implemented bill update

app/lib/actions.ts

@@ -1,2 +1,69 @@
 'use server';
 
+import { z } from 'zod';
+import { revalidatePath } from 'next/cache';
+import { redirect } from 'next/navigation';
+import clientPromise from './mongodb';
+import { ObjectId } from 'mongodb';
+
+export type State = {
+    errors?: {
+        billName?: string[];
+    };
+    message?:string | null;
+}
+
+const FormSchema = z.object({
+    _id: z.string(),
+    billName: z.string({
+      invalid_type_error: 'Please select a bill name',
+    }),
+  });
+
+const UpdateBill = FormSchema.omit({ _id: true });
+
+export async function updateBill(locationId: string, billId:string, prevState:State, formData: FormData) {
+
+    const validatedFields = UpdateBill.safeParse({
+        billName: formData.get('billName'),
+    });
+
+    // If form validation fails, return errors early. Otherwise, continue...
+    if(!validatedFields.success) {
+        console.log("updateBill.validation-error");
+        return({
+            errors: validatedFields.error.flatten().fieldErrors,
+            message: "Missing Fields. Field to Update Bill.",
+        });
+    }
+
+    const {
+        billName,
+    } = validatedFields.data;
+
+    // update the bill in the mongodb
+    const client = await clientPromise;
+    const db = client.db("rezije");
+
+    // find a location with the given locationID
+    const post = await db.collection<Location>("lokacije").updateOne(
+        {
+            _id: locationId // find a location with the given locationID
+        },
+        {
+            $set: {
+                "bills.$[elem].name": billName,
+            }
+        }, {
+            arrayFilters: [
+                { "elem._id": { $eq: new ObjectId(billId) } } // find a bill with the given billID
+            ]
+        });
+
+    console.log("updateBill.success", post);
+
+    // clear the cache for the path
+    revalidatePath('/');
+    // go to the bill list
+    redirect('/');
+}