from dataclasses import dataclass
from typing import Tuple, List, Optional


@dataclass
class Password:
    password:   Optional[str]
    login:      Optional[str] = None

#-------------------------------------------------------------------------------

class PasswordManager( object ):
    """
    An abstract password manager.

    Instanciate concrete instances via the Manager() function
    """

    def get( self, identifier: str ) -> Password:
        """
        Gets a password from the manager.

        This function is overriden by the concrete PasswordManager instances.

        Args:
            identifier: which password to get

        Returns:
            None if the password is not found,
            the password otherwise
        """
        return Password( None )

from .plaintext import PlainTextPasswordManager
from .gnupass import GNUPassPasswordManager

#-------------------------------------------------------------------------------

def verify( config: dict, path: str = "" ) -> Tuple[bool, List[str]]:
    """
    Verifies that the configuration is correct

    Args:
        config: dict with password manager configuration
        path: path to the "config" dict in the main configuration file

    Returns:
        bool: true if the config is correct
        List[str]: list of errors if the config is not correct
    """
    if "manager" not in config:
        return (False, [f'Missing "{path}.manager" value'])

    manager = config["manager"]
    for cls in PasswordManager.__subclasses__():
        if manager == cls.name():
            return cls.verify(config, path)
    return (False, [f'Unknown password manager "{manager}"'])

#-------------------------------------------------------------------------------

def Manager( config: dict ) -> PasswordManager:
    """
    Instanciates a PasswordManager instance from a given configuration
    """
    if "manager" not in config:
        raise ValueError
    manager = config["manager"]
    for cls in PasswordManager.__subclasses__():
        if manager == cls.name():
            return cls(config)
    raise ValueError