<?php

declare(strict_types=1);

namespace App\Services\Utils;

use Brick\DateTime\Duration;
use Brick\DateTime\LocalTime;

/*
 * Converts given dates and times into a Duration object.
 */
class DurationConvertor
{
    public function __construct()
    {
    }

    /**
     * Convert a given duration into working hours considering the given start and end workday. Duration is calculated from startWorkday
     * @param Duration $duration
     * @param LocalTime $startWorkday
     * @param LocalTime $endWorkday
     * @param \DateTimeInterface $startTime
     * @return DurationConvertorResult
     */
    public function convertIntoWorkDuration(Duration $duration, LocalTime $startWorkday, LocalTime $endWorkday, \DateTimeInterface $startTime): DurationConvertorResult
    {
        if ($endWorkday->isEqualTo($startWorkday)) {
            throw new \InvalidArgumentException("Start and end workday must be different");
        }

        $workDuration = $duration;
        $endDuration = Duration::zero();
        $workDaySeconds = $endWorkday->toSecondOfDay() - $startWorkday->toSecondOfDay();

        // handle first day
        $startDateTime = \DateTimeImmutable::createFromInterface($startTime)->setTime($startWorkday->getHour(), $startWorkday->getMinute());
        $availSecondsFirstDay =  $workDaySeconds - ($startTime->getTimestamp() - $startDateTime->getTimestamp());

        if ($availSecondsFirstDay >= $workDuration->toSeconds()) {
            // first day is enough time
            $endDuration->plusSeconds($workDaySeconds - $availSecondsFirstDay);

            return new DurationConvertorResult(
                false,
                $endDuration->plusSeconds($workDuration->toSeconds())
            );
        } else {
            $workDuration = $workDuration->minusSeconds($availSecondsFirstDay);
            $endDuration = $endDuration->plus(Duration::ofDays(1));
        }

        while ($workDuration->toSeconds() > $workDaySeconds) {
            $endDuration = $endDuration->plus(Duration::ofDays(1));
            $workDuration = $workDuration->minusSeconds($workDaySeconds);
        }

        return new DurationConvertorResult(
            true,
            $endDuration->plus($workDuration)
        );
    }
}