"""Unified input handler for all platforms."""

import string
import sys


class TextInputHandler:
    """Input handler with platform-specific key code support."""

    # Platform-specific key codes
    if sys.platform == "win32":
        # Windows uses \xe0 prefix for special keys when using msvcrt.getwch
        DOWN_KEY = "\xe0P"  # Down arrow
        UP_KEY = "\xe0H"  # Up arrow
        LEFT_KEY = "\xe0K"  # Left arrow
        RIGHT_KEY = "\xe0M"  # Right arrow
        DELETE_KEY = "\xe0S"  # Delete key
        BACKSPACE_KEY = "\x08"  # Backspace
        TAB_KEY = "\t"
        SHIFT_TAB_KEY = "\x00\x0f"  # Shift+Tab
        ENTER_KEY = "\r"

        # Alternative codes that might be sent
        ALT_BACKSPACE = "\x7f"
        ALT_DELETE = "\x00S"
    else:
        # Unix/Linux key codes (ANSI escape sequences)
        DOWN_KEY = "\x1b[B"
        UP_KEY = "\x1b[A"
        LEFT_KEY = "\x1b[D"
        RIGHT_KEY = "\x1b[C"
        BACKSPACE_KEY = "\x7f"
        DELETE_KEY = "\x1b[3~"
        TAB_KEY = "\t"
        SHIFT_TAB_KEY = "\x1b[Z"
        ENTER_KEY = "\r"

        # Alternative codes
        ALT_BACKSPACE = "\x08"
        ALT_DELETE = None

    def __init__(self):
        self.text = ""
        self.cursor_left = 0

    def _move_cursor_left(self) -> None:
        self.cursor_left = max(0, self.cursor_left - 1)

    def _move_cursor_right(self) -> None:
        self.cursor_left = min(len(self.text), self.cursor_left + 1)

    def _insert_char(self, char: str) -> None:
        self.text = self.text[: self.cursor_left] + char + self.text[self.cursor_left :]
        self._move_cursor_right()

    def _delete_char(self) -> None:
        """Delete character before cursor (backspace)."""
        if self.cursor_left == 0:
            return

        self.text = self.text[: self.cursor_left - 1] + self.text[self.cursor_left :]
        self._move_cursor_left()

    def _delete_forward(self) -> None:
        """Delete character at cursor (delete key)."""
        if self.cursor_left == len(self.text):
            return

        self.text = self.text[: self.cursor_left] + self.text[self.cursor_left + 1 :]

    def handle_key(self, key: str) -> None:
        # Handle backspace (both possible codes)
        if key == self.BACKSPACE_KEY or (
            self.ALT_BACKSPACE and key == self.ALT_BACKSPACE
        ):
            self._delete_char()
        # Handle delete key
        elif key == self.DELETE_KEY or (self.ALT_DELETE and key == self.ALT_DELETE):
            self._delete_forward()
        elif key == self.LEFT_KEY:
            self._move_cursor_left()
        elif key == self.RIGHT_KEY:
            self._move_cursor_right()
        elif key in (
            self.UP_KEY,
            self.DOWN_KEY,
            self.ENTER_KEY,
            self.SHIFT_TAB_KEY,
            self.TAB_KEY,
        ):
            pass
        else:
            # Handle regular text input
            # Special keys on Windows start with \x00 or \xe0
            if sys.platform == "win32" and key and key[0] in ("\x00", "\xe0"):
                # Skip special key sequences
                return

            # Even if we call this handle_key, in some cases we might receive
            # multiple keys at once (e.g., during paste operations)
            for char in key:
                if char in string.printable:
                    self._insert_char(char)