/*  Title:      Pure/System/options.scala

    Author:     Makarius

Stand-alone options with external string representation.

*/

package isabelle

import java.io.File

object Options

{

  abstract class Type

  {

    def print: String = toString.toLowerCase

    def init: String

  }

  case object Bool extends Type { def init = "false" }

  case object Int extends Type { def init = "0" }

  case object Real extends Type { def init = "0.0" }

  case object String extends Type { def init = "" }

  case class Opt(typ: Type, description: String, value: String)

  val empty: Options = new Options()

  /* parsing */

  private object Parser extends Parse.Parser

  {

    val DECLARE = "declare"

    val DEFINE = "define"

    val syntax = Outer_Syntax.empty + ":" + "=" + DECLARE + DEFINE

    val entry: Parser[Options => Options] =

    {

      val option_name = atom("option name", _.is_xname)

      val option_type = atom("option type", _.is_ident)

      val option_value = atom("option value", tok => tok.is_name || tok.is_float)

      keyword(DECLARE) ~! (option_name ~ keyword(":") ~ option_type ~ opt(text)) ^^

        { case _ ~ (x ~ _ ~ y ~ z) => (options: Options) =>

            options.declare(x, y, z.getOrElse("")) } |

      keyword(DEFINE) ~! (option_name ~ keyword("=") ~ option_value) ^^

        { case _ ~ (x ~ _ ~ y) => (options: Options) =>

            options.define(x, y) }

    }

    def parse_entries(file: File): List[Options => Options] =

    {

      val toks = syntax.scan(Standard_System.read_file(file))

      parse_all(rep(entry), Token.reader(toks, file.toString)) match {

        case Success(result, _) => result

        case bad => error(bad.toString)

      }

    }

  }

  val OPTIONS = Path.explode("etc/options")

  def init(): Options =

  {

    var options = empty

    for {

      dir <- Isabelle_System.components()

      file = Isabelle_System.platform_file(dir + OPTIONS)

      if file.isFile

      entry <- Parser.parse_entries(file)

    } {

      try { options = entry(options) }

      catch { case ERROR(msg) => error(msg + " (file " + quote(file.toString) + ")") }

    }

    options

  }

}

final class Options private(options: Map[String, Options.Opt] = Map.empty)

{

  override def toString: String = options.iterator.mkString("Options (", ",", ")")

  /* basic operations */

  private def check_name(name: String): Options.Opt =

    options.get(name) match {

      case Some(opt) => opt

      case None => error("Undeclared option " + quote(name))

    }

  private def check_type(name: String, typ: Options.Type): Options.Opt =

  {

    val opt = check_name(name)

    if (opt.typ == typ) opt

    else error("Ill-typed option " + quote(name) + " : " + opt.typ.print + " vs. " + typ.print)

  }

  private def get[A](name: String, typ: Options.Type, parse: String => Option[A]): A =

  {

    val opt = check_type(name, typ)

    parse(opt.value) match {

      case Some(x) => x

      case None =>

        error("Malformed value for option " + quote(name) +

          " : " + typ.print + " =\n" + quote(opt.value))

    }

  }

  private def put[A](name: String, typ: Options.Type, value: String): Options =

  {

    val opt = check_type(name, typ)

    new Options(options + (name -> opt.copy(value = value)))

  }

  /* external declare and define */

  def declare(name: String, typ_name: String, description: String = ""): Options =

  {

    options.get(name) match {

      case Some(_) => error("Duplicate declaration of option " + quote(name))

      case None =>

        val typ =

          typ_name match {

            case "bool" => Options.Bool

            case "int" => Options.Int

            case "real" => Options.Real

            case "string" => Options.String

            case _ => error("Malformed type for option " + quote(name) + " : " + quote(typ_name))

          }

        new Options(options + (name -> Options.Opt(typ, description, typ.init)))

    }

  }

  def define(name: String, value: String): Options =

  {

    val opt = check_name(name)

    val result = new Options(options + (name -> opt.copy(value = value)))

    opt.typ match {

      case Options.Bool => result.bool(name); ()

      case Options.Int => result.int(name); ()

      case Options.Real => result.real(name); ()

      case Options.String => result.string(name); ()

    }

    result

  }

  /* internal lookup and update */

  val bool = new Object

  {

    def apply(name: String): Boolean = get(name, Options.Bool, Properties.Value.Boolean.unapply)

    def update(name: String, x: Boolean): Options =

      put(name, Options.Bool, Properties.Value.Boolean(x))

  }

  val int = new Object

  {

    def apply(name: String): Int = get(name, Options.Int, Properties.Value.Int.unapply)

    def update(name: String, x: Int): Options =

      put(name, Options.Int, Properties.Value.Int(x))

  }

  val real = new Object

  {

    def apply(name: String): Double = get(name, Options.Real, Properties.Value.Double.unapply)

    def update(name: String, x: Double): Options =

      put(name, Options.Real, Properties.Value.Double(x))

  }

  val string = new Object

  {

    def apply(name: String): String = get(name, Options.String, s => Some(s))

    def update(name: String, x: String): Options = put(name, Options.String, x)

  }

}