Allow user-configurable invoice numbering start

Add a per-user invoice_starting_number setting (default 1) instead of
always starting invoice numbering at 001. Adds /api/settings endpoints,
a user_settings table, and a Číslování faktur panel in the account menu
where the user can pick the starting number for a year with no
invoices yet.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

app/src/app.js

@@ -227,6 +227,33 @@ app.put('/api/supplier', requireAuth, async (req, res, next) => {
     }
 });
 
+app.get('/api/settings', requireAuth, async (req, res, next) => {
+    try {
+        const result = await pool.query('SELECT invoice_starting_number FROM user_settings WHERE user_id = $1', [req.userId]);
+        res.json({ settings: { invoiceStartingNumber: result.rowCount ? result.rows[0].invoice_starting_number : 1 } });
+    } catch (error) {
+        next(error);
+    }
+});
+
+app.put('/api/settings', requireAuth, async (req, res, next) => {
+    try {
+        const invoiceStartingNumber = Number.parseInt(req.body.invoiceStartingNumber, 10);
+        if (!Number.isInteger(invoiceStartingNumber) || invoiceStartingNumber < 1) {
+            res.status(400).json({ error: 'Počáteční číslo faktury musí být kladné celé číslo.' });
+            return;
+        }
+        const result = await pool.query(`
+            INSERT INTO user_settings (user_id, invoice_starting_number) VALUES ($1, $2)
+            ON CONFLICT (user_id) DO UPDATE SET invoice_starting_number = EXCLUDED.invoice_starting_number
+            RETURNING invoice_starting_number
+            `, [req.userId, invoiceStartingNumber]);
+        res.json({ settings: { invoiceStartingNumber: result.rows[0].invoice_starting_number } });
+    } catch (error) {
+        next(error);
+    }
+});
+
 app.get('/api/clients', requireAuth, async (req, res, next) => {
     try {
         const result = await pool.query('SELECT * FROM clients WHERE user_id = $1 ORDER BY created_at, id', [req.userId]);
@@ -376,13 +403,21 @@ app.post('/api/invoices', requireAuth, async (req, res, next) => {
 
         const invoiceYear = new Date().getFullYear();
         await client.query('BEGIN');
+        const settingsResult = await client.query(
+            'SELECT invoice_starting_number FROM user_settings WHERE user_id = $1',
+            [req.userId]
+        );
+        const invoiceStartingNumber = settingsResult.rowCount ? settingsResult.rows[0].invoice_starting_number : 1;
         await client.query(`
             INSERT INTO invoice_counters (user_id, invoice_year, last_number)
-            SELECT $1, $2, COALESCE(MAX((substring(invoice_number FROM '^F-[0-9]{4}-([0-9]+)$'))::integer), 0)
+            SELECT $1, $2, GREATEST(
+                COALESCE(MAX((substring(invoice_number FROM '^F-[0-9]{4}-([0-9]+)$'))::integer), 0),
+                $4 - 1
+            )
             FROM invoices
             WHERE user_id = $1 AND invoice_number LIKE $3
             ON CONFLICT (user_id, invoice_year) DO NOTHING
-        `, [req.userId, invoiceYear, `F-${invoiceYear}-%`]);
+        `, [req.userId, invoiceYear, `F-${invoiceYear}-%`, invoiceStartingNumber]);
         const counterResult = await client.query(`
             UPDATE invoice_counters
             SET last_number = last_number + 1
@@ -572,22 +607,16 @@ const renderInvoicePdf = async (document, invoice) => {
     document.y += 35;
     document.moveTo(document.page.margins.left, document.y).lineTo(document.page.margins.left + pageWidth, document.y)
         .strokeColor(navy).lineWidth(1.5).stroke();
-    const paymentCardHeight = 105;
+    document.y += 12;
-    const paymentTop = document.page.height - document.page.margins.bottom - paymentCardHeight;
+    const paymentTop = document.y;
-    const paymentLineHeight = 18;
+    document.roundedRect(document.page.margins.left, paymentTop, pageWidth, 165, 4).fillAndStroke('#f4f7fb', line);
-    const qrSize = paymentLineHeight * 3;
-    document.roundedRect(document.page.margins.left, paymentTop, pageWidth, paymentCardHeight, 4)
-        .fillAndStroke('#f4f7fb', line);
     document.fillColor(navy).font(boldFont).fontSize(11).text('Platební údaje', document.page.margins.left + 10, paymentTop + 10);
     document.fillColor(bodyText).font(regularFont).fontSize(10)
         .text(`Číslo účtu: ${pdfText(payment.cisloUctu)}`, document.page.margins.left + 10, paymentTop + 35)
-        .text(`IBAN: ${pdfText(payment.iban)}`, document.page.margins.left + 10, paymentTop + 35 + paymentLineHeight)
+        .text(`IBAN: ${pdfText(payment.iban)}`, document.page.margins.left + 10, paymentTop + 55)
-        .text(`SWIFT: ${pdfText(payment.swift)}`, document.page.margins.left + 10, paymentTop + 35 + paymentLineHeight * 2);
+        .text(`SWIFT: ${pdfText(payment.swift)}`, document.page.margins.left + 10, paymentTop + 75);
     if (qrBuffer) {
-        document.image(qrBuffer, document.page.margins.left + pageWidth - qrSize - 10, paymentTop + 30, {
+        document.image(qrBuffer, document.page.margins.left + pageWidth - 155, paymentTop + 10, { width: 145, height: 145 });
-            width: qrSize,
-            height: qrSize
-        });
     }
     document.end();
 };

app/src/db.js

@@ -65,6 +65,11 @@ const initializeDatabase = () => {
                 PRIMARY KEY (user_id, invoice_year)
             );
 
+            CREATE TABLE IF NOT EXISTS user_settings (
+                user_id INTEGER PRIMARY KEY REFERENCES users(id) ON DELETE CASCADE,
+                invoice_starting_number INTEGER NOT NULL DEFAULT 1 CHECK (invoice_starting_number > 0)
+            );
+
             CREATE TABLE IF NOT EXISTS payment_presets (
                 id SERIAL PRIMARY KEY,
                 user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,

app/src/static/index.html

@@ -65,11 +65,28 @@
                 <summary><span class="account-mark" aria-hidden="true"></span><span id="navEmail" class="signed-in-email"></span></summary>
                 <div class="nav-menu-content account-menu-content">
                     <button type="button" id="passwordButton" class="text-button">Změnit heslo</button>
+                    <button type="button" id="numberingSettingsButton" class="text-button">Číslování faktur</button>
                     <button type="button" id="logoutButton" class="text-button">Odhlásit se</button>
                 </div>
             </details>
         </nav>
 
+        <section id="numberingSettingsPanel" class="password-panel" hidden>
+            <div id="numberingSettingsForm">
+                <h3>Číslování faktur</h3>
+                <div class="form-group">
+                    <label for="invoiceStartingNumber">Počáteční číslo faktury (pro aktuální rok)</label>
+                    <input id="invoiceStartingNumber" type="number" min="1" step="1" placeholder="1" />
+                    <p class="field-hint">Určuje, od jakého čísla se budou generovat nové faktury v roce, kdy zatím žádnou nemáte. Výchozí hodnota je 1.</p>
+                </div>
+                <div class="saved-data-actions">
+                    <button type="button" id="saveNumberingSettingsButton">Uložit</button>
+                    <button type="button" id="cancelNumberingSettingsButton" class="secondary-button">Zrušit</button>
+                    <span id="numberingSettingsStatus" role="status" aria-live="polite"></span>
+                </div>
+            </div>
+        </section>
+
         <section id="passwordPanel" class="password-panel" hidden>
             <div id="passwordForm">
                 <h3>Změnit heslo</h3>

app/src/static/script.js

@@ -40,6 +40,12 @@ const passwordForm = document.getElementById("passwordForm");
 const savePasswordButton = document.getElementById("savePasswordButton");
 const cancelPasswordButton = document.getElementById("cancelPasswordButton");
 const passwordStatus = document.getElementById("passwordStatus");
+const numberingSettingsButton = document.getElementById("numberingSettingsButton");
+const numberingSettingsPanel = document.getElementById("numberingSettingsPanel");
+const invoiceStartingNumberInput = document.getElementById("invoiceStartingNumber");
+const saveNumberingSettingsButton = document.getElementById("saveNumberingSettingsButton");
+const cancelNumberingSettingsButton = document.getElementById("cancelNumberingSettingsButton");
+const numberingSettingsStatus = document.getElementById("numberingSettingsStatus");
 const dueDateOption = document.getElementById("dueDateOption");
 const dueDateDisplay = document.getElementById("dueDateDisplay");
 const paymentPresetSelect = document.getElementById("paymentPresetSelect");
@@ -519,10 +525,27 @@ deleteClientButton.addEventListener("click", async () => {
 const showInvoiceApp = async () => {
     authScreen.hidden = true;
     document.getElementById("main-container").hidden = false;
-    await Promise.all([loadSupplier(), loadClients(), loadInvoices(), loadPaymentPresets()]);
+    await Promise.all([loadSupplier(), loadClients(), loadInvoices(), loadPaymentPresets(), loadNumberingSettings()]);
     showInvoiceScreen("list");
 };
 
+const loadNumberingSettings = async () => {
+    try {
+        const { settings } = await apiRequest("/api/settings");
+        invoiceStartingNumberInput.value = settings.invoiceStartingNumber;
+        invoiceStartingNumberInput.placeholder = String(settings.invoiceStartingNumber);
+    } catch {
+        // Keep the placeholder default if settings cannot be loaded.
+    }
+};
+
+const showNumberingSettingsPanel = (visible) => {
+    numberingSettingsPanel.hidden = !visible;
+    if (!visible) {
+        numberingSettingsStatus.textContent = "";
+    }
+};
+
 const showPasswordPanel = (visible) => {
     passwordPanel.hidden = !visible;
     if (!visible) {
@@ -575,6 +598,24 @@ logoutButton.addEventListener("click", async () => {
 passwordButton.addEventListener("click", () => showPasswordPanel(passwordPanel.hidden));
 cancelPasswordButton.addEventListener("click", () => showPasswordPanel(false));
 
+numberingSettingsButton.addEventListener("click", () => showNumberingSettingsPanel(numberingSettingsPanel.hidden));
+cancelNumberingSettingsButton.addEventListener("click", () => showNumberingSettingsPanel(false));
+
+saveNumberingSettingsButton.addEventListener("click", async () => {
+    numberingSettingsStatus.textContent = "";
+    const invoiceStartingNumber = Number.parseInt(invoiceStartingNumberInput.value, 10) || 1;
+    try {
+        const { settings } = await apiRequest("/api/settings", {
+            method: "PUT",
+            body: JSON.stringify({ invoiceStartingNumber })
+        });
+        invoiceStartingNumberInput.value = settings.invoiceStartingNumber;
+        numberingSettingsStatus.textContent = "Uloženo";
+    } catch (error) {
+        numberingSettingsStatus.textContent = error.message;
+    }
+});
+
 savePasswordButton.addEventListener("click", async () => {
     passwordStatus.textContent = "";
     try {

app/src/static/style.css

@@ -595,6 +595,12 @@ body {
     outline-offset: 1px;
 }
 
+.field-hint {
+    margin: 0.35rem 0 0;
+    color: var(--muted-ink);
+    font-size: 0.8rem;
+}
+
 .form-group output {
     min-height: 1.5rem;
     padding: 0.25rem 0;