//using OpenTK.Graphics.OpenGL;
using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework;

namespace SnakeMonoGame;

public class Snake
{
    //Declarations
    public int Width, Height;

    int Speed = 300;
    long UpdateTimer = Environment.TickCount;

    List<string> Direction = new List<string>();
    string CurrentDir = "RightArrow";
    Point Move = new Point(1, 0);
    public List<Point> Segments = new List<Point>();
    public Point Food;
    Random Random = new Random();
    bool Grow = false;
    //
    public Snake(int Width, int Height)
    {
        this.Width = Width;
        this.Height = Height;

        Segments.Add(new Point(this.Width / 2, this.Height / 2));
        PickFood();
    }
    public void Update()
    {
        if (Environment.TickCount > UpdateTimer + Speed)
        {
            UpdateTimer = Environment.TickCount;

            //Set Direction
            if (Direction.Count > 0)
            {
                SetDirection(Direction[0]);
                Direction.RemoveAt(0);
            }

            //Eat Food
            if (Segments[0] == Food) { Grow = true; PickFood(); }

            //Move
            Point nSegment = new Point(Segments[0].X + Move.X, Segments[0].Y + Move.Y);
            Segments.Insert(0, nSegment);
            if (Grow == false) { Segments.RemoveAt(Segments.Count - 1); }
            else { Grow = false; }

            //Death
            bool death = false;
            if (Segments[0].X < 0 || Segments[0].X >= Width || Segments[0].Y < 0 || Segments[0].Y >= Height)
            {
                death = true;
            }
            else
            {
                for (int i = 1; i < Segments.Count; i++)
                {
                    if (Segments[i] == Segments[0]) { death = true; break; }
                }
            }
            if (death) { Segments.Clear(); Segments.Add(new Point(this.Width / 2, this.Height / 2)); }
        }
    }
    public void AddDirection(string dir)
    {
        if (dir == "UpArrow" || dir == "DownArrow" || dir == "LeftArrow" || dir == "RightArrow")
        {
            if (Direction.Count > 0)
            {
                if (dir != Direction[Direction.Count - 1]) { Direction.Add(dir); }
            }
            else { Direction.Add(dir); }
        }
    }
    private void SetDirection(string dir)
    {
        if (CheckDirection(dir) == true)
        {
            switch (dir)
            {
                case "UpArrow": Move.X = 0; Move.Y = -1; break;
                case "DownArrow": Move.X = 0; Move.Y = 1; break;
                case "LeftArrow": Move.X = -1; Move.Y = 0; break;
                case "RightArrow": Move.X = 1; Move.Y = 0; break;
            }
            CurrentDir = dir;
        }
    }
    private bool CheckDirection(string dir)
    {
        if (dir == "LeftArrow" && CurrentDir == "RightArrow") { return false; }
        if (dir == "RightArrow" && CurrentDir == "LeftArrow") { return false; }
        if (dir == "UpArrow" && CurrentDir == "DownArrow") { return false; }
        if (dir == "DownArrow" && CurrentDir == "UpArrow") { return false; }
        return true;
    }
    private void PickFood()
    {
        bool Found = false;
        while (Found == false)
        {
            Found = true;
            Food = new Point(Random.Next(0, Width), Random.Next(0, Height));
            foreach (Point p in Segments) { if (Food == p) { Found = false; break; } }
        }
    }
}