<?php
/**
 * Time helpers: site-local input <-> UTC storage.
 *
 * @package Rentbaik
 */

namespace Rentbaik\Support;

use DateTimeImmutable;
use DateTimeZone;
use Exception;

defined( 'ABSPATH' ) || exit;

/**
 * Converts between the site timezone (what people type) and UTC (what is stored).
 */
final class Time {

	/**
	 * MySQL datetime format.
	 */
	public const MYSQL = 'Y-m-d H:i:s';

	/**
	 * Parse a local date-time string (e.g. "2026-11-05T10:00" from datetime-local) into UTC.
	 *
	 * @param string $local Local date-time in the site timezone.
	 * @return DateTimeImmutable|null UTC time, or null when invalid.
	 */
	public static function from_local( string $local ): ?DateTimeImmutable {
		$local = trim( str_replace( 'T', ' ', $local ) );
		if ( ! preg_match( '/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}(:\d{2})?$/', $local ) ) {
			return null;
		}
		try {
			$date = new DateTimeImmutable( $local, wp_timezone() );
		} catch ( Exception $e ) {
			return null;
		}
		return $date->setTimezone( new DateTimeZone( 'UTC' ) );
	}

	/**
	 * Parse a stored UTC MySQL datetime.
	 *
	 * @param string $utc UTC datetime (Y-m-d H:i:s).
	 * @return DateTimeImmutable|null
	 */
	public static function from_utc( string $utc ): ?DateTimeImmutable {
		if ( '' === $utc || 0 === strpos( $utc, '0000-00-00' ) ) {
			return null;
		}
		try {
			return new DateTimeImmutable( $utc, new DateTimeZone( 'UTC' ) );
		} catch ( Exception $e ) {
			return null;
		}
	}

	/**
	 * Current UTC time.
	 *
	 * @return DateTimeImmutable
	 */
	public static function now(): DateTimeImmutable {
		return new DateTimeImmutable( 'now', new DateTimeZone( 'UTC' ) );
	}

	/**
	 * UTC time as MySQL string.
	 *
	 * @param DateTimeImmutable $date Any time.
	 * @return string
	 */
	public static function to_mysql( DateTimeImmutable $date ): string {
		return $date->setTimezone( new DateTimeZone( 'UTC' ) )->format( self::MYSQL );
	}

	/**
	 * Value for a datetime-local input, in the site timezone.
	 *
	 * @param DateTimeImmutable|null $date UTC time.
	 * @return string
	 */
	public static function to_input( ?DateTimeImmutable $date ): string {
		return $date ? $date->setTimezone( wp_timezone() )->format( 'Y-m-d\TH:i' ) : '';
	}

	/**
	 * The same moment in the site timezone.
	 *
	 * @param DateTimeImmutable $date Any time.
	 * @return DateTimeImmutable
	 */
	public static function local( DateTimeImmutable $date ): DateTimeImmutable {
		return $date->setTimezone( wp_timezone() );
	}

	/**
	 * Start of today in the site timezone, as UTC.
	 *
	 * @param int $offset_days Days to add (negative for the past).
	 * @return DateTimeImmutable
	 */
	public static function local_midnight( int $offset_days = 0 ): DateTimeImmutable {
		$today = new DateTimeImmutable( 'today', wp_timezone() );
		if ( 0 !== $offset_days ) {
			$today = $today->modify( sprintf( '%+d days', $offset_days ) );
		}
		return $today->setTimezone( new DateTimeZone( 'UTC' ) );
	}
}