using System.Collections.ObjectModel;

namespace Snake.Model;

public class SnakeLevel{
    public int Size {get; }

    public enum LevelBlock{
        Empty,
        Obstacle,
        Egg,
        Snake,
        SnakeHead
    }

    public enum SnakeDirection{
        Up,
        Down,
        Left,
        Right
    }

    private readonly List<Point> _obstacles;
    public ReadOnlyCollection<Point> Obstacles => _obstacles.AsReadOnly();
    public Point SnakeHead {get; private set;}
    private readonly List<Point> _snake;
    // Head is not in snake
    public ReadOnlyCollection<Point> Snake => _snake.AsReadOnly();
    public int SnakeLength => Snake.Count + 1;
    private readonly List<Point> _eggs;
    public ReadOnlyCollection<Point> Eggs => _eggs.AsReadOnly();
    public SnakeDirection SnakeHeadDirection {get; private set;}

    public SnakeLevel(int size, IEnumerable<Point> obstacles, int snake_start_length){
        this.Size = size;
        _obstacles = new List<Point>(obstacles);
        _eggs = [];
        _snake = [];
        
        SnakeHead = (size / 2, snake_start_length-1);
        for(int i=0; i<snake_start_length-1; i++){
            _snake.Add((size / 2, i));
        }

        SnakeHeadDirection = SnakeDirection.Down;
    }

    public LevelBlock this[Point p]{
        get{
            if(_obstacles.Contains(p)){
                return LevelBlock.Obstacle;
            }else if(p == SnakeHead){
                return LevelBlock.SnakeHead;
            }else if(_snake.Contains(p)){
                return LevelBlock.Snake;
            }else if(_eggs.Contains(p)){
                return LevelBlock.Egg;
            }

            return LevelBlock.Empty;
        }
    }
}