More layout/header tweaks for purchase orders

inventory-server/src/routes/purchase-orders.js

@@ -836,4 +836,65 @@ router.get('/order-vs-received', async (req, res) => {
   }
 });
 
+// New endpoint for delivery metrics
+router.get('/delivery-metrics', async (req, res) => {
+  try {
+    const pool = req.app.locals.pool;
+    
+    const { rows: deliveryData } = await pool.query(`
+      WITH po_dates AS (
+        SELECT 
+          po_id,
+          date as order_date
+        FROM purchase_orders 
+        WHERE status != 'canceled'
+        GROUP BY po_id, date
+      ),
+      receiving_dates AS (
+        SELECT 
+          receiving_id as po_id,
+          MIN(received_date) as first_received_date
+        FROM receivings
+        GROUP BY receiving_id
+      ),
+      delivery_times AS (
+        SELECT 
+          po.po_id,
+          po.order_date,
+          r.first_received_date,
+          CASE 
+            WHEN r.first_received_date IS NOT NULL AND po.order_date IS NOT NULL
+            THEN (r.first_received_date::date - po.order_date::date)
+            ELSE NULL
+          END as delivery_days
+        FROM po_dates po
+        JOIN receiving_dates r ON po.po_id = r.po_id
+        WHERE 
+          r.first_received_date IS NOT NULL 
+          AND po.order_date IS NOT NULL
+          AND r.first_received_date::date >= po.order_date::date
+      )
+      SELECT 
+        ROUND(AVG(delivery_days)::numeric, 1) as avg_delivery_days,
+        ROUND(PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY delivery_days)::numeric, 1) as median_delivery_days,
+        MIN(delivery_days) as min_delivery_days,
+        MAX(delivery_days) as max_delivery_days,
+        COUNT(*) as total_orders_with_delivery
+      FROM delivery_times
+      WHERE delivery_days >= 0 AND delivery_days <= 365  -- Filter out unreasonable values
+    `);
+
+    res.json({
+      avg_delivery_days: Number(deliveryData[0]?.avg_delivery_days) || 0,
+      median_delivery_days: Number(deliveryData[0]?.median_delivery_days) || 0,
+      min_delivery_days: Number(deliveryData[0]?.min_delivery_days) || 0,
+      max_delivery_days: Number(deliveryData[0]?.max_delivery_days) || 0,
+      total_orders_with_delivery: Number(deliveryData[0]?.total_orders_with_delivery) || 0
+    });
+  } catch (error) {
+    console.error('Error fetching delivery metrics:', error);
+    res.status(500).json({ error: 'Failed to fetch delivery metrics' });
+  }
+});
+
 module.exports = router;