<?php
/**
 * Option-backed log of content changes, used for "Undo last bulk action".
 *
 * @package Unbreak
 */

namespace Unbreak\Fix;

use Unbreak\Support\Clock;

defined( 'ABSPATH' ) || exit;

/**
 * Keeps the last 200 changes with their "before" value (non-autoloaded option).
 */
final class ChangeLog {

	public const OPTION      = 'unbreak_changes';
	public const MAX_ENTRIES = 200;

	/**
	 * Upper bound for the whole option, so a few huge posts cannot bloat the database.
	 */
	private const MAX_BYTES = 4194304;

	/**
	 * Content hash used to detect edits made after our change.
	 *
	 * @param string $value Value.
	 */
	public static function hash( string $value ): string {
		return md5( $value );
	}

	/**
	 * All entries, oldest first.
	 *
	 * @return array<int,array<string,mixed>>
	 */
	public function all(): array {
		$entries = get_option( self::OPTION, array() );
		return is_array( $entries ) ? array_values( $entries ) : array();
	}

	/**
	 * Record a change.
	 *
	 * @param string   $batch       Batch ID (one bulk action).
	 * @param string   $action      Action name.
	 * @param string   $source_type Source type.
	 * @param int      $source_id   Source ID.
	 * @param string   $source_key  Source key.
	 * @param string   $before      Previous raw value.
	 * @param string   $after       New raw value.
	 * @param string[] $urls        URLs affected.
	 */
	public function record( string $batch, string $action, string $source_type, int $source_id, string $source_key, string $before, string $after, array $urls ): void {
		$entries   = $this->all();
		$entries[] = array(
			'batch'       => $batch,
			'action'      => $action,
			'time'        => Clock::now(),
			'user'        => get_current_user_id(),
			'source_type' => $source_type,
			'source_id'   => $source_id,
			'source_key'  => $source_key,
			'urls'        => array_values( array_slice( $urls, 0, 20 ) ),
			'before'      => $before,
			'after_hash'  => self::hash( $after ),
		);
		$entries   = array_slice( $entries, -self::MAX_ENTRIES );
		$size      = strlen( (string) maybe_serialize( $entries ) );
		// Never drop entries of the batch being recorded: the last action must stay fully undoable.
		while ( $size > self::MAX_BYTES && count( $entries ) > 1 && $batch !== $entries[0]['batch'] ) { // phpcs:ignore Squiz.PHP.DisallowSizeFunctionsInLoops.Found -- The array shrinks each iteration.
			$removed = array_shift( $entries );
			$size   -= strlen( (string) maybe_serialize( $removed ) );
		}
		update_option( self::OPTION, $entries, false );
	}

	/**
	 * Batch ID of the most recent change ('' if none).
	 */
	public function last_batch(): string {
		$entries = $this->all();
		if ( empty( $entries ) ) {
			return '';
		}
		$last = end( $entries );
		return (string) $last['batch'];
	}

	/**
	 * Entries of one batch, newest first.
	 *
	 * @param string $batch Batch ID.
	 * @return array<int,array<string,mixed>>
	 */
	public function batch( string $batch ): array {
		$out = array();
		foreach ( array_reverse( $this->all() ) as $entry ) {
			if ( $batch === $entry['batch'] ) {
				$out[] = $entry;
			}
		}
		return $out;
	}

	/**
	 * Remove a batch from the log (after it was undone).
	 *
	 * @param string $batch Batch ID.
	 */
	public function forget( string $batch ): void {
		$kept = array();
		foreach ( $this->all() as $entry ) {
			if ( $batch !== $entry['batch'] ) {
				$kept[] = $entry;
			}
		}
		update_option( self::OPTION, $kept, false );
	}

	/**
	 * Summaries for the UI (without the stored "before" values).
	 *
	 * @param int $limit Max entries.
	 * @return array<int,array<string,mixed>>
	 */
	public function recent( int $limit = 50 ): array {
		$out = array();
		foreach ( array_slice( array_reverse( $this->all() ), 0, $limit ) as $entry ) {
			unset( $entry['before'], $entry['after_hash'] );
			$out[] = $entry;
		}
		return $out;
	}
}