fix(alerts): limit alerts to 500 per type in SQL + frontend pagination with 'Ver más' + summary bar

pos/services/inventory_engine.py

@@ -272,38 +272,72 @@ def record_initial(conn, inventory_id, branch_id, quantity, cost=None):
     return result
 
 
-def get_alerts(conn, branch_id=None):
-    """Get stock alerts: zero stock, below minimum, above maximum."""
-    stock_map = get_stock_bulk(conn, branch_id)
+def get_alerts(conn, branch_id=None, limit_per_type=500):
+    """Get stock alerts: zero stock, below minimum, above maximum.
+    Returns at most limit_per_type alerts per severity to avoid browser freeze.
+    """
     cur = conn.cursor()
-
-    where = "WHERE i.is_active = true"
+    branch_filter = ""
     params = []
     if branch_id:
-        where += " AND i.branch_id = %s"
+        branch_filter = " AND i.branch_id = %s"
         params.append(branch_id)
 
+    # Use a single SQL query with window functions to rank and limit per type
     cur.execute(f"""
-        SELECT i.id, i.part_number, i.name, i.min_stock, i.max_stock, i.branch_id
-        FROM inventory i {where}
-    """, params)
+        WITH stock AS (
+            SELECT inventory_id, COALESCE(SUM(quantity), 0) AS qty
+            FROM inventory_operations
+            GROUP BY inventory_id
+        ),
+        alerts_raw AS (
+            SELECT
+                i.id AS inventory_id,
+                i.part_number,
+                i.name,
+                COALESCE(s.qty, 0) AS stock,
+                i.min_stock,
+                i.max_stock,
+                i.branch_id,
+                CASE
+                    WHEN COALESCE(s.qty, 0) <= 0 THEN 'zero'
+                    WHEN i.min_stock IS NOT NULL AND COALESCE(s.qty, 0) < i.min_stock THEN 'low'
+                    WHEN i.max_stock IS NOT NULL AND COALESCE(s.qty, 0) > i.max_stock THEN 'over'
+                END AS alert_type,
+                CASE
+                    WHEN COALESCE(s.qty, 0) <= 0 THEN 'critical'
+                    WHEN i.min_stock IS NOT NULL AND COALESCE(s.qty, 0) < i.min_stock THEN 'warning'
+                    WHEN i.max_stock IS NOT NULL AND COALESCE(s.qty, 0) > i.max_stock THEN 'info'
+                END AS severity
+            FROM inventory i
+            LEFT JOIN stock s ON s.inventory_id = i.id
+            WHERE i.is_active = true {branch_filter}
+        ),
+        ranked AS (
+            SELECT *,
+                ROW_NUMBER() OVER (PARTITION BY alert_type ORDER BY inventory_id) AS rn
+            FROM alerts_raw
+            WHERE alert_type IS NOT NULL
+        )
+        SELECT inventory_id, part_number, name, stock, min_stock, max_stock, branch_id, alert_type, severity
+        FROM ranked
+        WHERE rn <= %s
+        ORDER BY severity DESC, inventory_id
+    """, params + [limit_per_type])
 
     alerts = []
     for row in cur.fetchall():
-        inv_id, part_num, name, min_s, max_s, br_id = row
-        stock = stock_map.get(inv_id, 0)
-
-        if stock <= 0:
-            alerts.append({'type': 'zero', 'severity': 'critical', 'inventory_id': inv_id,
-                           'part_number': part_num, 'name': name, 'stock': stock, 'branch_id': br_id})
-        elif min_s and stock < min_s:
-            alerts.append({'type': 'low', 'severity': 'warning', 'inventory_id': inv_id,
-                           'part_number': part_num, 'name': name, 'stock': stock,
-                           'min_stock': min_s, 'branch_id': br_id})
-        elif max_s and stock > max_s:
-            alerts.append({'type': 'over', 'severity': 'info', 'inventory_id': inv_id,
-                           'part_number': part_num, 'name': name, 'stock': stock,
-                           'max_stock': max_s, 'branch_id': br_id})
+        alerts.append({
+            'inventory_id': row[0],
+            'part_number': row[1],
+            'name': row[2],
+            'stock': row[3],
+            'min_stock': row[4],
+            'max_stock': row[5],
+            'branch_id': row[6],
+            'type': row[7],
+            'severity': row[8],
+        })
 
     cur.close()
     return alerts