<?php
defined( 'ABSPATH' ) || exit;

/**
 * Safety Check. After the engine turns on (and whenever the theme, plugins or
 * rules change) the SaaS renders a few pages with and without the engine in
 * headless Chrome and reports which feature, if any, hurts the site. We switch
 * that single feature off and keep everything else.
 */
class ZeroConfig_Safe_Mode {

	const EVENT_RUN  = 'zeroconfig_selftest';
	const EVENT_POLL = 'zeroconfig_selftest_poll';

	public static function init() {
		add_action( self::EVENT_RUN, array( __CLASS__, 'run' ) );
		add_action( self::EVENT_POLL, array( __CLASS__, 'poll' ) );
		// These hooks pass their own arguments (theme name, upgrader object); never let them reach schedule().
		add_action( 'switch_theme', array( __CLASS__, 'on_change' ), 10, 0 );
		add_action( 'activated_plugin', array( __CLASS__, 'on_change' ), 10, 0 );
		add_action( 'upgrader_process_complete', array( __CLASS__, 'on_change' ), 10, 0 );
	}

	/** Theme, plugin or core changed: re-check after the dust settles. */
	public static function on_change() {
		self::schedule( 90 );
	}

	public static function schedule( $delay = 90, $mode = 'normal' ) {
		if ( ! ZeroConfig_Options::get( 'engine' ) || ! ZeroConfig_Options::is_connected() ) {
			return;
		}
		wp_unschedule_hook( self::EVENT_RUN ); // events carry a $mode arg; clear them all
		wp_schedule_single_event( time() + (int) $delay, self::EVENT_RUN, array( $mode ) );
	}

	/**
	 * The product to test and to build product-page critical CSS from: one with a gallery when there
	 * is one, since that is the layout that can break (slider, thumbnail strip), not a single image.
	 */
	public static function sample_product() {
		if ( ! function_exists( 'wc_get_products' ) ) {
			return 0;
		}
		$ids = wc_get_products( array( 'limit' => 20, 'status' => 'publish', 'return' => 'ids' ) );
		foreach ( (array) $ids as $id ) {
			$p = wc_get_product( $id );
			if ( $p && $p->get_image_id() && count( $p->get_gallery_image_ids() ) > 0 ) {
				return (int) $id;
			}
		}
		return $ids ? (int) $ids[0] : 0;
	}

	public static function sample_urls() {
		$urls = array( home_url( '/' ) );
		// A page the owner reported as broken goes first (the service checks at most four).
		$reported = get_transient( 'zeroconfig_issue_url' );
		// Then the pages where a switched-off feature broke: a feature only comes back after a
		// check that looked at those pages again.
		foreach ( array_reverse( (array) ZeroConfig_Options::get( 'disabled_pages' ) ) as $pages ) {
			foreach ( array_reverse( (array) $pages ) as $p ) {
				array_unshift( $urls, $p );
			}
		}
		if ( $reported ) {
			array_unshift( $urls, $reported );
		}
		$post = get_posts( array( 'numberposts' => 1, 'post_status' => 'publish', 'fields' => 'ids' ) );
		if ( $post ) {
			$urls[] = get_permalink( $post[0] );
		}
		$page = get_posts( array( 'numberposts' => 1, 'post_type' => 'page', 'post_status' => 'publish', 'fields' => 'ids', 'exclude' => array( (int) get_option( 'page_on_front' ) ) ) ); // phpcs:ignore WordPressVIPMinimum.Performance.WPQueryParams.PostNotIn_exclude -- one id, one result
		if ( $page ) {
			$urls[] = get_permalink( $page[0] );
		}
		if ( function_exists( 'wc_get_products' ) ) {
			$prod = self::sample_product();
			if ( $prod ) {
				$urls[] = get_permalink( $prod );
			}
		}
		return array_values( array_unique( array_filter( $urls ) ) );
	}

	public static function run( $mode = 'normal' ) {
		ZeroConfig_Page_Cache::purge_all( 'safety_start' ); // the check is about to load pages itself
		$res = ZeroConfig_API::request_selftest( self::sample_urls(), $mode );
		if ( is_wp_error( $res ) || empty( $res['job_id'] ) || ! preg_match( '/^[A-Za-z0-9_-]{1,64}$/', (string) $res['job_id'] ) ) {
			ZeroConfig_Options::set( 'last_selftest', array( 'status' => 'error', 'at' => time(), 'error' => is_wp_error( $res ) ? $res->get_error_message() : 'no job id' ) );
			return;
		}
		delete_transient( 'zeroconfig_issue_url' );
		ZeroConfig_Options::update( array( 'selftest_job' => (string) $res['job_id'], 'last_selftest' => array( 'status' => 'queued', 'at' => time(), 'started' => time() ) ) );
		wp_schedule_single_event( time() + 60, self::EVENT_POLL, array( 1 ) );
	}

	const MAX_WAIT = 2 * HOUR_IN_SECONDS; // a busy queue is not a failure; keep waiting this long

	/** Back-off between polls: 1, 2, 3 … minutes, at most 15. */
	public static function poll_delay( $attempt ) {
		return min( 15, max( 1, (int) $attempt ) ) * MINUTE_IN_SECONDS;
	}

	public static function poll( $attempt = 1 ) {
		$job = ZeroConfig_Options::get( 'selftest_job' );
		if ( ! $job ) {
			return;
		}
		$res = ZeroConfig_API::get_selftest( $job );
		if ( ! is_wp_error( $res ) && isset( $res['status'] ) && 'error' === $res['status'] ) {
			// The check could not run (edge busy, Chrome unavailable). Nothing is changed; say so.
			ZeroConfig_Options::update( array( 'selftest_job' => '', 'last_selftest' => array( 'status' => 'error', 'at' => time(), 'error' => isset( $res['error'] ) ? sanitize_text_field( $res['error'] ) : '' ) ) );
			return;
		}
		if ( is_wp_error( $res ) || empty( $res['status'] ) || 'done' !== $res['status'] ) {
			$st      = (array) ZeroConfig_Options::get( 'last_selftest' );
			$started = isset( $st['started'] ) ? (int) $st['started'] : time();
			if ( time() - $started < self::MAX_WAIT ) {
				// Still queued or running on the service (or it was briefly unreachable): show it and wait.
				if ( ! is_wp_error( $res ) ) {
					self::track( $res );
				}
				wp_schedule_single_event( time() + self::poll_delay( $attempt ), self::EVENT_POLL, array( $attempt + 1 ) );
			} else {
				ZeroConfig_Options::update( array( 'selftest_job' => '', 'last_selftest' => array( 'status' => 'timeout', 'at' => time() ) ) );
			}
			return;
		}
		if ( 'blocked' === ( $res['verdict'] ?? '' ) ) {
			// We could not see the site's own pages, so nothing was judged and nothing changes.
			ZeroConfig_Options::update(
				array(
					'selftest_job'  => '',
					'last_selftest' => array( 'status' => 'blocked', 'at' => time(), 'error' => sanitize_text_field( (string) ( $res['error'] ?? '' ) ) ),
				)
			);
			return;
		}
		self::apply_verdict( $res );
	}

	/**
	 * Verdict shape: { status: 'done', verdict: 'pass'|'rollback', disable: { js: 'reason', ... }, report: {...} }
	 */
	public static function apply_verdict( array $res ) {
		$known    = array( 'images', 'assets', 'js', 'delay', 'critical' );
		$disabled = (array) ZeroConfig_Options::get( 'disabled' );
		$pages    = (array) ZeroConfig_Options::get( 'disabled_pages' );
		$changed  = false;
		// A check that tested a switched-off feature and saw nothing wrong gives it back:
		// one flaky run (a slow third-party script, an update mid-check) must not cost the site a
		// feature for good. Only when the pages where it broke were among the pages compared.
		$checked = array();
		foreach ( isset( $res['report'] ) ? (array) $res['report'] : array() as $row ) {
			if ( is_array( $row ) && ! empty( $row['url'] ) ) {
				$checked[ (string) $row['url'] ] = true;
			}
		}
		foreach ( isset( $res['cleared'] ) ? (array) $res['cleared'] : array() as $feature ) {
			if ( ! in_array( $feature, $known, true ) || empty( $disabled[ $feature ] ) ) {
				continue;
			}
			$seen = true;
			foreach ( isset( $pages[ $feature ] ) ? (array) $pages[ $feature ] : array() as $p ) {
				$seen = $seen && isset( $checked[ $p ] );
			}
			if ( $seen ) {
				unset( $disabled[ $feature ], $pages[ $feature ] );
				$changed = true;
			}
		}
		if ( ! empty( $res['disable'] ) && is_array( $res['disable'] ) ) {
			foreach ( $res['disable'] as $feature => $reason ) {
				if ( in_array( $feature, $known, true ) && empty( $disabled[ $feature ] ) ) {
					$disabled[ $feature ] = sanitize_text_field( (string) $reason );
					$pages[ $feature ]    = self::failed_pages( $res, $feature );
					$changed              = true;
				}
			}
		}
		ZeroConfig_Options::update(
			array(
				'disabled'       => $disabled,
				'disabled_pages' => $pages,
				'selftest_job'  => '',
				'last_selftest' => array(
					'status'   => 'done',
					'verdict'  => isset( $res['verdict'] ) ? sanitize_text_field( $res['verdict'] ) : 'pass',
					'at'       => time(),
					'pages'    => isset( $res['report'] ) ? count( (array) $res['report'] ) : 0, // how many page checks ran
					'disabled' => array_keys( $disabled ),
				),
			)
		);
		if ( $changed ) {
			ZeroConfig_Page_Cache::purge_all( 'safety' );
		}
	}

	/** Pages of this site where the check saw the feature break (at most two). */
	private static function failed_pages( array $res, $feature ) {
		$out = array();
		foreach ( isset( $res['report'] ) ? (array) $res['report'] : array() as $row ) {
			if ( is_array( $row ) && empty( $row['ok'] ) && isset( $row['feature'], $row['url'] ) && $feature === $row['feature'] ) {
				$p = self::own_page( (string) $row['url'] );
				if ( '' !== $p && ! in_array( $p, $out, true ) ) {
					$out[] = $p;
				}
			}
		}
		return array_slice( $out, 0, 2 );
	}

	/**
	 * Remember where a queued/running check stands (queue position, steps done) for the admin card.
	 * Returns the stored state, or null when the answer was not a waiting state.
	 */
	public static function track( array $res ) {
		if ( ! in_array( $res['status'] ?? '', array( 'queued', 'running' ), true ) ) {
			return null;
		}
		$st             = (array) ZeroConfig_Options::get( 'last_selftest' );
		$st['status']   = $res['status'];
		$st['position'] = isset( $res['queue_position'] ) ? (int) $res['queue_position'] : 0;
		$st['eta']      = isset( $res['eta_seconds'] ) ? max( 0, (int) $res['eta_seconds'] ) : 0; // the service's estimate
		$p              = isset( $res['progress'] ) && is_array( $res['progress'] ) ? $res['progress'] : null;
		$st['progress'] = $p ? array(
			'done'     => max( 0, (int) ( $p['done'] ?? 0 ) ),
			'total'    => max( 1, (int) ( $p['total'] ?? 1 ) ),
			'url'      => esc_url_raw( (string) ( $p['url'] ?? '' ) ),
			'viewport' => sanitize_key( (string) ( $p['viewport'] ?? '' ) ),
			'feature'  => sanitize_key( (string) ( $p['feature'] ?? '' ) ),
		) : null;
		ZeroConfig_Options::set( 'last_selftest', $st );
		return $st;
	}

	/** User pressed "Something looks off?": strict check + diagnostic ticket. */
	public static function report_issue( $message = '', $url = '' ) {
		$url = self::own_page( $url );
		if ( $url ) {
			set_transient( 'zeroconfig_issue_url', $url, DAY_IN_SECONDS );
		}
		ZeroConfig_API::report_issue( $message, $url );
		self::schedule( 5, 'strict' );
	}

	/** A full URL or a path on this site, or '' for anything else (other hosts are never checked). */
	public static function own_page( $url ) {
		$url = trim( (string) $url );
		if ( '' === $url ) {
			return '';
		}
		if ( '/' === $url[0] && ( ! isset( $url[1] ) || '/' !== $url[1] ) ) {
			$url = home_url( $url );
		}
		$home = wp_parse_url( home_url() );
		$page = wp_parse_url( $url );
		if ( ! $page || empty( $page['host'] ) || ! in_array( $page['scheme'] ?? '', array( 'http', 'https' ), true ) ) {
			return '';
		}
		$strip = function ( $h ) { return preg_replace( '/^www[.]/', '', strtolower( $h ) ); };
		return $strip( $page['host'] ) === $strip( $home['host'] ?? '' ) ? esc_url_raw( $url ) : '';
	}

	/** Re-enable everything; the next check decides again. */
	public static function reset() {
		ZeroConfig_Options::update( array( 'disabled' => array(), 'disabled_pages' => array() ) );
		ZeroConfig_Page_Cache::purge_all( 'safety' );
		self::schedule( 30 );
	}
}