<?php
/**
 * TMDO_FSM_Automator — Opt-in automatic execution of FSM_Advisor PROMOTE
 * recommendations (v2.5.0 M13).
 *
 * Default OFF. When admin enables, runs daily at 04:30 UTC. For each module：
 *   - Calls TMDO_FSM_Advisor::advise()
 *   - Only auto-promotes when ALL 4 conditions true:
 *     1. wpdo_automator_enabled = 1
 *     2. module not in wpdo_automator_blacklist
 *     3. TMDO_Health_Cron::get_last_run() critical_count = 0 in last 7 days
 *        (cool-off — system is healthy)
 *     4. ≥ 24h since this module's last automated promotion
 *   - Destructive transitions (cutover→cleanup, cleanup→complete) are
 *     NEVER automated — admin must manually invoke.
 *
 * Audit trail: every automator action writes wp_wpdo_audit op='automator_promoted'
 * + fires action `wpdo/automator_promoted` for downstream subscribers.
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

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

/**
 * Automator — stateless static API.
 */
class TMDO_FSM_Automator {

	public const OPT_ENABLED     = 'wpdo_automator_enabled';
	public const OPT_BLACKLIST   = 'wpdo_automator_blacklist';
	public const OPT_LAST_ACTION = 'wpdo_automator_last_action';

	/** Cool-off window after critical health alert. */
	private const COOL_OFF_DAYS = 7;

	/** Minimum interval between automated promotions of the same module. */
	private const MIN_INTERVAL_HOURS = 24;

	/** Transitions that are never auto-executed (destructive). */
	private const FORBIDDEN_TRANSITIONS = array(
		array( 'verify', 'cutover' ),  // cutover starts reading from custom — needs manual sign-off.
		array( 'cutover', 'cleanup' ),  // cleanup purges wp_*meta — irreversible without snapshot.
		array( 'cleanup', 'complete' ),  // complete = no fallback path.
	);

	/**
	 * Cron handler.
	 *
	 * @return array {ok:bool, executed:int, skipped:int, errors:array}
	 */
	public static function run(): array {
		$result = array(
			'ok'       => true,
			'executed' => 0,
			'skipped'  => 0,
			'errors'   => array(),
			'actions'  => array(),
		);

		// Pre-flight: enabled?
		if ( ! self::is_enabled() ) {
			$result['ok']       = false;
			$result['errors'][] = 'automator disabled';
			return $result;
		}

		// Pre-flight: cool-off?
		if ( ! self::cool_off_clear() ) {
			$result['ok']       = false;
			$result['errors'][] = 'cool-off active (critical health in last ' . self::COOL_OFF_DAYS . ' days)';
			return $result;
		}

		// Iterate modules.
		if ( ! class_exists( 'TMDO_Feature_Flags' ) || ! class_exists( 'TMDO_FSM_Advisor' ) ) {
			$result['ok']       = false;
			$result['errors'][] = 'dependencies missing';
			return $result;
		}

		$blacklist    = (array) get_option( self::OPT_BLACKLIST, array() );
		$last_actions = (array) get_option( self::OPT_LAST_ACTION, array() );

		foreach ( TMDO_Feature_Flags::all() as $module => $current_state ) {
			// Blacklisted?
			if ( in_array( $module, $blacklist, true ) ) {
				++$result['skipped'];
				continue;
			}
			// Get advisor recommendation.
			$advice = TMDO_FSM_Advisor::advise( $module );
			if ( 'PROMOTE' !== ( $advice['action'] ?? '' ) || 'info' !== ( $advice['level'] ?? '' ) ) {
				++$result['skipped'];
				continue;
			}
			$next_state = (string) ( $advice['next_state'] ?? '' );
			if ( '' === $next_state ) {
				++$result['skipped'];
				continue;
			}
			// Forbidden destructive transition?
			if ( self::is_forbidden_transition( $current_state, $next_state ) ) {
				++$result['skipped'];
				continue;
			}
			// Recent action?
			if ( ! self::interval_clear( $module, $last_actions ) ) {
				++$result['skipped'];
				continue;
			}
			// All checks passed — execute.
			$set_result = TMDO_Feature_Flags::set( $module, $next_state );
			if ( true === $set_result ) {
				++$result['executed'];
				$result['actions'][]     = array(
					'module' => $module,
					'from'   => $current_state,
					'to'     => $next_state,
				);
				$last_actions[ $module ] = gmdate( 'Y-m-d H:i:s' );
				if ( class_exists( 'TMDO_Logger' ) ) {
					TMDO_Logger::info(
						'automator_promoted',
						array(
							'module' => $module,
							'from'   => $current_state,
							'to'     => $next_state,
						)
					);
				}
				do_action( 'wpdo/automator_promoted', $module, $current_state, $next_state );
			} else {
				$result['errors'][] = "{$module}: " . ( $set_result instanceof \WP_Error ? $set_result->get_error_code() : 'unknown' );
			}
		}

		update_option( self::OPT_LAST_ACTION, $last_actions, false );
		return $result;
	}

	// ─── settings accessors ─────────────────────────────────────────────

	/**
	 * Return whether the automator is enabled.
	 *
	 * @return bool
	 */
	public static function is_enabled(): bool {
		return '1' === (string) get_option( self::OPT_ENABLED, '0' );
	}

	/**
	 * Return the list of blacklisted module slugs.
	 *
	 * @return array
	 */
	public static function blacklist(): array {
		return (array) get_option( self::OPT_BLACKLIST, array() );
	}

	/**
	 * Return the map of module → last automated action timestamp.
	 *
	 * @return array
	 */
	public static function last_actions(): array {
		return (array) get_option( self::OPT_LAST_ACTION, array() );
	}

	// ─── private helpers ───────────────────────────────────────────────

	/**
	 * Cool-off: false when there's been a critical health alert in last N days.
	 *
	 * @return bool true = OK to act, false = blocked.
	 */
	private static function cool_off_clear(): bool {
		if ( ! class_exists( 'TMDO_Health_Cron' ) ) {
			return true; // No data — assume OK.
		}
		$last = TMDO_Health_Cron::get_last_run();
		if ( ! is_array( $last ) ) {
			return true;
		}
		$crit = (int) ( $last['critical_count'] ?? 0 );
		if ( 0 === $crit ) {
			return true;
		}
		$ts = isset( $last['ran_at'] ) ? strtotime( (string) $last['ran_at'] . ' UTC' ) : 0;
		if ( $ts <= 0 ) {
			return true;
		}
		// Critical alert exists; cool-off if within window.
		return ( time() - $ts ) > ( self::COOL_OFF_DAYS * DAY_IN_SECONDS );
	}

	/**
	 * Per-module interval: ≥ 24h since last automated action on this module.
	 *
	 * @param string $module Module slug.
	 * @param array  $last_actions Map of module → timestamp.
	 * @return bool true = OK to act.
	 */
	private static function interval_clear( string $module, array $last_actions ): bool {
		$last = (string) ( $last_actions[ $module ] ?? '' );
		if ( '' === $last ) {
			return true;
		}
		$ts = strtotime( $last . ' UTC' );
		if ( $ts <= 0 ) {
			return true;
		}
		return ( time() - $ts ) >= ( self::MIN_INTERVAL_HOURS * HOUR_IN_SECONDS );
	}

	/**
	 * Check if (from, to) is in FORBIDDEN_TRANSITIONS.
	 *
	 * @param string $from Current state.
	 * @param string $to   Target state.
	 * @return bool
	 */
	private static function is_forbidden_transition( string $from, string $to ): bool {
		foreach ( self::FORBIDDEN_TRANSITIONS as $pair ) {
			if ( $pair[0] === $from && $pair[1] === $to ) {
				return true;
			}
		}
		return false;
	}
}