first stab on bill model

db/bill.ts

@@ -0,0 +1,79 @@
+import * as mongoose from 'mongoose'
+import { BILL_STATUS, MILAGE_RATES } from './enums'
+import { BookingDocument } from './booking'
+
+export interface AdditionalCosts {
+  name: string
+  value: number
+}
+
+export interface BillDocument
+  extends mongoose.SchemaTimestampsConfig,
+    mongoose.Document {
+  booking: BookingDocument
+  milageStart: number
+  milageEnd: number
+  milage?: number
+  rate: MILAGE_RATES
+  status: BILL_STATUS
+  additionalCosts: AdditionalCosts[]
+}
+
+export interface BillModel extends mongoose.Model<BillDocument> {}
+
+const BillSchema = new mongoose.Schema<BillDocument>(
+  {
+    booking: {
+      type: mongoose.Schema.Types.ObjectId,
+      ref: 'Booking',
+      required: true,
+    },
+    milageStart: { type: Number, required: true },
+    milageEnd: { type: Number, required: true },
+    rate: {
+      type: Number,
+      enum: Object.values(MILAGE_RATES),
+      default: MILAGE_RATES.EXTERN_UP_TO_200,
+      required: true,
+    },
+    status: {
+      type: String,
+      enum: Object.values(BILL_STATUS),
+      default: BILL_STATUS.UNINVOICED,
+      required: true,
+    },
+    additionalCosts: [
+      {
+        name: { type: String, required: true },
+        value: { type: Number, required: true },
+      },
+    ],
+  },
+  { timestamps: true, collation: { locale: 'de', strength: 1 } }
+)
+
+BillSchema.virtual('milage').get(function () {
+  const bill = this as BillDocument
+
+  if (!bill.milageStart || !bill.milageEnd) {
+    return null
+  }
+  return bill.milageEnd - bill.milageStart
+})
+
+BillSchema.virtual('total').get(function () {
+  const bill = this as BillDocument
+
+  if (!bill.milageStart || !bill.milageEnd) {
+    return null
+  }
+  const milageCosts = bill.milage * bill.rate
+  const additionalCostSum = bill.additionalCosts
+    .map(({ value }) => value)
+    .reduce((acc, value) => acc + value, 0)
+
+  return milageCosts + additionalCostSum
+})
+
+export default <BillModel>mongoose.models.Bill ||
+  mongoose.model<BillDocument, BillModel>('Bill', BillSchema)