/**
 * 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 } = require('../config/qbo');
const { makeQboApiCall } = require('../../qbo_helper');

// 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.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];
        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 } = 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.` });
            }
        }

        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 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)
             VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13) 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]
        );
        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, pool);
            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 } = 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.` });
            }
        }

        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]
            );
        }

        // 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, pool);
            } else {
                qboResult = await exportInvoiceToQbo(id, pool);
            }

            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 == '5' ? "Labor:Labor" : "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" : "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);

        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);

        res.setHeader('Content-Type', 'text/html');
        res.send(html);
        
    } catch (error) {
        console.error('[HTML] ERROR:', error);
        res.status(500).json({ error: 'Error generating HTML' });
    }
});

module.exports = router;