<?php
/**
 * TMDO_Snapshot_Pruner — Daily prune of expired/over-cap snapshots
 * (v2.2.0 M1).
 *
 * Two pruning rules, applied in order:
 *   1. Drop catalog rows with `expires_at < NOW()`.
 *   2. If backup directory size still exceeds `$size_cap_bytes`, evict the
 *      oldest non-pre_uninstall / non-pre_v2_upgrade rows until under cap.
 *
 * pre_uninstall and pre_v2_upgrade snapshots are protected from size-cap
 * eviction (they are emergency restore points; only TTL prune touches them).
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

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

/**
 * Prune helper. Stateless static API.
 */
class TMDO_Snapshot_Pruner {

	/** Triggers exempt from size-cap eviction. */
	private const PROTECTED_TRIGGERS = array(
		'pre_uninstall',
		'pre_v2_upgrade',
	);

	/**
	 * Run prune.
	 *
	 * @param int $older_than_days Only used for the TTL phase logging summary;
	 *                              actual TTL is enforced via wp_wpdo_snapshots.expires_at.
	 * @param int $size_cap_bytes  Backup-dir size cap. 0 disables.
	 * @return array {pruned:int, freed_bytes:int, errors:array, ttl_pruned:int, sizecap_pruned:int}
	 */
	public static function prune( int $older_than_days, int $size_cap_bytes ): array {
		global $wpdb;
		$table = $wpdb->prefix . TMDO_Snapshot_Manager::TABLE_SLUG;

		$ttl_rows = $wpdb->get_results( // phpcs:ignore WordPress.DB
			"SELECT id, snapshot_id, file_path, size_bytes FROM `{$table}` WHERE expires_at IS NOT NULL AND expires_at < UTC_TIMESTAMP()", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- {$table} is a trusted table name via TMDO_DB::table()
			ARRAY_A
		);
		$result   = self::evict_rows( is_array( $ttl_rows ) ? $ttl_rows : array(), 'ttl' );

		if ( $size_cap_bytes > 0 ) {
			$current_size = self::current_dir_size();
			if ( $current_size > $size_cap_bytes ) {
				$over                     = $current_size - $size_cap_bytes;
				$candidates               = $wpdb->get_results(
					$wpdb->prepare( // phpcs:ignore WordPress.DB
						"SELECT id, snapshot_id, file_path, size_bytes FROM `{$table}` WHERE trigger_type NOT IN ('" . implode( "','", array_map( 'esc_sql', self::PROTECTED_TRIGGERS ) ) . "') ORDER BY created_at ASC LIMIT %d", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.PreparedSQLPlaceholders.QuotedDynamicPlaceholderGeneration -- dynamic IN clause with trusted table name and string-literal enum values
						100
					),
					ARRAY_A
				);
				$cap_result               = self::evict_to_recover( is_array( $candidates ) ? $candidates : array(), $over );
				$result['sizecap_pruned'] = $cap_result['pruned'];
				$result['freed_bytes']   += $cap_result['freed_bytes'];
				$result['pruned']        += $cap_result['pruned'];
				$result['errors']         = array_merge( $result['errors'], $cap_result['errors'] );
			} else {
				$result['sizecap_pruned'] = 0;
			}
		} else {
			$result['sizecap_pruned'] = 0;
		}

		TMDO_Logger::info(
			'snapshot_prune',
			array(
				'older_than_days' => $older_than_days,
				'size_cap_bytes'  => $size_cap_bytes,
				'pruned'          => $result['pruned'],
				'freed_bytes'     => $result['freed_bytes'],
				'ttl_pruned'      => $result['ttl_pruned'] ?? 0,
				'sizecap_pruned'  => $result['sizecap_pruned'],
			)
		);

		return $result;
	}

	/**
	 * Cron handler — called from class-tmdo-core.php via the wpdo_daily_health_check
	 * subroutine (v2.3.0) or its own scheduled hook.
	 *
	 * @return void
	 */
	public static function cron_run(): void {
		self::prune( TMDO_Snapshot_Manager::DEFAULT_RETENTION_DAYS, TMDO_Snapshot_Manager::DEFAULT_SIZE_CAP_BYTES );
	}

	// ─── private ──────────────────────────────────────────────────────────

	/**
	 * Delete rows + their files. Returns prune accounting.
	 *
	 * @param array  $rows  Rows to evict.
	 * @param string $phase Tag for logs.
	 * @return array {pruned:int,freed_bytes:int,ttl_pruned?:int,errors:array}
	 */
	private static function evict_rows( array $rows, string $phase ): array {
		global $wpdb;
		$table  = $wpdb->prefix . TMDO_Snapshot_Manager::TABLE_SLUG;
		$pruned = 0;
		$freed  = 0;
		$errors = array();
		foreach ( $rows as $row ) {
			$path = (string) ( $row['file_path'] ?? '' );
			if ( '' !== $path && file_exists( $path ) ) {
				$ok = @unlink( $path ); // phpcs:ignore WordPress.PHP.NoSilencedErrors
				if ( ! $ok ) {
					$errors[] = "unlink failed: {$path}";
				}
			}
			$deleted = $wpdb->delete( $table, array( 'id' => (int) $row['id'] ), array( '%d' ) ); // phpcs:ignore WordPress.DB
			if ( false === $deleted ) {
				$errors[] = 'db delete failed: ' . $row['snapshot_id'];
				continue;
			}
			++$pruned;
			$freed += (int) $row['size_bytes'];
		}
		$out = array(
			'pruned'      => $pruned,
			'freed_bytes' => $freed,
			'errors'      => $errors,
		);
		if ( 'ttl' === $phase ) {
			$out['ttl_pruned'] = $pruned;
		}
		return $out;
	}

	/**
	 * Evict from candidates until we've freed `$target_bytes` (or run out).
	 *
	 * @param array $candidates Sorted oldest-first.
	 * @param int   $target_bytes Bytes to free.
	 * @return array {pruned:int,freed_bytes:int,errors:array}
	 */
	private static function evict_to_recover( array $candidates, int $target_bytes ): array {
		global $wpdb;
		$table  = $wpdb->prefix . TMDO_Snapshot_Manager::TABLE_SLUG;
		$pruned = 0;
		$freed  = 0;
		$errors = array();
		foreach ( $candidates as $row ) {
			if ( $freed >= $target_bytes ) {
				break;
			}
			$path = (string) ( $row['file_path'] ?? '' );
			if ( '' !== $path && file_exists( $path ) ) {
				$ok = @unlink( $path ); // phpcs:ignore WordPress.PHP.NoSilencedErrors
				if ( ! $ok ) {
					$errors[] = "unlink failed: {$path}";
				}
			}
			$deleted = $wpdb->delete( $table, array( 'id' => (int) $row['id'] ), array( '%d' ) ); // phpcs:ignore WordPress.DB
			if ( false === $deleted ) {
				$errors[] = 'db delete failed: ' . $row['snapshot_id'];
				continue;
			}
			++$pruned;
			$freed += (int) $row['size_bytes'];
		}
		return array(
			'pruned'      => $pruned,
			'freed_bytes' => $freed,
			'errors'      => $errors,
		);
	}

	/**
	 * Sum all backup directory file sizes.
	 *
	 * @return int Bytes.
	 */
	private static function current_dir_size(): int {
		$dir = TMDO_Snapshot_Manager::backup_dir();
		if ( ! is_dir( $dir ) ) {
			return 0;
		}
		$total = 0;
		$it    = new RecursiveIteratorIterator( new RecursiveDirectoryIterator( $dir, FilesystemIterator::SKIP_DOTS ) );
		foreach ( $it as $file ) {
			if ( $file->isFile() ) {
				$total += $file->getSize();
			}
		}
		return $total;
	}
}