__all__ = ["CommandHandler", "CommandHandlers"]

from collections.abc import Iterator
from typing import Never

from argenta.app.protocols import HandlerFunc
from argenta.command import Command
from argenta.response import Response


class CommandHandler:
    def __init__(self, handler_as_func: HandlerFunc, handled_command: Command):
        """
        Private. Entity of the model linking the handler and the command being processed
        :param handler: the handler being called
        :param handled_command: the command being processed
        """
        self.handler_as_func: HandlerFunc = handler_as_func
        self.handled_command: Command = handled_command

    def handling(self, response: Response) -> None:
        """
        Private. Direct processing of an input command
        :param response: the entity of response: various groups of flags and status of response
        :return: None
        """
        self.handler_as_func(response)


class CommandHandlers:
    def __init__(self, command_handlers: tuple[CommandHandler] | tuple[Never, ...] = tuple()):
        """
        Private. The model that unites all CommandHandler of the routers
        :param command_handlers: list of CommandHandlers for register
        """
        self.command_handlers: list[CommandHandler] = list(command_handlers) if command_handlers else []
        self.paired_command_handler_trigger: dict[str, CommandHandler] = {x.handled_command.trigger: x for x in command_handlers}

    def add_handler(self, command_handler: CommandHandler) -> None:
        """
        Private. Adds a CommandHandler to the list of CommandHandlers
        :param command_handler: CommandHandler to be added
        :return: None
        """
        self.command_handlers.append(command_handler)
        self.paired_command_handler_trigger[command_handler.handled_command.trigger.lower()] = command_handler
        for alias in command_handler.handled_command.aliases:
            self.paired_command_handler_trigger[alias.lower()] = command_handler
            
    def get_command_handler_by_trigger(self, trigger: str) -> CommandHandler | None:
        return self.paired_command_handler_trigger.get(trigger)

    def __iter__(self) -> Iterator[CommandHandler]:
        return iter(self.command_handlers)
