default to max milage found for a new bill

db/index.ts

@@ -28,7 +28,6 @@ export async function getBookedDays() {
 export async function getBookingByUUID(uuid: string) {
   await connect()
   return Booking.findOne({ uuid })
-  //return booking.populate('bill').populate('booker').execPopulate()
 }
 
 export async function getBookings() {
@@ -116,3 +115,12 @@ export async function patchBill(bookingUUID: string, billData: BillDocument) {
 
   return bill.toJSON()
 }
+
+export async function getMilageMax(): Promise<number> {
+  const billMaxMilageEnd = await Bill.findOne({})
+    .sort('-milageEnd')
+    .select('milageEnd')
+    .exec()
+
+  return billMaxMilageEnd?.milageEnd
+}

pages/booking/[uuid]/bill.tsx

@@ -11,7 +11,7 @@ import {
   MILAGE_RATES,
   getMilageRateValue,
 } from '../../../db/enums'
-import { getBookingByUUID } from '../../../db/index'
+import { getBookingByUUID, getMilageMax } from '../../../db/index'
 import { dateFormatFrontend } from '../../../helpers/date'
 
 const milageRateOptions = Object.values(MILAGE_RATES).map((rate) => {
@@ -44,10 +44,13 @@ export const getServerSideProps: GetServerSideProps = async (context) => {
     res.end()
     return { props: {} }
   }
+
+  const milageMax = await getMilageMax()
+
   // TODO: hack, not sure why _id is not serilizable
   const bookingJSON = JSON.parse(JSON.stringify(booking.toJSON()))
   return {
-    props: { booking: bookingJSON },
+    props: { booking: bookingJSON, milageMax },
   }
 }
 
@@ -116,11 +119,15 @@ async function saveBill(
 
 export default function BillPage({
   booking: bookingProp,
+  milageMax,
 }: {
   booking: BookingDocument
+  milageMax: number
 }) {
   const [booking, setBooking] = useState(bookingProp)
-  const [milageStart, setMilageStart] = useState(booking.bill?.milageStart)
+  const [milageStart, setMilageStart] = useState(
+    booking.bill?.milageStart || milageMax
+  )
   const [milageEnd, setMilageEnd] = useState(booking.bill?.milageEnd)
   const [rate, setRate] = useState(
     booking.bill?.rate || MILAGE_RATES.EXTERN_LTE_200