<?php

declare(strict_types=1);

namespace Steuerkram\Models;

use Steuerkram\Database;

class Invoice
{
    public static function all(array $filter = [], int $page = 1, int $perPage = 30): array
    {
        $where  = ['1=1'];
        $params = [];

        if (!empty($filter['status'])) {
            $where[] = 'i.status = ?';
            $params[] = $filter['status'];
        }
        if (!empty($filter['year'])) {
            $where[] = 'YEAR(i.rechnungs_datum) = ?';
            $params[] = (int)$filter['year'];
        }
        if (!empty($filter['customer_id'])) {
            $where[] = 'i.customer_id = ?';
            $params[] = (int)$filter['customer_id'];
        }
        if (!empty($filter['search'])) {
            $where[] = '(i.rechnungs_nr LIKE ? OR i.betreff LIKE ? OR c.nachname LIKE ? OR c.firma LIKE ?)';
            $s = '%' . $filter['search'] . '%';
            $params = array_merge($params, [$s, $s, $s, $s]);
        }

        $offset = ($page - 1) * $perPage;
        $sql = 'SELECT i.*, c.firma, c.nachname, c.vorname, c.anrede, c.kundennummer
                FROM invoices i
                JOIN customers c ON i.customer_id = c.id
                WHERE ' . implode(' AND ', $where) . '
                ORDER BY i.rechnungs_datum DESC, i.id DESC
                LIMIT ? OFFSET ?';

        $params[] = $perPage;
        $params[] = $offset;
        $rows = Database::fetchAll($sql, $params);

        $countSql    = 'SELECT COUNT(*) as cnt FROM invoices i JOIN customers c ON i.customer_id = c.id WHERE ' . implode(' AND ', $where);
        $countParams = array_slice($params, 0, -2);
        $total       = (int)(Database::fetchOne($countSql, $countParams)['cnt'] ?? 0);

        return ['rows' => $rows, 'total' => $total, 'pages' => (int)ceil($total / $perPage)];
    }

    public static function find(int $id): array|false
    {
        return Database::fetchOne(
            'SELECT i.*, c.firma, c.nachname, c.vorname, c.anrede, c.kundennummer,
                    c.strasse, c.plz, c.ort, c.land, c.email, c.payment_days
             FROM invoices i
             JOIN customers c ON i.customer_id = c.id
             WHERE i.id = ?',
            [$id]
        );
    }

    public static function lines(int $invoiceId): array
    {
        return Database::fetchAll(
            'SELECT * FROM invoice_lines WHERE invoice_id = ? ORDER BY id',
            [$invoiceId]
        );
    }

    public static function create(array $data): int
    {
        $customer = Customer::find((int)$data['customer_id']);
        $payDays  = (int)($data['payment_days'] ?? $customer['payment_days'] ?? 14);
        $datum    = $data['rechnungs_datum'] ?? date('Y-m-d');
        $faellig  = date('Y-m-d', strtotime($datum . " +{$payDays} days"));

        Database::execute(
            'INSERT INTO invoices (customer_id, betreff, leistungszeitraum,
             rechnungs_datum, faellig_datum, status, notes)
             VALUES (?, ?, ?, ?, ?, \'Entwurf\', ?)',
            [
                (int)$data['customer_id'],
                $data['betreff'],
                ($data['leistungszeitraum'] ?? '') !== '' ? $data['leistungszeitraum'] : null,
                $datum,
                $faellig,
                $data['notes'] ?? null,
            ]
        );

        $id = (int)Database::lastInsertId();

        // Create lines
        if (!empty($data['lines'])) {
            self::saveLines($id, $data['lines']);
            self::recalcTotals($id);
        }

        return $id;
    }

    public static function update(int $id, array $data): void
    {
        $inv = self::find($id);
        if ($inv && $inv['status'] !== 'Entwurf') {
            throw new \RuntimeException('Nur Entwürfe können bearbeitet werden.');
        }

        $customer = Customer::find((int)$data['customer_id']);
        $payDays  = (int)($data['payment_days'] ?? $customer['payment_days'] ?? 14);
        $datum    = $data['rechnungs_datum'];
        $faellig  = date('Y-m-d', strtotime($datum . " +{$payDays} days"));

        Database::execute(
            'UPDATE invoices SET customer_id=?, betreff=?, leistungszeitraum=?,
             rechnungs_datum=?, faellig_datum=?, notes=?, updated_at=NOW()
             WHERE id=? AND status=\'Entwurf\'',
            [
                (int)$data['customer_id'],
                $data['betreff'],
                ($data['leistungszeitraum'] ?? '') !== '' ? $data['leistungszeitraum'] : null,
                $datum,
                $faellig,
                $data['notes'] ?? null,
                $id,
            ]
        );

        // Replace lines
        Database::execute('DELETE FROM invoice_lines WHERE invoice_id=?', [$id]);
        if (!empty($data['lines'])) {
            self::saveLines($id, $data['lines']);
        }
        self::recalcTotals($id);
    }

    public static function finalize(int $id): string
    {
        $inv = self::find($id);
        if (!$inv) throw new \RuntimeException('Rechnung nicht gefunden.');
        if ($inv['status'] !== 'Entwurf') throw new \RuntimeException('Rechnung ist kein Entwurf mehr.');

        $nr = self::generateRechnungsNr();

        // Set fiscal year
        $year = (int)date('Y', strtotime($inv['rechnungs_datum']));
        $fy   = FiscalYear::findOrCreateByYear($year);

        Database::execute(
            'UPDATE invoices SET rechnungs_nr=?, status=\'Finalisiert\', fiscal_year_id=?, updated_at=NOW() WHERE id=?',
            [$nr, $fy['id'], $id]
        );

        return $nr;
    }

    public static function markPaid(int $id): void
    {
        Database::execute('UPDATE invoices SET status=\'Bezahlt\', updated_at=NOW() WHERE id=?', [$id]);
    }

    public static function cancel(int $id): void
    {
        $invoice = self::find($id);
        if (!$invoice) return;

        // Stornobuchungen für alle gebuchten Buchungen des Belegs erzeugen
        if (!empty($invoice['beleg_id'])) {
            $bookings = Database::fetchAll(
                'SELECT id FROM bookings WHERE beleg_id = ? AND is_reversal = 0 AND reversed_by IS NULL',
                [(int)$invoice['beleg_id']]
            );
            foreach ($bookings as $bk) {
                Booking::reverse((int)$bk['id'], 'Storno Rechnung ' . ($invoice['rechnungs_nr'] ?? $id));
            }
        }

        Database::execute('UPDATE invoices SET status=\'Storniert\', updated_at=NOW() WHERE id=?', [$id]);
    }

    private static function saveLines(int $invoiceId, array $lines): void
    {
        $posCounter = 0;
        foreach ($lines as $line) {
            if (empty($line['bezeichnung'])) continue;
            $type = ($line['type'] ?? 'position') === 'heading' ? 'heading' : 'position';

            if ($type === 'heading') {
                Database::execute(
                    'INSERT INTO invoice_lines (invoice_id, position, bezeichnung, menge, einheit,
                     einzelpreis, ust_satz, betrag_netto, betrag_ust, betrag_brutto, type)
                     VALUES (?, ?, ?, 0, \'\', 0, 0, 0, 0, 0, ?)',
                    [$invoiceId, 0, $line['bezeichnung'], 'heading']
                );
            } else {
                $posCounter++;
                $menge   = round((float)$line['menge'], 3);
                $preis   = round((float)$line['einzelpreis'], 2);
                $ustSatz = round((float)$line['ust_satz'], 2);
                $netto   = round($menge * $preis, 2);
                $ust     = round($netto * $ustSatz / 100, 2);
                $brutto  = round($netto + $ust, 2);

                Database::execute(
                    'INSERT INTO invoice_lines (invoice_id, position, bezeichnung, menge, einheit,
                     einzelpreis, ust_satz, betrag_netto, betrag_ust, betrag_brutto, type)
                     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)',
                    [
                        $invoiceId,
                        $posCounter,
                        $line['bezeichnung'],
                        $menge,
                        $line['einheit'] ?? 'Stk.',
                        $preis,
                        $ustSatz,
                        $netto,
                        $ust,
                        $brutto,
                        'position',
                    ]
                );
            }
        }
    }

    private static function recalcTotals(int $id): void
    {
        $result = Database::fetchOne(
            'SELECT SUM(betrag_netto) as netto, SUM(betrag_ust) as ust, SUM(betrag_brutto) as brutto
             FROM invoice_lines WHERE invoice_id = ?',
            [$id]
        );
        Database::execute(
            'UPDATE invoices SET betrag_netto=?, betrag_ust=?, betrag_brutto=?, updated_at=NOW() WHERE id=?',
            [
                round((float)$result['netto'], 2),
                round((float)$result['ust'], 2),
                round((float)$result['brutto'], 2),
                $id,
            ]
        );
    }

    public static function delete(int $id): void
    {
        $invoice = self::find($id);
        if (!$invoice) return;

        $belegId = !empty($invoice['beleg_id']) ? (int)$invoice['beleg_id'] : null;

        Database::execute('DELETE FROM invoice_lines WHERE invoice_id = ?', [$id]);
        Database::execute('DELETE FROM invoices WHERE id = ?', [$id]);

        if ($belegId !== null) {
            Database::execute('DELETE FROM bookings WHERE beleg_id = ?', [$belegId]);
            Database::execute('DELETE FROM belege WHERE id = ?', [$belegId]);
        }
    }

    public static function generateRechnungsNr(): string
    {
        $settings   = Database::fetchOne(
            'SELECT invoice_nr_prefix, invoice_nr_next, invoice_nr_year, invoice_nr_month FROM company_settings WHERE id=1'
        );
        $prefix     = $settings['invoice_nr_prefix'] ?? 'AR';
        $next       = (int)($settings['invoice_nr_next'] ?? 1);
        $savedYear  = (int)($settings['invoice_nr_year'] ?? 0);
        $savedMonth = (int)($settings['invoice_nr_month'] ?? 0);
        $year       = (int)date('Y');
        $month      = (int)date('n');

        if ($savedYear !== $year || $savedMonth !== $month) {
            $next = 1;
        }

        $digits = max(2, strlen((string)$next));
        $nr = sprintf('%s%04d%02d-%0' . $digits . 'd', $prefix, $year, $month, $next);

        Database::execute(
            'UPDATE company_settings SET invoice_nr_next=?, invoice_nr_year=?, invoice_nr_month=? WHERE id=1',
            [$next + 1, $year, $month]
        );

        return $nr;
    }
}