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

namespace Eratosthenes
{
    public partial class Form1 : Form
    {
        ulong mez;
        ulong pocet;    
       
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            textBox_mez.Text = "";
            textBox_mez.Focus();
            textBox_vystup.Clear();
            label_pocet.Text = "";
            label_pocet.Visible = false;
        }

        private void textBox_mez_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!(e.KeyChar >= 48 && e.KeyChar <= 57))
            {
                e.KeyChar = Convert.ToChar(0);
            }

        }

        private void button_vymaz_Click(object sender, EventArgs e)
        {
            textBox_mez.Text = "";
            textBox_mez.Focus();
            textBox_vystup.Clear();
            label_pocet.Text = "";
            label_pocet.Visible = false;
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
            System.Diagnostics.Process.Start("https://www.itnetwork.cz/algoritmy/matematicke/algoritmus-eratosthenovo-sito");
        }

        private void button_vypocet_Click(object sender, EventArgs e)
        {
            pocet = 0;
            textBox_vystup.Clear();
            string hodnota;


            if (textBox_mez.Text == "")
            {
                MessageBox.Show("Musíte zadat číslo!", "Upozornění", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return;
            }
            else
            {
                try
                {
                   mez = Convert.ToUInt64(textBox_mez.Text); 
                }
                catch (OverflowException)
                {
                    MessageBox.Show("Zadejte menší číslo!", "Varování", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    textBox_mez.Text = "";
                    textBox_mez.Focus();
                    return;
                }

                if (mez > 10000000)
                {
                    MessageBox.Show("Algoritmus je efektivní do 10 000 000!", "Varování", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                    textBox_mez.Text = "";
                    textBox_mez.Focus();
                    return;
                }
                else
                {
                    bool[] sito = new bool[mez + 1];

                    for (ulong i = 0; i <= mez; i++)
                    {
                        sito[i] = true;  //true - je prvočíslo, false - není prvočíslo
                    }

                    sito[0] = false; sito[1] = false;

                    for (ulong j = 2; j <= Math.Sqrt(mez); j++)
                    {
                        if (sito[j] == true)
                        {
                            for (ulong k = j + 1; k <= mez; k++)
                            {
                                if (k % j == 0)
                                {
                                    sito[k] = false;
                                }
                            }
                        }
                    }

                   /*
                    //Výpis přímo do textBoxu

                    int vypis = 1;
                    char pad = ' ';

                    for (ulong cisla = 2; cisla <= mez; cisla++)
                    {
                        if (sito[cisla] == true)
                        {
                            hodnota = Convert.ToString(cisla);
                            textBox_vystup.AppendText(hodnota.PadLeft(10,pad));
                            vypis++;

                            if (vypis == 6)
                            {
                                textBox_vystup.AppendText(Environment.NewLine);
                                vypis = 1;
                            }

                            pocet++;

                        }
                    }

                    //Konec zápisu do textBoxu
                    
                    */ 

                    //Zápis do StringBuilderu

                    StringBuilder sb = new StringBuilder();
                    int vypis = 1;
                    char pad = ' ';

                    for (ulong cisla = 2; cisla <= mez; cisla++)
                    {
                        if (sito[cisla] == true)
                        {
                            sb.Append(Convert.ToString(cisla).PadLeft(10, pad));
                            vypis++;

                            if (vypis == 6)
                            {
                                sb.AppendLine();
                                vypis = 1;
                            }
                            pocet++;
                        }
                    }
                      textBox_vystup.Text = sb.ToString();

                    //Konec zápisu do StringBuilderu

                    label_pocet.Visible = true;
                    label_pocet.Text = "Počet prvočísel : "+pocet;
                       
                }
            }
        }

        private void textBox_mez_TextChanged(object sender, EventArgs e)
        {
            textBox_vystup.Clear();
            label_pocet.Text = "";
            label_pocet.Visible = false;
        }

        private void button_uloz_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveDialog = new SaveFileDialog();
            saveDialog.InitialDirectory = System.Environment.CurrentDirectory;
            saveDialog.Filter = "Textový soubor (*.txt)|*.txt";
            saveDialog.RestoreDirectory = true;

            if (saveDialog.ShowDialog() == DialogResult.OK)
            {
                string[] radky = new string[pocet];
                radky = textBox_vystup.Lines;
                File.WriteAllLines(saveDialog.FileName, radky);
            }
            else
            {
                MessageBox.Show("Data nebyla uložena!", "Varování", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

        }
                       
    }
}