(******************************************************************************)

(*  ocaml-fileutils: files and filenames common operations                    *)

(*                                                                            *)

(*  Copyright (C) 2003-2014, Sylvain Le Gall                                  *)

(*                                                                            *)

(*  This library is free software; you can redistribute it and/or modify it   *)

(*  under the terms of the GNU Lesser General Public License as published by  *)

(*  the Free Software Foundation; either version 2.1 of the License, or (at   *)

(*  your option) any later version, with the OCaml static compilation         *)

(*  exception.                                                                *)

(*                                                                            *)

(*  This library is distributed in the hope that it will be useful, but       *)

(*  WITHOUT ANY WARRANTY; without even the implied warranty of                *)

(*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the file         *)

(*  COPYING for more details.                                                 *)

(*                                                                            *)

(*  You should have received a copy of the GNU Lesser General Public License  *)

(*  along with this library; if not, write to the Free Software Foundation,   *)

(*  Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA             *)

(******************************************************************************)

open FileUtilTypes

open FilePath

open FileUtilTEST

let cmp ?(skip1 = 0) fln1 ?(skip2 = 0) fln2 =

  if (reduce fln1) = (reduce fln2) then

    None

  else if (test (And(Is_readable, Is_file)) fln1)

      && (test (And(Is_readable, Is_file)) fln2) then begin

    let fd1 = open_in_bin fln1 in

    let fd2 = open_in_bin fln2 in

    let clean_fd () =

      let () = try close_in fd1 with _ -> () in

      let () = try close_in fd2 with _ -> () in

        ()

    in

    let test_empty st =

      try

        Stream.empty st;

        true

      with Stream.Failure ->

        false

    in

    let _ = seek_in fd1 skip1 in

    let _ = seek_in fd2 skip2 in

    let stream1 = Stream.of_channel fd1 in

    let stream2 = Stream.of_channel fd2 in

    try

      begin

        while ((Stream.next stream1) = (Stream.next stream2)) do

          ()

        done;

        clean_fd ();

        Some (Stream.count stream1)

      end

    with

      | Stream.Failure ->

          begin

            match ((test_empty stream1), (test_empty stream2)) with

                true, true  ->

                  None

              | true, false

              | false, true

              (* Don't know how this case could be... *)

              | false, false ->

                  clean_fd ();

                  Some (Stream.count stream1)

          end

      | e ->

          clean_fd ();

          raise e

  end else

    Some (-1)