eva_bead_1/view/Form1.cs

using Snake.Model;
using Snake.Persistance;

namespace view
{
    public partial class Form1 : Form
    {
        Graphics graphics;
        int line_width = 2;
        SnakeLevel? CurrentLevel;
        SnakeLevelLoader level_loader;

        public Form1()
        {
            InitializeComponent();
            graphics = Canvas.CreateGraphics();
            level_loader = new SnakeLevelLoader(Path.Combine(Directory.GetCurrentDirectory(), "levels.json"));
        }

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            if (CurrentLevel == null) return;
            switch (e.KeyCode)
            {
                case Keys.Up:
                    CurrentLevel.SnakeHeadDirection = SnakeLevel.SnakeDirection.Up;
                    break;
                case Keys.Down:
                    CurrentLevel.SnakeHeadDirection = SnakeLevel.SnakeDirection.Down;
                    break;
                case Keys.Left:
                    CurrentLevel.SnakeHeadDirection = SnakeLevel.SnakeDirection.Left;
                    break;
                case Keys.Right:
                    CurrentLevel.SnakeHeadDirection = SnakeLevel.SnakeDirection.Right;
                    break;
                case Keys.Escape:
                    CurrentLevel.Pause();
                    break;

            }
        }

        private void Draw(SnakeLevel level)
        {
            var canvas_size = Math.Min(Canvas.Width, Canvas.Height);


            graphics.Clear(Color.White);
            double cell_size = (double)(canvas_size - (level.Size + 1) * line_width) / level.Size;
            // vertical lines
            for (int i = 0; i <= level.Size; i++)
            {
                int x = (int)(i * (cell_size + line_width));
                graphics.FillRectangle(Brushes.Black, x, 0, line_width, canvas_size);
            }
            // horizontal lines
            for (int i = 0; i <= level.Size; i++)
            {
                int y = (int)(i * (cell_size + line_width));
                graphics.FillRectangle(Brushes.Black, 0, y, canvas_size, line_width);
            }
            // Ssnake
            foreach (var pos in level.Snake)
            {
                int x = (int)(cell_size * pos.X + line_width * (pos.X + 1));
                int y = (int)(cell_size * pos.Y + line_width * (pos.Y + 1));
                graphics.FillRectangle(Brushes.Green, x, y, (int)cell_size, (int)cell_size);
            }
            // snake head
            int snake_head_x = (int)(cell_size * level.SnakeHead.X + line_width * (level.SnakeHead.X + 1));
            int snake_head_y = (int)(cell_size * level.SnakeHead.Y + line_width * (level.SnakeHead.Y + 1));
            graphics.FillRectangle(Brushes.Red, snake_head_x, snake_head_y, (int)cell_size, (int)cell_size);
            switch (level.SnakeHeadDirection)
            {
                case SnakeLevel.SnakeDirection.Up:
                    graphics.DrawLine(Pens.Black, snake_head_x + (int)cell_size / 2, snake_head_y, snake_head_x + (int)cell_size / 2, snake_head_y + (int)cell_size);
                    graphics.DrawLine(Pens.Black, snake_head_x + (int)cell_size / 2, snake_head_y, snake_head_x, snake_head_y + (int)cell_size / 2);
                    graphics.DrawLine(Pens.Black, snake_head_x + (int)cell_size / 2, snake_head_y, snake_head_x + (int)cell_size, snake_head_y + (int)cell_size / 2);
                    break;
                case SnakeLevel.SnakeDirection.Down:
                    graphics.DrawLine(Pens.Black, snake_head_x + (int)cell_size / 2, snake_head_y, snake_head_x + (int)cell_size / 2, snake_head_y + (int)cell_size);
                    graphics.DrawLine(Pens.Black, snake_head_x + (int)cell_size / 2, snake_head_y, snake_head_x, snake_head_y + (int)cell_size / 2);
                    graphics.DrawLine(Pens.Black, snake_head_x + (int)cell_size / 2, snake_head_y, snake_head_x + (int)cell_size, snake_head_y + (int)cell_size / 2);
                    break;
                case SnakeLevel.SnakeDirection.Left:
                    graphics.DrawLine(Pens.Black, snake_head_x, snake_head_y + (int)cell_size / 2, snake_head_x + (int)cell_size, snake_head_y + (int)cell_size / 2);
                    break;
                case SnakeLevel.SnakeDirection.Right:
                    graphics.DrawLine(Pens.Black, snake_head_x, snake_head_y + (int)cell_size / 2, snake_head_x + (int)cell_size, snake_head_y + (int)cell_size / 2);
                    break;

            }

            // obstacles
            foreach (var pos in level.Obstacles)
            {
                int x = (int)(cell_size * pos.X + line_width * (pos.X + 1));
                int y = (int)(cell_size * pos.Y + line_width * (pos.Y + 1));
                graphics.FillRectangle(Brushes.Black, x, y, (int)cell_size, (int)cell_size);
            }

            //eggs
            foreach (var pos in level.Eggs)
            {
                int x = (int)(cell_size * pos.X + line_width * (pos.X + 1));
                int y = (int)(cell_size * pos.Y + line_width * (pos.Y + 1));
                graphics.FillRectangle(Brushes.Pink, x, y, (int)cell_size, (int)cell_size);
            }
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            if (CurrentLevel is null || CurrentLevel.State != SnakeLevel.GameState.Running)
            {
                var MapChooser = new MapChooser(this.level_loader);
                MapChooser.ShowDialog();
                if (MapChooser.SelectedLevel != null)
                {
                    CurrentLevel = level_loader.LoadLevel(MapChooser.SelectedLevel);
                    CurrentLevel.GameStateUpdate += CurrentLevel_GameStateUpdate;
                    CurrentLevel.GameUpdate += CurrentLevel_GameUpdate;
                }
                else
                {
                    CurrentLevel = null;
                }
            }
            if (CurrentLevel != null)
            {
                CurrentLevel.Start();
                this.Focus();
            }
        }

        private void CurrentLevel_GameUpdate(object? sender, EventArgs e)
        {
            this.Invoke(() =>
            {
                if (CurrentLevel != null)
                {
                    Draw(CurrentLevel);
                    txtScore.Text = CurrentLevel.Score.ToString();
                }
            });
        }

        private void CurrentLevel_GameStateUpdate(object? sender, SnakeLevel.GameState e)
        {
            this.Invoke(() =>
            {
                if (CurrentLevel == null) return;
                switch (e)
                {
                    case SnakeLevel.GameState.Running:
                        btnStart.Visible = false;
                        Draw(CurrentLevel);
                        break;
                    case SnakeLevel.GameState.Paused:
                        btnStart.Visible = true;
                        break;
                    case SnakeLevel.GameState.Dead:
                        btnStart.Visible = true;
                        MessageBox.Show($"Skill issue.\nScore: {CurrentLevel.Score}", "Snake", MessageBoxButtons.OK, MessageBoxIcon.Information);
                        break;
                }
            });
        }

        private void Form1_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
        {
            if(CurrentLevel?.State is SnakeLevel.GameState.Running)
            {
                e.IsInputKey = true;
            }
        }
    }
}