CommandLine

import scala.collection.immutable.HashMap
import HelpCommand.CommandFactory

object CommandLine {

  def main(args: Array[String]): Unit = {
    println("Starting the utility console")
    read
  }

  /**
   * A simple utility method to read input from the user if needed
   */
  def read(): Unit = {
    val input = scala.io.StdIn.readLine(">")
    val commandString = input.split("(\\s+)")
    println("Incoming command sequence ", commandString.mkString(":"))
    val inputMap = new ConsoleInput
    inputMap.addInput(commandString)
    val command = CommandFactory.get(inputMap)
    command.validate(commandString)
    val output = command.execute(inputMap)
    println(output)
    if (input.isEmpty) () else read
  }

}

class ConsoleInput() {

  val inputArgs: HashMap[String, String] = HashMap.empty[String, String]

  def addInput(args: Array[String]): Unit = {

    for (i <- 0 until args.length) {
      val key = args.apply(i)
      val nextIdx = i + 1
      if (key.contains("--")) {
        val finalkey = key.substring(2, key.length());
        if (nextIdx <= args.length) {
          val value = args.apply(nextIdx)
          inputArgs + key -> value
        }
      }
    }

  }
  def command(): String = {
    inputArgs.get("command").getOrElse("help")
  }
}

case class FailureReason(reason: String)
trait Command {
  def execute(commandArgs: ConsoleInput): String
  def validate(args: Array[String]): Either[Boolean, FailureReason]
  def help(): String
}

object HelpCommand extends Command {
  def execute(commandArgs: ConsoleInput): String = {
    "This is a help command"
  }

  def help(): String = {
    "This is the help section for the help command"
  }

  def validate(args: Array[String]): Either[Boolean, FailureReason] = {
    if (args.length > 0)
      Left(true)
    else
      Right(FailureReason("Some exception"))
  }

  object CommandFactory {
    val commandStore: HashMap[String, Command] = HashMap("help" -> HelpCommand)
    
    println("Available commands =",commandStore)
    
    
    def get(inputArg: ConsoleInput): Command = {
      val cmdName = inputArg.command
      println("Incoming command=",cmdName)
      if (cmdName.isEmpty)
        commandStore.get("help").get
      else
        commandStore.get(cmdName).get
    }
  }

}