%%% BEGIN openflax/dispatch.erl %%%
%%%
%%% openflax - Open Source web server for Erlang/OTP
%%% Copyright (c)2004 Cat's Eye Technologies.  All rights reserved.
%%%
%%% Redistribution and use in source and binary forms, with or without
%%% 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,
%%% INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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%%% DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
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%% @doc Dispatching logic for OpenFlax.
%% 
%% @end

-module(openflax.dispatch).
-vsn('$Id: dispatch.erl 31 2004-04-23 07:00:11Z catseye $').
-author('catseye@catseye.mb.ca').
-copyright('Copyright (c)2004 Cat`s Eye Technologies. All rights reserved.').

-export([resolve_request/4]).       % External interface

-import(lists).
-import(regexp).

%% @spec resolve_request([dispatch()], Resource::string(), Args::string(),
%%   RemoteAddress::ip()) -> {response(), conf()}
%%           dispatch() = {resource_pattern(), args_pattern(),
%%               response(), conf_list(), allowed_ips()}
%%           resource_pattern() = regexp()
%%           args_pattern() = regexp()
%%           conf_list() = [{atom(), term()}]
%%           allowed_ips() = [ip()]
%%           regexp() = string()
%%           ip() = string()
%% @doc Returns the <code>response()</code> from the first entry in
%% the given dispatch rules which pattern-matches the given basic resource
%% and arguments of a URI <i>and</i> which is set to allow the given
%% IP address of the client.  Additional configuation settings may be
%% specified in a list in the dispatch (they will override existing ones.)

resolve_request([], _Resource, _Args, _RemoteIP) ->
  {not_found, openflax.conf:new()};
resolve_request([{ResPat, ArgsPat, Response, ConfList, AllowedIPs} | Tail],
                Resource, Args, RemoteIP) ->
  % determine whether the client is allowed to access this resource
  case lists:member(RemoteIP, AllowedIPs) of
    true ->
      resolve_request([{ResPat, ArgsPat, Response, ConfList} | Tail],
        Resource, Args, RemoteIP);
    false ->
      resolve_request(Tail, Resource, Args, RemoteIP)
  end;
resolve_request([{ResPat, ArgsPat, Response, ConfList} | Tail],
                Resource, Args, RemoteIP) ->
  case regexp:first_match(Resource, regexp:sh_to_awk(ResPat)) of
    {match, _, _} ->
      % The following is a total hack to make up for a limitation
      % in the regexp modules (can't match null strings!)
      case case Args of
             "" ->
	       case ArgsPat of
	         "*" ->
	           {match, [true]};
	         _ ->
	           {match, []}
	       end;
	     _ ->
	       regexp:matches(Args, regexp:sh_to_awk(ArgsPat))
           end of
        {match, [_FirstMatch | _OtherMatches]} ->
          {Response, openflax.conf:new(ConfList)};
        _ ->
          resolve_request(Tail, Resource, Args, RemoteIP)
      end;
    _ ->
      resolve_request(Tail, Resource, Args, RemoteIP)
  end;
resolve_request([{ResPat, ArgsPat, Response} | Tail],
                Resource, Args, RemoteIP) ->
  resolve_request([{ResPat, ArgsPat, Response, []} | Tail],
    Resource, Args, RemoteIP).

%%% END of openflax/dispatch.erl %%%