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

(*  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 FileUtilMisc

open FileUtilTEST

open FileUtilSTAT

open FileUtilREADLINK

let find ?(follow=Skip) ?match_compile tst fln exec user_acc =

  let user_test = compile_filter ?match_compile tst in

  let skip_action =

    match follow with

      | Skip | AskFollow _ | Follow -> ignore

      | SkipInform f -> f

  in

  let should_skip fln already_followed =

    match follow with

      | Skip | SkipInform _ -> true

      | AskFollow f ->

          if not already_followed then

            f fln

          else

            true

      | Follow ->

          if already_followed then

            raise (RecursiveLink fln)

          else

            false

  in

  let already_read = ref SetFilename.empty in

  let rec find_aux acc fln =

    let st_opt =

      try

        Some (stat fln)

      with FileDoesntExist _ ->

        None

    in

    let stL_opt =

      match st_opt with

        | Some st when st.is_link ->

            begin

              try

                Some (stat ~dereference:true fln)

              with FileDoesntExist _ ->

                None

            end

        | _ ->

            st_opt

    in

    let acc =

      if user_test ?st_opt ?stL_opt fln then

        exec acc fln

      else

        acc

    in

      match st_opt with

        | Some st ->

            if st.kind = Symlink then begin

              follow_symlink stL_opt acc fln

            end else if st.kind = Dir then begin

              enter_dir acc fln

            end else begin

              acc

            end

        | None -> acc

  and enter_dir acc drn =

    Array.fold_left

      (fun acc rfln ->

         if is_parent rfln || is_current rfln then

           acc

         else

           find_aux acc (concat drn rfln))

      acc

      (Sys.readdir drn)

  and follow_symlink stL_opt acc fln =

      match stL_opt with

        | Some stL when stL.kind = Dir ->

            let cur_link = readlink fln in

            let already_followed =

              try

                already_read := prevent_recursion !already_read cur_link;

                false

              with RecursiveLink _ ->

                true

            in

              if should_skip fln already_followed then begin

                skip_action fln;

                acc

              end else begin

                enter_dir acc fln

              end

        | _ ->

            acc

  in

    find_aux user_acc (reduce fln)