<?php

namespace App\Services;

use PDO;
use RuntimeException;

final class ExportService
{
    private const CSV_DELIMITER = ';';
    private const FLUSH_EVERY_ROWS = 250;

    public function __construct(private readonly PDO $pdo)
    {
    }

    public function streamMemberBalancesCsv(int $tenantId, ?string $filename = null): void
    {
        $this->assertTenantId($tenantId);

        $statement = $this->pdo->prepare(
            'SELECT
                m.id AS member_id,
                m.display_name,
                m.email,
                m.status,
                m.created_at,
                COALESCE(balance_summary.balance_cents, 0) AS balance_cents,
                balance_summary.last_occurred_at
             FROM members m
             LEFT JOIN (
                SELECT
                    ll.member_id,
                    SUM(ll.amount_cents) AS balance_cents,
                    MAX(le.occurred_at) AS last_occurred_at
                FROM ledger_lines ll
                INNER JOIN ledger_entries le
                    ON le.id = ll.ledger_entry_id
                   AND le.tenant_id = ll.tenant_id
                WHERE ll.tenant_id = :balance_tenant_id
                  AND ll.account_code = "member_balance"
                  AND ll.member_id IS NOT NULL
                GROUP BY ll.member_id
             ) balance_summary
               ON balance_summary.member_id = m.id
             WHERE m.tenant_id = :tenant_id
             ORDER BY m.display_name ASC, m.id ASC'
        );
        $statement->execute([
            'balance_tenant_id' => $tenantId,
            'tenant_id' => $tenantId,
        ]);

        $handle = $this->openCsvOutput($filename ?? $this->defaultFilename('member-balances', $tenantId));

        try {
            $this->writeCsvRow($handle, [
                'mitglied_id',
                'anzeigename',
                'email',
                'status',
                'saldo_cents',
                'saldo_eur',
                'letzte_buchung_am',
                'angelegt_am',
            ]);

            $rowCount = 0;

            while (($row = $statement->fetch(PDO::FETCH_ASSOC)) !== false) {
                $balanceCents = (int) $row['balance_cents'];

                $this->writeCsvRow($handle, [
                    (int) $row['member_id'],
                    (string) $row['display_name'],
                    $row['email'],
                    (string) $row['status'],
                    $balanceCents,
                    $this->formatMoneyFromCents($balanceCents),
                    $row['last_occurred_at'],
                    (string) $row['created_at'],
                ]);

                $rowCount++;
                $this->flushIfNeeded($rowCount);
            }
        } finally {
            fclose($handle);
        }
    }

    public function streamBookingsCsv(
        int $tenantId,
        ?int $memberId = null,
        ?string $from = null,
        ?string $until = null,
        ?string $filename = null
    ): void {
        $this->assertTenantId($tenantId);

        if ($memberId !== null && $memberId <= 0) {
            throw new RuntimeException('Die Mitglieds-ID muss groesser als 0 sein.');
        }

        $from = $this->normalizeDateTimeFilter($from, false);
        $until = $this->normalizeDateTimeFilter($until, true);

        $sql = 'SELECT
                    le.id AS booking_id,
                    le.type,
                    le.reference_type,
                    le.reference_id,
                    le.description,
                    le.occurred_at,
                    le.created_at AS entry_created_at,
                    le.member_id,
                    m.display_name AS member_name,
                    s.code AS source_code,
                    s.name AS source_name,
                    COALESCE(line_totals.member_balance_cents, 0) AS member_balance_cents,
                    COALESCE(line_totals.cashbox_cents, 0) AS cashbox_cents,
                    COALESCE(line_totals.coffee_revenue_cents, 0) AS coffee_revenue_cents,
                    c.id AS consumption_event_id,
                    c.quantity,
                    c.unit_price_cents,
                    c.total_cents,
                    c.effective_at,
                    c.recorded_at,
                    c.source_reference,
                    c.notes,
                    c.paper_sheet_line_id,
                    p.id AS product_id,
                    p.name AS product_name
                FROM ledger_entries le
                LEFT JOIN members m
                    ON m.id = le.member_id
                   AND m.tenant_id = le.tenant_id
                LEFT JOIN capture_sources s
                    ON s.id = le.source_id
                   AND s.tenant_id = le.tenant_id
                LEFT JOIN (
                    SELECT
                        ledger_entry_id,
                        SUM(CASE WHEN account_code = "member_balance" THEN amount_cents ELSE 0 END) AS member_balance_cents,
                        SUM(CASE WHEN account_code = "cashbox" THEN amount_cents ELSE 0 END) AS cashbox_cents,
                        SUM(CASE WHEN account_code = "coffee_revenue" THEN amount_cents ELSE 0 END) AS coffee_revenue_cents
                    FROM ledger_lines
                    WHERE tenant_id = :line_tenant_id
                    GROUP BY ledger_entry_id
                ) line_totals
                    ON line_totals.ledger_entry_id = le.id
                LEFT JOIN consumption_events c
                    ON c.id = le.reference_id
                   AND c.tenant_id = le.tenant_id
                   AND le.reference_type = "consumption_event"
                LEFT JOIN products p
                    ON p.id = c.product_id
                   AND p.tenant_id = c.tenant_id
                WHERE le.tenant_id = :tenant_id';

        $params = [
            'line_tenant_id' => $tenantId,
            'tenant_id' => $tenantId,
        ];

        if ($memberId !== null) {
            $sql .= ' AND le.member_id = :member_id';
            $params['member_id'] = $memberId;
        }

        if ($from !== null) {
            $sql .= ' AND le.occurred_at >= :from_occurred_at';
            $params['from_occurred_at'] = $from;
        }

        if ($until !== null) {
            $sql .= ' AND le.occurred_at <= :until_occurred_at';
            $params['until_occurred_at'] = $until;
        }

        $sql .= ' ORDER BY le.occurred_at DESC, le.id DESC';

        $statement = $this->pdo->prepare($sql);
        $statement->execute($params);

        $handle = $this->openCsvOutput($filename ?? $this->defaultFilename('bookings', $tenantId));

        try {
            $this->writeCsvRow($handle, [
                'buchung_id',
                'typ',
                'buchungsdatum',
                'mitglied_id',
                'mitglied_name',
                'beschreibung',
                'quellcode',
                'quelle',
                'referenz_typ',
                'referenz_id',
                'saldo_delta_cents',
                'saldo_delta_eur',
                'kasse_delta_cents',
                'kasse_delta_eur',
                'umsatz_delta_cents',
                'umsatz_delta_eur',
                'produkt_id',
                'produkt_name',
                'menge',
                'einzelpreis_cents',
                'einzelpreis_eur',
                'gesamt_cents',
                'gesamt_eur',
                'notizen',
                'wirksam_am',
                'erfasst_am',
                'quellreferenz',
                'papierlisten_zeile_id',
                'angelegt_am',
            ]);

            $rowCount = 0;

            while (($row = $statement->fetch(PDO::FETCH_ASSOC)) !== false) {
                $memberBalanceCents = (int) $row['member_balance_cents'];
                $cashboxCents = (int) $row['cashbox_cents'];
                $coffeeRevenueCents = (int) $row['coffee_revenue_cents'];
                $unitPriceCents = $row['unit_price_cents'] !== null ? (int) $row['unit_price_cents'] : null;
                $totalCents = $row['total_cents'] !== null ? (int) $row['total_cents'] : null;
                $recordedAt = $row['recorded_at'] ?? $row['entry_created_at'];

                $this->writeCsvRow($handle, [
                    (int) $row['booking_id'],
                    (string) $row['type'],
                    (string) $row['occurred_at'],
                    $row['member_id'] !== null ? (int) $row['member_id'] : '',
                    $row['member_name'],
                    (string) $row['description'],
                    $row['source_code'],
                    $row['source_name'],
                    $row['reference_type'],
                    $row['reference_id'],
                    $memberBalanceCents,
                    $this->formatMoneyFromCents($memberBalanceCents),
                    $cashboxCents,
                    $this->formatMoneyFromCents($cashboxCents),
                    $coffeeRevenueCents,
                    $this->formatMoneyFromCents($coffeeRevenueCents),
                    $row['product_id'] !== null ? (int) $row['product_id'] : '',
                    $row['product_name'],
                    $this->formatQuantity($row['quantity']),
                    $unitPriceCents ?? '',
                    $unitPriceCents !== null ? $this->formatMoneyFromCents($unitPriceCents) : '',
                    $totalCents ?? '',
                    $totalCents !== null ? $this->formatMoneyFromCents($totalCents) : '',
                    $row['notes'],
                    $row['effective_at'] ?? $row['occurred_at'],
                    $recordedAt,
                    $row['source_reference'],
                    $row['paper_sheet_line_id'],
                    (string) $row['entry_created_at'],
                ]);

                $rowCount++;
                $this->flushIfNeeded($rowCount);
            }
        } finally {
            fclose($handle);
        }
    }

    private function assertTenantId(int $tenantId): void
    {
        if ($tenantId <= 0) {
            throw new RuntimeException('Die Standort-ID muss größer als 0 sein.');
        }
    }

    private function defaultFilename(string $prefix, int $tenantId): string
    {
        return sprintf('%s-tenant-%d-%s.csv', $prefix, $tenantId, gmdate('Ymd-His'));
    }

    private function openCsvOutput(string $filename)
    {
        if (headers_sent($file, $line)) {
            throw new RuntimeException(sprintf('Export-Header können nicht mehr gesendet werden (%s:%d).', $file, $line));
        }

        $safeFilename = $this->sanitizeFilename($filename);

        header('Content-Type: text/csv; charset=UTF-8');
        header('Content-Disposition: attachment; filename="' . $safeFilename . '"; filename*=UTF-8\'\'' . rawurlencode($safeFilename));
        header('Cache-Control: no-store, no-cache, must-revalidate, max-age=0');
        header('Pragma: no-cache');
        header('Expires: 0');
        header('X-Accel-Buffering: no');
        header('X-Content-Type-Options: nosniff');

        $handle = fopen('php://output', 'wb');

        if ($handle === false) {
            throw new RuntimeException('Die Exportausgabe konnte nicht geöffnet werden.');
        }

        fwrite($handle, "\xEF\xBB\xBF");

        return $handle;
    }

    private function sanitizeFilename(string $filename): string
    {
        $sanitized = preg_replace('/[^A-Za-z0-9._-]+/', '-', trim($filename)) ?? '';
        $sanitized = trim($sanitized, '.-');

        if ($sanitized === '') {
            $sanitized = 'export';
        }

        if (!str_ends_with(strtolower($sanitized), '.csv')) {
            $sanitized .= '.csv';
        }

        return $sanitized;
    }

    private function writeCsvRow($handle, array $row): void
    {
        $values = array_map(function (mixed $value): string {
            return $this->sanitizeCsvValue($value);
        }, $row);

        if (fputcsv($handle, $values, self::CSV_DELIMITER) === false) {
            throw new RuntimeException('Die Exportzeile konnte nicht geschrieben werden.');
        }
    }

    private function sanitizeCsvValue(mixed $value): string
    {
        if ($value === null) {
            return '';
        }

        if (is_bool($value)) {
            return $value ? '1' : '0';
        }

        $string = str_replace(["\r\n", "\r"], "\n", (string) $value);

        // Prevent spreadsheet formula execution for user-controlled text cells.
        if (
            $string !== ''
            && in_array($string[0], ['=', '+', '-', '@', "\t"], true)
            && !is_numeric($string)
        ) {
            return "'" . $string;
        }

        return $string;
    }

    private function formatMoneyFromCents(int $amountCents): string
    {
        return number_format($amountCents / 100, 2, ',', '.');
    }

    private function formatQuantity(mixed $quantity): string
    {
        if ($quantity === null || $quantity === '') {
            return '';
        }

        return rtrim(rtrim(number_format((float) $quantity, 2, '.', ''), '0'), '.');
    }

    private function normalizeDateTimeFilter(?string $value, bool $endOfDay): ?string
    {
        $value = trim((string) $value);

        if ($value === '') {
            return null;
        }

        $value = str_replace('T', ' ', $value);

        if (preg_match('/^\d{4}-\d{2}-\d{2}$/', $value) === 1) {
            return $value . ($endOfDay ? ' 23:59:59' : ' 00:00:00');
        }

        if (preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}$/', $value) === 1) {
            return $value . ':00';
        }

        return $value;
    }

    private function flushIfNeeded(int $rowCount): void
    {
        if ($rowCount % self::FLUSH_EVERY_ROWS !== 0) {
            return;
        }

        if (ob_get_level() > 0) {
            ob_flush();
        }

        flush();
    }
}