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

namespace FileWatcher
{
    public static class RichTextBoxExtensions
    {
        // In case a string stream doesn't reset the text color, reset it automatically when done appending text
        // TODO: override the single parameter AppendText
        public static bool g_ResetANSIIColorOnAppend = true;

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

            string ANSIIEscape = "\u001B[";
            int index = text.IndexOf(ANSIIEscape);
            while (index != -1)
            {
                string substring = text.Substring(0, index);
                if (substring.Length > 0)
                {
                    box.AppendText(substring);
                }

                text = text.Substring(index + ANSIIEscape.Length);

                if (text.Length < 3)
                {
                    if (g_ResetANSIIColorOnAppend)
                    {
                        box.SelectionColor = box.ForeColor;
                    }
                    return;
                }

                int number;
                try
                {
                    number = Int32.Parse(text[0] + "" + text[1]);
                }
                catch (FormatException)
                {
                    box.SelectionColor = Color.Red;
                    box.AppendText("ERROR - Invalid ANSII Escape sequence: '" + text + "'");
                    if (g_ResetANSIIColorOnAppend)
                    {
                        box.SelectionColor = box.ForeColor;
                    }
                    return;
                }

                // http://en.wikipedia.org/wiki/ANSI_escape_code
                if (number / 10 == 3)
                {
                    switch (number)
                    {
                        case 30:
                            box.SelectionColor = Color.Black;
                            break;
                        case 31:
                            box.SelectionColor = Color.Red;
                            break;
                        case 32:
                            box.SelectionColor = Color.Green;
                            break;
                        case 3:
                            box.SelectionColor = Color.Yellow;
                            break;
                        case 34:
                            box.SelectionColor = Color.Blue;
                            break;
                        case 35:
                            box.SelectionColor = Color.Magenta;
                            break;
                        case 36:
                            box.SelectionColor = Color.Cyan;
                            break;
                        case 37:
                            box.SelectionColor = Color.White;
                            break;

                        case 39:
                            box.SelectionColor = color;
                            break;
                    }
                }

                index = text.IndexOf("m");
                if (index == -1)
                {
                    box.SelectionColor = Color.Red;
                    box.AppendText("ERROR - couldn't find the sequence escape, 'm', for the ANSII Escape sequence: '" + text + "'");
                    if (g_ResetANSIIColorOnAppend)
                    {
                        box.SelectionColor = box.ForeColor;
                    }
                    return;
                }

                text = text.Substring(index + 1);
                index = text.IndexOf(ANSIIEscape);
            }

            if (text.Length > 0)
            {
                box.SelectionColor = color;
                box.AppendText(text);
            }
            if (g_ResetANSIIColorOnAppend)
            {
                box.SelectionColor = box.ForeColor;
            }
        }
    }
}