Use IO monad when starting servers

Change-Id: I3e97161535fc721dda6109c4cb5f23a1db0afde3
Signed-off-by: Piotr Jaszczyk <piotr.jaszczyk@nokia.com>
Issue-ID: DCAEGEN2-601

2 files changed, 35 insertions, 30 deletions

diff --git a/hv-collector-dcae-app-simulator/src/main/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/main.kt b/hv-collector-dcae-app-simulator/src/main/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/main.kt
index f7d44ede..a8a4cf5a 100644
--- a/hv-collector-dcae-app-simulator/src/main/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/main.kt
+++ b/hv-collector-dcae-app-simulator/src/main/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/main.kt
@@ -19,30 +19,38 @@
  */
 package org.onap.dcae.collectors.veshv.simulators.dcaeapp
 
-import arrow.core.Failure
-import arrow.core.Success
 import org.onap.dcae.collectors.veshv.simulators.dcaeapp.config.ArgBasedDcaeAppSimConfiguration
 import org.onap.dcae.collectors.veshv.simulators.dcaeapp.config.DcaeAppSimConfiguration
 import org.onap.dcae.collectors.veshv.simulators.dcaeapp.kafka.KafkaSource
 import org.onap.dcae.collectors.veshv.simulators.dcaeapp.remote.ApiServer
-import org.onap.dcae.collectors.veshv.utils.commandline.handleErrorsInMain
+import org.onap.dcae.collectors.veshv.utils.arrow.ExitFailure
+import org.onap.dcae.collectors.veshv.utils.arrow.unsafeRunEitherSync
+import org.onap.dcae.collectors.veshv.utils.arrow.void
+import org.onap.dcae.collectors.veshv.utils.commandline.handleWrongArgumentErrorCurried
 import org.onap.dcae.collectors.veshv.utils.logging.Logger
 import org.slf4j.LoggerFactory
 
-private val logger = Logger(LoggerFactory.getLogger("DCAE simulator :: main"))
+private const val PACKAGE_NAME = "org.onap.dcae.collectors.veshv.simulators.dcaeapp"
+private val logger = Logger(PACKAGE_NAME)
+const val PROGRAM_NAME = "java $PACKAGE_NAME.MainKt"
 
-fun main(args: Array<String>) {
-    logger.info("Starting DCAE APP simulator")
+fun main(args: Array<String>) =
+        ArgBasedDcaeAppSimConfiguration().parse(args)
+                .mapLeft(handleWrongArgumentErrorCurried(PROGRAM_NAME))
+                .map(::startApp)
+                .unsafeRunEitherSync(
+                        { ex ->
+                            logger.error("Failed to start a server", ex)
+                            ExitFailure(1)
+                        },
+                        {
+                            logger.info("Started DCAE-APP Simulator API server")
+                        }
+                )
 
-    val config = ArgBasedDcaeAppSimConfiguration().parse(args)
-    when (config) {
-        is Success -> startApp(config.value).unsafeRunSync()
-        is Failure -> config.handleErrorsInMain("", logger)
-    }
-}
 
 private fun startApp(config: DcaeAppSimConfiguration) =
         KafkaSource.create(config.kafkaBootstrapServers, config.kafkaTopics)
                 .start()
                 .map(::ApiServer)
-                .flatMap { it.start(config.apiPort) }
+                .flatMap { it.start(config.apiPort).void() }
diff --git a/hv-collector-dcae-app-simulator/src/test/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/config/ArgBasedDcaeAppSimConfigurationTest.kt b/hv-collector-dcae-app-simulator/src/test/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/config/ArgBasedDcaeAppSimConfigurationTest.kt
index d99de17b..b73a788e 100644
--- a/hv-collector-dcae-app-simulator/src/test/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/config/ArgBasedDcaeAppSimConfigurationTest.kt
+++ b/hv-collector-dcae-app-simulator/src/test/kotlin/org/onap/dcae/collectors/veshv/simulators/dcaeapp/config/ArgBasedDcaeAppSimConfigurationTest.kt
@@ -21,12 +21,13 @@ package org.onap.dcae.collectors.veshv.simulators.dcaeapp.config
 
 import arrow.core.Failure
 import arrow.core.Success
+import arrow.core.identity
 import org.assertj.core.api.Assertions.assertThat
 import org.jetbrains.spek.api.Spek
 import org.jetbrains.spek.api.dsl.describe
 import org.jetbrains.spek.api.dsl.given
 import org.jetbrains.spek.api.dsl.it
-import org.onap.dcae.collectors.veshv.utils.commandline.WrongArgumentException
+import org.onap.dcae.collectors.veshv.utils.commandline.WrongArgumentError
 
 
 internal class ArgBasedDcaeAppSimConfigurationTest : Spek({
@@ -39,21 +40,17 @@ internal class ArgBasedDcaeAppSimConfigurationTest : Spek({
         cut = ArgBasedDcaeAppSimConfiguration()
     }
 
-    fun parseExpectingSuccess(vararg cmdLine: String): DcaeAppSimConfiguration {
-        val result = cut.parse(cmdLine)
-        return when (result) {
-            is Success -> result.value
-            is Failure -> throw AssertionError("Parsing result should be present")
-        }
-    }
+    fun parseExpectingSuccess(vararg cmdLine: String): DcaeAppSimConfiguration =
+            cut.parse(cmdLine).fold(
+                    { throw AssertionError("Parsing result should be present") },
+                    ::identity
+            )
 
-    fun parseExpectingFailure(vararg cmdLine: String): Throwable {
-        val result = cut.parse(cmdLine)
-        return when (result) {
-            is Success -> throw AssertionError("parsing should have failed")
-            is Failure -> result.exception
-        }
-    }
+    fun parseExpectingFailure(vararg cmdLine: String) =
+            cut.parse(cmdLine).fold(
+                    ::identity,
+                    { throw AssertionError("parsing should have failed") }
+            )
 
     describe("parsing arguments") {
         lateinit var result: DcaeAppSimConfiguration
@@ -121,14 +118,14 @@ internal class ArgBasedDcaeAppSimConfigurationTest : Spek({
             given("kafka topics are missing") {
                 it("should throw exception") {
                     assertThat(parseExpectingFailure("-s", kafkaBootstrapServers))
-                            .isInstanceOf(WrongArgumentException::class.java)
+                            .isInstanceOf(WrongArgumentError::class.java)
                 }
             }
 
             given("kafka bootstrap servers are missing") {
                 it("should throw exception") {
                     assertThat(parseExpectingFailure("-f", kafkaTopics))
-                            .isInstanceOf(WrongArgumentException::class.java)
+                            .isInstanceOf(WrongArgumentError::class.java)
                 }
             }
         }