Add UPC generation, add automatic correction of UPC check digits, properly deal with already existing UPCs, add in final results display after submitting with option to fix errored products

inventory-server/src/routes/import.js

@@ -955,6 +955,155 @@ router.get('/search-products', async (req, res) => {
   }
 });
 
+const UPC_SUPPLIER_PREFIX_LEADING_DIGIT = '4';
+const UPC_MAX_SEQUENCE = 99999;
+const UPC_RESERVATION_TTL = 5 * 60 * 1000; // 5 minutes
+
+function buildSupplierPrefix(supplierId) {
+  const numericId = Number.parseInt(String(supplierId), 10);
+  if (Number.isNaN(numericId) || numericId < 0) {
+    return null;
+  }
+
+  const padded = String(numericId).padStart(5, '0');
+  const prefix = `${UPC_SUPPLIER_PREFIX_LEADING_DIGIT}${padded}`;
+  return prefix.length === 6 ? prefix : null;
+}
+
+function calculateUpcCheckDigit(upcWithoutCheckDigit) {
+  if (!/^\d{11}$/.test(upcWithoutCheckDigit)) {
+    throw new Error('UPC body must be 11 numeric characters');
+  }
+
+  let sum = 0;
+  for (let i = 0; i < upcWithoutCheckDigit.length; i += 1) {
+    const digit = Number.parseInt(upcWithoutCheckDigit[i], 10);
+    sum += (i % 2 === 0) ? digit * 3 : digit;
+  }
+
+  const mod = sum % 10;
+  return mod === 0 ? 0 : 10 - mod;
+}
+
+const upcReservationCache = new Map();
+const upcGenerationLocks = new Map();
+
+function getReservedSequence(prefix) {
+  const entry = upcReservationCache.get(prefix);
+  if (!entry) {
+    return 0;
+  }
+
+  if (Date.now() > entry.expiresAt) {
+    upcReservationCache.delete(prefix);
+    return 0;
+  }
+
+  return entry.lastSequence;
+}
+
+function setReservedSequence(prefix, sequence) {
+  upcReservationCache.set(prefix, {
+    lastSequence: sequence,
+    expiresAt: Date.now() + UPC_RESERVATION_TTL
+  });
+}
+
+async function runWithSupplierLock(prefix, task) {
+  const previous = upcGenerationLocks.get(prefix) || Promise.resolve();
+  const chained = previous.catch(() => {}).then(() => task());
+  upcGenerationLocks.set(prefix, chained);
+
+  try {
+    return await chained;
+  } finally {
+    if (upcGenerationLocks.get(prefix) === chained) {
+      upcGenerationLocks.delete(prefix);
+    }
+  }
+}
+
+router.post('/generate-upc', async (req, res) => {
+  const { supplierId, increment } = req.body || {};
+
+  if (supplierId === undefined || supplierId === null || String(supplierId).trim() === '') {
+    return res.status(400).json({ error: 'Supplier ID is required to generate a UPC' });
+  }
+
+  const supplierPrefix = buildSupplierPrefix(supplierId);
+  if (!supplierPrefix) {
+    return res.status(400).json({ error: 'Supplier ID must be a non-negative number with at most 5 digits' });
+  }
+
+  const step = Number.parseInt(increment, 10);
+  const sequenceIncrement = Number.isNaN(step) || step < 1 ? 1 : step;
+
+  try {
+    const result = await runWithSupplierLock(supplierPrefix, async () => {
+      const { connection } = await getDbConnection();
+
+      const [rows] = await connection.query(
+        `SELECT CAST(SUBSTRING(upc,7,5) AS UNSIGNED) AS num
+           FROM products
+          WHERE LEFT(upc, 6) = ? AND LENGTH(upc) = 12
+       ORDER BY num DESC
+          LIMIT 1`,
+        [supplierPrefix]
+      );
+
+      const lastSequenceFromDb = rows && rows.length > 0 && rows[0].num !== null
+        ? Number.parseInt(rows[0].num, 10) || 0
+        : 0;
+
+      const cachedSequence = getReservedSequence(supplierPrefix);
+      const baselineSequence = Math.max(lastSequenceFromDb, cachedSequence);
+
+      let nextSequence = baselineSequence + sequenceIncrement;
+      let candidateUpc = null;
+      let attempts = 0;
+
+      while (attempts < 10 && nextSequence <= UPC_MAX_SEQUENCE) {
+        const sequencePart = String(nextSequence).padStart(5, '0');
+        const upcBody = `${supplierPrefix}${sequencePart}`;
+        const checkDigit = calculateUpcCheckDigit(upcBody);
+        const fullUpc = `${upcBody}${checkDigit}`;
+
+        const [existing] = await connection.query(
+          'SELECT 1 FROM products WHERE upc = ? LIMIT 1',
+          [fullUpc]
+        );
+
+        if (!existing || existing.length === 0) {
+          candidateUpc = { upc: fullUpc, sequence: nextSequence };
+          break;
+        }
+
+        nextSequence += 1;
+        attempts += 1;
+      }
+
+      if (!candidateUpc) {
+        const reason = nextSequence > UPC_MAX_SEQUENCE
+          ? 'UPC range exhausted for this supplier'
+          : 'Unable to find an available UPC';
+        const error = new Error(reason);
+        error.status = 409;
+        throw error;
+      }
+
+      setReservedSequence(supplierPrefix, candidateUpc.sequence);
+      return candidateUpc.upc;
+    });
+
+    return res.json({ success: true, upc: result });
+  } catch (error) {
+    console.error('Error generating UPC:', error);
+    const status = error.status && Number.isInteger(error.status) ? error.status : 500;
+    const message = status === 500 ? 'Failed to generate UPC' : error.message;
+    return res.status(status).json({ error: message, details: status === 500 ? error.message : undefined });
+  }
+});
+
 // Endpoint to check UPC and generate item number
 router.get('/check-upc-and-generate-sku', async (req, res) => {
   const { upc, supplierId } = req.query;
@@ -1149,4 +1298,4 @@ router.get('/product-categories/:pid', async (req, res) => {
   }
 });
 
-module.exports = router; 
+module.exports = router;