# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
import functools
from typing import Dict, List, NoReturn, Optional, Tuple

from pylint.exceptions import InvalidMessageError, UnknownMessageError


class MessageIdStore:

    """The MessageIdStore store MessageId and make sure that there is a 1-1 relation between msgid and symbol."""

    def __init__(self) -> None:
        self.__msgid_to_symbol: Dict[str, str] = {}
        self.__symbol_to_msgid: Dict[str, str] = {}
        self.__old_names: Dict[str, List[str]] = {}

    def __len__(self) -> int:
        return len(self.__msgid_to_symbol)

    def __repr__(self) -> str:
        result = "MessageIdStore: [\n"
        for msgid, symbol in self.__msgid_to_symbol.items():
            result += f"  - {msgid} ({symbol})\n"
        result += "]"
        return result

    def get_symbol(self, msgid: str) -> str:
        try:
            return self.__msgid_to_symbol[msgid.upper()]
        except KeyError as e:
            msg = f"'{msgid}' is not stored in the message store."
            raise UnknownMessageError(msg) from e

    def get_msgid(self, symbol: str) -> str:
        try:
            return self.__symbol_to_msgid[symbol]
        except KeyError as e:
            msg = f"'{symbol}' is not stored in the message store."
            raise UnknownMessageError(msg) from e

    def register_message_definition(
        self, msgid: str, symbol: str, old_names: List[Tuple[str, str]]
    ) -> None:
        self.check_msgid_and_symbol(msgid, symbol)
        self.add_msgid_and_symbol(msgid, symbol)
        for old_msgid, old_symbol in old_names:
            self.check_msgid_and_symbol(old_msgid, old_symbol)
            self.add_legacy_msgid_and_symbol(old_msgid, old_symbol, msgid)

    def add_msgid_and_symbol(self, msgid: str, symbol: str) -> None:
        """Add valid message id.

        There is a little duplication with add_legacy_msgid_and_symbol to avoid a function call,
        this is called a lot at initialization.
        """
        self.__msgid_to_symbol[msgid] = symbol
        self.__symbol_to_msgid[symbol] = msgid

    def add_legacy_msgid_and_symbol(
        self, msgid: str, symbol: str, new_msgid: str
    ) -> None:
        """Add valid legacy message id.

        There is a little duplication with add_msgid_and_symbol to avoid a function call,
        this is called a lot at initialization.
        """
        self.__msgid_to_symbol[msgid] = symbol
        self.__symbol_to_msgid[symbol] = msgid
        existing_old_names = self.__old_names.get(msgid, [])
        existing_old_names.append(new_msgid)
        self.__old_names[msgid] = existing_old_names

    def check_msgid_and_symbol(self, msgid: str, symbol: str) -> None:
        existing_msgid: Optional[str] = self.__symbol_to_msgid.get(symbol)
        existing_symbol: Optional[str] = self.__msgid_to_symbol.get(msgid)
        if existing_symbol is None and existing_msgid is None:
            return  # both symbol and msgid are usable
        if existing_msgid is not None:
            if existing_msgid != msgid:
                self._raise_duplicate_msgid(symbol, msgid, existing_msgid)
        if existing_symbol and existing_symbol != symbol:
            # See https://github.com/python/mypy/issues/10559
            self._raise_duplicate_symbol(msgid, symbol, existing_symbol)

    @staticmethod
    def _raise_duplicate_symbol(msgid: str, symbol: str, other_symbol: str) -> NoReturn:
        """Raise an error when a symbol is duplicated."""
        symbols = [symbol, other_symbol]
        symbols.sort()
        error_message = f"Message id '{msgid}' cannot have both "
        error_message += f"'{symbols[0]}' and '{symbols[1]}' as symbolic name."
        raise InvalidMessageError(error_message)

    @staticmethod
    def _raise_duplicate_msgid(symbol: str, msgid: str, other_msgid: str) -> NoReturn:
        """Raise an error when a msgid is duplicated."""
        msgids = [msgid, other_msgid]
        msgids.sort()
        error_message = (
            f"Message symbol '{symbol}' cannot be used for "
            f"'{msgids[0]}' and '{msgids[1]}' at the same time."
            f" If you're creating an 'old_names' use 'old-{symbol}' as the old symbol."
        )
        raise InvalidMessageError(error_message)

    @functools.lru_cache()
    def get_active_msgids(self, msgid_or_symbol: str) -> List[str]:
        """Return msgids but the input can be a symbol.

        The cache has no limit as its size will likely stay minimal. For each message we store
        about 1000 characters, so even if we would have 1000 messages the cache would only
        take up ~= 1 Mb.
        """
        msgid: Optional[str]
        if msgid_or_symbol[1:].isdigit():
            # Only msgid can have a digit as second letter
            msgid = msgid_or_symbol.upper()
            symbol = self.__msgid_to_symbol.get(msgid)
        else:
            msgid = self.__symbol_to_msgid.get(msgid_or_symbol)
            symbol = msgid_or_symbol
        if not msgid or not symbol:
            error_msg = f"No such message id or symbol '{msgid_or_symbol}'."
            raise UnknownMessageError(error_msg)
        return self.__old_names.get(msgid, [msgid])