from __future__ import annotations

from abc import ABC, abstractmethod
from typing import List

from PIL import ImageDraw

from .item import ListItem


class SelectableList(ABC):
    """Abstract base for list and carousel selection widgets.

    Manages a collection of :class:`ListItem` objects with a single
    *selected_index*, wrapping navigation, and a shared highlight-bar
    drawing primitive.  Concrete subclasses (:class:`ListView`,
    :class:`CarouselView`) only differ in how they render the items.

    The two subclasses expose an identical public interface so they can
    be swapped interchangeably.
    """

    def __init__(self,
                 items: List[ListItem] | None = None,
                 x_offset: int = 40,
                 max_visible: int = 5,
                 item_height: int = 20):
        self._items: List[ListItem] = list(items or [])
        self.selected_index: int = 0
        self.x_offset = x_offset
        self.max_visible = max_visible
        self.item_height = item_height

    # ---- item access ------------------------------------------------

    @property
    def items(self) -> List[ListItem]:
        return self._items

    @items.setter
    def items(self, value: List[ListItem]):
        self._items = list(value)
        if self._items and self.selected_index >= len(self._items):
            self.selected_index = len(self._items) - 1
        elif not self._items:
            self.selected_index = 0

    @property
    def selected_item(self) -> ListItem | None:
        if self._items and 0 <= self.selected_index < len(self._items):
            return self._items[self.selected_index]
        return None

    # ---- navigation -------------------------------------------------

    def select_previous(self):
        """Move selection to the previous item (wraps around)."""
        if self._items:
            self.selected_index = (self.selected_index - 1) % len(self._items)

    def select_next(self):
        """Move selection to the next item (wraps around)."""
        if self._items:
            self.selected_index = (self.selected_index + 1) % len(self._items)

    # ---- drawing helpers --------------------------------------------

    def _draw_highlight(self,
                        draw: ImageDraw.ImageDraw,
                        x: int,
                        y_center: int,
                        font_size: int = 10,
                        width: int = 90):
        """Draw a rounded highlight bar via overlapping circles.

        The bar radius is derived from *font_size* so the bar always
        fits snugly around the rendered text.
        """
        r = font_size // 2 + 4
        for i in range(0, width, max(1, r // 2)):
            draw.circle((x + i, y_center), r, fill='black')

    # ---- rendering (subclass) ---------------------------------------

    @abstractmethod
    def render(self, draw: ImageDraw.ImageDraw, y_start: int) -> None:
        """Render the widget onto *draw* starting at *y_start*."""
        ...