import sys
import termios
from typing import Optional, TextIO
from agame.color import colorize
from .display import Display

ESC = "\u001b"
ANSI_MOVE_BOTTOM = f"{ESC}[999;0f"


class ANSIDisplay(Display):
    """
    Display for a modern terminal.

    This display attempts to keep the input at the bottom, and the output
    scrolling up.

    This utilizes `termios` and is therefore UNIX-only.
    """

    def __init__(
        self,
        input_prompt: str = colorize("{{>}} "),
        stdin: TextIO = sys.stdin,
        stdout: TextIO = sys.stdout,
    ):
        self.input_prompt = input_prompt
        self.__stdin = stdin
        self.__stdout = stdout
        # Initial set-up:
        # . Move the cursor to the bottom left part of the screen (this will set
        #   the current line to a really high value and will move us to the
        #   bottom of the screen)
        self.stdout.write(ANSI_MOVE_BOTTOM)

        # . Disable echo, set cbreak
        fd = self.stdin.fileno()
        self.__old_attrs = termios.tcgetattr(fd)
        self.cbreak()

        # . Clear
        self.clear()

    def line(self, line: str = ""):
        self.stdout.write(line)
        self.stdout.write("\n")

    def input(self) -> str:
        try:
            self.nocbreak()
            return input(self.input_prompt)
        finally:
            self.cbreak()

    def wait_for_ack(self, prompt: Optional[str] = "Press any key to continue..."):
        # Flush unread data
        termios.tcflush(self.stdin.fileno(), termios.TCIFLUSH)
        if prompt is not None:
            self.line(prompt)
        self.stdin.read(1)

    def cbreak(self):
        fd = self.stdin.fileno()
        new = termios.tcgetattr(fd)
        new[3] &= ~(termios.ECHO | termios.ICANON)
        termios.tcsetattr(fd, termios.TCSADRAIN, new)

    def nocbreak(self):
        fd = self.stdin.fileno()
        new = termios.tcgetattr(fd)
        new[3] |= termios.ECHO | termios.ICANON
        termios.tcsetattr(fd, termios.TCSADRAIN, new)

    def finish(self):
        # Clean up by restoring the old terminal state
        fd = self.stdin.fileno()
        termios.tcsetattr(fd, termios.TCSADRAIN, self.__old_attrs)

    def clear(self):
        self.stdout.write(f"{ESC}[2J")

    @property
    def stdin(self) -> TextIO:
        return self.__stdin

    @property
    def stdout(self) -> TextIO:
        return self.__stdout