/*  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)

   }

 }