%%
%% Mod rewrite for Zend Framework
%%

-module(rewriter).

-export([arg_rewrite/1]).

-include_lib("yaws/include/yaws_api.hrl").

arg_rewrite(Arg) ->
    % Decode request path
    Req = Arg#arg.req,
    case Req#http_request.path of
        {abs_path, RawPath} ->
            case (catch yaws_api:url_decode_q_split(RawPath)) of
                {'EXIT', _} ->
                    Arg1 = Arg;
                {Path, _Query} ->
                    % Do not parse file types matching the regexp rule below.
		    % This rule is an exact copy of Apache .htaccess rule.
		    % You can modify it to match your needs.
                    case regexp:first_match(Path, "\.(js|ico|gif|jpg|png|css|html|htm)$") of
                        {match, _Start, _Lenght} ->
                            Arg1 = Arg;
                        _Else ->
                            Elems = string:tokens(Path, "/"),
                            case Elems of
                                [] ->
                                    % Rewrite request to index.php
                                    NewPath = "/index.php" ++ RawPath,
                                    Req1 = Req#http_request{path = {abs_path, NewPath}},
                                    Arg1 = Arg#arg{req = Req1};
                                [H|T] ->
                                    % Check if request already begins with index.php
                                    case string:equal(H, "index.php") of
                                        true ->
                                            % Check for possible index.php duplicates
                                            case T of
                                                [] ->
                                                    Arg1 = Arg;
                                                [H1|T1] ->
                                                    case string:equal(H1, "index.php") of
                                                        true ->
                                                            % If duplicates found, remove them
                                                            L = lremove("index.php", [T1]),
                                                            NewPath = "/index.php/" ++ join(L, "/"),
                                                            Req1 = Req#http_request{path = {abs_path, NewPath}},
                                                            Arg1 = Arg#arg{req = Req1};
                                                        false ->
                                                            Arg1 = Arg
                                                    end
                                            end;
                                        false ->
                                            % Rewrite request to index.php
                                            NewPath = "/index.php" ++ RawPath,
                                            Req1 = Req#http_request{path = {abs_path, NewPath}},
                                            Arg1 = Arg#arg{req = Req1}
                                    end
                            end
                    end
            end;
        _Else ->
            Arg1 = Arg
    end,
    Arg1.

% Remove all occurences of Elem from the beginning of the list
lremove(_Elem, []) ->
    [];
lremove(Elem, List) ->
    [H|T] = List,
    case string:equal(H, "index.php") of
        true ->
            lremove(Elem, T);
        false ->
            List
    end.

% Join list into a string with elements separated with Sep
join([], Sep) ->
    Sep;
join([H|T], Sep) ->
    H ++ lists:concat([Sep ++ X || X <- T]).