<?php
declare(strict_types=1);

/**
 * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 * @link          https://cakephp.org CakePHP(tm) Project
 * @since         3.2.0
 * @license       https://opensource.org/licenses/mit-license.php MIT License
 */
namespace Cake\I18n;

use Cake\Chronos\ChronosDate;
use Cake\Chronos\DifferenceFormatterInterface;
use DateTimeInterface;

/**
 * Helper class for formatting relative dates & times.
 *
 * @internal
 */
class RelativeTimeFormatter implements DifferenceFormatterInterface
{
    /**
     * Get the difference in a human readable format.
     *
     * @param \Cake\Chronos\ChronosDate|\DateTimeInterface $first The datetime to start with.
     * @param \Cake\Chronos\ChronosDate|\DateTimeInterface|null $second The datetime to compare against.
     * @param bool $absolute Removes time difference modifiers ago, after, etc.
     * @return string The difference between the two days in a human readable format.
     * @see \Cake\Chronos\Chronos::diffForHumans
     */
    public function diffForHumans(
        ChronosDate|DateTimeInterface $first,
        ChronosDate|DateTimeInterface|null $second = null,
        bool $absolute = false,
    ): string {
        $isNow = $second === null;
        if ($second === null) {
            if ($first instanceof ChronosDate) {
                $second = Date::now();
            } else {
                $second = DateTime::now($first->getTimezone());
            }
        }
        assert(
            ($first instanceof ChronosDate && $second instanceof ChronosDate) ||
            ($first instanceof DateTimeInterface && $second instanceof DateTimeInterface),
        );

        $diffInterval = $first->diff($second);

        switch (true) {
            case $diffInterval->y > 0:
                $count = $diffInterval->y;
                $message = __dn('cake', '{0} year', '{0} years', $count, $count);
                break;
            case $diffInterval->m > 0:
                $count = $diffInterval->m;
                $message = __dn('cake', '{0} month', '{0} months', $count, $count);
                break;
            case $diffInterval->d > 0:
                $count = $diffInterval->d;
                if ($count >= DateTime::DAYS_PER_WEEK) {
                    $count = (int)($count / DateTime::DAYS_PER_WEEK);
                    $message = __dn('cake', '{0} week', '{0} weeks', $count, $count);
                } else {
                    $message = __dn('cake', '{0} day', '{0} days', $count, $count);
                }
                break;
            case $diffInterval->h > 0:
                $count = $diffInterval->h;
                $message = __dn('cake', '{0} hour', '{0} hours', $count, $count);
                break;
            case $diffInterval->i > 0:
                $count = $diffInterval->i;
                $message = __dn('cake', '{0} minute', '{0} minutes', $count, $count);
                break;
            default:
                $count = $diffInterval->s;
                $message = __dn('cake', '{0} second', '{0} seconds', $count, $count);
                break;
        }
        if ($absolute) {
            return $message;
        }
        $isFuture = $diffInterval->invert === 1;
        if ($isNow) {
            return $isFuture ? __d('cake', '{0} from now', $message) : __d('cake', '{0} ago', $message);
        }

        return $isFuture ? __d('cake', '{0} after', $message) : __d('cake', '{0} before', $message);
    }

    /**
     * Format a into a relative timestring.
     *
     * @param \Cake\I18n\DateTime|\Cake\I18n\Date $time The time instance to format.
     * @param array<string, mixed> $options Array of options.
     * @return string Relative time string.
     * @see \Cake\I18n\Time::timeAgoInWords()
     */
    public function timeAgoInWords(DateTime|Date $time, array $options = []): string
    {
        $options = $this->_options($options, DateTime::class);
        if ($options['timezone']) {
            $time = $time->setTimezone($options['timezone']);
        }

        /** @var \Cake\Chronos\Chronos $from */
        $from = $options['from'];
        $now = (int)$from->format('U');
        $inSeconds = (int)$time->format('U');
        $backwards = ($inSeconds > $now);

        $futureTime = $now;
        $pastTime = $inSeconds;
        if ($backwards) {
            $futureTime = $inSeconds;
            $pastTime = $now;
        }
        $diff = $futureTime - $pastTime;

        if (!$diff) {
            return __d('cake', 'just now', 'just now');
        }

        if ($diff > abs($now - (int)(new DateTime($options['end']))->format('U'))) {
            return sprintf($options['absoluteString'], $time->i18nFormat($options['format']));
        }

        $diffData = $this->_diffData($futureTime, $pastTime, $backwards, $options);
        [$fNum, $fWord, $years, $months, $weeks, $days, $hours, $minutes, $seconds] = array_values($diffData);

        $relativeDate = [];
        if ($fNum >= 1 && $years > 0) {
            $relativeDate[] = __dn('cake', '{0} year', '{0} years', $years, $years);
        }
        if ($fNum >= 2 && $months > 0) {
            $relativeDate[] = __dn('cake', '{0} month', '{0} months', $months, $months);
        }
        if ($fNum >= 3 && $weeks > 0) {
            $relativeDate[] = __dn('cake', '{0} week', '{0} weeks', $weeks, $weeks);
        }
        if ($fNum >= 4 && $days > 0) {
            $relativeDate[] = __dn('cake', '{0} day', '{0} days', $days, $days);
        }
        if ($fNum >= 5 && $hours > 0) {
            $relativeDate[] = __dn('cake', '{0} hour', '{0} hours', $hours, $hours);
        }
        if ($fNum >= 6 && $minutes > 0) {
            $relativeDate[] = __dn('cake', '{0} minute', '{0} minutes', $minutes, $minutes);
        }
        if ($fNum >= 7 && $seconds > 0) {
            $relativeDate[] = __dn('cake', '{0} second', '{0} seconds', $seconds, $seconds);
        }
        $relativeDate = implode(', ', $relativeDate);

        // When time has passed
        if (!$backwards) {
            $aboutAgo = [
                'second' => __d('cake', 'about a second ago'),
                'minute' => __d('cake', 'about a minute ago'),
                'hour' => __d('cake', 'about an hour ago'),
                'day' => __d('cake', 'about a day ago'),
                'week' => __d('cake', 'about a week ago'),
                'month' => __d('cake', 'about a month ago'),
                'year' => __d('cake', 'about a year ago'),
            ];

            return $relativeDate ? sprintf($options['relativeString'], $relativeDate) : $aboutAgo[$fWord];
        }

        // When time is to come
        if ($relativeDate) {
            return $relativeDate;
        }
        $aboutIn = [
            'second' => __d('cake', 'in about a second'),
            'minute' => __d('cake', 'in about a minute'),
            'hour' => __d('cake', 'in about an hour'),
            'day' => __d('cake', 'in about a day'),
            'week' => __d('cake', 'in about a week'),
            'month' => __d('cake', 'in about a month'),
            'year' => __d('cake', 'in about a year'),
        ];

        return $aboutIn[$fWord];
    }

    /**
     * Calculate the data needed to format a relative difference string.
     *
     * @param string|int $futureTime The timestamp from the future.
     * @param string|int $pastTime The timestamp from the past.
     * @param bool $backwards Whether the difference was backwards.
     * @param array<string, mixed> $options An array of options.
     * @return array An array of values.
     */
    protected function _diffData(string|int $futureTime, string|int $pastTime, bool $backwards, array $options): array
    {
        $futureTime = (int)$futureTime;
        $pastTime = (int)$pastTime;
        $diff = $futureTime - $pastTime;

        // If more than a week, then take into account the length of months
        if ($diff >= 604800) {
            $future = [];
            [
                $future['H'],
                $future['i'],
                $future['s'],
                $future['d'],
                $future['m'],
                $future['Y'],
            ] = explode('/', date('H/i/s/d/m/Y', $futureTime));

            $past = [];
            [
                $past['H'],
                $past['i'],
                $past['s'],
                $past['d'],
                $past['m'],
                $past['Y'],
            ] = explode('/', date('H/i/s/d/m/Y', $pastTime));
            $weeks = 0;
            $days = 0;
            $hours = 0;
            $minutes = 0;
            $seconds = 0;

            $years = (int)$future['Y'] - (int)$past['Y'];
            $months = (int)$future['m'] + (12 * $years) - (int)$past['m'];

            if ($months >= 12) {
                $years = floor($months / 12);
                $months -= $years * 12;
            }
            if ((int)$future['m'] < (int)$past['m'] && (int)$future['Y'] - (int)$past['Y'] === 1) {
                $years--;
            }

            if ((int)$future['d'] >= (int)$past['d']) {
                $days = (int)$future['d'] - (int)$past['d'];
            } else {
                $daysInPastMonth = (int)date('t', $pastTime);
                $daysInFutureMonth = (int)date('t', (int)mktime(0, 0, 0, (int)$future['m'] - 1, 1, (int)$future['Y']));

                if (!$backwards) {
                    $days = $daysInPastMonth - (int)$past['d'] + (int)$future['d'];
                } else {
                    $days = $daysInFutureMonth - (int)$past['d'] + (int)$future['d'];
                }

                if ($future['m'] !== $past['m']) {
                    $months--;
                }
            }

            if (!$months && $years >= 1 && $diff < $years * 31536000) {
                $months = 11;
                $years--;
            }

            if ($months >= 12) {
                $years++;
                $months -= 12;
            }

            if ($days >= 7) {
                $weeks = floor($days / 7);
                $days -= $weeks * 7;
            }
        } else {
            $years = 0;
            $months = 0;
            $weeks = 0;
            $days = floor($diff / 86400);

            $diff -= $days * 86400;

            $hours = floor($diff / 3600);
            $diff -= $hours * 3600;

            $minutes = floor($diff / 60);
            $diff -= $minutes * 60;
            $seconds = $diff;
        }

        $fWord = $options['accuracy']['second'];
        if ($years > 0) {
            $fWord = $options['accuracy']['year'];
        } elseif (abs($months) > 0) {
            $fWord = $options['accuracy']['month'];
        } elseif (abs($weeks) > 0) {
            $fWord = $options['accuracy']['week'];
        } elseif (abs($days) > 0) {
            $fWord = $options['accuracy']['day'];
        } elseif (abs($hours) > 0) {
            $fWord = $options['accuracy']['hour'];
        } elseif (abs($minutes) > 0) {
            $fWord = $options['accuracy']['minute'];
        }

        $fNum = str_replace(
            ['year', 'month', 'week', 'day', 'hour', 'minute', 'second'],
            ['1', '2', '3', '4', '5', '6', '7'],
            $fWord,
        );

        return [
            $fNum,
            $fWord,
            (int)$years,
            (int)$months,
            (int)$weeks,
            (int)$days,
            (int)$hours,
            (int)$minutes,
            (int)$seconds,
        ];
    }

    /**
     * Format a into a relative date string.
     *
     * @param \Cake\I18n\DateTime|\Cake\I18n\Date $date The date to format.
     * @param array<string, mixed> $options Array of options.
     * @return string Relative date string.
     * @see \Cake\I18n\Date::timeAgoInWords()
     */
    public function dateAgoInWords(DateTime|Date $date, array $options = []): string
    {
        $options = $this->_options($options, Date::class);
        if ($date instanceof DateTime && $options['timezone']) {
            $date = $date->setTimezone($options['timezone']);
        }

        /** @var \Cake\Chronos\Chronos $from */
        $from = $options['from'];
        $now = (int)$from->format('U');
        $inSeconds = (int)$date->format('U');
        $backwards = ($inSeconds > $now);

        $futureTime = $now;
        $pastTime = $inSeconds;
        if ($backwards) {
            $futureTime = $inSeconds;
            $pastTime = $now;
        }
        $diff = $futureTime - $pastTime;

        if (!$diff) {
            return __d('cake', 'today');
        }

        if ($diff > abs($now - (int)(new Date($options['end']))->format('U'))) {
            return sprintf($options['absoluteString'], $date->i18nFormat($options['format']));
        }

        $diffData = $this->_diffData($futureTime, $pastTime, $backwards, $options);
        [$fNum, $fWord, $years, $months, $weeks, $days] = array_values($diffData);

        $relativeDate = [];
        if ($fNum >= 1 && $years > 0) {
            $relativeDate[] = __dn('cake', '{0} year', '{0} years', $years, $years);
        }
        if ($fNum >= 2 && $months > 0) {
            $relativeDate[] = __dn('cake', '{0} month', '{0} months', $months, $months);
        }
        if ($fNum >= 3 && $weeks > 0) {
            $relativeDate[] = __dn('cake', '{0} week', '{0} weeks', $weeks, $weeks);
        }
        if ($fNum >= 4 && $days > 0) {
            $relativeDate[] = __dn('cake', '{0} day', '{0} days', $days, $days);
        }
        $relativeDate = implode(', ', $relativeDate);

        // When time has passed
        if (!$backwards) {
            $aboutAgo = [
                'day' => __d('cake', 'about a day ago'),
                'week' => __d('cake', 'about a week ago'),
                'month' => __d('cake', 'about a month ago'),
                'year' => __d('cake', 'about a year ago'),
            ];

            return $relativeDate ? sprintf($options['relativeString'], $relativeDate) : $aboutAgo[$fWord];
        }

        // When time is to come
        if ($relativeDate) {
            return $relativeDate;
        }
        $aboutIn = [
            'day' => __d('cake', 'in about a day'),
            'week' => __d('cake', 'in about a week'),
            'month' => __d('cake', 'in about a month'),
            'year' => __d('cake', 'in about a year'),
        ];

        return $aboutIn[$fWord];
    }

    /**
     * Build the options for relative date formatting.
     *
     * @param array<string, mixed> $options The options provided by the user.
     * @param string $class The class name to use for defaults.
     * @return array<string, mixed> Options with defaults applied.
     * @phpstan-param class-string<\Cake\I18n\Date>|class-string<\Cake\I18n\DateTime> $class
     */
    protected function _options(array $options, string $class): array
    {
        $options += [
            'from' => $class::now(),
            'timezone' => null,
            'format' => $class::$wordFormat,
            'accuracy' => $class::$wordAccuracy,
            'end' => $class::$wordEnd,
            'relativeString' => __d('cake', '%s ago'),
            'absoluteString' => __d('cake', 'on %s'),
        ];
        if (is_string($options['accuracy'])) {
            $accuracy = $options['accuracy'];
            $options['accuracy'] = [];
            foreach ($class::$wordAccuracy as $key => $level) {
                $options['accuracy'][$key] = $accuracy;
            }
        } else {
            $options['accuracy'] += $class::$wordAccuracy;
        }

        return $options;
    }
}
