Ports to Scala 3 (#4)

Also tidies up, improves the README.

.gitignore

@@ -220,4 +220,6 @@ $RECYCLE.BIN/
 # Windows shortcuts
 *.lnk
 
-# End of https://www.gitignore.io/api/sbt,scala,linux,macos,windows,intellij,intellij+all
+# End of https://www.gitignore.io/api/sbt,scala,linux,macos,windows,intellij,intellij+all
+
+.bsp/

README.md

@@ -1,7 +1,7 @@
 # Welcome to PowerDale
 
-PowerDale is a small town with around 100 residents. Most houses have a smartmeter installed that can save and send information
-about how much energy a house has used.
+PowerDale is a small town with around 100 residents. Most houses have a smart meter installed that can save and send information
+about how much energy a house is using at a given point in time.
 
 There are three major providers of energy in town that charge different amounts for the power they supply.
 
@@ -12,7 +12,7 @@ There are three major providers of energy in town that charge different amounts
 # Introducing JOI Energy
 
 JOI Energy is a new startup in the energy industry.
-Rather than selling energy they want to differentiate themselves from the market by recording their customers' energy usage from their smartmeters and
+Rather than selling energy they want to differentiate themselves from the market by recording their customers' energy usage from their smart meters and
 recommending the best suppler to meet their needs.
 
 You have been placed into their development team, whose current goal is to produce an API which their customers and smart meters will interact with.
@@ -49,7 +49,7 @@ To trial the new JOI software 5 people from the JOI accounts team have agreed to
 ## Overview
 
 JOI Energy is a new energy company that uses data to ensure customers are 
-able to be on the best pricePlan for their energy consumption.
+able to be on the best price plan for their energy consumption.
 
 ## API
 
@@ -70,14 +70,14 @@ POST
 {
     "smartMeterId": <smartMeterId>,
     "electricityReadings": [
-        { "time": <timestamp>, "reading": <reading> },
+        { "time": "2019-01-24T18:11:27.142Z", "reading": <reading> },
         ...
     ]
 }
 ```
 
-`timestamp`: Unix timestamp, e.g. `1504777098`   
-`reading`: kW reading of meter at that time, e.g. `0.0503`
+`timestamp`: Timestamp in ISO Format   
+`reading`: kW reading of meter at that time as a number, e.g. `0.0503`
 
 ### Get Stored Readings
 
@@ -94,8 +94,8 @@ GET
 
 ```json
 [
-    { "time": "2017-09-07T10:37:52.362Z", "reading": 1.3524882598124337 },
-    ...
+  { "time": "2017-09-07T10:37:52.362Z", "reading": 1.3524882598124337 },
+  ...
 ]
 ```
 
@@ -148,14 +148,13 @@ GET
 
 ## Requirements
 
-- [Java 13](https://www.oracle.com/technetwork/java/javase/downloads/jdk13-downloads-5672538.html)
-- [Sbt 1.3.7+](https://www.scala-sbt.org/)
+The project is written in Scala 3. We recommend using  [Java 17](https://adoptium.net/en-GB/) or higher.
 
-## Build
+The build system is SBT - we are using the latest version, currently 1.9.3.
 
-```console
-$ sbt build
-```
+We use Akka HTTP in this implementation.
+
+## Build
 
 ## Test
 
@@ -166,5 +165,7 @@ $ sbt test
 ## Run
 
 ```console
-$ sbt run # available at localhost:8080 by default
+$ sbt run
 ```
+
+The application starts on `localhost:8080` by default.

build.sbt

@@ -1,30 +1,39 @@
 inThisBuild(
   List(
-    name := "joi-energy-scala",
     version := "0.1",
-    scalaVersion := "2.13.10",
-    Compile / mainClass := Some("com.tw.energy.WebApp"),
-    run / mainClass := Some("com.tw.energy.WebApp"),
-  ),
-)
+    scalaVersion := "3.3.0"
+))
+
 
 val circeVersion = "0.14.5"
-val akkaVersion = "2.6.20"
-val akkaHttpVersion = "10.2.10"
+val akkaVersion = "2.8.3"
+val akkaHttpVersion = "10.5.2"
 val akkaHttpCirceVersion = "1.39.2"
-val scalaTestVersion = "3.2.15"
+val scalaTestVersion = "3.2.16"
 
-libraryDependencies += "com.typesafe.akka" %% "akka-http" % akkaHttpVersion // Http Server library: https://doc.akka.io/docs/akka-http/current/server-side/index.html
-libraryDependencies += "com.typesafe.akka" %% "akka-stream" % akkaVersion // Required by akka-http
+lazy val circeCore = "io.circe" %% "circe-core" % circeVersion
+lazy val circeGeneric = "io.circe" %% "circe-generic" % circeVersion
+lazy val circeParser = "io.circe" %% "circe-parser" % circeVersion
+lazy val akkaHttp = "com.typesafe.akka" %% "akka-http" % akkaHttpVersion // Http Server library: https://doc.akka.io/docs/akka-http/current/server-side/index.html
+lazy val akkaStream = "com.typesafe.akka" %% "akka-stream" % akkaVersion // Required by akka-http
+// lazy val akkaHttpCirce = "de.heikoseeberger" %% "akka-http-circe" % akkaHttpCirceVersion
 
-//json library: https://circe.github.io/circe/
-libraryDependencies += "io.circe" %% "circe-core" % circeVersion
-libraryDependencies += "io.circe" %% "circe-generic" % circeVersion
-libraryDependencies += "io.circe" %% "circe-parser" % circeVersion
-libraryDependencies += "de.heikoseeberger" %% "akka-http-circe" % akkaHttpCirceVersion
+lazy val scalaTest = "org.scalatest" %% "scalatest" % scalaTestVersion % Test // Test framework: http://www.scalatest.org/
+lazy val akkaHttpTestKit = "com.typesafe.akka" %% "akka-http-testkit" % akkaHttpVersion % Test // utilities to test routes: https://doc.akka.io/docs/akka-http/current/routing-dsl/testkit.html
+lazy val akkaTestKit = "com.typesafe.akka" %% "akka-testkit" % akkaVersion % Test // required by akka-http-testkit
 
-libraryDependencies += "org.scalatest" %% "scalatest" % scalaTestVersion % Test //Test framework: http://www.scalatest.org/
-libraryDependencies += "com.typesafe.akka" %% "akka-http-testkit" % akkaHttpVersion % Test //utilities to test routes: https://doc.akka.io/docs/akka-http/current/routing-dsl/testkit.html
-libraryDependencies += "com.typesafe.akka" %% "akka-testkit" % akkaVersion % Test //required by akka-http-testkit
+libraryDependencies ++= List(
+  akkaHttp,
+  akkaStream,
+  akkaTestKit,
+  akkaHttpTestKit,
+  circeCore,
+  circeGeneric,
+  circeParser,
+  scalaTest
+)
 
 scalacOptions ++= Seq("-deprecation", "-feature")
+
+//conflictWarning := ConflictWarning.default
+conflictManager := ConflictManager.latestRevision

project/build.properties

@@ -1 +1 @@
-sbt.version = 1.8.2
+sbt.version = 1.9.3

src/main/scala/com/tw/energy/JOIEnergyApplication.scala → src/main/scala/com/tw/energy/Application.scala

@@ -2,8 +2,11 @@ package com.tw.energy
 
 import akka.http.scaladsl.server.Directives._
 import akka.http.scaladsl.server.Route
-import com.tw.energy.controller.{MeterReadingController, PricePlanComparatorController}
-import com.tw.energy.service.{AccountService, MeterReadingService, PricePlanService}
+import com.tw.energy.controller.MeterReadingController
+import com.tw.energy.controller.PricePlanComparatorController
+import com.tw.energy.service.AccountService
+import com.tw.energy.service.MeterReadingService
+import com.tw.energy.service.PricePlanService
 
 
 class JOIEnergyApplication {

src/main/scala/com/tw/energy/Configuration.scala

@@ -1,6 +1,7 @@
 package com.tw.energy
 
-import com.tw.energy.domain.{ElectricityReading, PricePlan}
+import com.tw.energy.domain.ElectricityReading
+import com.tw.energy.domain.PricePlan
 import com.tw.energy.generator.Generator
 
 object Configuration {

src/main/scala/com/tw/energy/WebServer.scala

@@ -4,13 +4,14 @@ import akka.actor.ActorSystem
 import akka.http.scaladsl.Http
 import akka.http.scaladsl.server.Route
 
-import scala.concurrent.{ExecutionContext, Future}
+import scala.concurrent.ExecutionContext
+import scala.concurrent.Future
 import scala.io.StdIn
 
 object WebServer
 
 class WebServer(val route: Route, val host: String = "localhost", val port: Int = 8080) {
-  implicit val system: ActorSystem = ActorSystem("joi-energy-system")
+  implicit val system: ActorSystem = ActorSystem("joy-of-energy-system")
   implicit val executionContext: ExecutionContext = system.dispatcher
 
   def start(): RunningServer = {

src/main/scala/com/tw/energy/controller/JsonSupport.scala

@@ -1,6 +1,42 @@
 package com.tw.energy.controller
 
-import de.heikoseeberger.akkahttpcirce.FailFastCirceSupport
+import akka.http.scaladsl.marshalling.{Marshaller, ToEntityMarshaller}
+import akka.http.scaladsl.model.{HttpCharsets, MediaTypes}
+import akka.http.scaladsl.unmarshalling.{FromEntityUnmarshaller, Unmarshaller}
+import akka.http.scaladsl.util.FastFuture
+import akka.util.ByteString
+import io.circe.{Decoder, Encoder, Error}
+import io.circe.syntax.*
+import io.circe.parser.decode
 
-trait JsonSupport extends FailFastCirceSupport {
-}
+import java.nio.charset.StandardCharsets
+
+/**
+ * Rudimentary support for handling json marshalling and unmarshalling JSON using Circe. To use,
+ * ensure that `Encoder` and `Decoder` implicits are available for the type you want to handle. For example,
+ * by `import io.circe.generic.auto.*` to gain automatic encoder and decoder generation for case classes.
+ *
+ * Inspired by Heiko Seeberger's code at https://github.com/hseeberger/akka-http-json/tree/master/akka-http-circe/src - but
+ * which doesn't yet support Scala 3 out of the box.
+ */
+trait JsonSupport {
+
+  implicit def jsonToEntityMarshaller[A](implicit encoder: Encoder[A]): ToEntityMarshaller[A] =
+    Marshaller.StringMarshaller.wrap(MediaTypes.`application/json`)((a:A) => a.asJson.noSpaces)
+
+  implicit def jsonFromEntityUnmarshaller[A](implicit decoder: Decoder[A]): FromEntityUnmarshaller[A] = {
+    Unmarshaller
+      .byteStringUnmarshaller
+      .forContentTypes(MediaTypes.`application/json`)
+      .andThen(stringViaDecoderUnmarshaller)
+  }
+
+  private def stringViaDecoderUnmarshaller[A](implicit decoder: Decoder[A]): Unmarshaller[ByteString, A] =
+    Unmarshaller.withMaterializer[ByteString, A](_ => _ => { bs =>
+      decode[A](bs.decodeString(StandardCharsets.UTF_8)).fold(
+        (error: Error) => FastFuture.failed(error),
+        (a: A) => FastFuture.successful(a)
+      )
+    })
+
+}

src/main/scala/com/tw/energy/controller/MeterReadingController.scala

@@ -1,15 +1,14 @@
 package com.tw.energy.controller
 
-import akka.http.scaladsl.marshalling.ToResponseMarshallable
-import akka.http.scaladsl.model._
-import akka.http.scaladsl.server.Directives.{complete, get, path, _}
+import akka.http.scaladsl.marshalling.{ToEntityMarshaller, ToResponseMarshallable, ToResponseMarshaller}
+import akka.http.scaladsl.model.*
+import akka.http.scaladsl.server.Directives.*
 import akka.http.scaladsl.server.PathMatchers.Segment
 import akka.http.scaladsl.server.Route
-import com.tw.energy.domain.MeterReadings
+import com.tw.energy.domain.{ElectricityReading, MeterReadings}
 import com.tw.energy.domain.StringTypes.SmartMeterId
 import com.tw.energy.service.MeterReadingService
-import io.circe.generic.auto._
-
+import io.circe.generic.auto.*
 
 class MeterReadingController(meterReadingService: MeterReadingService) extends JsonSupport {
   def routes: Route = pathPrefix("readings") {

src/main/scala/com/tw/energy/controller/PricePlanComparatorController.scala

@@ -1,17 +1,16 @@
 package com.tw.energy.controller
 
-import akka.http.scaladsl.marshalling.ToResponseMarshallable
-import akka.http.scaladsl.model._
-import akka.http.scaladsl.server.Directives.{complete, get, path, _}
+import akka.http.scaladsl.marshalling.{ToEntityMarshaller, ToResponseMarshallable}
+import akka.http.scaladsl.model.*
+import akka.http.scaladsl.server.Directives.*
 import akka.http.scaladsl.server.PathMatchers.Segment
 import akka.http.scaladsl.server.Route
-import com.tw.energy.domain.PricePlanCosts
+import com.tw.energy.domain.{ElectricityReading, PricePlanCosts}
 import com.tw.energy.domain.StringTypes.{PlanName, SmartMeterId}
 import com.tw.energy.service.{AccountService, PricePlanService}
-import io.circe.generic.auto._
+import io.circe.generic.auto.*
 
-
-class PricePlanComparatorController(pricePlanService: PricePlanService, accountService: AccountService) extends JsonSupport {
+class PricePlanComparatorController(pricePlanService: PricePlanService, accountService: AccountService) extends JsonSupport  {
   def routes: Route = pathPrefix("price-plans") {
     get {
       path("compare-all" / Segment) { smartMeterId =>

src/main/scala/com/tw/energy/domain/PricePlan.scala

@@ -1,8 +1,10 @@
 package com.tw.energy.domain
 
-import java.time.{DayOfWeek, LocalDateTime}
+import com.tw.energy.domain.StringTypes.EnergySupplier
+import com.tw.energy.domain.StringTypes.PlanName
 
-import com.tw.energy.domain.StringTypes.{EnergySupplier, PlanName}
+import java.time.DayOfWeek
+import java.time.LocalDateTime
 
 case class PricePlan(planName: PlanName, energySupplier: EnergySupplier, unitRate: BigDecimal, peakTimeMultipliers: List[PeakTimeMultiplier] = List()) {
   def calculatePrice(localDateTime: LocalDateTime): BigDecimal = {

src/main/scala/com/tw/energy/generator/Generator.scala

@@ -1,9 +1,8 @@
 package com.tw.energy.generator
 
-import java.time.Instant
-
 import com.tw.energy.domain.ElectricityReading
 
+import java.time.Instant
 import scala.util.Random
 
 object Generator {

src/main/scala/com/tw/energy/service/AccountService.scala

@@ -1,6 +1,7 @@
 package com.tw.energy.service
 
-import com.tw.energy.domain.StringTypes.{AccountId, SmartMeterId}
+import com.tw.energy.domain.StringTypes.AccountId
+import com.tw.energy.domain.StringTypes.SmartMeterId
 
 class AccountService(private val pricePlanIdByAccountId: Map[SmartMeterId, AccountId]) {
   def getPricePlanIdForSmartMeterId(smartMeterId: SmartMeterId): Option[AccountId] = {

src/main/scala/com/tw/energy/service/MeterReadingService.scala

@@ -1,7 +1,8 @@
 package com.tw.energy.service
 
+import com.tw.energy.domain.ElectricityReading
+import com.tw.energy.domain.MeterReadings
 import com.tw.energy.domain.StringTypes.SmartMeterId
-import com.tw.energy.domain.{ElectricityReading, MeterReadings}
 
 class MeterReadingService(private[service] var readingsByMeterId: Map[SmartMeterId, Seq[ElectricityReading]] = Map()) {
   def getReadings(smartMeterId: SmartMeterId): Option[Seq[ElectricityReading]] = {

src/main/scala/com/tw/energy/service/PricePlanService.scala

@@ -1,8 +1,10 @@
 package com.tw.energy.service
 
 
-import com.tw.energy.domain.StringTypes.{PlanName, SmartMeterId}
-import com.tw.energy.domain.{ElectricityReading, PricePlan}
+import com.tw.energy.domain.ElectricityReading
+import com.tw.energy.domain.PricePlan
+import com.tw.energy.domain.StringTypes.PlanName
+import com.tw.energy.domain.StringTypes.SmartMeterId
 
 class PricePlanService(pricePlans: Seq[PricePlan], meterReadingService: MeterReadingService) {
 

src/test/scala/EndpointIntegrationTest.scala

@@ -1,19 +1,21 @@
 import akka.actor.ActorSystem
 import akka.http.scaladsl.Http
-import akka.http.scaladsl.model._
+import akka.http.scaladsl.model.*
+import com.tw.energy.JOIEnergyApplication
+import com.tw.energy.WebServer
+import com.tw.energy.controller.JsonSupport
 import com.tw.energy.domain.MeterReadings
 import com.tw.energy.generator.Generator
-import com.tw.energy.{JOIEnergyApplication, WebServer}
-import io.circe.generic.auto._
-import io.circe.syntax._
+import io.circe.generic.auto.*
+import io.circe.syntax.*
 import org.scalatest.BeforeAndAfterAll
 import org.scalatest.flatspec.AsyncFlatSpec
 import org.scalatest.matchers.should.Matchers
 
 import scala.concurrent.Future
 import scala.util.Random
 
-class EndpointIntegrationTest extends AsyncFlatSpec with Matchers with BeforeAndAfterAll {
+class EndpointIntegrationTest extends AsyncFlatSpec with Matchers with BeforeAndAfterAll with JsonSupport {
   private implicit val system: ActorSystem = ActorSystem()
   private val application = new JOIEnergyApplication
   private val port = 8000 + Random.nextInt(1000)