<?php

declare(strict_types=1);

namespace Steuerkram\Models;

use Steuerkram\Database;

class BankTransaction
{
    public static function all(array $filter = [], int $page = 1, int $perPage = 50): array
    {
        $where  = ['1=1'];
        $params = [];

        $status = $filter['status'] ?? 'pending';
        if ($status === 'pending') {
            $where[] = "bt.status IN ('offen','teilweise')";
        } elseif ($status !== '') {
            $where[]  = 'bt.status = ?';
            $params[] = $status;
        }

        if (!empty($filter['year'])) {
            $where[]  = 'YEAR(bt.wertstellung) = ?';
            $params[] = (int)$filter['year'];
        }
        if (!empty($filter['month'])) {
            $where[]  = 'MONTH(bt.wertstellung) = ?';
            $params[] = (int)$filter['month'];
        }
        if (!empty($filter['typ'])) {
            if ($filter['typ'] === 'einnahme') {
                $where[] = 'bt.wert > 0';
            } elseif ($filter['typ'] === 'ausgabe') {
                $where[] = 'bt.wert < 0';
            }
        }
        if (!empty($filter['search'])) {
            $where[]  = '(bt.buchungstext LIKE ? OR bt.vorgang LIKE ?)';
            $s        = '%' . $filter['search'] . '%';
            $params[] = $s;
            $params[] = $s;
        }
        if (!empty($filter['format_id'])) {
            $where[]  = 'bib.format_id = ?';
            $params[] = (int)$filter['format_id'];
        }

        $sortMap = [
            'wertstellung' => 'bt.wertstellung',
            'buchungstag'  => 'bt.buchungstag',
            'betrag'       => 'bt.wert',
            'buchungstext' => 'bt.buchungstext',
            'status'       => 'bt.status',
        ];
        $sortCol = $sortMap[$filter['sort'] ?? ''] ?? 'bt.wertstellung';
        $sortDir = ($filter['dir'] ?? 'desc') === 'asc' ? 'ASC' : 'DESC';

        $whereStr = implode(' AND ', $where);
        $offset   = ($page - 1) * $perPage;

        $total = (int)(Database::fetchOne(
            "SELECT COUNT(*) AS n
             FROM bank_transactions bt
             JOIN bank_import_batches bib ON bt.batch_id = bib.id
             WHERE $whereStr",
            $params
        )['n'] ?? 0);

        $rows = Database::fetchAll(
            "SELECT bt.*, bib.filename AS batch_filename, bif.name AS format_name, bif.kuerzel, bif.farbe,
                    btb_agg.beleg_id AS beleg_id, btb_agg.beleg_count,
                    b.beleg_nr
             FROM bank_transactions bt
             JOIN bank_import_batches bib ON bt.batch_id = bib.id
             LEFT JOIN bank_import_formats bif ON bib.format_id = bif.id
             LEFT JOIN (
                 SELECT bank_tx_id, MIN(beleg_id) AS beleg_id, COUNT(*) AS beleg_count
                 FROM bank_transaction_belege
                 GROUP BY bank_tx_id
             ) btb_agg ON btb_agg.bank_tx_id = bt.id
             LEFT JOIN belege b ON b.id = btb_agg.beleg_id
             WHERE $whereStr
             ORDER BY $sortCol $sortDir, bt.wertstellung $sortDir, bt.buchungstag $sortDir, bt.id $sortDir
             LIMIT ? OFFSET ?",
            array_merge($params, [$perPage, $offset])
        );

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

    public static function find(int $id): ?array
    {
        $row = Database::fetchOne(
            'SELECT bt.*, bib.filename AS batch_filename, bif.name AS format_name, bif.kuerzel, bif.farbe
             FROM bank_transactions bt
             JOIN bank_import_batches bib ON bt.batch_id = bib.id
             JOIN bank_import_formats bif ON bib.format_id = bif.id
             WHERE bt.id = ?',
            [$id]
        );
        return $row ?: null;
    }

    public static function updateStatus(int $id, string $status): void
    {
        Database::execute(
            "UPDATE bank_transactions SET status = ? WHERE id = ?",
            [$status, $id]
        );
    }

    /** Verknüpft einen Beleg mit zugeordnetem Betrag und aktualisiert den Status. */
    public static function linkBeleg(int $txId, int $belegId, float $betrag): void
    {
        Database::execute(
            'INSERT INTO bank_transaction_belege (bank_tx_id, beleg_id, betrag)
             VALUES (?, ?, ?)
             ON DUPLICATE KEY UPDATE betrag = VALUES(betrag)',
            [$txId, $belegId, $betrag]
        );
        self::recalcStatus($txId);
    }

    /** Entfernt eine Beleg-Verknüpfung und aktualisiert den Status. */
    public static function unlinkBeleg(int $txId, int $belegId): void
    {
        Database::execute(
            'DELETE FROM bank_transaction_belege WHERE bank_tx_id = ? AND beleg_id = ?',
            [$txId, $belegId]
        );
        self::recalcStatus($txId);
    }

    /** Berechnet Status neu: 0 Links→offen, Restsaldo>0→teilweise, Restsaldo=0→gebucht. */
    public static function recalcStatus(int $txId): void
    {
        $row = Database::fetchOne(
            'SELECT ABS(bt.wert) AS brutto, COALESCE(SUM(btb.betrag), 0) AS allocated
             FROM bank_transactions bt
             LEFT JOIN bank_transaction_belege btb ON btb.bank_tx_id = bt.id
             WHERE bt.id = ?
             GROUP BY bt.id',
            [$txId]
        );
        if (!$row) return;

        $remaining = round((float)$row['brutto'] - (float)$row['allocated'], 2);
        $allocated = (float)$row['allocated'];

        if ($allocated <= 0) {
            $status = 'offen';
        } elseif ($remaining > 0.01) {
            $status = 'teilweise';
        } else {
            $status = 'gebucht';
        }

        Database::execute(
            "UPDATE bank_transactions SET status = ? WHERE id = ?",
            [$status, $txId]
        );
    }

    /** Gibt alle verknüpften Belege mit ihren Beträgen zurück. */
    public static function getLinkedBelege(int $txId): array
    {
        return Database::fetchAll(
            'SELECT btb.betrag, b.id AS beleg_id, b.beleg_nr, b.beleg_datum,
                    b.belegtyp, b.betrag_brutto, s.name AS supplier_name
             FROM bank_transaction_belege btb
             JOIN belege b ON b.id = btb.beleg_id
             LEFT JOIN suppliers s ON s.id = b.supplier_id
             WHERE btb.bank_tx_id = ?
             ORDER BY b.beleg_nr',
            [$txId]
        );
    }

    /** Gibt den noch nicht zugeordneten Restbetrag zurück. */
    public static function getRemainingBetrag(int $txId): float
    {
        $row = Database::fetchOne(
            'SELECT ABS(bt.wert) AS brutto, COALESCE(SUM(btb.betrag), 0) AS allocated
             FROM bank_transactions bt
             LEFT JOIN bank_transaction_belege btb ON btb.bank_tx_id = bt.id
             WHERE bt.id = ?
             GROUP BY bt.id',
            [$txId]
        );
        if (!$row) return 0.0;
        return round(max(0.0, (float)$row['brutto'] - (float)$row['allocated']), 2);
    }

    /** Sucht die Bankbuchung, die mit einem bestimmten Beleg verknüpft ist. */
    public static function findByBelegId(int $belegId): ?array
    {
        $row = Database::fetchOne(
            'SELECT bt.*, bib.filename AS batch_filename, bif.kuerzel, bif.farbe, btb.betrag AS alloc_betrag
             FROM bank_transaction_belege btb
             JOIN bank_transactions bt ON bt.id = btb.bank_tx_id
             JOIN bank_import_batches bib ON bib.id = bt.batch_id
             JOIN bank_import_formats bif ON bif.id = bib.format_id
             WHERE btb.beleg_id = ?
             LIMIT 1',
            [$belegId]
        );
        return $row ?: null;
    }

    /**
     * Teilt $rows in ['new' => [...], 'dup' => [...]] auf.
     */
    public static function findDuplicates(array $rows): array
    {
        if (empty($rows)) {
            return ['new' => [], 'dup' => []];
        }

        $placeholders = implode(',', array_fill(0, count($rows), '(?,?,?)'));
        $params = [];
        foreach ($rows as $r) {
            $params[] = $r['buchungstag'];
            $params[] = $r['wertstellung'];
            $params[] = (string)$r['wert'];
        }

        $existing = Database::fetchAll(
            "SELECT buchungstag, wertstellung, CAST(wert AS CHAR) AS wert
             FROM bank_transactions
             WHERE (buchungstag, wertstellung, CAST(wert AS CHAR)) IN ($placeholders)",
            $params
        );

        $lookup = [];
        foreach ($existing as $e) {
            $lookup[$e['buchungstag'] . '|' . $e['wertstellung'] . '|' . $e['wert']] = true;
        }

        $new = [];
        $dup = [];
        foreach ($rows as $row) {
            $key = $row['buchungstag'] . '|'
                 . $row['wertstellung'] . '|'
                 . (string)$row['wert'];
            if (isset($lookup[$key])) {
                $dup[] = $row;
            } else {
                $new[] = $row;
            }
        }

        return ['new' => $new, 'dup' => $dup];
    }

    public static function createBatch(int $formatId, string $filename, int $rowCount): int
    {
        Database::execute(
            'INSERT INTO bank_import_batches (format_id, filename, row_count) VALUES (?, ?, ?)',
            [$formatId, $filename, $rowCount]
        );
        return (int)Database::lastInsertId();
    }

    public static function insertRow(int $batchId, array $data): void
    {
        Database::execute(
            'INSERT INTO bank_transactions
             (batch_id, buchungstag, wertstellung, vorgang, buchungstext, wert, raw_line)
             VALUES (?, ?, ?, ?, ?, ?, ?)',
            [
                $batchId,
                $data['buchungstag'],
                $data['wertstellung'],
                $data['vorgang'],
                $data['buchungstext'],
                $data['wert'],
                $data['raw_line'] ?? null,
            ]
        );
    }
}