(* HQ9+.ml -- HQ9+ Interpreter in Ocaml v0.1

   Markus Kliegl <markus.kliegl@t-online.de>

   Compile with: ocamlopt -o HQ9+ HQ9+.ml
   Usage: HQ9+ <file>

   For information on HQ9+ see
   http://www.cliff.biffle.org/hq.html

   This version implements the h, 9 and q commands and ignores
   the + command, because the author has no clue as to what it's
   supposed to do
*)

let hello () =
  print_endline "Hello World!";
  exit 0
;;

let rec beer n =
  if n = 1 then begin
    print_endline "1 bottle of beer on the wall";
    print_endline "1 bottle of beer";
    print_endline "Take one down and pass it around";
    print_endline "No bottles of beer on the wall"
  end else begin
    print_int n; print_endline " bottles of beer on the wall";
    print_int n; print_endline " bottles of beer";
    print_endline "Take one down and pass it around";
    print_int (n - 1); print_endline " bottles of beer on the wall";
    print_newline ();
    beer (n - 1)
  end
;;

let quine chan =
  try
    while true do
      print_char (input_char chan)
    done
  with _ -> exit 0
;;

let accumulate () =
  ()
;;

let err_unknown c =
  print_string "Unknown command: "; print_char c;
  print_newline ();
  exit 1
;;

let err_unexpected_eof () =
  print_endline "Unexpected end of file";
  exit 1
;;

let interpret chan =
  try let c = input_char chan in
    begin
      match c with
	  'h' -> hello ()
	| '9' -> beer 99
	| 'q' -> print_char c; quine chan
	| '+' -> accumulate ()
	| _ -> err_unknown c
    end
  with End_of_file -> err_unexpected_eof ()
;;

let main argc argv =
  if argc <> 2 then begin
    print_string "Usage: "; print_string argv.(0);
    print_endline " <file>"
  end else try
    let chan = open_in argv.(1) in
      interpret chan;
      close_in chan
  with Sys_error s -> print_endline s
;;

main (Array.length Sys.argv) Sys.argv

(* HQ9+.ml ends here *)