using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp13
{
    public partial class Form1 : Form
    {
        public List<Point> centers;
        public List<System.Diagnostics.Stopwatch> ages;
        public static int R = 40;
        public static int GREEN_THRESHOLD = 750;
        public static int YELLOW_THRESHOLD = 900;
        public static int RED_THRESHOLD = 1200;

        System.Windows.Forms.Timer myTimer;
        System.Windows.Forms.Timer colorTimer;
        Random rng;

        public Form1()
        {
            InitializeComponent();

            myTimer = new System.Windows.Forms.Timer(); // Interval set to 10 seconds

            myTimer.Interval = 1000; // measured in milliseconds
            myTimer.Tick += new EventHandler(AddAnotherCircle);
            myTimer.Enabled = true;

            colorTimer = new System.Windows.Forms.Timer(); // Interval set to 10 seconds

            colorTimer.Interval = 200; // measured in milliseconds
            colorTimer.Tick += new EventHandler(RefreshColors);
            colorTimer.Enabled = true;

            rng = new Random();
            centers = new List<Point>();
            ages = new List<System.Diagnostics.Stopwatch>();
        }

        public void RefreshColors(object sender, EventArgs args)
        {
            Canvas.Refresh();
        }

        public void AddAnotherCircle(object sender, EventArgs args)
        {
            if (centers.Count >= 20)
                return;

            Boolean candidateViable = true;
            Point slacker; 

            do
            {
                slacker = new Point(rng.Next(Canvas.Width - (R * 2)) + R,
                                    rng.Next(Canvas.Height - (R * 2)) + R);

                candidateViable = true;

                foreach (Point i in centers.ToList())
                {
                    if (Math.Sqrt(((slacker.X - i.X) * (slacker.X - i.X)) +
                         ((slacker.Y - i.Y) * (slacker.Y - i.Y))) < (R * 2)) // Bingo!
                    {
                        candidateViable = false;
                        break;
                    }
                }
            } while (!candidateViable);

            centers.Add(slacker);
            ages.Add(new System.Diagnostics.Stopwatch());
            ages[ages.Count - 1].Start();

            myTimer.Interval = rng.Next(3500) + 1000;

            Canvas.Refresh(); // This directs us to the Paint event
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            myTimer.Dispose();
        }

        private void Canvas_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            Brush myBrush;

            int index = 0;
            foreach (Point i in centers.ToList())
            {
                if (ages[index].ElapsedMilliseconds < GREEN_THRESHOLD)
                    myBrush = new SolidBrush(Color.Green);
                else if (ages[index].ElapsedMilliseconds > GREEN_THRESHOLD &&
                         ages[index].ElapsedMilliseconds < YELLOW_THRESHOLD)
                    myBrush = new SolidBrush(Color.Yellow);
                else // It's red
                    myBrush = new SolidBrush(Color.Red);

                g.FillCircle(myBrush, i.X, i.Y, R);

                index++;
                myBrush.Dispose();
            }
        }

        private void Canvas_MouseDown(object sender, MouseEventArgs e)
        {
            int index = 0;
            foreach (Point i in centers.ToList())
            {
                // (x - h)^2 + (y - k)^2 < R^2
                // Where (x, y) == where I clicked
                // and (h, k) == the center of the circle

                if ( ( ((e.X - i.X) * (e.X - i.X)) +
                       ((e.Y - i.Y) * (e.Y - i.Y)) ) < (R * R) ) // Bingo!
                {
                    centers.Remove(i);
                    ages.RemoveAt(index);
                    break;
                }
                index++;
            }

            Canvas.Refresh();
        }
    }
    public static class GraphicsExtensions
    {
        public static void DrawCircle(this Graphics g, Pen pen,
                                      float centerX, float centerY, float radius)
        {
            g.DrawEllipse(pen, centerX - radius, centerY - radius,
                          radius + radius, radius + radius);
        }

        public static void FillCircle(this Graphics g, Brush brush,
                                      float centerX, float centerY, float radius)
        {
            g.FillEllipse(brush, centerX - radius, centerY - radius,
                          radius + radius, radius + radius);
        }
    }
}