<?php

/**
 * webtrees: online genealogy
 * Copyright (C) 2020 webtrees development team
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

declare(strict_types=1);

namespace Fisharebest\Webtrees;

use function view;

/**
 * The difference between two GEDCOM dates.
 */
class Age
{
    /** @var int */
    private $years;

    /** @var int */
    private $months;

    /** @var int */
    private $days;

    /** @var int */
    private $total_days;

    /** @var bool */
    private $is_exact;

    /** @var bool */
    private $is_valid;

    /**
     * Age constructor.
     *
     * @param Date $x - The first date
     * @param Date $y - The second date
     */
    public function __construct(Date $x, Date $y)
    {
        // If the dates are ranges, use the start/end calendar dates.
        $start = $x->minimumDate();
        $end   = $y->maximumDate();

        [$this->years, $this->months, $this->days] = $start->ageDifference($end);

        $this->total_days = $end->minimumJulianDay() - $start->minimumJulianDay();

        // Use the same precision as found in the dates.
        if ($start->day() === 0 || $end->day() === 0) {
            $this->days = 0;
        }

        if ($start->month() === 0 || $end->month() === 0) {
            $this->months = 0;
        }

        // Are the dates exact?
        $this->is_exact = $start->day() !== 0 && $end->day() !== 0;

        // Are the dates valid?
        $this->is_valid = $x->isOK() && $y->isOK();
    }

    /**
     * Show an age in a human-friendly form, such as "34 years", "8 months", "20 days".
     * Show an empty string for invalid/missing dates.
     * Show a warning icon for negative ages.
     * Show zero ages without any units.
     *
     * @return string
     */
    public function ageString(): string
    {
        if (!$this->is_valid) {
            return '';
        }

        if ($this->years < 0) {
            return view('icons/warning');
        }

        if ($this->years > 0) {
            return I18N::plural('%s year', '%s years', $this->years, I18N::number($this->years));
        }

        if ($this->months > 0) {
            return I18N::plural('%s month', '%s months', $this->months, I18N::number($this->months));
        }

        if ($this->days > 0 || $this->is_exact) {
            return I18N::plural('%s day', '%s days', $this->days, I18N::number($this->days));
        }

        return I18N::number(0);
    }

    /**
     * How many days between two events?
     * If either date is invalid return -1.
     *
     * @return int
     */
    public function ageDays(): int
    {
        if ($this->is_valid) {
            return $this->total_days;
        }

        return -1;
    }

    /**
     * How many years between two events?
     * Return -1 for invalid or reversed dates.
     *
     * @return int
     */
    public function ageYears(): int
    {
        if ($this->is_valid) {
            return $this->years;
        }

        return -1;
    }

    /**
     * How many years between two events?
     * If either date is invalid return -1.
     *
     * @return string
     */
    public function ageYearsString(): string
    {
        if (!$this->is_valid) {
            return '';
        }

        if ($this->years < 0) {
            return view('icons/warning');
        }


        return I18N::number($this->years);
    }

    /**
     * @param bool $living
     *
     * @return string
     */
    public function ageAtEvent(bool $living): string
    {
        $age = $this->ageString();

        if ($age === '') {
            return '';
        }

        if ($living) {
            /* I18N: The current age of a living individual */
            return I18N::translate('(age %s)', $age);
        }

        /* I18N: The age of an individual at a given date */
        return I18N::translate('(aged %s)', $age);
    }

    /**
     * Similar to ageAtEvent, but for events such as burial, cremation, etc.
     *
     * @return string
     */
    public function timeAfterDeath(): string
    {
        if (!$this->is_valid) {
            return '';
        }

        if ($this->years === 0 && $this->months === 0 && $this->days === 0) {
            if ($this->is_exact) {
                return I18N::translate('(on the date of death)');
            }

            return '';
        }

        return I18N::translate('(%s after death)', $this->ageString());
    }
}