open Ocamlbuild_plugin

(* these functions are not really officially exported *)
let run_and_read = Ocamlbuild_pack.My_unix.run_and_read
let blank_sep_strings = Ocamlbuild_pack.Lexers.blank_sep_strings

let split s ch =
  let x = ref [] in
  let rec go s =
    let pos = String.index s ch in
    x := (String.before s pos)::!x;
    go (String.after s (pos + 1))
  in
  try
    go s
  with Not_found -> !x

let split_nl s = split s '\n'

let before_space s =
  try
    String.before s (String.index s ' ')
  with Not_found -> s

(* this lists all supported packages *)
let find_packages () =
  List.map before_space (split_nl & run_and_read "ocamlfind list")

(* this is supposed to list available syntaxes, but I don't know how to do it. *)
let find_syntaxes () = ["camlp4o"; "camlp4r"]

(* ocamlfind command *)
let ocamlfind x = S[A"ocamlfind"; x]

let ocamlfind_before_options () =
       (* by using Before_options one let command line options have an higher priority *)
       (* on the contrary using After_options will guarantee to have the higher priority *)

       (* override default commands by ocamlfind ones *)
       Options.ocamlc     := ocamlfind & A"ocamlc";
       Options.ocamlopt   := ocamlfind & A"ocamlopt";
       Options.ocamldep   := ocamlfind & A"ocamldep";
       Options.ocamldoc   := ocamlfind & A"ocamldoc";
       Options.ocamlmktop := ocamlfind & A"ocamlmktop"

let ocamlfind_after_rules () =
       (* When one link an OCaml library/binary/package, one should use -linkpkg *)
       flag ["ocaml"; "link"; "program"] & A"-linkpkg";

       (* For each ocamlfind package one inject the -package option when
       	* compiling, computing dependencies, generating documentation and
       	* linking. *)
       List.iter begin fun pkg ->
         flag ["ocaml"; "compile";  "pkg_"^pkg] & S[A"-package"; A pkg];
         flag ["ocaml"; "ocamldep"; "pkg_"^pkg] & S[A"-package"; A pkg];
         flag ["ocaml"; "doc";      "pkg_"^pkg] & S[A"-package"; A pkg];
         flag ["ocaml"; "link";     "pkg_"^pkg] & S[A"-package"; A pkg];
         flag ["ocaml"; "infer_interface"; "pkg_"^pkg] & S[A"-package"; A pkg];
       end (find_packages ());

       (* Like -package but for extensions syntax. Morover -syntax is useless
       	* when linking. *)
       List.iter begin fun syntax ->
         flag ["ocaml"; "compile";  "syntax_"^syntax] & S[A"-syntax"; A syntax];
         flag ["ocaml"; "ocamldep"; "syntax_"^syntax] & S[A"-syntax"; A syntax];
         flag ["ocaml"; "doc";      "syntax_"^syntax] & S[A"-syntax"; A syntax];
         flag ["ocaml"; "infer_interface"; "syntax_"^syntax] & S[A"-syntax"; A syntax];
       end (find_syntaxes ());

       (* The default "thread" tag is not compatible with ocamlfind.
          Indeed, the default rules add the "threads.cma" or "threads.cmxa"
          options when using this tag. When using the "-linkpkg" option with
          ocamlfind, this module will then be added twice on the command line.

          To solve this, one approach is to add the "-thread" option when using
          the "threads" package using the previous plugin.
        *)
       flag ["ocaml"; "pkg_threads"; "compile"] (S[A "-thread"]);
       flag ["ocaml"; "pkg_threads"; "link"] (S[A "-thread"]);
       flag ["ocaml"; "pkg_threads"; "infer_interface"] (S[A "-thread"])