using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Media;
using System.Text;
using System.Threading.Tasks;

namespace W4Gui.Components
{
    public class HexInputBox : TextBox
    {
        string lastText = "";
        public HexInputBox()
        {

        }
        public byte[] Value
        {
            get
            {
                return convertHexStringToByteArray(this.Text.Replace(" ", ""));
            }
            set
            {
                this.Text = BitConverter.ToString(value).Replace('-', ' ');
            }
        }

        private byte[] convertHexStringToByteArray(string hexString)
        {
            if (hexString.Length % 2 != 0)
                hexString += "0";

            byte[] data = new byte[hexString.Length / 2];
            for (int index = 0; index < data.Length; index++)
            {
                string byteValue = hexString.Substring(index * 2, 2);
                data[index] = byte.Parse(byteValue, NumberStyles.HexNumber, CultureInfo.InvariantCulture);
            }

            return data;
        }

        private bool checkChars(KeyPressEventArgs e)
        {
            if (e.KeyChar == (char)Keys.Insert) return false;
            else if (Char.IsAsciiHexDigit(e.KeyChar)) return true;
            else if (e.KeyChar == '\b') return true;
            else if ((ModifierKeys & (Keys.Control | Keys.Alt)) != 0) return true;
            
            return false;
        }
        protected override void OnTextChanged(EventArgs e)
        {
            int cacheSelectionStart = this.SelectionStart;
            try
            {
                string newText = this.Text;
                this.Text = BitConverter.ToString(convertHexStringToByteArray(newText.Replace(" ", ""))).Replace('-', ' ');
                this.lastText = this.Text;
            }
            catch
            {
                this.Text = lastText;
                this.SelectionStart = cacheSelectionStart;
            }

            base.OnTextChanged(e);
        }
        protected override void OnKeyDown(KeyEventArgs e)
        {

            if(e.KeyCode == Keys.Right)
            {
                int cacheSelectionStart = this.SelectionStart;
                cacheSelectionStart++;
                if (cacheSelectionStart < this.TextLength)
                {
                    if (this.TextLength > 0 && this.Text[cacheSelectionStart] == ' ') cacheSelectionStart++;
                    this.SelectionStart = cacheSelectionStart;
                }
                else
                {
                    this.SelectionStart = this.TextLength;
                }

                e.SuppressKeyPress = true;
            }
            else if (e.KeyCode == Keys.Left)
            {
                int cacheSelectionStart = this.SelectionStart;
                cacheSelectionStart--;
               

                if (cacheSelectionStart > 0)
                {
                    if (this.TextLength > 0 && this.Text[cacheSelectionStart] == ' ') cacheSelectionStart--;
                    this.SelectionStart = cacheSelectionStart;
                }
                else
                {
                    this.SelectionStart = 0;
                }

                e.SuppressKeyPress = true;
            }
            else if (e.KeyCode == Keys.Delete)
            {
                int cacheSelectionStart = this.SelectionStart;
                StringBuilder text = new StringBuilder(this.Text);
                if (cacheSelectionStart < text.Length)
                {
                    if (cacheSelectionStart != 0)
                    {
                        if (text[cacheSelectionStart] != ' ') cacheSelectionStart--;

                        if (text[cacheSelectionStart] == ' ')
                        {
                            text.Remove(cacheSelectionStart, (text.Length >= 3) ? 3 : 2);
                        }
                        else
                        {
                            cacheSelectionStart++;
                        }
                    }
                    else
                    {
                        if (text.Length > 0)
                        {
                            text.Remove(0, (text.Length >= 3) ? 3 : 2);
                        }
                    }
                }

                this.Text = text.ToString();
                this.SelectionStart = cacheSelectionStart;

                e.SuppressKeyPress = true;

            }
            base.OnKeyDown(e);
        }
        protected override void OnKeyPress(KeyPressEventArgs e)
        {
            
            if (!checkChars(e))
            {
                e.Handled = true;
                SystemSounds.Beep.Play();
                base.OnKeyPress(e);
                return;
            }

            char toWrite = (e.KeyChar).ToString().ToUpper().First();
            if (!Char.IsAsciiHexDigit(toWrite))
            {
                if (toWrite == '\b')
                {
                    int cacheSelectionStart = this.SelectionStart;
                    StringBuilder text = new StringBuilder(this.Text);

                    if (cacheSelectionStart < text.Length)
                    {
                        if (text[cacheSelectionStart] != ' ') cacheSelectionStart--;

                        if (text[cacheSelectionStart] == ' ')
                        {
                            if(cacheSelectionStart > 3)
                            {
                                text.Remove(cacheSelectionStart - 3, 3);
                                cacheSelectionStart -= 3;
                            }
                            else
                            {
                                text.Remove(cacheSelectionStart - 2, 2);
                                cacheSelectionStart -= 2;
                            }
                        }
                        else
                        {
                            cacheSelectionStart++;
                        }
                    }
                    else
                    {
                        text.Remove(text.Length - 3, 3);
                        cacheSelectionStart -= 3;
                    }
                    

                    this.Text = text.ToString();
                    this.SelectionStart = cacheSelectionStart;
                    e.Handled = true;
                }


                base.OnKeyPress(e);
                return;
            }
            else
            {
                int cacheSelectionStart = this.SelectionStart;
                StringBuilder text = new StringBuilder(this.Text);

                if (cacheSelectionStart < text.Length)
                {
                    
                    if (text[cacheSelectionStart] == ' ') cacheSelectionStart++;

                    text[cacheSelectionStart] = toWrite;
                    cacheSelectionStart++;
                }
                else
                {
                    if (cacheSelectionStart != 0)
                    {
                        text.Append(" ");
                        cacheSelectionStart++;
                    }

                    text.Append(toWrite + "0");
                    cacheSelectionStart++;

                }

                this.Text = text.ToString();
                this.SelectionStart = cacheSelectionStart;
                e.Handled = true;

                base.OnKeyPress(e);
                return;
            }

            
        }
    }
}