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;
using MySql.Data.MySqlClient;
using System.Security.Cryptography;
using System.IO;

namespace Könsord {
    public partial class frmMain : Form {

        MySqlConnection Connection { get; set; }
        private string lastId;
        private string currentUser;
        private int color;
        Panel currentPanel;

        public frmMain() {
            InitializeComponent();
            #region Hide
            Connection = new MySqlConnection(
                "SERVER=LOCALHOST;DATABASE=seecret;UID=root;PASSWORD=secure");
            #endregion
            currentPanel = panel2;
            this.AcceptButton = btnConnect;
        }


        private void btnSend_Click(object sender, EventArgs e) {
            Connection.Open();
            if (!string.IsNullOrWhiteSpace(txtSend.Text)) {
                MySqlCommand c = new MySqlCommand(
                "INSERT INTO anteckningar (TEXT, DATE, USER)" +
                $"VALUES ('{txtSend.Text}', CURRENT_TIME(), '{currentUser}')", Connection);
                MySqlDataReader r = c.ExecuteReader();
                txtSend.Text = "";
            }


            Connection.Close();
        }

        private void timer1_Tick(object sender, EventArgs e) {
            Connection.Open();
            MySqlCommand c = new MySqlCommand(
                "SELECT * FROM anteckningar ORDER BY ID DESC LIMIT 1", Connection);
            MySqlDataReader r = c.ExecuteReader();
            string user = "";
            string id = "";
            string date = "";
            string text = "";

            while (r.Read()) {
                id = r["ID"].ToString();
                date = r["date"].ToString();
                text = r["text"].ToString();
                user = r["user"].ToString();
            }

            r.Close();
            c = new MySqlCommand(
                $"SELECT color FROM usernames where Username='{user}'", Connection);
            r = c.ExecuteReader();
            if (r.HasRows) {
                while (r.Read()) {
                    if (lastId != id) {

                        lastId = id;
                        txtNote.AppendText(((string.IsNullOrWhiteSpace(txtNote.Text) ? "" : Environment.NewLine)) + date);
                        txtNote.AppendText(" " + user, Color.FromArgb(int.Parse(r["color"].ToString())));
                        txtNote.AppendText(" " + text);
                    }
                }
            }
            else {
                if (lastId != id) {
                    lastId = id;
                    txtNote.AppendText((string.IsNullOrWhiteSpace(txtNote.Text) ? "" : Environment.NewLine) + date);
                    txtNote.AppendText(" " + user, Color.Gray);
                    txtNote.AppendText(" " + text);
                }
            }


            Connection.Close();
        }

        private void txtSend_Click(object sender, EventArgs e) {
            if (txtSend.Text == "Write here fgt...") {
                txtSend.Text = "";
            }
        }

        private void txtPwd_Click(object sender, EventArgs e) {
            if (txtPwd.Text == "Password...") {
                txtPwd.Text = "";
            }
        }

        private void txtUser_Click(object sender, EventArgs e) {
            if (txtUser.Text == "Username...") {
                txtUser.Text = "";
            }
        }

        private void btnConnect_Click(object sender, EventArgs e) {
            if (txtUser.Text.ToLower() == "guest") {
                Connection.Open();

                Random rand = new Random();
                currentUser = "Guest_" + rand.Next(int.MaxValue);
                color = Color.Gray.ToArgb();

                this.AcceptButton = btnSend;
                currentPanel.Visible = false;
                currentPanel = panel1;
                currentPanel.Visible = true;

                MySqlCommand c = new MySqlCommand(
    "SELECT * FROM anteckningar ORDER BY ID DESC LIMIT 10", Connection);
                MySqlDataReader r = c.ExecuteReader();
                List<string> eUser = new List<string>();
                List<string> eId = new List<string>();
                List<string> eDate = new List<string>();
                List<string> eText = new List<string>();


                while (r.Read()) {
                    eId.Add(r["ID"].ToString());
                    eDate.Add(r["date"].ToString());
                    eText.Add(r["text"].ToString());
                    eUser.Add(r["user"].ToString());
                }

                eId.Reverse();
                eUser.Reverse();
                eDate.Reverse();
                eText.Reverse();
                txtNote.Clear();

                for (int i = 0; i < eId.Count; i++) {
                    r.Close();

                    c = new MySqlCommand(
                    $"SELECT color FROM usernames where Username='{eUser[i]}'", Connection);
                    r = c.ExecuteReader();
                    if (r.HasRows) {
                        while (r.Read()) {
                            if (lastId != eId[i]) {

                                lastId = eId[i];
                                txtNote.AppendText((string.IsNullOrWhiteSpace(txtNote.Text) ? "" : Environment.NewLine) + eDate[i]);
                                txtNote.AppendText(" " + eUser[i], Color.FromArgb(int.Parse(r["color"].ToString())));
                                txtNote.AppendText(" " + eText[i]);
                            }
                        }
                    }
                    else {
                        if (lastId != eId[i]) {
                            lastId = eId[i];
                            txtNote.AppendText((string.IsNullOrWhiteSpace(txtNote.Text) ? "" : Environment.NewLine) + eDate[i]);
                            txtNote.AppendText(" " + eUser[i], Color.Gray);
                            txtNote.AppendText(" " + eText[i]);
                        }
                    }
                }
                Connection.Close();
            }
            else {
                Connection.Open();

                MySqlCommand c = new MySqlCommand(
                $"SELECT id from Usernames where Username='{txtUser.Text}'", Connection);
                MySqlDataReader r = c.ExecuteReader();

                if (r.HasRows) {
                    string id = "";
                    while (r.Read()) {
                        id = r["id"].ToString();
                    }
                    r.Close();
                    c = new MySqlCommand(
                        $"SELECT * from Usernames where ID={id}", Connection);
                    r = c.ExecuteReader();
                    while (r.Read()) {
                        if (r["Username"].ToString() == txtUser.Text && StringCipher.Decrypt(r["password"].ToString(), "onemoretime") == txtPwd.Text) {
                            currentUser = txtUser.Text;
                            color = int.Parse(r["color"].ToString());

                            this.AcceptButton = btnSend;
                            currentPanel.Visible = false;
                            currentPanel = panel1;
                            currentPanel.Visible = true;

                            r.Close();

                            c = new MySqlCommand(
                "SELECT * FROM anteckningar ORDER BY id desc LIMIT 10", Connection);
                            r = c.ExecuteReader();
                            List<string> eUser = new List<string>();
                            List<string> eId = new List<string>();
                            List<string> eDate = new List<string>();
                            List<string> eText = new List<string>();
                            while (r.Read()) {
                                eId.Add(r["ID"].ToString());
                                eDate.Add(r["date"].ToString());
                                eText.Add(r["text"].ToString());
                                eUser.Add(r["user"].ToString());
                            }

                            eId.Reverse();
                            eUser.Reverse();
                            eDate.Reverse();
                            eText.Reverse();
                            txtNote.Clear();


                            for (int i = 0; i < eId.Count; i++) {
                                r.Close();

                                c = new MySqlCommand(
                                $"SELECT color FROM usernames where Username='{eUser[i]}'", Connection);
                                r = c.ExecuteReader();
                                if (r.HasRows) {
                                    while (r.Read()) {
                                        lastId = eId[i];
                                        txtNote.AppendText((string.IsNullOrWhiteSpace(txtNote.Text) ? "" : Environment.NewLine) + eDate[i]);
                                        txtNote.AppendText(" " + eUser[i], Color.FromArgb(int.Parse(r["color"].ToString())));
                                        txtNote.AppendText(" " + eText[i]);

                                    }
                                }
                                else {

                                    lastId = eId[i];
                                    txtNote.AppendText((string.IsNullOrWhiteSpace(txtNote.Text) ? "" : Environment.NewLine) + eDate[i]);
                                    txtNote.AppendText(" " + eUser[i], Color.Gray);
                                    txtNote.AppendText(" " + eText[i]);

                                }
                            }

                        }
                    }
                }

                Connection.Close();
            }
        }

        private new void KeyDown(object sender, KeyEventArgs e) {
            if (e.KeyData == Keys.Enter) {
                btnConnect_Click(new object(), new EventArgs());
            }
        }

        private void KeyDownSend(object sender, KeyEventArgs e) {
            if (e.KeyData == Keys.Enter) {
                btnSend_Click(new object(), new EventArgs());
            }
        }

        private void txtNote_TextChanged(object sender, EventArgs e) {
            txtNote.SelectionStart = txtNote.Text.Length;
            txtNote.ScrollToCaret();
        }

        private void button1_Click_1(object sender, EventArgs e) {
            Form2 form2 = new Form2(this, Connection);
            form2.Visible = true;
        }

        private void button2_Click(object sender, EventArgs e) {
            Form3 form3 = new Form3(Connection, currentUser, color);
            form3.Visible = true;
        }

        private void button3_Click(object sender, EventArgs e) {
            currentUser = null;
            color = Color.Gray.ToArgb();
            currentPanel.Visible = false;
            txtNote.Clear();
            txtSend.Clear();
            txtUser.Text = "Username...";
            txtPwd.Text = "Password...";
            this.AcceptButton = btnConnect;
            currentPanel = panel2;
            currentPanel.Visible = true;
        }
    }

    public static class RichTextBoxExtensions {
        public static void AppendText(this RichTextBox box, string text, Color color) {
            box.SelectionStart = box.TextLength;
            box.SelectionLength = 0;

            box.SelectionColor = color;
            box.AppendText(text);
            box.SelectionColor = box.ForeColor;
        }
    }

    public static class StringCipher {
        // This constant is used to determine the keysize of the encryption algorithm in bits.
        // We divide this by 8 within the code below to get the equivalent number of bytes.
        private const int Keysize = 256;

        // This constant determines the number of iterations for the password bytes generation function.
        private const int DerivationIterations = 1000;

        public static string Encrypt(string plainText, string passPhrase) {
            // Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
            // so that the same Salt and IV values can be used when decrypting.
            var saltStringBytes = Generate256BitsOfRandomEntropy();
            var ivStringBytes = Generate256BitsOfRandomEntropy();
            var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations)) {
                var keyBytes = password.GetBytes(Keysize / 8);
                using (var symmetricKey = new RijndaelManaged()) {
                    symmetricKey.BlockSize = 256;
                    symmetricKey.Mode = CipherMode.CBC;
                    symmetricKey.Padding = PaddingMode.PKCS7;
                    using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes)) {
                        using (var memoryStream = new MemoryStream()) {
                            using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write)) {
                                cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                                cryptoStream.FlushFinalBlock();
                                // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
                                var cipherTextBytes = saltStringBytes;
                                cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
                                cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
                                memoryStream.Close();
                                cryptoStream.Close();
                                return Convert.ToBase64String(cipherTextBytes);
                            }
                        }
                    }
                }
            }
        }

        public static string Decrypt(string cipherText, string passPhrase) {
            // Get the complete stream of bytes that represent:
            // [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
            var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
            // Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
            var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
            // Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
            var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
            // Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
            var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();

            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations)) {
                var keyBytes = password.GetBytes(Keysize / 8);
                using (var symmetricKey = new RijndaelManaged()) {
                    symmetricKey.BlockSize = 256;
                    symmetricKey.Mode = CipherMode.CBC;
                    symmetricKey.Padding = PaddingMode.PKCS7;
                    using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes)) {
                        using (var memoryStream = new MemoryStream(cipherTextBytes)) {
                            using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read)) {
                                var plainTextBytes = new byte[cipherTextBytes.Length];
                                var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                                memoryStream.Close();
                                cryptoStream.Close();
                                return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
                            }
                        }
                    }
                }
            }
        }

        private static byte[] Generate256BitsOfRandomEntropy() {
            var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
            using (var rngCsp = new RNGCryptoServiceProvider()) {
                // Fill the array with cryptographically secure random bytes.
                rngCsp.GetBytes(randomBytes);
            }
            return randomBytes;
        }
    }
}