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

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        Thread thr;
        Stopwatch stoper = new Stopwatch();
        int n, sil, progres, czas;

        int stan_value = 0; //0 - stop, 1 - run, 2 - pause
        int stan
        {
            get { return stan_value; }
            set
            {
                stan_value = value;
                zmiana_stanu();
            }
        }

        int silnia(int n)
        {
            int s = 1;
            for (int i = 1; i <= n; i++)
            {
                s *= i;
            }
            return s;
        }

        void zmiana_stanu()
        {
            switch (stan)
            {
                case 0: //stop
                    stoper.Stop();
                    numericUpDown1.Enabled = true;
                    button1.Enabled = true;
                    button2.Enabled = false;
                    button3.Enabled = false;
                    break;
                case 1: //run
                    stoper.Start();
                    numericUpDown1.Enabled = false;
                    button1.Enabled = false;
                    button2.Enabled = true;
                    button3.Enabled = true;
                    break;
                case 2: //pause
                    stoper.Stop();
                    numericUpDown1.Enabled = false;
                    button1.Enabled = true;
                    button2.Enabled = false;
                    button3.Enabled = false;
                    break;
            }
        }

        void reset()
        {
            progres = 0;
            czas = 0;
            progressBar1.Value = 0;
            stoper.Reset();
            textBox1.Clear();
            label3.Text = "0 %";
            label4.Text = "Czas od początku obliczeń: " + stoper.Elapsed;
            label5.Text = "Czas do zakończenia obliczeń: 0 s";
            stan = 0;
        }

        void wyswietl(int[] a)
        {
            string perm = "";
            for (int i = 0; i < a.Length; i++)
                perm += a[i] + " ";

            progres++;
            czas = (int)((sil - progres) * stoper.ElapsedMilliseconds / progres) / 1000;

            textBox1.Invoke(new MethodInvoker(() => textBox1.AppendText(perm + "\n")));
            progressBar1.Invoke(new MethodInvoker(() => progressBar1.Value = progres));
            label3.Invoke(new MethodInvoker(() => label3.Text = string.Format("{0} %", (int)((float)progres / sil * 100))));
            label4.Invoke(new MethodInvoker(() => label4.Text = "Czas od początku obliczeń: " + stoper.Elapsed));
            if (czas < 60)
                label5.Invoke(new MethodInvoker(() => label5.Text = "Czas do zakończenia obliczeń: " + czas + " s"));
            else
                label5.Invoke(new MethodInvoker(() => label5.Text = "Czas do zakończenia obliczeń: " + czas / 60 + " min " + czas % 60 + " s"));
        }

        void koniec()
        {
            stan_value = 0; //metoda zmiana_stanu tu nie działa, trzeba to zrobić ręcznie.
            stoper.Stop();
            numericUpDown1.Invoke(new MethodInvoker(() => numericUpDown1.Enabled = true));
            button1.Invoke(new MethodInvoker(() => button1.Enabled = true));
            button2.Invoke(new MethodInvoker(() => button2.Enabled = false));
            button3.Invoke(new MethodInvoker(() => button3.Enabled = false));
        }

        void QuickPerm() //http://www.c-sharpcorner.com/Forums/Thread/213338/C-Sharp-windows-form-application-pleasee-helllppp.aspx
        {
            int[] a = new int[n];
            int[] p = new int[n]; // all zero by default
            int i, j, tmp;
            for (i = 0; i < n; i++)
                a[i] = i + 1;
            wyswietl(a);
            i = 1;
            while (i < n)
            {
                if (p[i] < i)
                {
                    j = i % 2 * p[i];
                    tmp = a[j];
                    a[j] = a[i];
                    a[i] = tmp;
                    wyswietl(a);
                    p[i]++;
                    i = 1;
                }
                else
                {
                    p[i] = 0;
                    i++;
                }
            }
            koniec();
        }

        private void numericUpDown1_ValueChanged(object sender, EventArgs e)
        {
            label2.Text = "n! = " + silnia((int)numericUpDown1.Value).ToString();
        }

        private void button1_Click(object sender, EventArgs e) //Start
        {
            if (stan == 2)
            {
                try
                {
                    thr.Resume();
                    stan = 1;
                }
                catch { }
            }
            else
            {
                reset();
                n = (int)numericUpDown1.Value;
                sil = silnia(n);
                progressBar1.Maximum = sil;
                thr = new Thread(QuickPerm);
                thr.Start();
                stan = 1;
            }
        }

        private void button2_Click(object sender, EventArgs e) //Pauza
        {
            try
            {
                thr.Suspend();
                stan = 2;
            }
            catch { }
        }

        private void button3_Click(object sender, EventArgs e) //Stop
        {
            try
            {
                thr.Abort();
                stan = 0;
            }
            catch { }
            reset();
        }

        public Form1()
        {
            InitializeComponent();
            reset();
        }

        /*
        void swap(int a, int b)
        {
            int tmp = list[a];
            list[a] = list[b];
            list[b] = tmp;
        }

        void perm(int k) //Heap's algorithm
        {
            if (k == 0)
                wyswietl_liste();
            else
            {
                for (int i = 0; i <= k; i++)
                {
                    swap(i, k);
                    perm(k - 1);
                    swap(i, k);
                }
            }
        }
        */
    }
}