use "Result.sml";
use "Map.sml";
use "Syntax.sml";
use "Parser.sml";
use "Opts.sml";

val header = "\
  \fun intToStringI (_ : string) (i : int) : string = Int.toString i\n\
  \\n\
  \fun varToStringI (_ : string) (v : Syntax.var) : string = \"Var \" ^ Int.toString v\n\
  \\n\
  \fun stringToStringI (_ : string) (s : string) : string = \"\\\"\" ^ String.toString s ^ \"\\\"\"\n\
  \\n\
  \fun optionToString (_ : string -> 'a -> string) (_ : string) NONE : string = \"NONE\"\n\
  \  | optionToString show indent (SOME x) = \"SOME (\" ^ show indent x ^ \")\"\n\
  \\n\
  \fun listToString (_ : string -> 'a -> string) (_ : string) ([] : 'a list) : string = \"[]\"\n\
  \  | listToString show indent [x] = \"[\" ^ show indent x ^ \"]\"\n\
  \  | listToString show indent xs =\n\
  \      let val indent' = indent ^ \"  \" in\n\
  \          \"[\\n\"\n\
  \        ^ indent' ^ String.concatWith (\",\\n\" ^ indent') (map (show indent') xs) ^ \"\\n\"\n\
  \        ^ indent ^ \"]\"\n\
  \      end\n\
\"

fun showTy (Syntax.Tyvar var) : string = var ^ "ToStringI"
  | showTy (Syntax.Tycon ([ty], con)) = con ^ "ToString (" ^ showTy ty ^ ")"
  | showTy (Syntax.TyTuple tys) =
      let val vars = List.tabulate (length tys, fn i => "x" ^ Int.toString i) in
        "(fn indent => fn (" ^ String.concatWith ", " vars ^ ") => let val indent' = indent ^ \"  \" in \"(\\n\" ^ indent' ^ " ^ String.concatWith " ^ \",\\n\" ^ indent' ^ " (map (fn (var, ty) => showTy ty ^ " indent' " ^ var) (ListPair.zipEq (vars, tys))) ^ " ^ \"\\n\" ^ indent ^ \")\" end)"
      end
  | showTy _ = "(fn _ => fn _ => \"UNHANDLED\")"

val opts = { o = ref "/dev/stdout" }
val flags =
  [ ("o", Opts.StringOpt (fn arg => #o opts := arg)) ]
val filename =
  case Opts.getOpt flags (CommandLine.arguments ()) of
    [arg] => arg
  | _ => raise Fail "usage: showsyntax <filename>"
val ast =
  case Parser.parse filename of
    Result.Left e => raise Fail e
  | Result.Right x => x
val (structName, decls) =
  case ast of
    Syntax.ELet (Syntax.DStruct (structName, Syntax.SStruct decls) :: _, _) => (structName, decls)
  | _ => raise Fail "ast has unexpected format (I can't print it sorry)"
val out = TextIO.openOut (!(#o opts))
val _ = TextIO.output (out, "(*\n  This file was generated by generate-show-syntax.sml. Do not edit manually.\n  To regenerate, use\n\n    sml generate-show-syntax.sml -o " ^ !(#o opts) ^ " " ^ filename ^ "\n*)\n\n")
val _ = TextIO.output (out, "structure Show" ^ structName ^ " = struct\n")
val _ = TextIO.output (out, header)
val _ = map
  (fn (i, Syntax.DDatatype (_, typeName, cases)) =>
      (TextIO.output (out,
          "\n" ^ (if i = 0 then "fun" else "and") ^ " "
        ^ String.concatWith "\n  | " (map
            (fn (caseName, NONE) => typeName ^ "ToStringI (indent : string) (" ^ structName ^ "." ^ caseName ^ " : " ^ structName ^ "." ^ typeName ^ ") : string =\n      \"" ^ caseName ^ "\""
              | (caseName, SOME ty) => typeName ^ "ToStringI (indent : string) (" ^ structName ^ "." ^ caseName ^ " x : " ^ structName ^ "." ^ typeName ^ ") : string =\n      \"" ^ caseName ^ " \" ^ " ^ showTy ty ^ " indent x")
            cases)
        ^ "\n") ;
      TextIO.output (out, "and " ^ typeName ^ "ToString (x : " ^ structName ^ "." ^ typeName ^ ") : string = " ^ typeName ^ "ToStringI \"\" x\n"))
    | _ => ())
  (ListPair.zip (List.tabulate (length decls, fn i => i), decls))
val _ = TextIO.output(out, "end\n")
val _ = OS.Process.exit OS.Process.success