/**
 * Invoice Routes
 * Handles invoice CRUD operations, QBO sync, and PDF generation
 */
const express = require('express');
const router = express.Router();
const path = require('path');
const fs = require('fs').promises;
const { pool } = require('../config/database');
const { getNextInvoiceNumber } = require('../utils/numberGenerators');
const { formatDate, formatMoney } = require('../utils/helpers');
const { getBrowser, generatePdfFromHtml, getLogoHtml, renderInvoiceItems, formatAddressLines } = require('../services/pdf-service');
const { exportInvoiceToQbo, syncInvoiceToQbo } = require('../services/qbo-service');
const { getOAuthClient, getQboBaseUrl, makeQboApiCall } = require('../config/qbo');
const { sendInvoiceEmail } = require('../services/email-service');
const { createPaymentLink, checkPaymentStatus, deactivatePaymentLink } = require('../services/stripe-service');
const { recordStripePaymentInQbo } = require('../services/qbo-service');

function calculateNextRecurringDate(invoiceDate, interval) {
    const d = new Date(invoiceDate);
    if (interval === 'monthly') {
        d.setMonth(d.getMonth() + 1);
    } else if (interval === 'yearly') {
        d.setFullYear(d.getFullYear() + 1);
    }
    return d.toISOString().split('T')[0];
}
/**
 * Build HTML block for Stripe Payment Link on PDF invoice.
 * Returns empty string if no link or invoice is already paid.
 */
function buildPaymentLinkHtml(invoice) {
    if (!invoice.stripe_payment_link_url) return '';
    if (invoice.paid_date || invoice.stripe_payment_status === 'paid') return '';

    return `
        <div style="margin-top: 30px; padding: 16px 20px; border: 2px solid #635bff; border-radius: 8px; text-align: center;">
            <p style="font-size: 14px; font-weight: bold; color: #635bff; margin: 0 0 8px 0;">
                Pay Online — Credit Card or ACH
            </p>
            <a href="${invoice.stripe_payment_link_url}" 
               style="font-size: 13px; color: #635bff; word-break: break-all;">
                ${invoice.stripe_payment_link_url}
            </a>
            <p style="font-size: 11px; color: #888; margin: 8px 0 0 0;">
                Secure payment powered by Stripe. ACH payments incur lower processing fees.
            </p>
        </div>`;
}
// GET all invoices
router.get('/', async (req, res) => {
    try {
        const result = await pool.query(`
            SELECT i.*, c.name as customer_name, c.qbo_id as customer_qbo_id,
                   COALESCE((SELECT SUM(pi.amount) FROM payment_invoices pi WHERE pi.invoice_id = i.id), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            ORDER BY i.created_at DESC
        `);
        const rows = result.rows.map(r => ({
            ...r,
            amount_paid: parseFloat(r.amount_paid) || 0,
            balance: (parseFloat(r.total) || 0) - (parseFloat(r.amount_paid) || 0)
        }));
        res.json(rows);
    } catch (error) {
        console.error('Error fetching invoices:', error);
        res.status(500).json({ error: 'Error fetching invoices' });
    }
});

// GET next invoice number
router.get('/next-number', async (req, res) => {
    try {
        const nextNumber = await getNextInvoiceNumber();
        res.json({ next_number: nextNumber });
    } catch (error) {
        console.error('Error getting next invoice number:', error);
        res.status(500).json({ error: 'Error getting next invoice number' });
    }
});

// GET single invoice
router.get('/:id', async (req, res) => {
    const { id } = req.params;
    try {
        const invoiceResult = await pool.query(`
            SELECT
                i.*,
                c.name as customer_name,
                c.qbo_id as customer_qbo_id,
                c.email,
                c.line1,
                c.line2,
                c.line3,
                c.line4,
                c.city,
                c.state,
                c.zip_code,
                c.account_number,
                src.invoice_number AS recurring_source_invoice_number,
                COALESCE((
                    SELECT SUM(pi.amount)
                    FROM payment_invoices pi
                    WHERE pi.invoice_id = i.id
                ), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c
                ON i.customer_id = c.id
            LEFT JOIN invoices src
                ON src.id = i.recurring_source_id
            WHERE i.id = $1
        `, [id]);

        if (invoiceResult.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }

        const invoice = invoiceResult.rows[0];
        invoice.amount_paid = parseFloat(invoice.amount_paid) || 0;
        invoice.balance = (parseFloat(invoice.total) || 0) - invoice.amount_paid;

        const itemsResult = await pool.query(
            'SELECT * FROM invoice_items WHERE invoice_id = $1 ORDER BY item_order',
            [id]
        );

        res.json({ invoice, items: itemsResult.rows });
    } catch (error) {
        console.error('Error fetching invoice:', error);
        res.status(500).json({ error: 'Error fetching invoice' });
    }
});

// POST create invoice
router.post('/', async (req, res) => {
    const { invoice_number, customer_id, invoice_date, terms, auth_code, tax_exempt, items, scheduled_send_date, bill_to_name, created_from_quote_id, is_recurring, recurring_interval } = req.body;

    const client = await pool.connect();
    try {
        await client.query('BEGIN');

        // Validate invoice_number if provided
        if (invoice_number && !/^\d+$/.test(invoice_number)) {
            await client.query('ROLLBACK');
            return res.status(400).json({ error: 'Invoice number must be numeric.' });
        }

        const tempNumber = invoice_number || `DRAFT-${Date.now()}`;

        if (invoice_number) {
            const existing = await client.query('SELECT id FROM invoices WHERE invoice_number = $1', [invoice_number]);
            if (existing.rows.length > 0) {
                await client.query('ROLLBACK');
                return res.status(400).json({ error: `Invoice number ${invoice_number} already exists.` });
            }
        }
        // Validate items
        if (!Array.isArray(items) || items.length === 0) {
            await client.query('ROLLBACK');
            return res.status(400).json({ error: 'Please add at least one item.' });
        }

        // Recurring invoices must contain at least one Subscription item
        if (is_recurring) {
            const subscriptionItems = items.filter(item => String(item.qbo_item_id) === '115');

            if (subscriptionItems.length === 0) {
                await client.query('ROLLBACK');
                return res.status(400).json({
                    error: 'Recurring invoices must contain at least one Subscription item.'
                });
            }
        }
        let subtotal = 0;
        for (const item of items) {
            const amount = parseFloat(item.amount.replace(/[$,]/g, ''));
            if (!isNaN(amount)) subtotal += amount;
        }

        const tax_rate = 8.25;
        const tax_amount = tax_exempt ? 0 : (subtotal * tax_rate / 100);
        const total = subtotal + tax_amount;
        const next_recurring_date = is_recurring ? calculateNextRecurringDate(invoice_date, recurring_interval) : null;
        const invoiceResult = await client.query(
                `INSERT INTO invoices (invoice_number, customer_id, invoice_date, terms, auth_code, tax_exempt, tax_rate, subtotal, tax_amount, total, scheduled_send_date, bill_to_name, created_from_quote_id, is_recurring, recurring_interval, next_recurring_date)
                    VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16) RETURNING *`,
                [tempNumber, customer_id, invoice_date, terms, auth_code, tax_exempt, tax_rate, subtotal, tax_amount, total, scheduled_send_date || null, bill_to_name || null, created_from_quote_id, is_recurring || false, recurring_interval || null, next_recurring_date]
        );
        const invoiceId = invoiceResult.rows[0].id;

        for (let i = 0; i < items.length; i++) {
            await client.query(
                'INSERT INTO invoice_items (invoice_id, quantity, description, rate, amount, item_order, qbo_item_id) VALUES ($1, $2, $3, $4, $5, $6, $7)',
                [invoiceId, items[i].quantity, items[i].description, items[i].rate, items[i].amount, i, items[i].qbo_item_id || '9']
            );
        }

        await client.query('COMMIT');

        // Auto QBO Export
        let qboResult = null;
        try {
            qboResult = await exportInvoiceToQbo(invoiceId, client);
            if (qboResult.skipped) {
                console.log(`ℹ️ Invoice ${invoiceId} not exported to QBO: ${qboResult.reason}`);
            }
        } catch (qboErr) {
            console.error(`⚠️ Auto QBO export failed for Invoice ${invoiceId}:`, qboErr.message);
        }

        res.json({
            ...invoiceResult.rows[0],
            qbo_id: qboResult?.qbo_id || null,
            qbo_doc_number: qboResult?.qbo_doc_number || null
        });

    } catch (error) {
        await client.query('ROLLBACK');
        console.error('Error creating invoice:', error);
        res.status(500).json({ error: 'Error creating invoice' });
    } finally {
        client.release();
    }
});

// PUT update invoice
router.put('/:id', async (req, res) => {
    const { id } = req.params;
    const { invoice_number, customer_id, invoice_date, terms, auth_code, tax_exempt, items, scheduled_send_date, bill_to_name, is_recurring, recurring_interval } = req.body;

    const client = await pool.connect();
    try {
        await client.query('BEGIN');

        // Validate invoice_number if provided
        if (invoice_number && !/^\d+$/.test(invoice_number)) {
            await client.query('ROLLBACK');
            return res.status(400).json({ error: 'Invoice number must be numeric.' });
        }

        if (invoice_number) {
            const existing = await client.query('SELECT id FROM invoices WHERE invoice_number = $1 AND id != $2', [invoice_number, id]);
            if (existing.rows.length > 0) {
                await client.query('ROLLBACK');
                return res.status(400).json({ error: `Invoice number ${invoice_number} already exists.` });
            }
        }
        // Validate items
        if (!Array.isArray(items) || items.length === 0) {
            await client.query('ROLLBACK');
            return res.status(400).json({ error: 'Please add at least one item.' });
        }

        // Recurring invoices must contain at least one Subscription item
        if (is_recurring) {
            const subscriptionItems = items.filter(item => String(item.qbo_item_id) === '115');

            if (subscriptionItems.length === 0) {
                await client.query('ROLLBACK');
                return res.status(400).json({
                    error: 'Recurring invoices must contain at least one Subscription item.'
                });
            }
        }
        let subtotal = 0;
        for (const item of items) {
            const amount = parseFloat(item.amount.replace(/[$,]/g, ''));
            if (!isNaN(amount)) subtotal += amount;
        }

        const tax_rate = 8.25;
        const tax_amount = tax_exempt ? 0 : (subtotal * tax_rate / 100);
        const total = subtotal + tax_amount;

        // Update local
        if (invoice_number) {
            await client.query(
                `UPDATE invoices SET invoice_number = $1, customer_id = $2, invoice_date = $3, terms = $4, auth_code = $5, tax_exempt = $6,
                 tax_rate = $7, subtotal = $8, tax_amount = $9, total = $10, scheduled_send_date = $11, bill_to_name = $12, updated_at = CURRENT_TIMESTAMP
                 WHERE id = $13`,
                [invoice_number, customer_id, invoice_date, terms, auth_code, tax_exempt, tax_rate, subtotal, tax_amount, total, scheduled_send_date || null, bill_to_name || null, id]
            );
        } else {
            await client.query(
                `UPDATE invoices SET customer_id = $1, invoice_date = $2, terms = $3, auth_code = $4, tax_exempt = $5,
                 tax_rate = $6, subtotal = $7, tax_amount = $8, total = $9, scheduled_send_date = $10, bill_to_name = $11, updated_at = CURRENT_TIMESTAMP
                 WHERE id = $12`,
                [customer_id, invoice_date, terms, auth_code, tax_exempt, tax_rate, subtotal, tax_amount, total, scheduled_send_date || null, bill_to_name || null, id]
            );
        }

        // Preserve existing next_recurring_date when editing an already-recurring invoice.
        // Otherwise editing an old invoice can move next_recurring_date backwards and create duplicates.
        const existingRecurringResult = await client.query(
            'SELECT is_recurring, next_recurring_date, recurring_source_id FROM invoices WHERE id = $1',
            [id]
        );

        const existingRecurring = existingRecurringResult.rows[0];

        let next_recurring_date = null;

        // Automatically generated child invoices should not become recurring masters.
        // recurring_source_id != null means: this invoice was created from another recurring invoice.
        const isGeneratedRecurringChild = !!existingRecurring?.recurring_source_id;

        if (isGeneratedRecurringChild) {
            next_recurring_date = null;
        } else if (is_recurring) {
            next_recurring_date = existingRecurring?.next_recurring_date
                ? existingRecurring.next_recurring_date
                : calculateNextRecurringDate(invoice_date, recurring_interval);
        }

        await client.query(
            `
            UPDATE invoices
            SET is_recurring = $1,
                recurring_interval = $2,
                next_recurring_date = $3
            WHERE id = $4
            `,
            [
                isGeneratedRecurringChild ? false : (is_recurring || false),
                isGeneratedRecurringChild ? null : (recurring_interval || null),
                next_recurring_date,
                id
            ]
        );

        // Delete and re-insert items
        await client.query('DELETE FROM invoice_items WHERE invoice_id = $1', [id]);
        for (let i = 0; i < items.length; i++) {
            await client.query(
                'INSERT INTO invoice_items (invoice_id, quantity, description, rate, amount, item_order, qbo_item_id) VALUES ($1, $2, $3, $4, $5, $6, $7)',
                [id, items[i].quantity, items[i].description, items[i].rate, items[i].amount, i, items[i].qbo_item_id || '9']
            );
        }

        await client.query('COMMIT');

        // Auto QBO: Export if not yet in QBO, Sync if already in QBO
        let qboResult = null;
        try {
            const checkRes = await client.query('SELECT qbo_id FROM invoices WHERE id = $1', [id]);
            const hasQboId = !!checkRes.rows[0]?.qbo_id;

            if (hasQboId) {
                qboResult = await syncInvoiceToQbo(id, client);
            } else {
                qboResult = await exportInvoiceToQbo(id, client);
            }

            if (qboResult.skipped) {
                console.log(`ℹ️ Invoice ${id}: ${qboResult.reason}`);
            }
        } catch (qboErr) {
            console.error(`⚠️ Auto QBO failed for Invoice ${id}:`, qboErr.message);
        }

        res.json({ success: true, qbo_synced: !!qboResult?.success, qbo_id: qboResult?.qbo_id || null, qbo_doc_number: qboResult?.qbo_doc_number || null });

    } catch (error) {
        await client.query('ROLLBACK');
        console.error('Error updating invoice:', error);
        res.status(500).json({ error: 'Error updating invoice' });
    } finally {
        client.release();
    }
});

// DELETE invoice
router.delete('/:id', async (req, res) => {
    const { id } = req.params;
    const client = await pool.connect();
    try {
        await client.query('BEGIN');

        // Load invoice to check qbo_id
        const invResult = await client.query('SELECT qbo_id, qbo_sync_token, invoice_number FROM invoices WHERE id = $1', [id]);
        if (invResult.rows.length === 0) {
            await client.query('ROLLBACK');
            return res.status(404).json({ error: 'Invoice not found' });
        }

        const invoice = invResult.rows[0];

        // Delete in QBO if present
        if (invoice.qbo_id) {
            try {
                const oauthClient = getOAuthClient();
                const companyId = oauthClient.getToken().realmId;
                const baseUrl = getQboBaseUrl();

                const qboRes = await makeQboApiCall({
                    url: `${baseUrl}/v3/company/${companyId}/invoice/${invoice.qbo_id}`,
                    method: 'GET'
                });
                const qboData = qboRes.getJson ? qboRes.getJson() : qboRes.json;
                const syncToken = qboData.Invoice?.SyncToken;

                if (syncToken !== undefined) {
                    console.log(`🗑️ Voiding QBO Invoice ${invoice.qbo_id} (DocNumber: ${invoice.invoice_number})...`);

                    await makeQboApiCall({
                        url: `${baseUrl}/v3/company/${companyId}/invoice?operation=void`,
                        method: 'POST',
                        headers: { 'Content-Type': 'application/json' },
                        body: JSON.stringify({
                            Id: invoice.qbo_id,
                            SyncToken: syncToken
                        })
                    });

                    console.log(`✅ QBO Invoice ${invoice.qbo_id} voided.`);
                }
            } catch (qboError) {
                console.error(`⚠️ QBO void failed for Invoice ${invoice.qbo_id}:`, qboError.message);
            }
        }

        // Delete locally
        await client.query('DELETE FROM invoice_items WHERE invoice_id = $1', [id]);
        await client.query('DELETE FROM payment_invoices WHERE invoice_id = $1', [id]);
        await client.query('DELETE FROM invoices WHERE id = $1', [id]);
        await client.query('COMMIT');

        res.json({ success: true });
    } catch (error) {
        await client.query('ROLLBACK');
        console.error('Error deleting invoice:', error);
        res.status(500).json({ error: 'Error deleting invoice' });
    } finally {
        client.release();
    }
});

// PATCH invoice email status
router.patch('/:id/email-status', async (req, res) => {
    const { id } = req.params;
    const { status } = req.body;

    if (!['sent', 'open'].includes(status)) {
        return res.status(400).json({ error: 'Status must be "sent" or "open".' });
    }

    try {
        const invResult = await pool.query('SELECT qbo_id FROM invoices WHERE id = $1', [id]);
        if (invResult.rows.length === 0) return res.status(404).json({ error: 'Invoice not found' });

        const invoice = invResult.rows[0];

        // Update QBO if present
        if (invoice.qbo_id) {
            const oauthClient = getOAuthClient();
            const companyId = oauthClient.getToken().realmId;
            const baseUrl = getQboBaseUrl();

            const qboRes = await makeQboApiCall({
                url: `${baseUrl}/v3/company/${companyId}/invoice/${invoice.qbo_id}`,
                method: 'GET'
            });
            const qboData = qboRes.getJson ? qboRes.getJson() : qboRes.json;
            const syncToken = qboData.Invoice?.SyncToken;

            if (syncToken !== undefined) {
                const emailStatus = status === 'sent' ? 'EmailSent' : 'NotSet';

                await makeQboApiCall({
                    url: `${baseUrl}/v3/company/${companyId}/invoice`,
                    method: 'POST',
                    headers: { 'Content-Type': 'application/json' },
                    body: JSON.stringify({
                        Id: invoice.qbo_id,
                        SyncToken: syncToken,
                        sparse: true,
                        EmailStatus: emailStatus
                    })
                });

                console.log(`✅ QBO Invoice ${invoice.qbo_id} email status → ${emailStatus}`);
            }
        }

        // Update local
        await pool.query(
            'UPDATE invoices SET email_status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2',
            [status, id]
        );

        res.json({ success: true, status });

    } catch (error) {
        console.error('Error updating email status:', error);
        res.status(500).json({ error: 'Failed to update status: ' + error.message });
    }
});

// PATCH mark invoice as paid
router.patch('/:id/mark-paid', async (req, res) => {
    const { id } = req.params;
    const { paid_date } = req.body;
    
    try {
        const dateToUse = paid_date || new Date().toISOString().split('T')[0];
        const result = await pool.query(
            'UPDATE invoices SET paid_date = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2 RETURNING *',
            [dateToUse, id]
        );
        
        if (result.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }
        
        console.log(`💰 Invoice #${result.rows[0].invoice_number} als bezahlt markiert (${dateToUse})`);
        res.json(result.rows[0]);
    } catch (error) {
        console.error('Error marking invoice as paid:', error);
        res.status(500).json({ error: 'Error marking invoice as paid' });
    }
});

// PATCH mark invoice as unpaid
router.patch('/:id/mark-unpaid', async (req, res) => {
    const { id } = req.params;
    
    try {
        const result = await pool.query(
            'UPDATE invoices SET paid_date = NULL, updated_at = CURRENT_TIMESTAMP WHERE id = $1 RETURNING *',
            [id]
        );
        
        if (result.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }
        
        console.log(`↩️ Invoice #${result.rows[0].invoice_number} als unbezahlt markiert`);
        res.json(result.rows[0]);
    } catch (error) {
        console.error('Error marking invoice as unpaid:', error);
        res.status(500).json({ error: 'Error marking invoice as unpaid' });
    }
});

// PATCH reset QBO link
router.patch('/:id/reset-qbo', async (req, res) => {
    const { id } = req.params;
    
    try {
        const result = await pool.query(
            `UPDATE invoices 
             SET qbo_id = NULL, qbo_sync_token = NULL, qbo_doc_number = NULL, invoice_number = NULL, 
                 updated_at = CURRENT_TIMESTAMP 
             WHERE id = $1 RETURNING *`,
            [id]
        );
        
        if (result.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }
        
        console.log(`🔄 Invoice ID ${id} QBO-Verknüpfung zurückgesetzt`);
        res.json(result.rows[0]);
    } catch (error) {
        console.error('Error resetting QBO link:', error);
        res.status(500).json({ error: 'Error resetting QBO link' });
    }
});

// POST export to QBO
router.post('/:id/export', async (req, res) => {
    const { id } = req.params;
    
    const client = await pool.connect();
    try {
        const invoiceRes = await client.query(`
            SELECT i.*, c.qbo_id as customer_qbo_id, c.name as customer_name, c.email
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);

        if (invoiceRes.rows.length === 0) return res.status(404).json({ error: 'Invoice not found' });
        const invoice = invoiceRes.rows[0];

        if (!invoice.customer_qbo_id) {
            return res.status(400).json({ error: `Kunde "${invoice.customer_name}" ist noch nicht mit QBO verknüpft.` });
        }

        const itemsRes = await client.query('SELECT * FROM invoice_items WHERE invoice_id = $1', [id]);
        const items = itemsRes.rows;

        const oauthClient = getOAuthClient();
        const companyId = oauthClient.getToken().realmId;
        const baseUrl = getQboBaseUrl();

        const maxNumResult = await client.query(`
            SELECT GREATEST(
                COALESCE((SELECT MAX(CAST(qbo_doc_number AS INTEGER)) FROM invoices WHERE qbo_doc_number ~ '^[0-9]+$'), 0),
                COALESCE((SELECT MAX(CAST(invoice_number AS INTEGER)) FROM invoices WHERE invoice_number ~ '^[0-9]+$'), 0)
            ) as max_num
        `);
        let nextDocNumber = (parseInt(maxNumResult.rows[0].max_num) + 1).toString();

        const lineItems = items.map(item => {
            const rate = parseFloat(item.rate.replace(/[^0-9.]/g, '')) || 0;
            const amount = parseFloat(item.amount.replace(/[^0-9.]/g, '')) || 0;
            const itemRefId = item.qbo_item_id || '9';
            const itemRefName = itemRefId == QBO_LABOR_ID ? "Labor:Labor"
                : itemRefId == '115' ? "Subscription"
                : "Parts:Parts";

            return {
                "DetailType": "SalesItemLineDetail",
                "Amount": amount,
                "Description": item.description,
                "SalesItemLineDetail": {
                    "ItemRef": { "value": itemRefId, "name": itemRefName },
                    "UnitPrice": rate,
                    "Qty": parseFloat(item.quantity) || 1
                }
            };
        });

        const qboInvoicePayload = {
            "CustomerRef": { "value": invoice.customer_qbo_id },
            "DocNumber": nextDocNumber,
            "TxnDate": invoice.invoice_date.toISOString().split('T')[0],
            "Line": lineItems,
            "CustomerMemo": { "value": invoice.auth_code ? `Auth: ${invoice.auth_code}` : "" },
            "EmailStatus": "EmailSent",
            "BillEmail": { "Address": invoice.email || "" }
        };

        let qboInvoice = null;
        const MAX_RETRIES = 5;

        for (let attempt = 0; attempt < MAX_RETRIES; attempt++) {
            console.log(`📤 Sende Rechnung an QBO (DocNumber: ${qboInvoicePayload.DocNumber})...`);

            const createResponse = await makeQboApiCall({
                url: `${baseUrl}/v3/company/${companyId}/invoice`,
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(qboInvoicePayload)
            });

            const responseData = createResponse.getJson ? createResponse.getJson() : createResponse.json;

            if (responseData.Fault?.Error?.[0]?.code === '6140') {
                const oldNum = parseInt(qboInvoicePayload.DocNumber);
                qboInvoicePayload.DocNumber = (oldNum + 1).toString();
                console.log(`⚠️ DocNumber ${oldNum} existiert bereits. Versuche ${qboInvoicePayload.DocNumber}...`);
                continue;
            }

            qboInvoice = responseData.Invoice || responseData;

            if (qboInvoice.Id) {
                break;
            } else {
                console.error("FULL RESPONSE DUMP:", JSON.stringify(responseData, null, 2));
                throw new Error("QBO hat keine ID zurückgegeben: " +
                    (responseData.Fault?.Error?.[0]?.Message || JSON.stringify(responseData)));
            }
        }

        if (!qboInvoice || !qboInvoice.Id) {
            throw new Error(`Konnte nach ${MAX_RETRIES} Versuchen keine freie DocNumber finden.`);
        }

        console.log(`✅ QBO Rechnung erstellt! ID: ${qboInvoice.Id}, DocNumber: ${qboInvoice.DocNumber}`);

        await client.query(
            `UPDATE invoices SET qbo_id = $1, qbo_sync_token = $2, qbo_doc_number = $3, invoice_number = $4 WHERE id = $5`,
            [qboInvoice.Id, qboInvoice.SyncToken, qboInvoice.DocNumber, qboInvoice.DocNumber, id]
        );

        res.json({ success: true, qbo_id: qboInvoice.Id, qbo_doc_number: qboInvoice.DocNumber });            

    } catch (error) {
        console.error("QBO Export Error:", error);
        let errorDetails = error.message;
        if (error.response?.data?.Fault?.Error?.[0]) {
             errorDetails = error.response.data.Fault.Error[0].Message + ": " + error.response.data.Fault.Error[0].Detail;
        }
        res.status(500).json({ error: "QBO Export failed: " + errorDetails });
    } finally {
        client.release();
    }
});

// POST update in QBO
router.post('/:id/update-qbo', async (req, res) => {
    const { id } = req.params;
    const QBO_LABOR_ID = '5';
    const QBO_PARTS_ID = '9';

    const dbClient = await pool.connect();
    try {
        const invoiceRes = await dbClient.query(`
            SELECT i.*, c.qbo_id as customer_qbo_id, c.name as customer_name, c.email
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);

        if (invoiceRes.rows.length === 0) return res.status(404).json({ error: 'Invoice not found' });
        const invoice = invoiceRes.rows[0];

        if (!invoice.qbo_id) {
            return res.status(400).json({ error: 'Invoice has not been exported to QBO yet. Use QBO Export first.' });
        }
        if (!invoice.qbo_sync_token && invoice.qbo_sync_token !== '0') {
            return res.status(400).json({ error: 'Missing QBO SyncToken. Try resetting and re-exporting.' });
        }

        const itemsRes = await dbClient.query('SELECT * FROM invoice_items WHERE invoice_id = $1 ORDER BY item_order', [id]);
        const items = itemsRes.rows;

        const oauthClient = getOAuthClient();
        const companyId = oauthClient.getToken().realmId;
        const baseUrl = getQboBaseUrl();

        console.log(`🔍 Lade aktuelle QBO Invoice ${invoice.qbo_id}...`);
        const currentQboRes = await makeQboApiCall({
            url: `${baseUrl}/v3/company/${companyId}/invoice/${invoice.qbo_id}`,
            method: 'GET'
        });
        const currentQboData = currentQboRes.getJson ? currentQboRes.getJson() : currentQboRes.json;
        const currentQboInvoice = currentQboData.Invoice;

        if (!currentQboInvoice) {
            return res.status(500).json({ error: 'Could not load current invoice from QBO.' });
        }

        const currentSyncToken = currentQboInvoice.SyncToken;
        console.log(`   SyncToken: lokal=${invoice.qbo_sync_token}, QBO=${currentSyncToken}`);

        const lineItems = items.map(item => {
            const rate = parseFloat(item.rate.replace(/[^0-9.]/g, '')) || 0;
            const amount = parseFloat(item.amount.replace(/[^0-9.]/g, '')) || 0;
            const itemRefId = item.qbo_item_id || QBO_PARTS_ID;
            const itemRefName = itemRefId == QBO_LABOR_ID ? "Labor:Labor"
                : itemRefId == '115' ? "Subscription"
                : "Parts:Parts";

            return {
                "DetailType": "SalesItemLineDetail",
                "Amount": amount,
                "Description": item.description,
                "SalesItemLineDetail": {
                    "ItemRef": { "value": itemRefId, "name": itemRefName },
                    "UnitPrice": rate,
                    "Qty": parseFloat(item.quantity) || 1
                }
            };
        });

        const updatePayload = {
            "Id": invoice.qbo_id,
            "SyncToken": currentSyncToken,
            "sparse": true,
            "Line": lineItems,
            "CustomerRef": { "value": invoice.customer_qbo_id },
            "TxnDate": invoice.invoice_date.toISOString().split('T')[0],
            "CustomerMemo": { "value": invoice.auth_code ? `Auth: ${invoice.auth_code}` : "" }
        };

        console.log(`📤 Update QBO Invoice ${invoice.qbo_id} (DocNumber: ${invoice.qbo_doc_number})...`);

        const updateResponse = await makeQboApiCall({
            url: `${baseUrl}/v3/company/${companyId}/invoice`,
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify(updatePayload)
        });

        const updateData = updateResponse.getJson ? updateResponse.getJson() : updateResponse.json;
        const updatedInvoice = updateData.Invoice || updateData;

        if (!updatedInvoice.Id) {
            console.error("QBO Update Response:", JSON.stringify(updateData, null, 2));
            throw new Error("QBO did not return an updated invoice.");
        }

        console.log(`✅ QBO Invoice updated! New SyncToken: ${updatedInvoice.SyncToken}`);

        await dbClient.query(
            'UPDATE invoices SET qbo_sync_token = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2',
            [updatedInvoice.SyncToken, id]
        );

        res.json({
            success: true,
            qbo_id: updatedInvoice.Id,
            sync_token: updatedInvoice.SyncToken,
            message: `Invoice #${invoice.qbo_doc_number || invoice.invoice_number} updated in QBO.`
        });

    } catch (error) {
        console.error("QBO Update Error:", error);
        let errorDetails = error.message;
        if (error.response?.data?.Fault?.Error?.[0]) {
            errorDetails = error.response.data.Fault.Error[0].Message + ": " + error.response.data.Fault.Error[0].Detail;
        }
        res.status(500).json({ error: "QBO Update failed: " + errorDetails });
    } finally {
        dbClient.release();
    }
});

// GET invoice PDF
router.get('/:id/pdf', async (req, res) => {
    const { id } = req.params;
    console.log(`[INVOICE-PDF] Starting invoice PDF generation for ID: ${id}`);
    
    try {
        const invoiceResult = await pool.query(`
            SELECT i.*, c.name as customer_name, c.line1, c.line2, c.line3, c.line4, c.city, c.state, c.zip_code, c.account_number,
            COALESCE((SELECT SUM(pi.amount) FROM payment_invoices pi WHERE pi.invoice_id = i.id), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);
        
        if (invoiceResult.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }
        
        const invoice = invoiceResult.rows[0];
        const itemsResult = await pool.query(
            'SELECT * FROM invoice_items WHERE invoice_id = $1 ORDER BY item_order',
            [id]
        );
        
        const templatePath = path.join(__dirname, '..', '..', 'templates', 'invoice-template.html');
        let html = await fs.readFile(templatePath, 'utf-8');
        
        const logoHTML = await getLogoHtml();
        const itemsHTML = renderInvoiceItems(itemsResult.rows, invoice);

        const authHTML = invoice.auth_code ? `<p style="margin-bottom: 20px; font-size: 13px;"><strong>Authorization:</strong> ${invoice.auth_code}</p>` : '';
        
        const streetBlock = formatAddressLines(invoice.line1, invoice.line2, invoice.line3, invoice.line4, invoice.customer_name);

        html = html
            .replace('{{LOGO_HTML}}', logoHTML)
            .replace('{{CUSTOMER_NAME}}', invoice.bill_to_name || invoice.customer_name || '')
            .replace('{{CUSTOMER_STREET}}', streetBlock)
            .replace('{{CUSTOMER_CITY}}', invoice.city || '')
            .replace('{{CUSTOMER_STATE}}', invoice.state || '')
            .replace('{{CUSTOMER_ZIP}}', invoice.zip_code || '')
            .replace('{{INVOICE_NUMBER}}', invoice.invoice_number || '')
            .replace('{{ACCOUNT_NUMBER}}', invoice.account_number || '')
            .replace('{{INVOICE_DATE}}', formatDate(invoice.invoice_date))
            .replace('{{TERMS}}', invoice.terms)
            .replace('{{AUTHORIZATION}}', authHTML)
            .replace('{{ITEMS}}', itemsHTML)
            .replace('{{PAYMENT_LINK}}', buildPaymentLinkHtml(invoice));

        const pdf = await generatePdfFromHtml(html);
        
        res.set({
            'Content-Type': 'application/pdf',
            'Content-Length': pdf.length,
            'Content-Disposition': `attachment; filename="Invoice-${invoice.invoice_number}.pdf"`
        });
        res.end(pdf, 'binary');
        console.log('[INVOICE-PDF] Invoice PDF sent successfully');
        
    } catch (error) {
        console.error('[INVOICE-PDF] ERROR:', error);
        res.status(500).json({ error: 'Error generating PDF', details: error.message });
    }
});

// GET invoice HTML (debug)
router.get('/:id/html', async (req, res) => {
    const { id } = req.params;
    
    try {
        const invoiceResult = await pool.query(`
            SELECT i.*, c.name as customer_name, c.line1, c.line2, c.line3, c.line4, c.city, c.state, c.zip_code, c.account_number,
            COALESCE((SELECT SUM(pi.amount) FROM payment_invoices pi WHERE pi.invoice_id = i.id), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);
        
        if (invoiceResult.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }
        
        const invoice = invoiceResult.rows[0];
        const itemsResult = await pool.query(
            'SELECT * FROM invoice_items WHERE invoice_id = $1 ORDER BY item_order',
            [id]
        );
        
        const templatePath = path.join(__dirname, '..', '..', 'templates', 'invoice-template.html');
        let html = await fs.readFile(templatePath, 'utf-8');
        
        const logoHTML = await getLogoHtml();
        const itemsHTML = renderInvoiceItems(itemsResult.rows, invoice);

        const authHTML = invoice.auth_code ? `<p style="margin-bottom: 20px; font-size: 13px;"><strong>Authorization:</strong> ${invoice.auth_code}</p>` : '';
        
        const streetBlock = formatAddressLines(invoice.line1, invoice.line2, invoice.line3, invoice.line4, invoice.customer_name);

        html = html
            .replace('{{LOGO_HTML}}', logoHTML)
            .replace('{{CUSTOMER_NAME}}', invoice.bill_to_name || invoice.customer_name || '')
            .replace('{{CUSTOMER_STREET}}', streetBlock)
            .replace('{{CUSTOMER_CITY}}', invoice.city || '')
            .replace('{{CUSTOMER_STATE}}', invoice.state || '')
            .replace('{{CUSTOMER_ZIP}}', invoice.zip_code || '')
            .replace('{{INVOICE_NUMBER}}', invoice.invoice_number || '')
            .replace('{{ACCOUNT_NUMBER}}', invoice.account_number || '')
            .replace('{{INVOICE_DATE}}', formatDate(invoice.invoice_date))
            .replace('{{TERMS}}', invoice.terms)
            .replace('{{AUTHORIZATION}}', authHTML)
            .replace('{{ITEMS}}', itemsHTML)
            .replace('{{PAYMENT_LINK}}', buildPaymentLinkHtml(invoice));

        res.setHeader('Content-Type', 'text/html');
        res.send(html);
        
    } catch (error) {
        console.error('[HTML] ERROR:', error);
        res.status(500).json({ error: 'Error generating HTML' });
    }
});
router.post('/:id/send-email', async (req, res) => {
    const { id } = req.params;
    const { recipientEmail, customText } = req.body;

    if (!recipientEmail) {
        return res.status(400).json({ error: 'Recipient email is required.' });
    }

    try {
        // 1. Rechnungsdaten und Items laden (analog zu deiner PDF-Route)
        const invoiceResult = await pool.query(`
            SELECT i.*, c.name as customer_name, c.line1, c.line2, c.line3, c.line4, c.city, c.state, c.zip_code, c.account_number,
            COALESCE((SELECT SUM(pi.amount) FROM payment_invoices pi WHERE pi.invoice_id = i.id), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);
        
        if (invoiceResult.rows.length === 0) return res.status(404).json({ error: 'Invoice not found' });
        const invoice = invoiceResult.rows[0];

        const itemsResult = await pool.query('SELECT * FROM invoice_items WHERE invoice_id = $1 ORDER BY item_order', [id]);

        // 2. PDF generieren, aber nur im Speicher halten
        const templatePath = path.join(__dirname, '..', '..', 'templates', 'invoice-template.html');
        let html = await fs.readFile(templatePath, 'utf-8');
        
        const logoHTML = await getLogoHtml();
        const itemsHTML = renderInvoiceItems(itemsResult.rows, invoice);
        const authHTML = invoice.auth_code ? `<p style="margin-bottom: 20px; font-size: 13px;"><strong>Authorization:</strong> ${invoice.auth_code}</p>` : '';
        const streetBlock = formatAddressLines(invoice.line1, invoice.line2, invoice.line3, invoice.line4, invoice.customer_name);

        html = html
            .replace('{{LOGO_HTML}}', logoHTML)
            .replace('{{CUSTOMER_NAME}}', invoice.bill_to_name || invoice.customer_name || '')
            .replace('{{CUSTOMER_STREET}}', streetBlock)
            .replace('{{CUSTOMER_CITY}}', invoice.city || '')
            .replace('{{CUSTOMER_STATE}}', invoice.state || '')
            .replace('{{CUSTOMER_ZIP}}', invoice.zip_code || '')
            .replace('{{INVOICE_NUMBER}}', invoice.invoice_number || '')
            .replace('{{ACCOUNT_NUMBER}}', invoice.account_number || '')
            .replace('{{INVOICE_DATE}}', formatDate(invoice.invoice_date))
            .replace('{{TERMS}}', invoice.terms)
            .replace('{{AUTHORIZATION}}', authHTML)
            .replace('{{ITEMS}}', itemsHTML)
            .replace('{{PAYMENT_LINK}}', buildPaymentLinkHtml(invoice));
        
        const pdfBuffer = await generatePdfFromHtml(html);

        // 3. E-Mail über SES versenden
        const stripeLink = invoice.stripe_payment_link_url || null;
        const info = await sendInvoiceEmail(invoice, recipientEmail, customText, stripeLink, pdfBuffer);

        // 4. Status in der DB aktualisieren
        await pool.query(
            `UPDATE invoices 
            SET email_status = 'sent', 
                sent_dates = array_append(COALESCE(sent_dates, '{}'), CURRENT_DATE),
                updated_at = CURRENT_TIMESTAMP 
            WHERE id = $1`,
            [id]
        );

        res.json({ success: true, messageId: info.messageId });

    } catch (error) {
        console.error('Error sending invoice email:', error);
        res.status(500).json({ error: 'Failed to send email: ' + error.message });
    }
});
// POST create Stripe Payment Link
router.post('/:id/create-payment-link', async (req, res) => {
    const { id } = req.params;

    try {
        // Load invoice with balance
        const invoiceResult = await pool.query(`
            SELECT i.*, c.name as customer_name,
                   COALESCE((SELECT SUM(pi.amount) FROM payment_invoices pi WHERE pi.invoice_id = i.id), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);

        if (invoiceResult.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }

        const invoice = invoiceResult.rows[0];
        invoice.amount_paid = parseFloat(invoice.amount_paid) || 0;
        invoice.balance = (parseFloat(invoice.total) || 0) - invoice.amount_paid;

        if (invoice.balance <= 0) {
            return res.status(400).json({ error: 'Invoice has no balance due.' });
        }

        // Deactivate existing payment link if present
        if (invoice.stripe_payment_link_id) {
            await deactivatePaymentLink(invoice.stripe_payment_link_id);
            console.log(`♻️ Old payment link deactivated for Invoice #${invoice.invoice_number}`);
        }

        // Create new payment link
        const { paymentLinkId, paymentLinkUrl } = await createPaymentLink(invoice);

        // Save to DB
        await pool.query(
            `UPDATE invoices 
             SET stripe_payment_link_id = $1, 
                 stripe_payment_link_url = $2, 
                 stripe_payment_status = 'pending',
                 updated_at = CURRENT_TIMESTAMP 
             WHERE id = $3`,
            [paymentLinkId, paymentLinkUrl, id]
        );

        res.json({
            success: true,
            paymentLinkId,
            paymentLinkUrl,
            amount: invoice.balance
        });

    } catch (error) {
        console.error('Stripe Payment Link Error:', error);
        res.status(500).json({ error: 'Failed to create payment link: ' + error.message });
    }
});
// POST check Stripe payment status
// POST check Stripe payment status (with QBO payment + fee booking)
router.post('/:id/check-payment', async (req, res) => {
    const { id } = req.params;
    const dbClient = await pool.connect();

    try {
        const invoiceResult = await dbClient.query(`
            SELECT i.*, c.name as customer_name, c.qbo_id as customer_qbo_id,
                   COALESCE((SELECT SUM(pi.amount) FROM payment_invoices pi WHERE pi.invoice_id = i.id), 0) as amount_paid
            FROM invoices i
            LEFT JOIN customers c ON i.customer_id = c.id
            WHERE i.id = $1
        `, [id]);

        if (invoiceResult.rows.length === 0) {
            return res.status(404).json({ error: 'Invoice not found' });
        }

        const invoice = invoiceResult.rows[0];
        invoice.amount_paid = parseFloat(invoice.amount_paid) || 0;

        if (!invoice.stripe_payment_link_id) {
            return res.status(400).json({ error: 'No Stripe payment link exists for this invoice.' });
        }

        // Already fully processed?
        if (invoice.stripe_payment_status === 'paid') {
            return res.json({
                status: 'paid',
                message: 'Stripe payment already recorded.',
                alreadyProcessed: true
            });
        }

        const result = await checkPaymentStatus(invoice.stripe_payment_link_id);

        // Update stripe_payment_status in DB regardless
        if (result.status !== invoice.stripe_payment_status) {
            await dbClient.query(
                'UPDATE invoices SET stripe_payment_status = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2',
                [result.status, id]
            );
        }

        // If not paid yet, return current status
        if (!result.paid) {
            return res.json({
                status: result.status,
                paid: false,
                details: result.details,
                message: result.status === 'processing'
                    ? 'ACH payment is processing (3-5 business days).'
                    : 'No payment received yet.'
            });
        }

        // === PAID — full processing ===
        const amountReceived = result.details.amountReceived;
        const paymentMethod = result.details.paymentMethod;
        const stripeFee = result.details.stripeFee;
        const methodLabel = paymentMethod === 'us_bank_account' ? 'ACH' : 'Credit Card';

        await dbClient.query('BEGIN');

        // 1. Record local payment (payment + payment_invoices)
        const payResult = await dbClient.query(
            `INSERT INTO payments (payment_date, payment_method, total_amount, customer_id, reference_number, notes, created_at)
             VALUES (CURRENT_DATE, $1, $2, $3, $4, $5, CURRENT_TIMESTAMP)
             RETURNING id`,
            [
                `Stripe ${methodLabel}`,
                amountReceived,
                invoice.customer_id,
                result.details.paymentIntentId || result.details.sessionId,
                `Stripe ${methodLabel} — Fee: $${stripeFee.toFixed(2)}`
            ]
        );
        const paymentId = payResult.rows[0].id;

        await dbClient.query(
            'INSERT INTO payment_invoices (payment_id, invoice_id, amount) VALUES ($1, $2, $3)',
            [paymentId, id, amountReceived]
        );

        // 2. Check if invoice is fully paid
        const newTotalPaid = invoice.amount_paid + amountReceived;
        const invoiceTotal = parseFloat(invoice.total) || 0;
        const fullyPaid = newTotalPaid >= (invoiceTotal - 0.01); // Cent-Toleranz

        await dbClient.query(
            `UPDATE invoices SET 
                stripe_payment_status = 'paid',
                paid_date = ${fullyPaid ? 'COALESCE(paid_date, CURRENT_DATE)' : 'paid_date'},
                payment_status = $1,
                updated_at = CURRENT_TIMESTAMP
             WHERE id = $2`,
            [fullyPaid ? 'Stripe' : 'Partial', id]
        );

        // 3. Deactivate the payment link
        await deactivatePaymentLink(invoice.stripe_payment_link_id);

        // 4. QBO: Record Payment + Expense (if QBO-linked)
        qboResult = await recordStripePaymentInQbo(
            invoice, amountReceived, methodLabel, stripeFee,
            result.details.paymentIntentId || ''
            // kein source-Parameter — default ist 'manual'
        );

        await dbClient.query('COMMIT');

        console.log(`✅ Invoice #${invoice.invoice_number}: Stripe ${methodLabel} $${amountReceived.toFixed(2)} recorded (Fee: $${stripeFee.toFixed(2)})`);

        res.json({
            status: 'paid',
            paid: true,
            fullyPaid,
            details: result.details,
            qbo: qboResult,
            message: `Payment received: $${amountReceived.toFixed(2)} via Stripe ${methodLabel}. Fee: $${stripeFee.toFixed(2)}.`
        });

    } catch (error) {
        await dbClient.query('ROLLBACK').catch(() => {});
        console.error('Stripe Check Payment Error:', error);
        res.status(500).json({ error: 'Failed to check payment: ' + error.message });
    } finally {
        dbClient.release();
    }
});


// PATCH update sent dates only
router.patch('/:id/sent-dates', async (req, res) => {
    const { id } = req.params;
    const { sent_dates } = req.body;

    if (!Array.isArray(sent_dates)) {
        return res.status(400).json({ error: 'sent_dates must be an array of date strings.' });
    }

    // Validate each date
    for (const d of sent_dates) {
        if (!/^\d{4}-\d{2}-\d{2}$/.test(d)) {
            return res.status(400).json({ error: `Invalid date format: ${d}. Expected YYYY-MM-DD.` });
        }
    }

    try {
        // Sort chronologically
        const sorted = [...sent_dates].sort();

        await pool.query(
            'UPDATE invoices SET sent_dates = $1, updated_at = CURRENT_TIMESTAMP WHERE id = $2',
            [sorted, id]
        );

        res.json({ success: true, sent_dates: sorted });
    } catch (error) {
        console.error('Error updating sent dates:', error);
        res.status(500).json({ error: 'Failed to update sent dates.' });
    }
});
module.exports = router;