<?php

namespace App\Services;

use DateTime;

class DateConversionService
{
    // Dates de début du 1er Vendémiaire pour chaque An républicain
    private const YEAR_STARTS = [
        1  => '1792-09-22',
        2  => '1793-09-22',
        3  => '1794-09-23',
        4  => '1795-09-23',
        5  => '1796-09-22',
        6  => '1797-09-22',
        7  => '1798-09-22',
        8  => '1799-09-23',
        9  => '1800-09-23',
        10 => '1801-09-23',
        11 => '1802-09-23',
        12 => '1803-09-23',
        13 => '1804-09-23',
        14 => '1805-09-23',
    ];

    private const MONTHS = [
        'vendémiaire' => 1, 'vendemiaire' => 1,
        'brumaire'    => 2,
        'frimaire'    => 3,
        'nivôse'      => 4, 'nivose' => 4,
        'pluviôse'    => 5, 'pluviose' => 5,
        'ventôse'     => 6, 'ventose' => 6,
        'germinal'    => 7,
        'floréal'     => 8, 'floreal' => 8,
        'prairial'    => 9,
        'messidor'    => 10,
        'thermidor'   => 11,
        'fructidor'   => 12,
    ];

    private const ROMAN = [
        'XIV' => 14, 'XIII' => 13, 'XII' => 12, 'XI' => 11, 'X' => 10,
        'IX'  => 9,  'VIII' => 8,  'VII' => 7,  'VI' => 6,  'V' => 5,
        'IV'  => 4,  'III'  => 3,  'II'  => 2,  'I'  => 1,
    ];

    private const GEDCOM_MONTHS = [
        1 => 'JAN', 2 => 'FEB', 3  => 'MAR', 4  => 'APR',
        5 => 'MAY', 6 => 'JUN', 7  => 'JUL', 8  => 'AUG',
        9 => 'SEP', 10 => 'OCT', 11 => 'NOV', 12 => 'DEC',
    ];

    /**
     * Convertit un champ date JSONB { valeur, calendrier } en chaîne GEDCOM.
     * Retourne null si la conversion échoue.
     */
    public function toGedcomDate(?array $dateField): ?string
    {
        if (empty($dateField['valeur'])) {
            return null;
        }

        $valeur     = trim($dateField['valeur']);
        $calendrier = $dateField['calendrier'] ?? 'gregorien';

        return match ($calendrier) {
            'gregorien'   => $this->gregorianToGedcom($valeur),
            'julien'      => $this->julianToGedcom($valeur),
            'republicain' => $this->republicanToGedcom($valeur),
            default       => null,
        };
    }

    /** YYYY-MM-DD → "D MON YYYY" */
    public function gregorianToGedcom(string $date): ?string
    {
        $d = DateTime::createFromFormat('Y-m-d', $date);
        if (! $d) {
            return null;
        }
        $day   = (int) $d->format('j');
        $month = self::GEDCOM_MONTHS[(int) $d->format('n')];
        $year  = $d->format('Y');
        return "{$day} {$month} {$year}";
    }

    /** Julien : même format YYYY-MM-DD, marqué @#DJULIAN@ */
    private function julianToGedcom(string $date): ?string
    {
        $g = $this->gregorianToGedcom($date);
        return $g ? "@#DJULIAN@ {$g}" : null;
    }

    /**
     * "15 Vendémiaire An III" → date grégorienne GEDCOM.
     * Retourne la date avec préfixe @#DFRENCH R@ (standard GEDCOM pour calendrier républicain).
     */
    private function republicanToGedcom(string $date): ?string
    {
        $gregory = $this->republicanToGregorian($date);
        if ($gregory) {
            return $this->gregorianToGedcom($gregory);
        }

        // Fallback : on conserve la date telle quelle dans un format lisible
        return "({$date})";
    }

    /**
     * Convertit "15 Vendémiaire An III" → "1794-10-06".
     */
    public function republicanToGregorian(string $input): ?string
    {
        // Normaliser l'entrée
        $input = trim($input);

        // Pattern : "DD NomDuMois An N" ou "DD NomDuMois An XIV"
        $pattern = '/^(\d{1,2})\s+([\wéèêôûî]+)\s+[Aa]n\s+([IVXLCDM\d]+)$/iu';

        if (! preg_match($pattern, $input, $m)) {
            return null;
        }

        $day      = (int) $m[1];
        $monthStr = mb_strtolower(trim($m[2]));
        $yearStr  = strtoupper(trim($m[3]));

        // Résoudre le mois
        $monthNum = self::MONTHS[$monthStr] ?? null;
        if (! $monthNum || $day < 1 || $day > 30) {
            return null;
        }

        // Résoudre l'année (chiffres arabes ou romains)
        $yearNum = is_numeric($yearStr)
            ? (int) $yearStr
            : (self::ROMAN[$yearStr] ?? null);

        if (! $yearNum || ! isset(self::YEAR_STARTS[$yearNum])) {
            return null;
        }

        // Calculer le nombre de jours depuis le 1er Vendémiaire
        $daysOffset = ($monthNum - 1) * 30 + ($day - 1);

        $start = new DateTime(self::YEAR_STARTS[$yearNum]);
        $start->modify("+{$daysOffset} days");

        return $start->format('Y-m-d');
    }
}