Forex task

.gitignore

@@ -21,3 +21,4 @@ TAGS
 tests.iml
 # Auto-copied by sbt-microsites
 docs/src/main/tut/contributing.md
+.sdkmanrc

forex-mtl/README.md

@@ -0,0 +1,69 @@
+# Forex
+
+A micro-service which proxies requests to a rate service.
+
+## API
+
+`/rates?from=currency&to=currency` - returns rate for provided currencies
+
+Available currencies:
+
+- AUD
+- CAD
+- CHF
+- EUR
+- GBP
+- NZD
+- JPY
+- SGD
+- USD
+
+## Internals
+
+Internally the service uses in-memory cache with `EXPIRE_PERIOD` ttl. When request comes, it tries to get data from the cache.
+If it doesn't have a rate for provided currencies, the service sends requests to the rate API and obtains rates for all 
+possible pairs of supported currencies and put them into the cache.
+
+## Running
+
+### Prerequisites
+
+You should have installed and running docker
+
+### Starting the app
+
+1. Run image [one-frame](https://hub.docker.com/r/paidyinc/one-frame) by a command:
+    ```shell
+    docker run -p 8087:8080 paidyinc/one-frame
+    ```
+2. Run the app by a command:
+    ```shell
+    sbt run
+    ```
+
+    If you want to set env variables you should use next command(example):
+    ```shell
+    API_URI=http://localhost:9090 sbt run
+    ```
+
+    Available ENV variables:
+    * API_URI - url to API of rate service. Format is: `http://host:port`
+    * API_TOKEN - auth token of the rate service API. It is passed in a header `token`
+    * EXPIRE_PERIOD - cache entry ttl. Format is: `length units`, e.g. `5 minutes`. PLease note this value is being 
+validated in order to prevent exceeding API requests limit. If you enter too small number, for example, `1 minute` then the service won't start.
+It happens because API requests limit is 1000 requests per day and validation looks like: `24 * 60 / EXPIRE_PERIOD (in minutes) < 1000`
+
+## Testing
+
+### Prerequisites
+
+You should have installed and running docker
+
+- simple tests running
+    ```shell
+    sbt test
+    ```
+- running tests with coverage
+    ```shell
+    sbt coverage test coverageReport coverageAggregate
+    ```

forex-mtl/build.sbt

@@ -54,6 +54,11 @@ libraryDependencies ++= Seq(
   Libraries.cats,
   Libraries.catsEffect,
   Libraries.fs2,
+  Libraries.fs2SttpBackend,
+  Libraries.sttpCirce,
+  Libraries.scalaCacheEffect,
+  Libraries.scalaCacheCaffeine,
+  Libraries.enumeratum,
   Libraries.http4sDsl,
   Libraries.http4sServer,
   Libraries.http4sCirce,
@@ -63,7 +68,9 @@ libraryDependencies ++= Seq(
   Libraries.circeParser,
   Libraries.pureConfig,
   Libraries.logback,
-  Libraries.scalaTest        % Test,
-  Libraries.scalaCheck       % Test,
-  Libraries.catsScalaCheck   % Test
+  Libraries.scalaTest           % Test,
+  Libraries.scalaCheck          % Test,
+  Libraries.catsScalaCheck      % Test,
+  Libraries.testContainers      % Test,
+  Libraries.catsEffectScalaTest % Test
 )

forex-mtl/project/Dependencies.scala

@@ -3,47 +3,62 @@ import sbt._
 object Dependencies {
 
   object Versions {
-    val cats                = "2.5.0"
-    val catsEffect          = "2.4.1"
-    val fs2                 = "2.5.4"
-    val http4s              = "0.21.22"
-    val circe               = "0.13.0"
-    val pureConfig          = "0.14.1"
-
-    val kindProjector       = "0.10.3"
-    val logback             = "1.2.3"
-    val scalaCheck          = "1.15.3"
-    val scalaTest           = "3.2.7"
-    val catsScalaCheck      = "0.3.0"
+    val cats        = "2.5.0"
+    val catsEffect  = "2.5.3"
+    val fs2         = "2.5.4"
+    val sttpBackend = "3.3.6"
+    val http4s      = "0.21.22"
+    val circe       = "0.13.0"
+    val pureConfig  = "0.14.1"
+    val scalaCache  = "0.28.0"
+    val enumeratum  = "1.7.3"
+
+    val kindProjector  = "0.10.3"
+    val logback        = "1.2.3"
+    val scalaCheck     = "1.15.3"
+    val scalaTest      = "3.2.7"
+    val catsScalaCheck = "0.3.0"
+    val testContainers = "0.40.12"
+    val scalatestCats  = "0.5.4"
   }
 
   object Libraries {
-    def circe(artifact: String): ModuleID = "io.circe"    %% artifact % Versions.circe
-    def http4s(artifact: String): ModuleID = "org.http4s" %% artifact % Versions.http4s
-
-    lazy val cats                = "org.typelevel"         %% "cats-core"                  % Versions.cats
-    lazy val catsEffect          = "org.typelevel"         %% "cats-effect"                % Versions.catsEffect
-    lazy val fs2                 = "co.fs2"                %% "fs2-core"                   % Versions.fs2
-
-    lazy val http4sDsl           = http4s("http4s-dsl")
-    lazy val http4sServer        = http4s("http4s-blaze-server")
-    lazy val http4sCirce         = http4s("http4s-circe")
-    lazy val circeCore           = circe("circe-core")
-    lazy val circeGeneric        = circe("circe-generic")
-    lazy val circeGenericExt     = circe("circe-generic-extras")
-    lazy val circeParser         = circe("circe-parser")
-    lazy val pureConfig          = "com.github.pureconfig" %% "pureconfig"                 % Versions.pureConfig
+    def circe(artifact: String): ModuleID       = "io.circe"                      %% artifact % Versions.circe
+    def http4s(artifact: String): ModuleID      = "org.http4s"                    %% artifact % Versions.http4s
+    def scalaCache(artifact: String): ModuleID  = "com.github.cb372"              %% artifact % Versions.scalaCache
+    def sttpBackend(artifact: String): ModuleID = "com.softwaremill.sttp.client3" %% artifact % Versions.sttpBackend
+
+    lazy val cats           = "org.typelevel" %% "cats-core" % Versions.cats
+    lazy val catsEffect     = "org.typelevel" %% "cats-effect" % Versions.catsEffect
+    lazy val fs2            = "co.fs2" %% "fs2-core" % Versions.fs2
+    lazy val fs2SttpBackend = sttpBackend("async-http-client-backend-fs2-ce2")
+    lazy val sttpCirce      = sttpBackend("circe")
+    lazy val enumeratum     = "com.beachape" %% "enumeratum" % Versions.enumeratum
+
+    lazy val scalaCacheEffect   = scalaCache("scalacache-cats-effect")
+    lazy val scalaCacheCaffeine = scalaCache("scalacache-caffeine")
+
+    lazy val http4sDsl       = http4s("http4s-dsl")
+    lazy val http4sServer    = http4s("http4s-blaze-server")
+    lazy val http4sCirce     = http4s("http4s-circe")
+    lazy val circeCore       = circe("circe-core")
+    lazy val circeGeneric    = circe("circe-generic")
+    lazy val circeGenericExt = circe("circe-generic-extras")
+    lazy val circeParser     = circe("circe-parser")
+    lazy val pureConfig      = "com.github.pureconfig" %% "pureconfig" % Versions.pureConfig
 
     // Compiler plugins
-    lazy val kindProjector       = "org.typelevel"         %% "kind-projector"             % Versions.kindProjector
+    lazy val kindProjector = "org.typelevel" %% "kind-projector" % Versions.kindProjector
 
     // Runtime
-    lazy val logback             = "ch.qos.logback"        %  "logback-classic"            % Versions.logback
+    lazy val logback = "ch.qos.logback" % "logback-classic" % Versions.logback
 
     // Test
-    lazy val scalaTest           = "org.scalatest"         %% "scalatest"                  % Versions.scalaTest
-    lazy val scalaCheck          = "org.scalacheck"        %% "scalacheck"                 % Versions.scalaCheck
-    lazy val catsScalaCheck      = "io.chrisdavenport"     %% "cats-scalacheck"            % Versions.catsScalaCheck
+    lazy val scalaTest           = "org.scalatest"     %% "scalatest"                      % Versions.scalaTest
+    lazy val scalaCheck          = "org.scalacheck"    %% "scalacheck"                     % Versions.scalaCheck
+    lazy val catsScalaCheck      = "io.chrisdavenport" %% "cats-scalacheck"                % Versions.catsScalaCheck
+    lazy val testContainers      = "com.dimafeng"      %% "testcontainers-scala-scalatest" % Versions.testContainers
+    lazy val catsEffectScalaTest = "com.codecommit"    %% "cats-effect-testing-scalatest"  % Versions.scalatestCats
   }
 
 }

forex-mtl/project/plugins.sbt

@@ -1,3 +1,5 @@
-addSbtPlugin("com.lucidchart"    % "sbt-scalafmt-coursier" % "1.16")
-addSbtPlugin("com.timushev.sbt" % "sbt-updates" % "0.5.3")
-addSbtPlugin("io.spray" % "sbt-revolver" % "0.9.1")
+addSbtPlugin("com.lucidchart"   % "sbt-scalafmt-coursier" % "1.16")
+addSbtPlugin("com.timushev.sbt" % "sbt-updates"           % "0.5.3")
+addSbtPlugin("io.spray"         % "sbt-revolver"          % "0.9.1")
+addSbtPlugin("org.scoverage"    % "sbt-scoverage"         % "1.9.3")
+addSbtPlugin("org.scalameta"    % "sbt-scalafmt"          % "2.4.6")

forex-mtl/src/main/resources/application.conf

@@ -4,5 +4,18 @@ app {
     port = 8080
     timeout = 40 seconds
   }
+
+  storage {
+    expire-after = "5 minutes"
+    expire-after = ${?EXPIRE_PERIOD}
+    api-limit = 1000
+  }
+
+  provider {
+    uri = "http://0.0.0.0:8087"
+    uri = ${API_URI}
+    token = "10dc303535874aeccc86a8251e6992f5"
+    token = ${?API_TOKEN}
+  }
 }
 

forex-mtl/src/main/scala/forex/Main.scala

@@ -1,25 +1,31 @@
 package forex
 
 import scala.concurrent.ExecutionContext
-
 import cats.effect._
 import forex.config._
 import fs2.Stream
 import org.http4s.server.blaze.BlazeServerBuilder
+import sttp.client3.SttpBackend
+import sttp.client3.asynchttpclient.fs2.AsyncHttpClientFs2Backend
 
 object Main extends IOApp {
 
   override def run(args: List[String]): IO[ExitCode] =
-    new Application[IO].stream(executionContext).compile.drain.as(ExitCode.Success)
+    (for {
+      blocker <- Blocker.apply[IO]
+      backend <- AsyncHttpClientFs2Backend.resource[IO](blocker)
+    } yield backend).use { backend =>
+      new Application[IO].stream(executionContext, backend).compile.drain.as(ExitCode.Success)
+    }
 
 }
 
 class Application[F[_]: ConcurrentEffect: Timer] {
 
-  def stream(ec: ExecutionContext): Stream[F, Unit] =
+  def stream(ec: ExecutionContext, backend: SttpBackend[F, _]): Stream[F, Unit] =
     for {
       config <- Config.stream("app")
-      module = new Module[F](config)
+      module = new Module[F](config, backend)
       _ <- BlazeServerBuilder[F](ec)
             .bindHttp(config.http.port, config.http.host)
             .withHttpApp(module.httpApp)

forex-mtl/src/main/scala/forex/Module.scala

@@ -8,12 +8,15 @@ import forex.programs._
 import org.http4s._
 import org.http4s.implicits._
 import org.http4s.server.middleware.{ AutoSlash, Timeout }
+import sttp.client3.SttpBackend
 
-class Module[F[_]: Concurrent: Timer](config: ApplicationConfig) {
+class Module[F[_]: Concurrent: Timer](config: ApplicationConfig, backend: SttpBackend[F, _]) {
 
-  private val ratesService: RatesService[F] = RatesServices.dummy[F]
+  private val storageService: StorageService[F] = StorageService.inMemory[F](config.storage)
 
-  private val ratesProgram: RatesProgram[F] = RatesProgram[F](ratesService)
+  private val ratesService: RatesService[F] = RatesServices.live[F](config.provider, backend)
+
+  private val ratesProgram: RatesProgram[F] = RatesProgram[F](ratesService, storageService)
 
   private val ratesHttpRoutes: HttpRoutes[F] = new RatesHttpRoutes[F](ratesProgram).routes
 

forex-mtl/src/main/scala/forex/config/ApplicationConfig.scala

@@ -1,11 +1,27 @@
 package forex.config
 
+import java.util.concurrent.TimeUnit
 import scala.concurrent.duration.FiniteDuration
 
 case class ApplicationConfig(
     http: HttpConfig,
+    storage: StorageConfig,
+    provider: ProviderConfig
 )
 
+case class StorageConfig(expireAfter: FiniteDuration, apiLimit: Int) {
+
+  /**
+    * Ensures that we don't exceed API queries limit with provided pull period
+    */
+  require(
+    24 * 60 / expireAfter.toUnit(TimeUnit.MINUTES) < apiLimit,
+    s"The service might exceed API limit with an expire period ${expireAfter.toString()}"
+  )
+}
+
+case class ProviderConfig(uri: String, token: String)
+
 case class HttpConfig(
     host: String,
     port: Int,

forex-mtl/src/main/scala/forex/config/Config.scala

@@ -9,11 +9,9 @@ import pureconfig.generic.auto._
 object Config {
 
   /**
-   * @param path the property path inside the default configuration
-   */
-  def stream[F[_]: Sync](path: String): Stream[F, ApplicationConfig] = {
-    Stream.eval(Sync[F].delay(
-      ConfigSource.default.at(path).loadOrThrow[ApplicationConfig]))
-  }
+    * @param path the property path inside the default configuration
+    */
+  def stream[F[_]: Sync](path: String): Stream[F, ApplicationConfig] =
+    Stream.eval(Sync[F].delay(ConfigSource.default.at(path).loadOrThrow[ApplicationConfig]))
 
 }

forex-mtl/src/main/scala/forex/domain/Currency.scala

@@ -1,10 +1,11 @@
 package forex.domain
 
 import cats.Show
+import enumeratum._
 
-sealed trait Currency
+sealed trait Currency extends EnumEntry
 
-object Currency {
+object Currency extends Enum[Currency] {
   case object AUD extends Currency
   case object CAD extends Currency
   case object CHF extends Currency
@@ -15,6 +16,8 @@ object Currency {
   case object SGD extends Currency
   case object USD extends Currency
 
+  val values = findValues
+
   implicit val show: Show[Currency] = Show.show {
     case AUD => "AUD"
     case CAD => "CAD"

forex-mtl/src/main/scala/forex/domain/Price.scala

@@ -3,6 +3,6 @@ package forex.domain
 case class Price(value: BigDecimal) extends AnyVal
 
 object Price {
-  def apply(value: Integer): Price =
-    Price(BigDecimal(value))
+  def apply(value: Int): Price    = Price(BigDecimal(value))
+  def apply(value: Double): Price = Price(BigDecimal(value))
 }

forex-mtl/src/main/scala/forex/domain/Rate.scala

@@ -1,12 +1,19 @@
 package forex.domain
 
+import cats.Show
+import cats.syntax.all._
+
 case class Rate(
     pair: Rate.Pair,
     price: Price,
     timestamp: Timestamp
 )
 
 object Rate {
+  object Pair {
+    implicit def show: Show[Pair] = pair => pair.from.show + pair.to.show
+  }
+
   final case class Pair(
       from: Currency,
       to: Currency

forex-mtl/src/main/scala/forex/http/package.scala

@@ -16,6 +16,6 @@ package object http {
   implicit def enumDecoder[A: EnumerationDecoder]: Decoder[A] = implicitly
 
   implicit def jsonDecoder[A <: Product: Decoder, F[_]: Sync]: EntityDecoder[F, A] = jsonOf[F, A]
-  implicit def jsonEncoder[A <: Product: Encoder, F[_]]: EntityEncoder[F, A] = jsonEncoderOf[F, A]
+  implicit def jsonEncoder[A <: Product: Encoder, F[_]]: EntityEncoder[F, A]       = jsonEncoderOf[F, A]
 
 }