-module(ephp_lib_func).

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

-behaviour(ephp_lib).

-export([init_func/0, init_config/0, init_const/0, get_classes/0,
         register_shutdown_function/3, get_defined_functions/2, function_exists/3, func_num_args/2,
         func_get_arg/3, func_get_args/2, call_user_func/3, call_user_func_array/4,
         create_function/4]).

-include("ephp.hrl").
-include("ephp_parser.hrl").
-include("ephp_array.hrl").

-spec init_func() -> ephp_lib:php_function_results().
init_func() ->
    [{register_shutdown_function, [pack_args]},
     get_defined_functions,
     function_exists,
     func_num_args,
     func_get_args,
     {func_get_arg, [{args, [integer]}]},
     {call_user_func, [pack_args]},
     {call_user_func_array, [callable, array]},
     {create_function, [{args, [string, string]}]}].

-spec init_config() -> ephp_lib:php_config_results().
init_config() ->
    [].

-spec init_const() -> ephp_lib:php_const_results().
init_const() ->
    [].

-spec get_classes() -> [class()].
get_classes() ->
    ephp_class_closure:get_classes().

-spec register_shutdown_function(ephp:context_id(), line(), [var_value()]) -> ok.
register_shutdown_function(Context, _Line, [{_, Callback} | _RawArgs]) ->
    %% TODO: add params to call the functions.
    ephp_context:register_shutdown_func(Context, Callback),
    ok.

-spec func_num_args(ephp:context_id(), line()) -> non_neg_integer().
func_num_args(Context, _Line) ->
    ephp_context:get_active_function_arity(Context).

-spec func_get_args(ephp:context_id(), line()) -> mixed().
func_get_args(Context, _Line) ->
    ephp_context:get_active_function_args(Context).

-spec func_get_arg(ephp:context_id(), line(), Pos :: var_value()) -> mixed().
func_get_arg(Context, _Line, {_, Pos}) ->
    ephp_context:get_active_function_arg(Context, Pos).

-spec get_defined_functions(ephp:context_id(), line()) -> ephp_array:ephp_array().
get_defined_functions(Context, _Line) ->
    Append =
        fun({Func, Type}, {I, Dict}) ->
           NewTypeDict =
               case ephp_array:find(Type, Dict) of
                   {ok, TypeDict} ->
                       ephp_array:store(I, Func, TypeDict)
               end,
           {I + 1, ephp_array:store(Type, NewTypeDict, Dict)}
        end,
    BaseDict =
        ephp_array:store(<<"user">>,
                         ephp_array:new(),
                         ephp_array:store(<<"internal">>, ephp_array:new(), ephp_array:new())),
    Functions = ephp_context:get_functions(Context),
    {_, FuncList} = lists:foldl(Append, {0, BaseDict}, Functions),
    FuncList.

-spec function_exists(ephp:context_id(), line(), FuncName :: var_value()) -> boolean().
function_exists(Context, _Line, {_, FuncName}) ->
    %% TODO split NS from FuncName
    ephp_context:get_function(Context, FuncName) =/= error.

-spec call_user_func_array(ephp:context_id(), line(), var_value(), var_value()) ->
                              mixed().
call_user_func_array(Context, Line, {_, FuncName}, {_, Args}) ->
    call(Context, Line, FuncName, ephp_array:values(Args)).

-spec call_user_func(ephp:context_id(), line(), [var_value()]) -> mixed().
call_user_func(Context, Line, [{_, FuncName} | Args])
    when is_binary(FuncName) orelse ?IS_ARRAY(FuncName) orelse ?IS_OBJECT(FuncName) ->
    call(Context, Line, FuncName, [Arg || {_, Arg} <- Args]);
call_user_func(Context, Line, _Args) ->
    File = ephp_context:get_active_file(Context),
    Data = {<<"call_user_func">>, 1, <<"a valid callback">>, <<"no array or string">>},
    Error = {error, ewrongarg, Line, File, ?E_WARNING, Data},
    ephp_error:handle_error(Context, Error),
    false.

-spec create_function(ephp:context_id(),
                      line(),
                      Args :: var_value(),
                      Code :: var_value()) ->
                         obj_ref().
create_function(Context, {{line, Line}, _}, {_, Args}, {_, Code}) ->
    Pos = #parser{level = code, row = Line},
    {_, _, A} = ephp_parser_func:funct_args(<<Args/binary, ")">>, Pos, []),
    {_, _, C} = ephp_parser:code(Code, Pos, []),
    Closure = ephp_parser:add_line(#function{args = A, code = C}, Pos),
    ObjRef = ephp_context:solve(Context, Closure),
    ObjCtx = ephp_object:get_context(ObjRef),
    ephp_context:set_meta(ObjCtx, is_lambda, true),
    ObjRef.

call(Context, Line, FuncName, Args) when is_binary(FuncName) andalso is_list(Args) ->
    case binary:split(FuncName, <<"::">>) of
        [ClassName, StaticMethod] ->
            Call =
                #call{name = StaticMethod,
                      class = ClassName,
                      type = class,
                      line = Line},
            ephp_context:call_function(Context, Call);
        [FuncName] ->
            Call = #call{name = FuncName, args = Args},
            ephp_context:call_function(Context, Call)
    end;
call(Context, Line, Callable, Args) when ?IS_ARRAY(Callable) andalso is_list(Args) ->
    case ephp_array:to_list(Callable) of
        [{_, Object}, {_, Method}] when ?IS_OBJECT(Object) andalso is_binary(Method) ->
            Call =
                #call{name = Method,
                      type = object,
                      args = Args,
                      line = Line},
            ephp_context:call_method(Context, Object, Call);
        [{_, Class}, {_, Method}] when is_binary(Class) andalso is_binary(Method) ->
            case binary:split(Method, <<"::">>) of
                [Method] ->
                    Call =
                        #call{name = Method,
                              class = Class,
                              type = class,
                              line = Line},
                    ephp_context:call_function(Context, Call);
                [<<"parent">>, ParentMethod] ->
                    %% TODO: when parent isn't defined
                    {ClassNS, ClassName} = ephp_ns:parse(Class),
                    {ParentNS, ParentName} = ephp_class:get_parent(Context, ClassNS, ClassName),
                    Call =
                        #call{name = ParentMethod,
                              class = ParentName,
                              namespace = ParentNS,
                              type = class},
                    ephp_context:call_function(Context, Call)
            end
    end;
call(Context, Line, Object, Args) when ?IS_OBJECT(Object) andalso is_list(Args) ->
    %% TODO: error when __invoke is not defined
    Call =
        #call{name = <<"__invoke">>,
              type = object,
              args = Args,
              line = Line},
    ephp_context:call_method(Context, Object, Call).