structure Options = 
struct

structure G = GetOpt

exception Error
	      

datatype flag =  Help | Time of real | Timestep of real | Tol of real


fun showflag (Help)       = "Help"
  | showflag (Time x)     = ("Time" ^ (Real.toString x))
  | showflag (Timestep x) = ("Timestep" ^ (Real.toString x))
  | showflag (Tol x)      = ("Tol" ^ (Real.toString x))
		   

val options = 
    [
     {short="h",
      long=["help"],
      desc=G.NoArg (fn() => Help),
      help="show help"},

     {short="d",
      long=["duration"],
      desc=G.ReqArg (fn(x) => Time (valOf(Real.fromString x)), "N"),
      help="simulation duration"},

     {short="",
      long=["tol"],
      desc=G.ReqArg (fn(x) => Tol (valOf(Real.fromString x)),"N"),
      help="error tolerance"},

     {short="",
      long=["timestep"],
      desc=G.ReqArg (fn(x) => Timestep (valOf(Real.fromString x)),"N"),
      help="simulation timestep"}
    ]

fun optError (status) (msg) = (status := SOME msg)

fun getopt status = (G.getOpt {argOrder=G.Permute, errFn=optError status,
			       options=options}) 

fun header (progname) = concat ["Usage: ", progname, " [OPTION...] files..."]

fun usage (progname) = G.usageInfo {header=(header progname), options=options}

fun getstate (opts) =

    let
	val O_HELP       = ref false
	val O_TOL        = ref NONE
	val O_TIME       = ref NONE
	val O_TIMESTEP   = ref NONE

	fun getstate' (opt) = 
	    (case opt of 
		 Help        => O_HELP := true	
	       | Tol x         => O_TOL := SOME x
	       | Time x       => O_TIME := SOME x
	       | Timestep x    => O_TIMESTEP := SOME x
            )

	val _ = app getstate' opts

    in {
        is_help=(!O_HELP), 
        is_tol=(!O_TOL), 
        is_time=(!O_TIME),
	is_timestep=(!O_TIMESTEP)
       }
    end

end