#ifndef INCLUDED_METHOD_MACRO_H
#define INCLUDED_METHOD_MACRO_H

#if __has_attribute(always_inline)
#    define always_inline inline __attribute__((always_inline))
#else
#    define always_inline inline
#endif

#if __has_attribute(unused)
#    define UNUSED __attribute__((unused))
#else
#    define UNUSED
#endif

// clang-format off
#define _ELEVENTH(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, ...) a11
#define _COUNT_ARGS(...) _ELEVENTH(__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
#define _GLUE(a, b) a##b
#define _GLUE2(a, b) _GLUE(a, b)
#define _IGNORE(...)
#define _REMOVE_FIRST(a1, ...) __VA_ARGS__
#define _EVAL(...) __VA_ARGS__
// clang-format on

// This is needed because C11 doesn't allow empty __VA_ARGS__
#define _GET_1_1(a1)                     a1
#define _GET_1_2(a1, a2)                 a1
#define _GET_1_3(a1, a2, a3)             a1
#define _GET_1_4(a1, a2, a3, a4)         a1
#define _GET_1_5(a1, a2, a3, a4, a5)     a1
#define _GET_1_6(a1, a2, a3, a4, a5, a6) a1

#define _GET_2_2(a1, a2)                 a2
#define _GET_2_3(a1, a2, a3)             a2
#define _GET_2_4(a1, a2, a3, a4)         a2
#define _GET_2_5(a1, a2, a3, a4, a5)     a2
#define _GET_2_6(a1, a2, a3, a4, a5, a6) a2

#define _GET_3_3(a1, a2, a3)             a3
#define _GET_3_4(a1, a2, a3, a4)         a3
#define _GET_3_5(a1, a2, a3, a4, a5)     a3
#define _GET_3_6(a1, a2, a3, a4, a5, a6) a3

#define _GET_4_4(a1, a2, a3, a4)         a4
#define _GET_4_5(a1, a2, a3, a4, a5)     a4
#define _GET_4_6(a1, a2, a3, a4, a5, a6) a4

#define _GET_5_5(a1, a2, a3, a4, a5)     a5
#define _GET_5_6(a1, a2, a3, a4, a5, a6) a5

#define _GET_6_6(a1, a2, a3, a4, a5, a6) a6

#define _GET_NTH(n, args) \
    _EVAL(_GLUE2(_GLUE2(_GLUE2(_GET_, n), _), _COUNT_ARGS args) args)

#define METHOD_CALLBACK_NAME(name) _##name##__as_callback

#define _CB_DECL_ARGS_1        Object *
#define _CB_DECL_ARGS_2        Object *, _CB_DECL_ARGS_1
#define _CB_DECL_ARGS_3        Object *, _CB_DECL_ARGS_2
#define _CB_DECL_ARGS_4        Object *, _CB_DECL_ARGS_3
#define _CB_DECL_ARGS_5        Object *, _CB_DECL_ARGS_4
#define _CB_DECL_ARGS_6        Object *, _CB_DECL_ARGS_5
#define _CB_DECL_ARGS_N(count) (_GLUE(_CB_DECL_ARGS_, count))
#define _CB_DECL_ARGS_FOR(...) _CB_DECL_ARGS_N(_COUNT_ARGS(__VA_ARGS__))
#define _GEN_CB_DECL(name, args)       \
    Object *METHOD_CALLBACK_NAME(name) \
    _CB_DECL_ARGS_FOR args

#define _ARG_NAME_1(args)    _IGNORE _GET_NTH(1, args)
#define _ARG_NAME_2(args)    _IGNORE _GET_NTH(2, args)
#define _ARG_NAME_3(args)    _IGNORE _GET_NTH(3, args)
#define _ARG_NAME_4(args)    _IGNORE _GET_NTH(4, args)
#define _ARG_NAME_5(args)    _IGNORE _GET_NTH(5, args)
#define _ARG_NAME_6(args)    _IGNORE _GET_NTH(6, args)
#define _ARG_NAME_N(n, args) _EVAL(_GLUE(_ARG_NAME_, n)(args))

#define _VOID_ARG_N(n, args)  (void *) _ARG_NAME_N(n, args)
#define _CALL_ARGS_1(args)    _VOID_ARG_N(1, args)
#define _CALL_ARGS_2(args)    _CALL_ARGS_1(args), _VOID_ARG_N(2, args)
#define _CALL_ARGS_3(args)    _CALL_ARGS_2(args), _VOID_ARG_N(3, args)
#define _CALL_ARGS_4(args)    _CALL_ARGS_3(args), _VOID_ARG_N(4, args)
#define _CALL_ARGS_5(args)    _CALL_ARGS_4(args), _VOID_ARG_N(5, args)
#define _CALL_ARGS_6(args)    _CALL_ARGS_5(args), _VOID_ARG_N(6, args)
#define _CALL_ARGS_N(n, args) _GLUE(_CALL_ARGS_, n)(args)
#define _GEN_REAL_CALL(name, args) \
    METHOD_CALLBACK_NAME(name)(_CALL_ARGS_N(_COUNT_ARGS args, args))

#define _UNWRAP_TYPE(arg)       _EVAL arg
#define _UNWRAP_ARG_N(n, args)  _UNWRAP_TYPE(_GET_NTH(n, args))
#define _UNWRAP_ARGS_1(args)    _UNWRAP_ARG_N(1, args)
#define _UNWRAP_ARGS_2(args)    _UNWRAP_ARGS_1(args), _UNWRAP_ARG_N(2, args)
#define _UNWRAP_ARGS_3(args)    _UNWRAP_ARGS_2(args), _UNWRAP_ARG_N(3, args)
#define _UNWRAP_ARGS_4(args)    _UNWRAP_ARGS_3(args), _UNWRAP_ARG_N(4, args)
#define _UNWRAP_ARGS_5(args)    _UNWRAP_ARGS_4(args), _UNWRAP_ARG_N(5, args)
#define _UNWRAP_ARGS_6(args)    _UNWRAP_ARGS_5(args), _UNWRAP_ARG_N(6, args)
#define _UNWRAP_ARGS_N(n, args) _GLUE(_UNWRAP_ARGS_, n)(args)
#define _UNWRAP_ARGS(args)      _UNWRAP_ARGS_N(_COUNT_ARGS args, args)

#define _METHOD_RAW(rtype, ret_stmt, name, args)          \
    _GEN_CB_DECL(name, args);                             \
    static always_inline rtype name(_UNWRAP_ARGS(args)) { \
        ret_stmt _GEN_REAL_CALL(name, args);              \
    }                                                     \
    struct __dummy_struct

#define METHOD(rtype, name, args) _METHOD_RAW(rtype, return (rtype), name, args)
#define VOID_METHOD(name, args)   _METHOD_RAW(void, , name, args)

#define _CB_DEF_ARGS_1        Object *_internal_arg1
#define _CB_DEF_ARGS_2        _CB_DEF_ARGS_1, Object *_internal_arg2
#define _CB_DEF_ARGS_3        _CB_DEF_ARGS_2, Object *_internal_arg3
#define _CB_DEF_ARGS_4        _CB_DEF_ARGS_3, Object *_internal_arg4
#define _CB_DEF_ARGS_5        _CB_DEF_ARGS_4, Object *_internal_arg5
#define _CB_DEF_ARGS_6        _CB_DEF_ARGS_5, Object *_internal_arg6
#define _CB_DEF_ARGS_N(count) (_GLUE(_CB_DEF_ARGS_, count))
#define _CB_DEF_ARGS_FOR(...) _CB_DEF_ARGS_N(_COUNT_ARGS(__VA_ARGS__))
#define _GEN_CB_DEF(name, args)        \
    Object *METHOD_CALLBACK_NAME(name) \
    _CB_DEF_ARGS_FOR args

#define _SET_NTH_ARG(n, args) \
    UNUSED _GET_NTH(n, args) = (void *) _internal_arg##n;
#define _SET_ARGS_1(args)    _SET_NTH_ARG(1, args)
#define _SET_ARGS_2(args)    _SET_ARGS_1(args) _SET_NTH_ARG(2, args)
#define _SET_ARGS_3(args)    _SET_ARGS_2(args) _SET_NTH_ARG(3, args)
#define _SET_ARGS_4(args)    _SET_ARGS_3(args) _SET_NTH_ARG(4, args)
#define _SET_ARGS_5(args)    _SET_ARGS_4(args) _SET_NTH_ARG(5, args)
#define _SET_ARGS_6(args)    _SET_ARGS_5(args) _SET_NTH_ARG(6, args)
#define _SET_ARGS_N(n, args) _GLUE(_SET_ARGS_, n)(args)

#define DEFINE_METHOD(rtype, name, args, body) \
    _GEN_CB_DEF(name, args) {                  \
        _SET_ARGS_N(_COUNT_ARGS args, args)    \
        body                                   \
    }

#endif