from typing import IO
from io import IOBase
from sys import stdout


class MessageFormatter():
    __terminator: str
    def __init__(self, terminator: str):
        """Create a new MessageFormatter"""
        if not isinstance(terminator, str):
            raise TypeError(f"terminator must be a str")
            
        self.__terminator = terminator
    

    def set_terminator(self, terminator: str):
        """Set termination character(s)"""
        if not isinstance(terminator, str):
            raise TypeError(f"terminator must be a str")
        
        self.__terminator = terminator

    def get_terminator(self) -> str:
        """Get termination character(s)"""
        return self.__terminator


    def format(self, message: str) -> str:
        """Formats a given message"""
        if not isinstance(message, str):
            raise TypeError(f"message must be a str")
        return f"{message}{self.__terminator}"


class Printer:
    __target: IO
    __message: str

    def __init__(self, target: IO, message: str):
        """Creates a new Printer"""
        if not isinstance(target, IOBase):
            raise TypeError(f"target must be a file object")
        if not isinstance(message, str):
            raise TypeError(f"message must be a str")
        
        self.__target = target
        self.__message = message


    def set_target(self, target: IO):
        """Sets the printer target (destination file object)"""
        if not isinstance(target, IOBase):
            raise TypeError(f"target must be a file object")

        self.__target = target
    
    def get_target(self) -> IO:
        """Gets the printer target (destination file object)"""
        return self.__target
    

    def set_message(self, message: str):
        """Sets the printer message"""
        if not isinstance(message, str):
            raise TypeError(f"message must be a str")

        self.__message = message
    
    def get_message(self) -> str:
        """Gets the printer message"""
        return self.__message
        

    def print_message(self, formatter: MessageFormatter):
        """Formats the message with the given formatter, and prints to target"""
        output = formatter.format(self.__message)
        self.__target.write(output)


if __name__ == "__main__":
    formatter = MessageFormatter("\n")

    printer = Printer(stdout, "Hello world")
    printer.print_message(formatter)