import gdb


class KstdErrorCodePrinter(gdb.ValuePrinter):
    def __init__(self, val):
        self.__val = val

    def _error_value(self):
        return int(self.__val["m_value"])

    def _category_name(self):
        try:
            category_pointer = self.__val["m_category"]
            if int(category_pointer) == 0:
                return "<null category>"
            category = category_pointer.dereference()
            try:
                dynamic = category.dynamic_type
                name = str(dynamic)
            except gdb.error:
                name = str(category.type)
            name = name.replace("(anonymous namespace)::", "")
            if name.endswith("_t"):
                name = name[:-2]
            return name
        except (gdb.error, AttributeError):
            return "?"

    def _message(self):
        try:
            category_pointer = self.__val["m_category"]
            if int(category_pointer) == 0:
                return None
            value = self._error_value()
            address = int(category_pointer)
            result = gdb.parse_and_eval(
                f"((kstd::error_category const *){address:#x})->message({value})"
            )
            try:
                ptr = result["_M_str"]
                length = int(result["_M_len"])
                if int(ptr) != 0 and length > 0:
                    return ptr.string(length=length)
            except (gdb.error, AttributeError, KeyError):
                pass
            return str(result)
        except (gdb.error, RuntimeError):
            return None

    def to_string(self):
        value = self._error_value()
        category = self._category_name()
        msg = self._message()
        if msg is not None:
            return f"{category}:{value} ({msg})"
        return f"{category}:{value}"

    def children(self):
        yield ("value", self.__val["m_value"])
        category_pointer = self.__val["m_category"]
        if int(category_pointer) != 0:
            yield ("category", category_pointer.dereference())

    def display_hint(self):
        return None