(* run-dnorm_sml.in
 *
 * COPYRIGHT (c) 2012 The Diderot Project (http://diderot-language.cs.uchicago.edu)
 * All rights reserved.
 *
 * This module supports running the dnorm program on a nrrd file.
 *)

structure RunDNorm : sig

    val run : string -> {
	    version : string,
	    header : (string * string) list
	  }

  end = struct

    structure SS = Substring

  (* search path for the dnorm executable *)
    val paths = [
	    "@DIDEROT_ROOT@/bin", "@prefix@/bin"
	  ]

    fun findExe () = (case PathUtil.findExe paths "dnorm"
	   of SOME cmd => cmd
	    | NONE => raise Fail "unable to find dnorm executable"
	  (* end case *))

    fun run srcFile = if OS.FileSys.access(srcFile, [OS.FileSys.A_READ])
	  then let
	    val proc = Unix.execute (findExe(), ["-h", "-i", srcFile])
	    val inS = Unix.textInstreamOf proc
	    fun stripWS ss = SS.string (SS.dropl Char.isSpace (SS.dropr Char.isSpace ss))
	    fun read content = (case TextIO.inputLine inS
		   of SOME "\n" => read content (* dnorm outputs an extra blank line at the end *)
		    | SOME ln => (
			case SS.fields (fn #":" => true | _ => false) (SS.full ln)
			 of [name, value] =>
			      read((SS.string name, stripWS value)::content)
			  | _ => raise Fail(concat["bogus nrrd header line \"", String.toString ln, "\""])
			(* end case *))
		    | NONE => List.rev content
		  (* end case *))
	    val info = (case TextIO.inputLine inS
		   of SOME version => {
			  version = stripWS(SS.full version),
			  header = read []
			}
		    | NONE => raise Fail "bogus nrrd file"
		  (* end case *))
	    val sts = Unix.reap proc
	    in
	      if OS.Process.isSuccess sts
		then info
		else raise Fail "error running dnorm"
	    end
	  else raise Fail(concat["image file \"", srcFile, "\" not found"])

  end