<?php
/**
 * Runs repairs: preview, apply, verify, log and roll back.
 *
 * @package OrbitstemSEO
 */

namespace Orbitstem\SEO\Repair;

use Orbitstem\SEO\Diagnostics\Issues;
use WP_Error;

defined( 'ABSPATH' ) || exit;

/**
 * One code path for every automated change, so each one is previewed,
 * re-checked right before it happens, logged with its before state, verified
 * afterwards and can be rolled back.
 */
class RepairCenter {

	const MAX_PER_REQUEST = 50;

	/**
	 * Change log.
	 *
	 * @var ChangeLog
	 */
	private $log;

	/**
	 * Fixers keyed by id.
	 *
	 * @var array<string,Fixer>
	 */
	private $fixers = array();

	/**
	 * Constructor.
	 *
	 * @param ChangeLog $log    Change log.
	 * @param Fixer[]   $fixers Fixers.
	 */
	public function __construct( ChangeLog $log, array $fixers ) {
		$this->log = $log;
		foreach ( $fixers as $fixer ) {
			$this->fixers[ $fixer->id() ] = $fixer;
		}
	}

	/**
	 * All fixers.
	 *
	 * @return array<string,Fixer>
	 */
	public function fixers() {
		return $this->fixers;
	}

	/**
	 * Fixers that offer repairs (have candidates), for the Repair screen.
	 *
	 * @return array<string,Fixer>
	 */
	public function repair_fixers() {
		return array_filter(
			$this->fixers,
			function ( Fixer $fixer ) {
				return (bool) $fixer->issue_ids();
			}
		);
	}

	/**
	 * Fixer for an issue id, or null.
	 *
	 * @param string $issue_id Issue id.
	 * @return Fixer|null
	 */
	public function fixer_for_issue( $issue_id ) {
		foreach ( $this->fixers as $fixer ) {
			if ( in_array( $issue_id, $fixer->issue_ids(), true ) ) {
				return $fixer;
			}
		}
		return null;
	}

	/**
	 * Applies a fixer to selected candidates.
	 *
	 * @param string   $fixer_id Fixer id.
	 * @param string[] $keys     Candidate keys.
	 * @param bool     $confirmed Whether the user confirmed a destructive repair.
	 * @return array<string,array{ok:bool,message:string,change_id:int}>|WP_Error Results keyed by candidate key.
	 */
	public function apply( $fixer_id, array $keys, $confirmed = false ) {
		if ( ! isset( $this->fixers[ $fixer_id ] ) ) {
			return new WP_Error( 'unknown', __( 'Unknown repair.', 'orbitstem-seo' ) );
		}
		$fixer = $this->fixers[ $fixer_id ];
		if ( $fixer->is_destructive() && ! $confirmed ) {
			return new WP_Error( 'confirm', __( 'This repair removes content. Tick the confirmation box to continue.', 'orbitstem-seo' ) );
		}

		$results = array();
		foreach ( array_slice( array_unique( $keys ), 0, self::MAX_PER_REQUEST ) as $key ) {
			$results[ $key ] = $this->apply_one( $fixer, (string) $key );
		}
		delete_transient( Issues::SUMMARY_TRANSIENT );
		return $results;
	}

	/**
	 * Applies one candidate.
	 *
	 * @param Fixer  $fixer Fixer.
	 * @param string $key   Candidate key.
	 * @return array{ok:bool,message:string,change_id:int}
	 */
	private function apply_one( Fixer $fixer, $key ) {
		$item = $fixer->find( $key );
		if ( ! $item ) {
			return $this->result( false, __( 'Skipped: this no longer needs repair (it changed since the preview).', 'orbitstem-seo' ) );
		}
		if ( ! $fixer->can_apply( $item ) ) {
			return $this->result( false, __( 'Skipped: you do not have permission to change this item.', 'orbitstem-seo' ) );
		}
		$applied = $fixer->apply( $item );
		if ( is_wp_error( $applied ) ) {
			return $this->result( false, $applied->get_error_message() );
		}
		$change_id = $this->log->record( $fixer->id(), $item['object_type'], $item['object_id'], $applied['summary'], $applied['before'], $applied['after'] );
		$verify    = $fixer->verify( $this->log->get( $change_id ) );
		$this->log->set_verified( $change_id, $verify['ok'], $verify['note'] );
		return $this->result( true, $applied['summary'] . ( $verify['ok'] ? '' : ' (' . $verify['note'] . ')' ), $change_id, $verify['ok'] );
	}

	/**
	 * Rolls back one logged change.
	 *
	 * @param int $change_id Change ID.
	 * @return true|WP_Error
	 */
	public function rollback( $change_id ) {
		$change = $this->log->get( $change_id );
		if ( ! $change ) {
			return new WP_Error( 'missing', __( 'That change is not in the log.', 'orbitstem-seo' ) );
		}
		if ( 'applied' !== $change['status'] ) {
			return new WP_Error( 'state', __( 'That change was already rolled back.', 'orbitstem-seo' ) );
		}
		if ( ! isset( $this->fixers[ $change['fixer'] ] ) ) {
			return new WP_Error( 'unknown', __( 'This kind of change cannot be rolled back here.', 'orbitstem-seo' ) );
		}
		$result = $this->fixers[ $change['fixer'] ]->rollback( $change );
		if ( is_wp_error( $result ) ) {
			return $result;
		}
		$this->log->set_rolled_back( $change_id );
		delete_transient( Issues::SUMMARY_TRANSIENT );
		return true;
	}

	/**
	 * Result row.
	 *
	 * @param bool   $ok        Success.
	 * @param string $message   Message.
	 * @param int    $change_id Change ID.
	 * @param bool   $verified  Whether verification passed.
	 * @return array
	 */
	private function result( $ok, $message, $change_id = 0, $verified = false ) {
		return array(
			'ok'        => $ok,
			'message'   => $message,
			'change_id' => $change_id,
			'verified'  => $verified,
		);
	}
}