from __future__ import annotations

from dataclasses import dataclass, field
from typing import Deque, Dict, List, Optional, Tuple
from collections import deque

from .protocol import Direction


Coord = Tuple[int, int]


@dataclass
class Snake:
    snake_id: int
    head: Coord
    direction: Direction
    body: Deque[Coord] = field(default_factory=deque)  # includes head at index 0

    @property
    def length(self) -> int:
        return len(self.body)


@dataclass
class PlayerSession:
    player_id: int
    name: str
    color_id: int
    peer: object  # transport-specific handle
    input_seq: int = 0


@dataclass
class GameState:
    width: int
    height: int
    snakes: Dict[int, Snake] = field(default_factory=dict)
    apples: List[Coord] = field(default_factory=list)
    tick: int = 0
    occupancy: Dict[Coord, Tuple[int, int]] = field(default_factory=dict)  # cell -> (snake_id, index)

    def in_bounds(self, x: int, y: int) -> bool:
        return 0 <= x < self.width and 0 <= y < self.height

    def cell_free(self, x: int, y: int) -> bool:
        return (x, y) not in self.occupancy

    def occupy_snake(self, snake: Snake) -> None:
        for idx, (cx, cy) in enumerate(snake.body):
            self.occupancy[(cx, cy)] = (snake.snake_id, idx)

    def clear_snake(self, snake: Snake) -> None:
        for (cx, cy) in list(snake.body):
            self.occupancy.pop((cx, cy), None)