_id'  => $target_id,
				'message'    => $message,
				'metadata'   => empty( $metadata ) ? null : wp_json_encode( $metadata ),
			),
			array( '%s', '%s', '%s', '%d', '%d', '%s', '%s' )
		);

		return $inserted ? (int) $wpdb->insert_id : 0;
	}

	/**
	 * Retrieve log entries.
	 *
	 * @param array $args {
	 *     Optional. Query arguments.
	 *
	 *     @type string $type    Filter by type: 'success', 'skipped', or 'error'.
	 *     @type string $context Filter by context: 'site_relation', 'post_relation', 'term_relation', or 'cleanup'.
	 *     @type int    $limit   Maximum number of rows to return. Default 50.
	 *     @type int    $offset  Row offset for pagination. Default 0.
	 *     @type string $order   Sort direction: 'ASC' or 'DESC'. Default 'DESC'.
	 * }
	 *
	 * @return array Array of row objects, or an empty array.
	 */
	public static function get_entries( array $args = array() ): array {
		global $wpdb;

		$args = wp_parse_args(
			$args,
			array(
				'type'    => '',
				'context' => '',
				'limit'   => 50,
				'offset'  => 0,
				'order'   => 'DESC',
			)
		);

		$table  = self::table_name();
		$order  = 'ASC' === strtoupper( (string) $args['order'] ) ? 'ASC' : 'DESC';
		$where  = '';
		$values = array();

		if ( ! empty( $args['type'] ) ) {
			$where   .= ' AND type = %s';
			$values[] = $args['type'];
		}

		if ( ! empty( $args['context'] ) ) {
			$where   .= ' AND context = %s';
			$values[] = $args['context'];
		}

		$values[] = (int) $args['limit'];
		$values[] = (int) $args['offset'];

		// Table name and ORDER BY direction are hardcoded — not from user input.
		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber
		return (array) $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM {$table} WHERE 1=1{$where} ORDER BY id {$order} LIMIT %d OFFSET %d",
				$values
			)
		);
		// phpcs:enable
	}

	/**
	 * Count log entries.
	 *
	 * Accepts the same filter arguments as get_entries() except limit, offset, and order.
	 *
	 * @param array $args Optional. 'type' and/or 'context' filter keys.
	 *
	 * @return int Total count of matching entries.
	 */
	public static function count( array $args = array() ): int {
		global $wpdb;

		$table  = self::table_name();
		$where  = '';
		$values = array();

		if ( ! empty( $args['type'] ) ) {
			$where   .= ' AND type = %s';
			$values[] = $args['type'];
		}

		if ( ! empty( $args['context'] ) ) {
			$where   .= ' AND context = %s';
			$values[] = $args['context'];
		}

		if ( empty( $values ) ) {
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			return (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$table}" );
		}

		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare
		return (int) $wpdb->get_var(
			$wpdb->prepare( "SELECT COUNT(*) FROM {$table} WHERE 1=1{$where}", $values )
		);
		// phpcs:enable
	}

	/**
	 * Truncate the log table.
	 *
	 * Removes all rows without dropping the table structure. Used when
	 * restarting a migration from scratch.
	 */
	public static function clear(): void {
		global $wpdb;

		$table = self::table_name();

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.DirectDatabaseQuery.SchemaChange, WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		$wpdb->query( "TRUNCATE TABLE {$table}" );
	}

	/**
	 * Export the full log as a CSV string.
	 *
	 * Columns: id, created_at, type, context, source_id, target_id, message, metadata.
	 * Rows are ordered by id ASC.
	 *
	 * @return string CSV content with a header row, or an empty string on failure.
	 */
	public static function export_csv(): string {
		global $wpdb;

		$table = self::table_name();

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.InterpolatedNotPrepared
		$rows = $wpdb->get_results( "SELECT * FROM {$table} ORDER BY id ASC", ARRAY_A );

		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fopen
		$buffer = fopen( 'php://temp', 'r+' );

		if ( false === $buffer ) {
			return '';
		}

		fputcsv( $buffer, array( 'id', 'created_at', 'type', 'context', 'source_id', 'target_id', 'message', 'metadata' ) );

		if ( ! empty( $rows ) ) {
			foreach ( $rows as $row ) {
				fputcsv(
					$buffer,
					array(
						$row['id'],
						$row['created_at'],
						$row['type'],
						$row['context'],
						$row['source_id'] ?? '',
						$row['target_id'] ?? '',
						$row['message'],
						$row['metadata'] ?? '',
					)
				);
			}
		}

		rewind( $buffer );
		$csv = stream_get_contents( $buffer );
		fclose( $buffer ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_fclose

		return is_string( $csv ) ? $csv : '';
	}
}