/*  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

  }

  case object Bool extends Type

  case object Int extends Type

  case object Real extends Type

  case object String extends Type

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

      keyword("=") ~ option_value ~ opt(text)) ^^

        { case _ ~ (a ~ _ ~ b ~ _ ~ c ~ d) =>

            (options: Options) => options.declare(a, b, c, d.getOrElse("")) } |

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

        { case _ ~ (a ~ _ ~ b) => (options: Options) => options.define(a, b) }

    }

    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 = (dir + OPTIONS).file

      if file.isFile

      entry <- Parser.parse_entries(file)

    } {

      try { options = entry(options) }

      catch { case ERROR(msg) => error(msg + Position.str_of(Position.file(file))) }

    }

    options

  }

}

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

{

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

  /* check */

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

    options.get(name) match {

      case Some(opt) => opt

      case None => error("Unknown 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)

  }

  /* basic operations */

  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)))

  }

  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))

    }

  }

  /* 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)

  }

  /* external declare and define */

  private def check_value(name: String): Options =

  {

    val opt = check_name(name)

    opt.typ match {

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

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

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

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

    }

  }

  def declare(name: String, typ_name: String, value: 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, value, description)))).check_value(name)

    }

  }

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

  {

    val opt = check_name(name)

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

  }

  def define(name: String, opt_value: Option[String]): Options =

  {

    val opt = check_name(name)

    opt_value match {

      case Some(value) => define(name, value)

      case None if opt.typ == Options.Bool => define(name, "true")

      case None => error("Missing value for option " + quote(name) + " : " + opt.typ.print)

    }

  }

  def define_simple(str: String): Options =

  {

    str.indexOf('=') match {

      case -1 => define(str, None)

      case i => define(str.substring(0, i), str.substring(i + 1))

    }

  }

}