<?php
require_once(__DIR__ . '/struct/TimeParams.php');

/**
 * Russian dates without locales
 * Class Dt
 * @package php_rutils
 */
class Dt
{
    public static $PREFIX_IN = "через"; //Prefix 'in' (i.e. B{in} three hours)
    public static $SUFFIX_AGO = "назад"; //Prefix 'ago' (i.e. three hours B{ago})

    private static $_DAY_NAMES = array(
        array('пн', 'понедельник', 'понедельник', "в\xC2\xA0"),
        array('вт', 'вторник', 'вторник', "во\xC2\xA0"),
        array('ср', 'среда', 'среду', "в\xC2\xA0"),
        array('чт', 'четверг', 'четверг', "в\xC2\xA0"),
        array('пт', 'пятница', 'пятницу', "в\xC2\xA0"),
        array('сб', 'суббота', 'субботу', "в\xC2\xA0"),
        array('вск', 'воскресенье', 'воскресенье', "в\xC2\xA0")
    ); //Day alternatives (i.e. one day ago -> yesterday)

    private static $_MONTH_NAMES = array(
        array("янв", "январь", "января"),
        array("фев", "февраль", "февраля"),
        array("мар", "март", "марта"),
        array("апр", "апрель", "апреля"),
        array("май", "май", "мая"),
        array("июн", "июнь", "июня"),
        array("июл", "июль", "июля"),
        array("авг", "август", "августа"),
        array("сен", "сентябрь", "сентября"),
        array("окт", "октябрь", "октября"),
        array("ноя", "ноябрь", "ноября"),
        array("дек", "декабрь", "декабря"),
    ); //Forms (1, 2, 5) for noun 'day'

    private static $_PAST_ALTERNATIVES = array("вчера", "позавчера");
    private static $_YEAR_VARIANTS = array("год", "года", "лет"); //Forms (1, 2, 5) for noun 'year'
    private static $_MONTH_VARIANTS = array("месяц", "месяца", "месяцев");
    private static $_DAY_VARIANTS = array("день", "дня", "дней");
    private static $_HOUR_VARIANTS = array("час", "часа", "часов");
    private static $_MINUTE_VARIANTS = array("минуту", "минуты", "минут");

    private static $_DISTANCE_FIELDS = array('y', 'm', 'd', 'h', 'i');

    /**
     * Russian \DateTime::format
     * @param array|\php_rutils\struct\TimeParams $params Params structure
     * @return string Date/time string representation
     */
    public function ruStrFTime($params = null)
    {
        //Params handle
        if ($params === null)
            $params = new TimeParams();
        elseif (is_array($params))
            $params = TimeParams::create($params);
        else
            $params = clone $params;

        if ($params->date === null)
            $params->date = new \DateTime();
        else
            $params->date = $this->_processDateTime($params->date);

        if (is_string($params->timezone))
            $params->timezone = new \DateTimeZone($params->timezone);
        if ($params->timezone)
            $params->date->setTimezone($params->timezone);

        //Format processing
        $weekday = $params->date->format('N') - 1;
        $month = $params->date->format('n') - 1;

        $prepos = $params->preposition ? self::$_DAY_NAMES[$weekday][3] : '';

        $monthIdx = $params->monthInflected ? 2 : 1;
        $dayIdx = ($params->dayInflected || $params->preposition) ? 2 : 1;

        $search = array('D', 'l', 'M', 'F');
        $replace = array(
            $prepos.self::$_DAY_NAMES[$weekday][0],
            $prepos.self::$_DAY_NAMES[$weekday][$dayIdx],
            self::$_MONTH_NAMES[$month][0],
            self::$_MONTH_NAMES[$month][$monthIdx],
        );

        //for russian typography standard,
        //1 April 2007, but 01.04.2007
        if (strpos($params->format, 'F') !== false || strpos($params->format, 'M') !== false) {
            $search[] = 'd';
            $replace[] = 'j';
        }

        $params->format = str_replace($search, $replace, $params->format);

        //Create date/time string
        return $params->date->format($params->format);
    }

    /**
     * Process mixed format date
     * @param mixed $dateTime
     * @return \DateTime
     * @throws \InvalidArgumentException
     */
    private function _processDateTime($dateTime)
    {
        if (is_numeric($dateTime)) {
            $timestamp = $dateTime;
            $dateTime = new \DateTime();
            $dateTime->setTimestamp($timestamp);
        }
        elseif (empty($dateTime)) {
            throw new \InvalidArgumentException('Date/time is empty');
        }
        elseif (is_string($dateTime)) {
            $dateTime = new \DateTime($dateTime);
        }

        if (!($dateTime instanceof \DateTime)) {
            throw new \InvalidArgumentException('Incorrect date/time type');
        }
        return $dateTime;
    }

    /**
     * Represents distance of time in words
     * @param string|int|\DateTime $toTime Source time
     * @param string|int|\DateTime $fromTime Target time
     * @param int $accuracy Level of accuracy (year, month, day, hour, minute), default=year
     * @throws \InvalidArgumentException
     * @throws \RuntimeException
     * @return string Distance of time in words
     */
    public function distanceOfTimeInWords($toTime, $fromTime=null, $accuracy=RUtils::ACCURACY_YEAR) {
        $accuracy = (int)$accuracy;
        if ($accuracy < 1 || $accuracy > 5)
            throw new \InvalidArgumentException('Wrong accuracy value (must be 1..5)');

        /* @var $toTime \DateTime */
        /* @var $fromTime \DateTime */
        /* @var $timeZone \DateTimeZone */
        /* @var $fromCurrent bool */
        list($toTime, $fromTime, $timeZone, $fromCurrent) = $this->_processFunctionParams($toTime, $fromTime);
        $interval = $toTime->diff($fromTime);

        //if diff less than one minute
        if ($interval->days == 0 && $interval->h == 0 && $interval->i == 0) {
            if ($interval->invert)
                $result = 'менее чем через минуту';
            else
                $result = 'менее минуты назад';
            return $result;
        }

        //create distance table
        $distanceData = $this->_createDistanceData($interval, $fromCurrent);
        $words = $this->_getResultWords($accuracy, $distanceData);

        //check short result
        if ($fromCurrent && min($accuracy, sizeof($words)) == 1) {
            //if diff expressed in one word
            $result = $this->_getOneWordResult($interval);
            if ($result) {
                return $result;
            }
            elseif ($interval->days < 3) {
                //if diff 1 or 2 days
                $result = $this->_getTwoDaysResult($interval, $toTime, $timeZone);
                if ($result)
                    return $result;
            }
        }

        //general case
        $result = implode(', ', $words);
        return $this->_addResultSuffix($interval, $result);
    }

    private function _processFunctionParams($toTime, $fromTime)
    {
        $toTime = $this->_processDateTime($toTime);
        $timeZone = $toTime->getTimezone();

        $fromCurrent = false;
        if ($fromTime === null) {
            $fromTime = new \DateTime('now', $timeZone);
            $fromCurrent = true;
        }
        else {
            $fromTime = $this->_processDateTime($fromTime);
        }

        return array($toTime, $fromTime, $timeZone, $fromCurrent);
    }

    private function _createDistanceData(\DateInterval $interval)
    {
        $distanceData = array(); //table of word representations
        $numeral = RUtils::numeral();

        $years = $interval->y;
        if ($years)
            $distanceData['y'] = $numeral->getPlural($years, self::$_YEAR_VARIANTS);

        $months = $interval->m;
        if ($months)
            $distanceData['m'] = $numeral->getPlural($months, self::$_MONTH_VARIANTS);

        $days = $interval->d;
        if ($days)
            $distanceData['d'] = $numeral->getPlural($days, self::$_DAY_VARIANTS);

        $hours = $interval->h;
        if ($hours)
            $distanceData['h'] = $numeral->getPlural($hours, self::$_HOUR_VARIANTS);

        $minutes = $interval->i;
        if ($minutes)
            $distanceData['i'] = $numeral->getPlural($minutes, self::$_MINUTE_VARIANTS);

        return $distanceData;
    }

    private function _getYearResult(array $distanceData)
    {
        return $this->_getLevelResult('y', $distanceData);
    }

    private function _getMonthResult(array $distanceData)
    {
        list($words, $borderField) = $this->_getYearResult($distanceData);
        return $this->_getLevelResult('m', $distanceData, $words, $borderField);
    }

    private function _getDaysResult(array $distanceData)
    {
        list($words, $borderField) = $this->_getMonthResult($distanceData);
        return $this->_getLevelResult('d', $distanceData, $words, $borderField);
    }

    private function _getHoursResult(array $distanceData)
    {
        list($words, $borderField) = $this->_getDaysResult($distanceData);
        return $this->_getLevelResult('h', $distanceData, $words, $borderField);
    }

    private function _getMinutesResult(array $distanceData)
    {
        list($words, $borderField) = $this->_getHoursResult($distanceData);
        return $this->_getLevelResult('i', $distanceData, $words, $borderField);
    }

    private function _getLevelResult($fieldCode, array $distanceData, array $words=array(), $borderField=-1)
    {
        $curPos = array_search($fieldCode, self::$_DISTANCE_FIELDS);
        if ($borderField >= $curPos)
            return array($words, $borderField);

        $nextField = $borderField + 1;
        $length = sizeof(self::$_DISTANCE_FIELDS);
        for ($i=$nextField; $i < $length; ++$i) {
            $field = self::$_DISTANCE_FIELDS[$i];
            if ($borderField != -1 && $i > $curPos) {
                break;
            }
            elseif (isset($distanceData[$field])) {
                $words[] = $distanceData[$field];
                $borderField = $i;
                break;
            }
        }
        return array($words, $borderField);
    }

    private function _getOneWordResult(\DateInterval $interval)
    {
        $result = null;
        if ($interval->days == 0 && $interval->h == 0 && $interval->i == 1)
            $result = 'минуту';
        elseif ($interval->days == 0 && $interval->h == 1)
            $result = 'час';
        elseif ($interval->y == 0 && $interval->m == 1)
            $result = 'месяц';
        elseif ($interval->y == 1)
            $result = 'год';

        if ($result)
            $result = $this->_addResultSuffix($interval, $result);
        return $result;
    }

    /**
     * Add suffix or Postfix to string.
     * @param \DateInterval $interval
     * @param $result string
     * @return string modified $result.
     */
    private function _addResultSuffix(\DateInterval $interval, $result)
    {
        return $interval->invert ? self::$PREFIX_IN . "\xC2\xA0" . $result : $result . "\xC2\xA0" . self::$SUFFIX_AGO;
    }

    private function _getTwoDaysResult(\DateInterval $interval, \DateTime $toTime, \DateTimeZone $timeZone = null)
    {
        $result = null;
        $days = $interval->days;

        if ($interval->invert == 0 && ($days == 1 || $days == 2)) {
            $variant = $days - 1;
            $result = self::$_PAST_ALTERNATIVES[$variant];
        }
        elseif ($interval->invert && ($days == 0 || $days == 1)) {
            $tomorrow = new \DateTime('today', $timeZone);
            $tomorrow->add(new \DateInterval('P1D'));
            $afterTomorrow = new \DateTime('today', $timeZone);
            $afterTomorrow->add(new \DateInterval('P2D'));

            if ($toTime >= $tomorrow && $toTime < $afterTomorrow)
                $result = 'завтра';
            elseif ($days == 1 && $toTime >= $afterTomorrow)
                $result = 'послезавтра';
        }

        return $result;
    }

    private function _getResultWords($accuracy, $distanceData)
    {
        switch ($accuracy) {
            case RUtils::ACCURACY_YEAR:
                list($words,) = $this->_getYearResult($distanceData);
                break;
            case RUtils::ACCURACY_MONTH:
                list($words,) = $this->_getMonthResult($distanceData);
                break;
            case RUtils::ACCURACY_DAY:
                list($words,) = $this->_getDaysResult($distanceData);
                break;
            case RUtils::ACCURACY_HOUR:
                list($words,) = $this->_getHoursResult($distanceData);
                break;
            case RUtils::ACCURACY_MINUTE:
                list($words,) = $this->_getMinutesResult($distanceData);
                break;
            default:
                throw new \RuntimeException("Unexpected accuracy level: $accuracy");
        }
        return $words;
    }

    /**
     * Calculates age
     * @param string|int|\DateTime $birthDate Date of birth
     * @throws \InvalidArgumentException
     * @return int Full years age
     */
    public function getAge($birthDate)
    {
        $birthDate = $this->_processDateTime($birthDate);
        $interval = $birthDate->diff(new \DateTime());
        if ($interval->invert)
            throw new \InvalidArgumentException('Birth date is in future');
        return $interval->y;
    }
}
