<?php
/**
 * Daily retention sweep.
 *
 * The queue table holds rendered customer emails and the attachment directories
 * hold their invoices — retention here is a privacy control, not only
 * housekeeping.
 *
 * @package studiou-wc-mail-queue
 * @copyright 2026 QUADARAX
 * @author    Dalibor Votruba <dvotruba@quadarax.com>
 * @license   GPL-2.0-or-later
 */

defined( 'ABSPATH' ) || exit;

/**
 * Class Studiou_WCMQ_Retention
 */
class Studiou_WCMQ_Retention {

	const HOOK      = 'studiou_wcmq_retention';
	const BATCH     = 500;
	const MAX_LOOPS = 200;

	/**
	 * Register hooks.
	 */
	public static function init() {
		add_action( self::HOOK, array( __CLASS__, 'run' ) );
	}

	/**
	 * Schedule the daily sweep, exactly once.
	 */
	public static function schedule() {
		if ( ! function_exists( 'as_next_scheduled_action' ) || ! function_exists( 'as_schedule_recurring_action' ) ) {
			return;
		}
		if ( as_next_scheduled_action( self::HOOK, array(), Studiou_WCMQ_Queue::GROUP ) ) {
			return;
		}
		as_schedule_recurring_action(
			time() + DAY_IN_SECONDS,
			DAY_IN_SECONDS,
			self::HOOK,
			array(),
			Studiou_WCMQ_Queue::GROUP,
			true
		);
	}

	/**
	 * Sweep old rows, log entries and orphaned attachment directories.
	 */
	public static function run() {
		Studiou_WCMQ_Reaper::run();

		$now = time();

		// Every retention setting is in DAYS; every timestamp column is in
		// SECONDS. Written as `sent_at < now - retention_sent_days`, a 7-day
		// retention would delete sent rows seven SECONDS after sending, silently,
		// while reporting success.
		$sent_days   = (int) Studiou_WCMQ_Settings::get( 'retention_sent_days' );
		$failed_days = (int) Studiou_WCMQ_Settings::get( 'retention_failed_days' );
		$log_days    = (int) Studiou_WCMQ_Settings::get( 'retention_log_days' );

		$deleted = 0;

		if ( $sent_days > 0 ) {
			$deleted += self::purge_queue_rows(
				Studiou_WCMQ_DB::STATE_SENT,
				'sent_at',
				$now - ( $sent_days * DAY_IN_SECONDS )
			);
		}

		if ( $failed_days > 0 ) {
			// `created_at`, NOT `sent_at`. A failed row has sent_at IS NULL by
			// definition, so the obvious parallel to the rule above would match
			// nothing and failed rows would accumulate forever.
			$deleted += self::purge_queue_rows(
				Studiou_WCMQ_DB::STATE_FAILED,
				'created_at',
				$now - ( $failed_days * DAY_IN_SECONDS )
			);
		}

		if ( $log_days > 0 ) {
			self::purge_log_rows( $now - ( $log_days * DAY_IN_SECONDS ) );
		}

		self::purge_orphan_attachment_dirs();

		if ( $deleted > 0 ) {
			Studiou_WCMQ_DB::log( 'info', sprintf( 'Retention sweep removed %d queue rows.', $deleted ) );
		}
	}

	/**
	 * Delete queue rows in a state, older than a cutoff, in batches.
	 *
	 * Attachment directories are removed first: sent rows already had theirs
	 * deleted at send, but failed rows keep theirs until now.
	 *
	 * @param string $state       Row state.
	 * @param string $time_column Timestamp column to compare.
	 * @param int    $cutoff      Unix timestamp.
	 * @return int Rows deleted.
	 */
	private static function purge_queue_rows( $state, $time_column, $cutoff ) {
		global $wpdb;

		$table = Studiou_WCMQ_DB::queue_table();
		$total = 0;

		if ( ! in_array( $time_column, array( 'sent_at', 'created_at' ), true ) ) {
			return 0;
		}

		for ( $i = 0; $i < self::MAX_LOOPS; $i++ ) {
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery
			$rows = $wpdb->get_results(
				$wpdb->prepare(
					"SELECT id, attachment_dir FROM {$table}
					  WHERE state = %s AND {$time_column} IS NOT NULL AND {$time_column} < %d
					  LIMIT %d",
					$state,
					(int) $cutoff,
					self::BATCH
				)
			);

			if ( ! is_array( $rows ) || empty( $rows ) ) {
				break;
			}

			$ids = array();
			foreach ( $rows as $row ) {
				Studiou_WCMQ_Queue::delete_attachment_dir( $row->attachment_dir );
				$ids[] = (int) $row->id;
			}

			$placeholders = implode( ',', array_fill( 0, count( $ids ), '%d' ) );
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery
			$n = $wpdb->query( $wpdb->prepare( "DELETE FROM {$table} WHERE id IN ({$placeholders})", $ids ) );

			$total += (int) $n;

			if ( count( $ids ) < self::BATCH ) {
				break;
			}
		}

		return $total;
	}

	/**
	 * Delete old log rows in batches.
	 *
	 * @param int $cutoff Unix timestamp.
	 */
	private static function purge_log_rows( $cutoff ) {
		global $wpdb;
		$table = Studiou_WCMQ_DB::log_table();

		for ( $i = 0; $i < self::MAX_LOOPS; $i++ ) {
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery
			$n = $wpdb->query(
				$wpdb->prepare( "DELETE FROM {$table} WHERE created_at < %d LIMIT %d", (int) $cutoff, self::BATCH )
			);
			if ( ! $n ) {
				break;
			}
		}
	}

	/**
	 * Remove attachment directories whose token matches no surviving row.
	 *
	 * Collects directories orphaned by a fatal between mkdir and INSERT. Only
	 * touches directories older than a day so an in-flight enqueue is never
	 * raced.
	 */
	private static function purge_orphan_attachment_dirs() {
		global $wpdb;

		$base = Studiou_WCMQ_Queue::attachments_basedir();
		if ( '' === $base || ! is_dir( $base ) ) {
			return;
		}

		$entries = @scandir( $base ); // phpcs:ignore
		if ( ! is_array( $entries ) ) {
			return;
		}

		$table  = Studiou_WCMQ_DB::queue_table();
		$cutoff = time() - DAY_IN_SECONDS;

		foreach ( $entries as $entry ) {
			if ( ! preg_match( '/^[a-f0-9]{32}$/', $entry ) ) {
				continue;
			}
			$path = $base . '/' . $entry;
			if ( ! is_dir( $path ) ) {
				continue;
			}
			$mtime = @filemtime( $path ); // phpcs:ignore
			if ( $mtime && $mtime > $cutoff ) {
				continue;
			}
			// phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery
			$exists = (int) $wpdb->get_var(
				$wpdb->prepare( "SELECT COUNT(*) FROM {$table} WHERE attachment_dir = %s", $entry )
			);
			if ( $exists ) {
				continue;
			}
			Studiou_WCMQ_Queue::rmdir_recursive( $path );
			Studiou_WCMQ_DB::log( 'debug', sprintf( 'Removed orphaned attachment directory %s.', $entry ) );
		}
	}
}