from typing import Callable, Optional, Tuple

from PIL import ImageDraw, Image

from .base import View
from .button_interface import ButtonInterface
from .draw_utils import draw_bluetooth_icon


class BluetoothPairingView(View, ButtonInterface):
    """Shows a 'waiting for connection' screen while BT pairing is active.

    ``start_command`` is called once when the view is first rendered, to
    trigger pairing mode on the hardware side.
    ``stop_command`` is called when the user cancels (left long press).
    ``on_connected(device_name)`` is called by external code when a device
    has paired; it transitions back by calling ``deactivate_command``.
    ``deactivate_command`` returns to the previous screen.
    """

    def __init__(self, parent, im_size, center,
                 start_command: Optional[Callable] = None,
                 stop_command: Optional[Callable] = None,
                 on_connected: Optional[Callable[[str], None]] = None,
                 deactivate_command: Optional[Callable] = None):
        self.start_command = start_command
        self.stop_command = stop_command
        self.on_connected = on_connected
        self.deactivate_command = deactivate_command
        self._frame = 0           # used for the waiting animation
        self._started = False
        super().__init__(parent, im_size, center)

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

    def update_weight(self, weight: float) -> Image.Image:
        if not self._started:
            self._started = True
            if self.start_command:
                self.start_command()

        im = self.bkg_im.copy()
        draw = ImageDraw.Draw(im)
        cx = self.size[0] // 2

        # Large BT icon centred
        draw_bluetooth_icon(draw, (cx, 52), size=20)

        draw.text((cx - 28, 80), "Pairing", fill='black')

        # Three animated dots
        self._frame = (self._frame + 1) % 6
        for i in range(3):
            r = 3 if i < self._frame // 2 + 1 else 1
            draw.circle((cx - 8 + i * 8, 100), r, fill='black')

        return im

    def notify_connected(self, device_name: str = ''):
        """Call this from the outside when a BT device has connected."""
        if self.on_connected:
            self.on_connected(device_name)
        self._cancel()

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

    def _cancel(self):
        if self.stop_command:
            self.stop_command()
        if self.deactivate_command:
            self.deactivate_command()

    def left_long_press(self):
        self._cancel()

    def has_button(self) -> Tuple[bool, bool, bool, bool]:
        return False, True, False, False

    def render_left_long_press(self, draw, x, y):
        draw.text((x, y - 5), 'Cancel', fill='black')