<?php
// TimeSpan.php
// Created: 2021-06-11
// Updated: 2022-02-27

namespace Index;

use DateInterval;
use JsonSerializable;
use Stringable;

/**
 * Represents a duration of time.
 */
class TimeSpan extends DateInterval implements JsonSerializable, Stringable, IComparable, IEquatable {
    private const HOURS_IN_DAY = 24;
    private const MINS_IN_HOUR = 60;
    private const SECS_IN_MIN = 60;
    private const MILLIS_IN_SEC = 1000;
    private const MINS_IN_DAY = 1440;
    private const SECS_IN_HOUR = 3600;
    private const MILLIS_IN_MIN = 60000;
    private const SECS_IN_DAY = 86400;
    private const MICROS_IN_SEC = 1000000;
    private const MILLIS_IN_HOUR = 3600000;
    private const MICROS_IN_MIN = 60000000;
    private const MILLIS_IN_DAY = 86400000;
    private const MICROS_IN_HOUR = 3600000000;
    private const MICROS_IN_DAY = 86400000000;

    private int $realDays = -1;

    /**
     * Creates a new instance of TimeSpan.
     *
     * @param string $duration An ISO8601 duration string.
     * @return TimeSpan A TimeSpan instance representing the given duration.
     */
    public function __construct(string $duration = 'PT0S') {
        parent::__construct($duration);
        $this->realDays = $this->days === false ? $this->calculateRealDays() : $this->days;
    }

    private function calculateRealDays(): int {
        return ($this->y * 365)
             + ($this->m * 31)
             +  $this->d;
    }

    /**
     * Gets the amount of days this TimeSpan represents.
     *
     * @return int Amount of days.
     */
    public function getDays(): int {
        return $this->realDays;
    }

    /**
     * Gets the amount of hours this TimeSpan represents.
     *
     * @retunr int Amount of hours.
     */
    public function getHours(): int {
        return $this->h;
    }

    /**
     * Gets the amount of minutes this TimeSpan represents.
     *
     * @return int Amount of minutes.
     */
    public function getMinutes(): int {
        return $this->i;
    }

    /**
     * Gets the amount of seconds this TimeSpan represents.
     *
     * @return int Amount of seconds.
     */
    public function getSeconds(): int {
        return $this->s;
    }

    /**
     * Gets the amount of milliseconds this TimeSpan represents.
     *
     * @return int Amount of milliseconds.
     */
    public function getMilliseconds(): int {
        return (int)($this->f * 1000);
    }

    /**
     * Gets the amount of microseconds this TimeSpan represents.
     *
     * @return int Amount of microseconds.
     */
    public function getMicroseconds(): int {
        return (int)($this->f * 1000000);
    }

    /**
     * Gets whether this TimeSpan represents a negative amount of time.
     *
     * @return bool true if negative, false if positive.
     */
    public function isNegative(): bool {
        return $this->invert !== 0;
    }

    /**
     * Counts the total amount of days this TimeSpan contains.
     *
     * @return float Total amount of days.
     */
    public function totalDays(): float {
        $days  = $this->getDays();
        $days += $this->getHours() / self::HOURS_IN_DAY;
        $days += $this->getMinutes() / self::MINS_IN_DAY;
        $days += $this->getSeconds() / self::SECS_IN_DAY;
        $days += $this->getMicroseconds() / self::MICROS_IN_DAY;
        return $days;
    }

    /**
     * Counts the total amount of hours this TimeSpan contains.
     *
     * @return float Total amount of hours.
     */
    public function totalHours(): float {
        $hours  = $this->getDays() * self::HOURS_IN_DAY;
        $hours += $this->getHours();
        $hours += $this->getMinutes() / self::MINS_IN_HOUR;
        $hours += $this->getSeconds() / self::SECS_IN_HOUR;
        $hours += $this->getMicroseconds() / self::MICROS_IN_HOUR;
        return $hours;
    }

    /**
     * Counts the total amount of minutes this TimeSpan contains.
     *
     * @return float Total amount of minutes.
     */
    public function totalMinutes(): float {
        $mins  = $this->getDays() * self::MINS_IN_DAY;
        $mins += $this->getHours() * self::MINS_IN_HOUR;
        $mins += $this->getMinutes();
        $mins += $this->getSeconds() / self::SECS_IN_MIN;
        $mins += $this->getMicroseconds() / self::MICROS_IN_MIN;
        return $mins;
    }

    /**
     * Counts the total amount of seconds this TimeSpan contains.
     *
     * @return float Total amount of seconds.
     */
    public function totalSeconds(): float {
        $secs  = $this->getDays() * self::SECS_IN_DAY;
        $secs += $this->getHours() * self::SECS_IN_HOUR;
        $secs += $this->getMinutes() * self::SECS_IN_MIN;
        $secs += $this->getSeconds();
        $secs += $this->getMicroseconds() * self::MICROS_IN_SEC;
        return $secs;
    }

    /**
     * Counts the total amount of milliseconds this TimeSpan contains.
     *
     * @return float Total amount of milliseconds.
     */
    public function totalMilliseconds(): float {
        $millis  = $this->getDays() * self::MILLIS_IN_DAY;
        $millis += $this->getHours() * self::MILLIS_IN_HOUR;
        $millis += $this->getMinutes() * self::MILLIS_IN_MIN;
        $millis += $this->getSeconds() * self::MILLIS_IN_SEC;
        $millis += $this->getMilliseconds();
        return $millis;
    }

    /**
     * Counts the total amount of microseconds this TimeSpan contains.
     *
     * @return float Total amount of microseconds.
     */
    public function totalMicroseconds(): float {
        $micros  = $this->getDays() * self::MICROS_IN_DAY;
        $micros += $this->getHours() * self::MICROS_IN_HOUR;
        $micros += $this->getMinutes() * self::MICROS_IN_MIN;
        $micros += $this->getSeconds() * self::MICROS_IN_SEC;
        $micros += $this->getMicroseconds();
        return $micros;
    }

    /**
     * Returns a new TimeSpan whose value is the sum of this instance and the provided instance.
     *
     * @param DateInterval $timeSpan Interval to add.
     * @return TimeSpan Instance that represents this instance plus the value of $timeSpan.
     */
    public function add(DateInterval $timeSpan): TimeSpan {
        $timeSpan = self::cast($timeSpan);

        $days1 = $this->totalDays();
        if($this->isNegative())
            $days1 *= -1;

        $days2 = $timeSpan->totalDays();
        if($timeSpan->isNegative())
            $days2 *= -1;

        return self::fromDays($days1 + $days2);
    }

    /**
     * Returns a new TimeSpan whose value is the difference of this instance and the provided instance.
     *
     * @param DateInterval $timeSpan Interval to subtract.
     * @return TimeSpan Instance that represents this instance minus the value of $timeSpan.
     */
    public function subtract(DateInterval $timeSpan): TimeSpan {
        $timeSpan = self::cast($timeSpan);

        $days1 = $this->totalDays();
        if($this->isNegative())
            $days1 *= -1;

        $days2 = $timeSpan->totalDays();
        if($timeSpan->isNegative())
            $days2 *= -1;

        return self::fromDays($days1 - $days2);
    }

    /**
     * Returns the result of a division of this instance and the provided instance.
     *
     * @param DateInterval $timeSpan Interval to be divided by.
     * @return float $timeSpan Number that represents this instance divided by the value of $timeSpan.
     */
    public function divideTimeSpan(DateInterval $timeSpan): float {
        $timeSpan = self::cast($timeSpan);

        $days1 = $this->totalDays();
        if($this->isNegative())
            $days1 *= -1;

        $days2 = $timeSpan->totalDays();
        if($timeSpan->isNegative())
            $days2 *= -1;

        if($days2 === 0.0)
            return 0.0;

        return $days1 / $days2;
    }

    /**
     * Returns the result of a division of this instance and the provided divisor.
     *
     * @param float $divisor Value to divide by.
     * @return TimeSpan Instance that represents this instance divided by the value of $divisor.
     */
    public function divideFloat(float $divisor): TimeSpan {
        $totalDays = $this->totalDays();
        if($this->isNegative())
            $totalDays *= -1;
        $totalDays /= $divisor;
        return self::fromDays($totalDays);
    }

    /**
     * Returns a new TimeSpan whose alue is the result of a multiplication of this oinstance and the provided factor.
     *
     * @param float $factor Value to multiply with.
     * @return TimeSpan Instance that represents this instance multiplied by the value of $factor.
     */
    public function multiply(float $factor): TimeSpan {
        $totalDays = $this->totalDays();
        if($this->isNegative())
            $totalDays *= -1;
        $totalDays *= $factor;
        return self::fromDays($totalDays);
    }

    /**
     * Return a new TimeSpan whose value is the negated value of this instance.
     *
     * @return TimeSpan Negated copy of this instance.
     */
    public function negate(): TimeSpan {
        return self::create(
            $this->getDays(),
            $this->getHours(),
            $this->getMinutes(),
            $this->getSeconds(),
            $this->getMicroseconds(),
            !$this->isNegative()
        );
    }

    public function compare(mixed $other): int {
        if(!($other instanceof DateInterval))
            return -1;
        $other = self::cast($other);

        $diff = $this->getDays() <=> $other->getDays();
        if($diff) return $diff;

        $diff = $this->getHours() <=> $other->getHours();
        if($diff) return $diff;

        $diff = $this->getMinutes() <=> $other->getMinutes();
        if($diff) return $diff;

        $diff = $this->getSeconds() <=> $other->getSeconds();
        if($diff) return $diff;

        $diff = $this->getMicroseconds() <=> $other->getMicroseconds();
        if($diff) return $diff;

        $diff = $this->isNegative() <=> $other->isNegative();
        if($diff) return $diff;

        return 0;
    }

    public function equals(mixed $other): bool {
        if(!($other instanceof DateInterval))
            return false;
        $other = self::cast($other);
        return $this->getDays() === $other->getDays()
            && $this->getHours() === $other->getHours()
            && $this->getMinutes() === $other->getMinutes()
            && $this->getSeconds() === $other->getSeconds()
            && $this->getMicroseconds() === $other->getMicroseconds()
            && $this->isNegative() === $other->isNegative();
    }

    /**
     * Returns the data which should be serialized as json.
     *
     * @see https://www.php.net/manual/en/jsonserializable.jsonserialize.php
     * @return mixed Data to be passed to json_encode.
     */
    public function jsonSerialize(): mixed {
        return (string)$this;
    }

    /**
     * Creates a string representation of this object.
     *
     * @return string Representation of this object.
     */
    public function __toString(): string {
        $string = $this->isNegative() ? '-' : '';
        return sprintf(
            '%sP%dY%dM%dDT%dH%dM%d.%dS',
            $this->isNegative() ? '-' : '',
            $this->y,
            $this->m,
            $this->d,
            $this->getHours(),
            $this->getMinutes(),
            $this->getSeconds(),
            $this->getMicroseconds()
        );
    }

    /**
     * Creates a new TimeSpan instance that represents the specified number of days.
     *
     * @param float $days Number of days.
     * @return TimeSpan Instance representing the provided number of days.
     */
    public static function fromDays(float $days): TimeSpan {
        $abs = abs($days);
        $round = (int)floor($abs);
        $hours = ($abs - $round) * self::HOURS_IN_DAY;
        $hoursRound = (int)floor($hours);
        $minutes = ($hours - $hoursRound) * self::MINS_IN_HOUR;
        $minsRound = (int)floor($minutes);
        $seconds = ($minutes - $minsRound) * self::SECS_IN_MIN;
        $secsRound = (int)floor($seconds);
        $micros = (int)floor(($seconds - $secsRound) * self::MICROS_IN_SEC);
        return self::create($round, $hoursRound, $minsRound, $secsRound, $micros, $days < 0);
    }

    /**
     * Creates a new TimeSpan instance that represents the specified number of hours.
     *
     * @param float $hours Number of hours.
     * @return TimeSpan Instance representing the provided number of hours.
     */
    public static function fromHours(float $hours): TimeSpan {
        $abs = abs($hours);
        $round = (int)floor($abs);
        $minutes = ($abs - $round) * self::MINS_IN_HOUR;
        $minsRound = (int)floor($minutes);
        $seconds = ($minutes - $minsRound) * self::SECS_IN_MIN;
        $secsRound = (int)floor($seconds);
        $micros = (int)floor(($seconds - $secsRound) * self::MICROS_IN_SEC);
        return self::create(0, $round, $minsRound, $secsRound, $micros, $hours < 0);
    }

    /**
     * Creates a new TimeSpan instance that represents the specified number of minutes.
     *
     * @param float $minutes Number of minutes.
     * @return TimeSpan Instance representing the provided number of minutes.
     */
    public static function fromMinutes(float $minutes): TimeSpan {
        $abs = abs($minutes);
        $round = (int)floor($abs);
        $seconds = ($abs - $round) * self::SECS_IN_MIN;
        $secsRound = (int)floor($seconds);
        $micros = (int)floor(($seconds - $secsRound) * self::MICROS_IN_SEC);
        return self::create(0, 0, $round, $secsRound, $micros, $minutes < 0);
    }

    /**
     * Creates a new TimeSpan instance that represents the specified number of seconds.
     *
     * @param float $seconds Number of seconds.
     * @return TimeSpan Instance representing the provided number of seconds.
     */
    public static function fromSeconds(float $seconds): TimeSpan {
        $abs = abs($seconds);
        $round = (int)floor($abs);
        $micros = (int)floor(($abs - $round) * self::MICROS_IN_SEC);
        return self::create(0, 0, 0, $round, $micros, $seconds < 0);
    }

    /**
     * Creates a new TimeSpan instance that represents the specified number of milliseconds.
     *
     * @param float $millis Number of milliseconds.
     * @return TimeSpan Instance representing the provided number of milliseconds.
     */
    public static function fromMilliseconds(float $millis): TimeSpan {
        return self::fromMicroseconds($millis * 1000);
    }

    /**
     * Creates a new TimeSpan instance that represents the specified number of microseconds.
     *
     * @param float $micros Number of microseconds.
     * @return TimeSpan Instance representing the provided number of microseconds.
     */
    public static function fromMicroseconds(float $micros): TimeSpan {
        return self::create(0, 0, 0, 0, (int)floor(abs($micros)), $micros < 0);
    }

    /**
     * Creates a new TimeSpan using the given parameters.
     *
     * @param int $days Number of days.
     * @param int $hours Number of hours.
     * @param int $minutes Number of minutes.
     * @param int $seconds Number of seconds.
     * @param int $micros Number of microseconds.
     * @param bool $negative true for a negative TimeSpan, false for positive.
     * @return TimeSpan A new TimeSpan from the provided parameters.
     */
    public static function create(int $days, int $hours, int $minutes, int $seconds, int $micros = 0, bool $negative = false): TimeSpan {
        $ts = new TimeSpan;
        $ts->realDays = $days = max(0, $days);
        $ts->h = max(0, min(23, $hours));
        $ts->i = max(0, min(59, $minutes));
        $ts->s = max(0, min(59, $seconds));
        $ts->f = $micros / self::MICROS_IN_SEC;
        $ts->invert = $negative ? 1 : 0;

        // this may still be stupid
        if($days > 0) {
            $days /= 365;
            $ts->y = (int)$days;
            $days -= $ts->y;
            $days *= 12;
            $ts->m = (int)$days;
            $days -= $ts->m;
            $days *= 31;
            $ts->d = (int)$days;
        }

        return $ts;
    }

    /**
     * Creates a TimeSpan from the relative parts of a string.
     *
     * Uses the same parser as strtotime and the DateTime constructor internally.
     *
     * @param string $dateTime A date with relative parts.
     * @return TimeSpan A TimeSpan representing the given
     */
    public static function createFromDateString(string $dateTime): TimeSpan {
        return self::cast(parent::createFromDateString($dateTime));
    }

    /**
     * Makes sure a DateInterval inheriting object is a TimeSpan instance.
     *
     * @param DateInterval $dateInterval Input object.
     * @return TimeSpan If the input was a TimeSpan, the same instance will be returned.
     *                  If the input was something else, a new TimeSpan instance will be returned based on the input.
     */
    public static function cast(DateInterval $dateInterval): TimeSpan {
        if($dateInterval instanceof TimeSpan)
            return $dateInterval;

        $timeSpan = new TimeSpan;
        $timeSpan->y = $dateInterval->y;
        $timeSpan->m = $dateInterval->m;
        $timeSpan->d = $dateInterval->d;
        $timeSpan->h = $dateInterval->h;
        $timeSpan->i = $dateInterval->i;
        $timeSpan->s = $dateInterval->s;
        $timeSpan->f = $dateInterval->f;
        $timeSpan->invert = $dateInterval->invert;
        $timeSpan->realDays = $timeSpan->calculateRealDays();
        return $timeSpan;
    }
}