%%% BEGIN openflax/handler/random.erl %%%
%%%
%%% openflax - Open Source web server for Erlang/OTP
%%% Copyright (c)2003 Cat's Eye Technologies.  All rights reserved.
%%%
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%%% modification, are permitted provided that the following conditions
%%% are met:
%%%
%%%   Redistributions of source code must retain the above copyright
%%%   notice, this list of conditions and the following disclaimer.
%%%
%%%   Redistributions in binary form must reproduce the above copyright
%%%   notice, this list of conditions and the following disclaimer in
%%%   the documentation and/or other materials provided with the
%%%   distribution.
%%%
%%%   Neither the name of Cat's Eye Technologies nor the names of its
%%%   contributors may be used to endorse or promote products derived
%%%   from this software without specific prior written permission.
%%%
%%% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
%%% CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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%% @doc Display a random file from a certain directory.
%%
%% <p>This handler's security/featurefulness tradeoff level is
%% 3 (Unobtrusive.)  If not all the files are of the same
%% content type, it might confuse some user agents.
%% The <code>res_content_type</code> setting should be specified
%% in the config file.</p>
%%
%% <p>This handler requires <code>openflax.handler.file</code>.</p>
%%
%% @end

-module(openflax.handler.random).
-vsn('$Id: random.erl 31 2004-04-23 07:00:11Z catseye $').
-author('cpressey@catseye.mine.nu').
-copyright('Copyright (c)2003 Cat`s Eye Technologies. All rights reserved.').

-behaviour(openflax.handler).

-export([start/1, stop/1, serve/1]). % behaviour

-import(lists).
-import(random).
-import(filename).
-import(file).

%% @spec start(conf()) -> conf()
%% @doc Initializes the random-file-serving subsystem.

start(Conf) ->
  {A1, A2, A3} = now(),
  random:seed(A3, A2, A1),
  openflax.conf:new().

%% @spec stop(conf()) -> conf()
%% @doc Shuts down the random-file serving subsystem.

stop(Conf) ->
  Conf.
 
%% @spec serve(conf()) -> {response(), conf()}
%% @doc Serves a random file from this directory.

serve(Conf) ->
  Dir = filename:dirname(openflax.handler.file:document(Conf)),
  {ok, Files} = file:list_dir(Dir),
  Filename = pick(Dir, Files, Conf),
  % set new basic resource
  BasicResource = openflax.conf:get_string(sreq_basic_resource, Conf),
  NewResource = filename:join([filename:dirname(BasicResource), Filename]),
  openflax.log:write("new resource: ~p", [NewResource]),
  Conf0 = openflax.conf:put_value(sreq_basic_resource, NewResource, Conf),
  {openflax.handler.file, Conf0}.

pick(Dir, Files, Conf) ->
  PickedFile = lists:nth(random:uniform(length(Files)), Files),
  Filename = filename:join([Dir, PickedFile]),
  case openflax.handler.file:is_accessible(Filename, Conf) of
    true ->
      PickedFile;
    false ->
      pick(Dir, Files -- [PickedFile], Conf)
  end.

%%% END of openflax/handler/random.erl %%%