<?php
/**
 * The plugin's own deletions from the log.
 *
 * @package ActivityLog404
 */

namespace ActivityLog404\Chain;

use ActivityLog404\Database;

defined( 'ABSPATH' ) || exit;

/**
 * Retention (ActivityLog::purge_old_events()) and the Pro archive's prune
 * both remove rows by timestamp; both come through here so the chain is told
 * first. The order is deliberate: the cut is recorded, then the DELETE runs.
 * A crash between them leaves a recorded cut for rows that still exist,
 * which hides nothing (it bridges a gap that is not there); the other order
 * would leave a gap the plugin made and nobody recorded, an alarm on a log
 * nobody touched.
 */
final class Pruner {

	/** Rows read per batch while the doomed run is worked out. */
	private const BATCH = 2000;

	/**
	 * Delete rows with `timestamp` in `[from, to)`; `from` null means every
	 * row before `to`.
	 *
	 * @param string|null $from First timestamp removed (inclusive), or null.
	 * @param string      $to   First timestamp kept (exclusive).
	 * @return int Rows deleted.
	 */
	public static function delete( ?string $from, string $to ): int {
		global $wpdb;

		$table = Database::get_table_name();
		$key   = Key::get();

		$state = Ledger::cuts( $key );
		$floor = Ledger::OK === $state['status'] ? $state['floor'] : 0;

		// The range, prepared once; every later query embeds this fragment.
		$where = null === $from
			? $wpdb->prepare( 'timestamp < %s', $to )
			: $wpdb->prepare( 'timestamp >= %s AND timestamp < %s', $from, $to );

		$runs  = array();
		$open  = null;
		$after = $floor;

		do {
			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- the plugin's own table; $table and $where are literals of this class, every value is a placeholder.
			$batch = $wpdb->get_results(
				$wpdb->prepare(
					"SELECT id, chain_prev, chain_hash FROM $table WHERE $where AND chain_hash IS NOT NULL AND id > %d ORDER BY id ASC LIMIT %d",
					$after,
					self::BATCH
				),
				ARRAY_A
			);
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching

			$batch = is_array( $batch ) ? $batch : array();
			$got   = count( $batch );

			foreach ( $batch as $row ) {
				$after = max( $after, (int) $row['id'] );

				if ( Seal::is_digest( $row['chain_prev'] ) && Seal::is_digest( $row['chain_hash'] ) ) {
					$open = Cuts::feed( $open, $runs, $row['chain_prev'], $row['chain_hash'] );
				}
			}
		} while ( self::BATCH === $got );

		if ( null !== $open ) {
			$runs[] = $open;
		}

		Ledger::record( $key, $runs );

		// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- as above.
		$deleted = $wpdb->query( "DELETE FROM $table WHERE $where" );
		// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching

		return is_int( $deleted ) ? $deleted : 0;
	}
}