refactor: add Money entity (#49)

* refactor: add `Money` entity
* refactor: remove `formatFiat`

Author: erectfully

src/modules/statistics/commands/get-monthly-stats/get-monthly-stats.service.ts

@@ -1,11 +1,9 @@
-import { dinero, toDecimal } from 'dinero.js'
 import { Usecase } from '../../../../common/domain/usecase/usecase'
-import { Distance } from '../../../geocoding/entities/distance'
 import { TripRepository } from '../../../trips/trip.repository'
-import { PLN } from '@dinero.js/currencies'
 import { Injectable } from '@nestjs/common'
 import { GetMonthlyStatsResponse } from './get-monthly-stats.response'
 import { Formatter } from '../../../../utilities/formatter'
+import { Money } from '../../../trips/entities/money'
 
 @Injectable()
 export class GetMonthlyStatsService implements Usecase<undefined, GetMonthlyStatsResponse[]> {
@@ -22,7 +20,7 @@ export class GetMonthlyStatsService implements Usecase<undefined, GetMonthlyStat
         day: Formatter.formatDateToMonthAndDayOfMonthFormat(summarised.day),
         total_distance: Formatter.formatDistance(summarised.totalDistance),
         avg_ride: Formatter.formatDistance(summarised.averageDistance),
-        avg_price: Formatter.formatFiat(summarised.averagePrice),
+        avg_price: Money.fromFloat(summarised.averagePrice).toString(),
       })
     })
 

src/modules/statistics/commands/get-weekly-stats/get-weekly.stats.service.ts

@@ -1,11 +1,9 @@
-import { dinero, toDecimal } from 'dinero.js'
 import { Usecase } from '../../../../common/domain/usecase/usecase'
 import { Distance } from '../../../geocoding/entities/distance'
 import { TripRepository } from '../../../trips/trip.repository'
 import { GetWeeklyStatsResponse } from './get-weekly.stats.response'
-import { PLN } from '@dinero.js/currencies'
 import { Injectable } from '@nestjs/common'
-import { Formatter } from '../../../../utilities/formatter'
+import { Money } from '../../../trips/entities/money'
 
 @Injectable()
 export class GetWeeklyStatsService implements Usecase<undefined, GetWeeklyStatsResponse> {
@@ -17,7 +15,7 @@ export class GetWeeklyStatsService implements Usecase<undefined, GetWeeklyStatsR
 
     return {
       total_distance: new Distance(distance).toString(),
-      total_price: Formatter.formatFiat(price),
+      total_price: Money.fromFloat(price).toString(),
     }
   }
 }

src/modules/trips/commands/create-trip/create-trip.service.ts

@@ -4,13 +4,11 @@ import { CreateTripResponse } from './data-transfering/create-trip.response'
 import { TripRepository } from '../../trip.repository'
 import { CreateTripRequest } from './data-transfering/create-trip.request'
 import { Trip } from '../../trip.entity'
-import { dinero } from 'dinero.js'
-import { PLN } from '@dinero.js/currencies'
 import { Usecase } from '../../../../common/domain/usecase/usecase'
-import { Formatter } from '../../../../utilities/formatter'
 import { InvalidAddressError } from '../../../geocoding/errors/invalid-address.error'
 import { Result, err, ok } from 'neverthrow'
 import { Coordinates } from '../../../geocoding/entities/coordinates'
+import { Money } from '../../entities/money'
 
 @Injectable()
 export class CreateTripService implements Usecase<CreateTripRequest, Result<CreateTripResponse, InvalidAddressError>> {
@@ -37,7 +35,7 @@ export class CreateTripService implements Usecase<CreateTripRequest, Result<Crea
 
     const distance = coordinatedOfStartingPoint.getDistanceBetweenCoordinates(coordinatedOfDestinationPoint)
 
-    const price = dinero({ amount: Number.parseFloat((request.price * 100).toFixed(2)), currency: PLN })
+    const price = Money.fromFloat(request.price)
 
     let trip = new Trip({
       startAddress: request.start_address,
@@ -55,7 +53,7 @@ export class CreateTripService implements Usecase<CreateTripRequest, Result<Crea
       id: trip.id,
       startAddress: trip.properties.startAddress,
       endAddress: trip.properties.endAddress,
-      price: Formatter.formatFiat(trip.properties.price.toJSON().amount / 100),
+      price: trip.properties.price.toString(),
       date: trip.properties.date,
       distance: trip.properties.distance.toString(),
     })

src/modules/trips/entities/money.spec.ts

@@ -0,0 +1,14 @@
+import { PLN } from '@dinero.js/currencies'
+import { Money } from './money'
+
+describe('Money', () => {
+  it('should return money in float', () => {
+    const money = new Money(100, PLN)
+    expect(money.toFloat()).toBe(1)
+  })
+
+  it('should return money in string', () => {
+    const money = Money.fromFloat(1, PLN)
+    expect(money.toString()).toBe('1.00PLN')
+  })
+})

src/modules/trips/entities/money.ts

@@ -0,0 +1,40 @@
+import { PLN } from '@dinero.js/currencies'
+import { Currency, Dinero, dinero, toDecimal } from 'dinero.js'
+import { Formatter } from '../../../utilities/formatter'
+
+export class Money {
+  private readonly baseAmount: Dinero<number>
+
+  constructor(baseAmount: number, public readonly currency: Currency<number>) {
+    if (baseAmount < 0) {
+      throw new Error('Money amount cannot be negative')
+    }
+
+    if (currency !== PLN) {
+      throw new Error('Money currency must be PLN')
+    }
+
+    this.baseAmount = dinero({ amount: baseAmount, currency })
+  }
+
+  static fromFloat(amount: number, currency: Currency<number> = PLN): Money {
+    const amountInGrosze = amount * 100
+    const amountInGroszeRounded = Math.round(amountInGrosze)
+    return new Money(amountInGroszeRounded, currency)
+  }
+
+  toString(): string {
+    const amountInDecimal = toDecimal(this.baseAmount)
+    let valueInSubunits = Number.parseFloat(amountInDecimal) * 100
+    valueInSubunits = Math.round(valueInSubunits)
+
+    return toDecimal(
+      dinero({ amount: valueInSubunits, currency: PLN }),
+      ({ value, currency }) => `${value}${currency.code}`,
+    )
+  }
+
+  toFloat(): number {
+    return parseFloat(toDecimal(this.baseAmount))
+  }
+}

src/modules/trips/trip.entity.ts

@@ -1,12 +1,12 @@
 import { Entity } from '../../common/domain/entity'
 import { Coordinates } from '../geocoding/entities/coordinates'
 import { Distance } from '../geocoding/entities/distance'
-import { Dinero } from 'dinero.js'
+import { Money } from './entities/money'
 
 interface TripProperties {
   startAddress: string
   endAddress: string
-  price: Dinero<number>
+  price: Money
   date: Date
   distance?: Distance
   startCoordinates?: Coordinates

src/modules/trips/trip.mapper.ts

@@ -1,19 +1,18 @@
 import { Trip } from './trip.entity'
 import { Prisma, Trip as _Trip } from '@prisma/client'
 import { Injectable } from '@nestjs/common'
-import { dinero } from 'dinero.js'
-import { PLN } from '@dinero.js/currencies'
 import { Distance } from '../geocoding/entities/distance'
 import { DatabaseRecords } from '../../configuration/database-records'
 import { Mapper } from '../../common/persistance/mapper'
+import { Money } from './entities/money'
 
 @Injectable()
 export class TripMapper implements Mapper<Trip, DatabaseRecords.TripCreateRecord, DatabaseRecords.TripRecord> {
   toPersistence(entity: Trip): Prisma.TripCreateInput {
     return {
       startingAddress: entity.properties.startAddress,
       endingAddress: entity.properties.endAddress,
-      priceInPLN: entity.properties.price.toJSON().amount / 100,
+      priceInPLN: entity.properties.price.toFloat(),
       date: entity.properties.date,
       distanceInKilometers: entity.properties.distance.baseScalar,
     }
@@ -23,7 +22,7 @@ export class TripMapper implements Mapper<Trip, DatabaseRecords.TripCreateRecord
       {
         startAddress: record.startingAddress,
         endAddress: record.endingAddress,
-        price: dinero({ amount: record.priceInPLN * 100, currency: PLN }),
+        price: Money.fromFloat(record.priceInPLN),
         date: record.date,
         distance: new Distance(record.distanceInKilometers),
       },

src/utilities/formatter.ts

@@ -1,15 +1,7 @@
-import { PLN } from '@dinero.js/currencies'
-import { dinero, toDecimal } from 'dinero.js'
 import { Distance } from '../modules/geocoding/entities/distance'
 
 // eslint-disable-next-line @typescript-eslint/no-namespace
 export namespace Formatter {
-  export function formatFiat(fiat: number) {
-    return toDecimal(
-      dinero({ amount: Number.parseFloat(fiat.toFixed(2)) * 100, currency: PLN }),
-      ({ value, currency }) => `${value}${currency.code}`,
-    )
-  }
   export function formatDistance(distance: number) {
     return new Distance(distance).toString()
   }