#57 add some command line options

src/main/scala/bad/robot/temperature/Main.scala

@@ -1,6 +1,7 @@
 package bad.robot.temperature
 
-import bad.robot.logging.error
+import bad.robot.logging._
+import bad.robot.temperature.CommandLineHelp._
 import bad.robot.temperature.client.Client
 import bad.robot.temperature.config.ConfigFile
 import bad.robot.temperature.server.Server
@@ -10,21 +11,54 @@ import fs2.{Stream, StreamApp}
 
 object Main extends StreamApp[IO] {
 
-  private val printErrorAndExit = (cause: ConfigurationError) => Stream.eval(error(cause.message)).flatMap(_ => Stream.emit(ExitCode(1)))
-
   override def stream(args: List[String], requestShutdown: IO[Unit]): fs2.Stream[IO, ExitCode] = {
+    args match {
+      case option :: Nil if List("-v", "--version").contains(option) => printVersion
+      case option :: Nil if List("-h", "--help").contains(option)    => printUsage
+      case Nil                                                       => startupBasedOnConfigFile(requestShutdown)
+      case options                                                   => Stream
+                                                                          .eval(IO(print(s"Invalid option: ${options.mkString(" ")}")))
+                                                                          .flatMap(_ => printUsage)
+    }
+  }
+
+  private def startupBasedOnConfigFile(requestShutdown: IO[Unit]) = {
+    def start(config: ConfigFile): IO[Unit] => Stream[IO, ExitCode] = {
+      config.mode match {
+        case "client" => Client.stream(Nil, _)
+        case "server" => Server.stream(config.hosts, _)
+        case mode     => _ => printConfigError(mode)
+      }
+    }
+
     Stream
       .eval(ConfigFile.loadOrCreate())
       .flatMap(_.fold(printErrorAndExit, start(_)(requestShutdown)))
   }
-
-  def start(config: ConfigFile): IO[Unit] => Stream[IO, ExitCode] = {
-    config.mode match {
-      case "server" => Server.stream(config.hosts, _)
-      case "client" => Client.stream(Nil, _)
-//      case _ => ???   
-// todo error case?
-    }
-  }
-
+}
+
+object CommandLineHelp {
+
+  val printErrorAndExit = (cause: ConfigurationError) => exitAfter(Stream.eval(error(cause.message)))
+
+  def printVersion = exitAfter(Stream.eval(IO(println(s"${BuildInfo.name} ${BuildInfo.version} (${BuildInfo.latestSha})"))))
+
+  def printUsage = exitAfter(Stream.eval(IO(println(
+    """
+      |Usage: temperature-machine [options]
+      |
+      |-v, --version        display the current version
+      |-h, --help           this page, try 'man temperature-machine' or http://temperature-machine.com for more help
+      |-i, --init           create the default config file. Once the config file exists, modify it as 
+      |                     required then run again with no options to start the temperature machine
+      |
+      |Run with no options to start the temperature-machine
+      |
+    """.stripMargin))))
+
+  def printConfigError(mode: String) = exitAfter(Stream.eval(error(
+    s"""Error in configuration file, 'mode' was set to "$mode" but only "client" or "server" are allowed"""
+  )))
+
+  def exitAfter(io: Stream[IO, _]) = io.flatMap(_ => Stream.emit(ExitCode(1)))
 }