%% @doc This module stores handle the way to use namespaces. The namespaces
%%      are needed mainly during parsing (compilation-time) but dynamically
%%      it's sometimes needed as well.
%% @end
-module(ephp_ns).

-author('manuel@altenwald.com').

-include("ephp.hrl").

-export([normalize/1, join/2, split/1, to_bin/1, to_bin/2, parse/1, find/2, translate/3]).

-type namespace() :: [binary()].

-export_type([namespace/0]).

-spec normalize(namespace()) -> namespace().
%% @doc normalize namespace removing initial empty (absolute) if any.
normalize([<<>> | NS]) ->
    NS;
normalize(NS) ->
    NS.

-spec join(namespace(), namespace()) -> namespace().
%% @doc join two namespaces to generate only one, checking for absolute and relative.
join(_BaseNS, [<<>> | RelativeNS]) ->
    RelativeNS;
join(BaseNS, RelativeNS) ->
    BaseNS ++ RelativeNS.

-spec split(namespace()) -> {namespace(), binary()}.
%% @doc retrieve last part of the namespace.
split([Name]) ->
    {[], Name};
split(NS) when is_list(NS) andalso length(NS) > 1 ->
    {lists:droplast(NS), lists:last(NS)}.

-spec to_bin(namespace()) -> binary().
%% @doc converts a namespace to the string representation.
to_bin(NS) ->
    ephp_string:join(NS, <<"\\">>).

-spec to_bin(namespace(), class_name()) -> binary().
%% @doc converts a namespace and class or function name to the string representation.
to_bin(NS, <<>>) ->
    to_bin(NS);
to_bin(NS, ClassName) ->
    to_bin(NS ++ [ClassName]).

-spec parse(binary()) -> {namespace(), class_name()}.
%% @doc converts a string into a 2-tuple: namespace and class name.
parse(Str) ->
    case binary:split(Str, <<"\\">>, [global]) of
        [ClassName] ->
            {[], ClassName};
        Parts ->
            {lists:droplast(Parts), lists:last(Parts)}
    end.

-spec find(namespace(), [{namespace(), namespace()}]) ->
              {namespace(), namespace()} | false.
%% @doc find a matching namespace based on the initial match.
find(NS, NSList) ->
    lists:foldl(fun ({MatchNS, RealNS}, false) ->
                        case lists:prefix(MatchNS, NS) of
                            true ->
                                {MatchNS, RealNS};
                            false ->
                                false
                        end;
                    (_, Acc) ->
                        Acc
                end,
                false,
                NSList).

-spec translate(Source :: namespace(), Match :: namespace(), Target :: namespace()) ->
                   namespace().
%% @doc translate a namespace into another based on match one.
translate(Source, Match, Target) ->
    MatchSize = length(Match),
    Suffix = lists:sublist(Source, MatchSize + 1, length(Source) - MatchSize),
    Target ++ Suffix.