<?php

namespace RoosterLMS\Events;

use RoosterLMS\Core\Clock;

defined( 'ABSPATH' ) || exit;

final class History {

	public const OPTION = 'rooster_lms_events_history';

	public const MAX = 2000;

	private static array $counted = array();

	public static function on_moved( $old_id = 0, $new_id = 0, $session_id = 0 ): void {
		unset( $session_id );
		$old_id = (int) $old_id;
		$new_id = (int) $new_id;
		if ( $old_id <= 0 || $new_id <= 0 ) {
			return;
		}
		$all   = self::all();
		$entry = $all[ $old_id ] ?? array(
			'o' => $old_id,
			'n' => 0,
			'p' => '',
			'e' => '',
		);
		++$entry['n'];
		if ( $old_id !== $new_id ) {
			unset( $all[ $old_id ] );
		}
		$all[ $new_id ]           = $entry;
		self::$counted[ $new_id ] = true;
		self::save( $all, $new_id );
	}

	public static function on_rescheduled( $session_id = 0, $old_start = '', $old_end = '', $new_start = '', $new_end = '', $occurrence_id = 0 ): void {
		unset( $session_id, $old_end );
		$id = (int) $occurrence_id;
		if ( $id <= 0 || '' === (string) $new_start || (string) $old_start === (string) $new_start ) {
			return;
		}
		$all   = self::all();
		$entry = $all[ $id ] ?? array(
			'o' => $id,
			'n' => 0,
			'p' => '',
			'e' => '',
		);
		if ( ! isset( self::$counted[ $id ] ) ) {
			++$entry['n'];
			self::$counted[ $id ] = true;
		}
		$entry['p'] = self::utc( (string) $old_start );
		$entry['e'] = self::utc( (string) $new_end );
		$all[ $id ] = $entry;
		self::save( $all, 0 );
	}

	public static function on_state( $session_id = 0, $change = '' ): void {
		if ( 'created' === $change ) {
			return;
		}
		$session = \RoosterLMS\Domain\Services::live_session_repo()->get( (int) $session_id );
		if ( null === $session ) {
			return;
		}
		$now   = new \DateTimeImmutable( '@' . Clock::timestamp() );
		$all   = self::all();
		$dirty = false;
		foreach ( \RoosterLMS\Domain\Services::live_session_repo()->occurrences( $session->id, $now, $now->modify( '+' . Feed::WINDOW_MONTHS . ' months' ) ) as $o ) {
			$cancelled = $o->is_cancelled() || ! $session->is_active();
			$entry     = $all[ $o->id ] ?? array(
				'o' => $o->id,
				'n' => 0,
				'p' => '',
				'e' => $o->ends_at,
			);
			if ( (bool) ( $entry['k'] ?? false ) === $cancelled ) {
				continue;
			}
			$entry['k']    = $cancelled;
			$entry['c']    = (int) ( $entry['c'] ?? 0 ) + 1;
			$entry['e']    = $o->ends_at;
			$all[ $o->id ] = $entry;
			$dirty         = true;
		}
		if ( $dirty ) {
			self::save( $all, 0 );
		}
	}

	public static function on_occurrence_cancelled( $occurrence_id = 0, $session_id = 0 ): void {
		unset( $occurrence_id );
		self::on_state( $session_id, 'occurrence' );
	}

	public static function of( int $occurrence_id ): array {
		$entry = self::all()[ $occurrence_id ] ?? null;
		return array(
			'o' => is_array( $entry ) ? max( 1, (int) ( $entry['o'] ?? $occurrence_id ) ) : $occurrence_id,
			'n' => is_array( $entry ) ? max( 0, (int) ( $entry['n'] ?? 0 ) ) : 0,
			'p' => is_array( $entry ) ? (string) ( $entry['p'] ?? '' ) : '',
		);
	}

	public static function uid( int $occurrence_id ): string {
		$host = (string) wp_parse_url( home_url( '/' ), PHP_URL_HOST );
		return 'rooster-lms-event-' . self::of( $occurrence_id )['o'] . '@' . ( '' !== $host ? $host : 'localhost' );
	}

	public static function sequence( int $occurrence_id, bool $cancelled ): int {
		$entry = self::all()[ $occurrence_id ] ?? array();
		$steps = is_array( $entry ) ? max( 0, (int) ( $entry['c'] ?? 0 ) ) : 0;
		return self::of( $occurrence_id )['n'] + $steps + ( $cancelled && 0 === $steps ? 1 : 0 );
	}

	public static function reset(): void {
		self::$counted = array();
	}

	private static function all(): array {
		$all   = wp_load_alloptions();
		$value = isset( $all[ self::OPTION ] ) ? maybe_unserialize( $all[ self::OPTION ] ) : array();
		return is_array( $value ) ? $value : array();
	}

	private static function save( array $all, int $fresh ): void {
		if ( $fresh > 0 && '' === (string) ( $all[ $fresh ]['e'] ?? '' ) ) {
			$o                  = \RoosterLMS\Domain\Services::live_session_repo()->occurrence( $fresh );
			$all[ $fresh ]['e'] = null === $o ? '' : $o->ends_at;
		}
		$now = gmdate( 'Y-m-d H:i:s', Clock::timestamp() - DAY_IN_SECONDS );
		foreach ( $all as $id => $entry ) {
			$end = is_array( $entry ) ? (string) ( $entry['e'] ?? '' ) : '';
			if ( ! is_array( $entry ) || ( '' !== $end && $end < $now ) ) {
				unset( $all[ $id ] );
			}
		}
		if ( count( $all ) > self::MAX ) {
			$all = array_slice( $all, -self::MAX, null, true );
		}
		update_option( self::OPTION, $all, true );
	}

	private static function utc( string $value ): string {
		return 1 === preg_match( '/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/', $value ) ? $value : '';
	}
}