%% ---
%%  Excerpted from "Programming Erlang, Second Edition",
%%  published by The Pragmatic Bookshelf.
%%  Copyrights apply to this code. It may not be used to create training material, 
%%  courses, books, articles, and the like. Contact us if you are in doubt.
%%  We make no guarantees that this code is fit for any purpose. 
%%  Visit http://www.pragmaticprogrammer.com/titles/jaerlang2 for more book information.
%%---
-module(lib_find).
-export([files/3, files/5]).
-import(lists, [reverse/1]).

-include_lib("kernel/include/file.hrl").

files(Dir, Re, Flag) -> 
    Re1 = xmerl_regexp:sh_to_awk(Re),
    reverse(files(Dir, Re1, Flag, fun(File, Acc) ->[File|Acc] end, [])).

files(Dir, Reg, Recursive, Fun, Acc) ->
    case file:list_dir(Dir) of
	{ok, Files} -> find_files(Files, Dir, Reg, Recursive, Fun, Acc);
	{error, _}  -> Acc
    end.

find_files([File|T], Dir, Reg, Recursive, Fun, Acc0) ->
    FullName = filename:join([Dir,File]),
    case file_type(FullName) of
	regular ->
	    case re:run(FullName, Reg, [{capture,none}]) of
		match  -> 
		    Acc = Fun(FullName, Acc0),
		    find_files(T, Dir, Reg, Recursive, Fun, Acc);
		nomatch ->
		    find_files(T, Dir, Reg, Recursive, Fun, Acc0)
	    end;
	directory -> 
	    case Recursive of
		true ->
		    Acc1 = files(FullName, Reg, Recursive, Fun, Acc0),
		    find_files(T, Dir, Reg, Recursive, Fun, Acc1);
		false ->
		    find_files(T, Dir, Reg, Recursive, Fun, Acc0)
	    end;
	error -> 
	    find_files(T, Dir, Reg, Recursive, Fun, Acc0)
    end;
find_files([], _, _, _, _, A) ->
    A.

file_type(File) ->
    case file:read_file_info(File) of
	{ok, Facts} ->
	    case Facts#file_info.type of
		regular   -> regular;
		directory -> directory;
		_         -> error
	    end;
	_ ->
	    error
    end.