import gdb


def _dereference_dynamic(pointer):
    target = pointer.dereference()
    try:
        dynamic_type = target.dynamic_type
        if dynamic_type != target.type:
            target = target.cast(dynamic_type)
    except gdb.error:
        pass
    return target


class KstdUniquePtrPrinter(gdb.ValuePrinter):
    def __init__(self, val):
        self.__val = val
        self.__type = val.type.template_argument(0)

    def to_string(self):
        pointer = self.__val["m_storage"]
        if int(pointer) == 0:
            return f"kstd::unique_ptr<{self.__type}> (empty)"
        return f"kstd::unique_ptr<{self.__type}>"

    def children(self):
        pointer = self.__val["m_storage"]
        if int(pointer) != 0:
            if pointer.type.target().code == gdb.TYPE_CODE_VOID:
                yield ("get()", pointer)
            else:
                yield ("get()", _dereference_dynamic(pointer))

    def display_hint(self):
        return None


class KstdSharedPtrPrinter(gdb.ValuePrinter):
    def __init__(self, val):
        self.__val = val
        self.__type = val.type.template_argument(0)

    def to_string(self):
        pointer = self.__val["m_pointer"]
        control_block = self.__val["m_control_block"]

        if int(pointer) == 0 or int(control_block) == 0:
            return f"shared_ptr<{self.__type}> (empty)"

        strong_refs = int(control_block["m_strong_count"]["_M_i"])
        weak_refs = int(control_block["m_weak_count"]["_M_i"])

        return (
            f"shared_ptr<{self.__type}> use count {strong_refs}, weak count {weak_refs}"
        )

    def children(self):
        pointer = self.__val["m_pointer"]
        control_block = self.__val["m_control_block"]

        if int(pointer) != 0:
            if pointer.type.target().code == gdb.TYPE_CODE_VOID:
                # GDB cannot dereference a void* - there's no size/layout to interpret it with. This is the
                # shared_ptr<void> case (e.g. kapi::devices::device::driver_data) - show the raw address instead
                # of crashing.
                yield ("get()", pointer)
            else:
                yield ("get()", _dereference_dynamic(pointer))

    def display_hint(self):
        return None


class KstdWeakPtrPrinter(gdb.ValuePrinter):
    def __init__(self, val):
        self.__val = val
        self.__type = val.type.template_argument(0)

    def to_string(self):
        pointer = self.__val["m_pointer"]
        control_block = self.__val["m_control_block"]

        if int(pointer) == 0 or int(control_block) == 0:
            return f"weak_ptr<{self.__type}> (empty)"

        strong_refs = int(control_block["m_strong_count"]["_M_i"])
        weak_refs = int(control_block["m_weak_count"]["_M_i"])
        return (
            f"weak_ptr<{self.__type}> use count {strong_refs}, weak count {weak_refs}"
        )

    def children(self):
        pointer = self.__val["m_pointer"]

        if int(pointer) != 0:
            if pointer.type.target().code == gdb.TYPE_CODE_VOID:
                yield ("get()", pointer)
            else:
                yield ("get()", _dereference_dynamic(pointer))

    def display_hint(self):
        return None


class KstdObserverPtrPrinter(gdb.ValuePrinter):
    def __init__(self, val):
        self.__val = val
        self.__type = val.type.template_argument(0)
        self.__pointer = val["m_ptr"]

    def to_string(self):
        return f"{(self.__pointer)}"

    def children(self):
        if int(self.__pointer) != 0:
            if self.__pointer.type.target().code == gdb.TYPE_CODE_VOID:
                yield ("get()", self.__pointer)
            else:
                yield ("get()", _dereference_dynamic(self.__pointer))

    def display_hint(self):
        return None