using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Snake
{
    public class Game
    {
        Worm worm;
        private Directions _direction = Directions.Down;
        Random random = new Random();
        Map map;
        Form1 form;

        int mapSize = 20;

        public Game(Form1 form)
        {
            this.form = form;
        }

        public void Start()
        {
            Cell startCell = new Cell(10, 10, CellTypes.Snake);
            map = new Map(mapSize, mapSize);
            map.SetCell(startCell);
            worm = new Worm(startCell);
            SpawnApple();
        }

        public void UpdateInput(Directions direction)
        {
            if (_direction == Directions.Down && direction == Directions.Up) return;
            if (_direction == Directions.Up && direction == Directions.Down) return;
            if (_direction == Directions.Left && direction == Directions.Right) return;
            if (_direction == Directions.Right && direction == Directions.Left) return;

            _direction = direction;
        }

        public Cell GetNextCell()
        {
            int x = worm.Body[0].X;
            int y = worm.Body[0].Y;

            if (_direction == Directions.Up)
            {
                return map.Cells[x, y + 1];
            }

            if (_direction == Directions.Left)
            {
                return map.Cells[x - 1, y];
            }

            if (_direction == Directions.Down)
            {
                return map.Cells[x, y - 1];
            }

            // Right
            return map.Cells[x + 1, y];
        }

        public bool IsNextPosOutOfBounds()
        {
            int x = worm.Body[0].X;
            int y = worm.Body[0].Y;

            if (_direction == Directions.Up)
                if (y + 1 >= mapSize) return true;

            if (_direction == Directions.Left)
                if (x - 1 < 0) return true;

            if (_direction == Directions.Down)
                if (y - 1 < 0) return true;

            if (_direction == Directions.Right)
                if (x + 1 >= mapSize) return true;

            return false;
        }

        public void SpawnApple()
        {
            int x = random.Next(mapSize);
            int y = random.Next(mapSize);

            Cell cell = map.Cells[x, y];

            if (cell.Type == CellTypes.None)
            {
                cell.Type = CellTypes.Food;
                return;
            }

            SpawnApple();
        }

        public void Update()
        {
            if (IsNextPosOutOfBounds())
            {
                Die();
                return;
            }

            int x = worm.Body[0].X;
            int y = worm.Body[0].Y;

            Cell snakeCell = map.Cells[x, y];
            Cell nextCell = GetNextCell();

            if (nextCell.Type == CellTypes.Snake)
            {
                Die();
                return;
            }

            if (nextCell.Type == CellTypes.Food)
            {
                worm.Eat(ref nextCell);
                SpawnApple();
            }

            map.SwapCells(snakeCell, nextCell);
            worm.Move(x, y, map);

            map.Render(form.gamearea.CreateGraphics());
            form.Invalidate();
        }

        public void Die()
        {
            form.timer.Enabled = false;
        }
    }
}