Form - output_log parser

using System;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Windows.Forms;
using output_parser.Properties;

namespace output_parser
{
    public partial class Form : System.Windows.Forms.Form
    {
        private static string[] toAppend;
        private static Font defaultFont;

        public Form()
        {
            InitializeComponent();
            defaultFont = text_box.Font;
            Load += load;
            FormClosing += close;
        }

        private void btn_browse_Click(object sender, EventArgs e)
        {
            var result = fileDialog.ShowDialog();
            if (result == DialogResult.OK)
                path.Text = fileDialog.FileName;
            else
                return;
            btn_open_Click(sender, e);
        }

        private void btn_open_Click(object sender, EventArgs e)
        {
            text_box.Clear();
            if (!string.IsNullOrEmpty(path.Text))
                toAppend = File.ReadAllLines(path.Text);
            remove_stuff();
            parse_text();
            parse_stack_trace();
        }

        private static void remove_stuff()
        {
            var str = toAppend.Aggregate("", (current, s) => current + (s + "\n"));
            //str = Regex.Replace(str, @"\(Filename.+?:\s([\-\d]+)\)", "--------------------$1--------------------");
            str = Regex.Replace(str, @"\(Filename: .*?\)\n\n", "");  //(Filename:  Line: 1638)
            str = Regex.Replace(str, @"Loading.+\n", "");  //Loading C:\...\*.dll into Unity Child Domain
            str = Regex.Replace(str, @"The.+Beh.+sing!\s+", "");  //The referenced script on this Behaviour is missing!
            str = Regex.Replace(str, @"\n(?=\s+\n)", "");  //space & new line
            str = str.Replace("(this message is harmless)", "");
            str = Regex.Replace(str, @"(\..+)\s(\(.*?\))", "$1$2");
            toAppend = str.Split(new []{ "\n" }, StringSplitOptions.None);
        }

        private void parse_text()
        {
            for (var i = 0; i < toAppend.Length - 1; i++)
            {
                var str = toAppend[i];
                var color = Color.White;
                var nFont = defaultFont;
                if (Regex.Match(str, @"^(?:\s+)?[\w\d]+?:").Success && !str.Contains("Exception")) //todo put me in a method
                    color = Color.FromArgb(0, 255, 81);
                if (Regex.Match(str, @"^(?:.+)?assembly:").Success)
                    color = Color.FromArgb(255, 200, 0);
                if (str.Contains("nused"))
                    color = Color.FromArgb(117, 209, 191);
                if (Regex.Match(str, @"^On[\w\d]+").Success)
                    color = Color.FromArgb(0, 182, 255);
                if (str.Contains("/") && str.Contains("\""))
                   color = Color.FromArgb(255, 70, 0);
                if (str.Contains(">>>>"))
                    color = Color.FromArgb(232, 0, 255);
                if (str.Contains("Exception"))
                    color = Color.FromArgb(255, 130, 177);
                if (str.StartsWith("  at"))
                    color = Color.FromArgb(187, 62, 109);
                if (str.StartsWith("="))
                {
                    color = Color.FromArgb(255, 50, 50);
                    nFont = new Font(defaultFont.FontFamily, 17, FontStyle.Bold);
                }

                text_box.SelectionColor = color;
                text_box.SelectionFont = nFont;
                text_box.AppendText(str);
                if (!toAppend[i + 1].StartsWith("  at") || str.Contains("Exception"))
                    text_box.AppendText("\n");
                /*if (!toAppend[i + 1].StartsWith("  at") || !str.Contains("Exception"))
                    text_box.AppendText("\n");*/
            }
        }

        private void parse_stack_trace()
        {
            var matches = Regex.Matches(text_box.Text, @"t\s([A-Za-z0-9_]+)\.(.+){1}(\(.*?\))");
            for (var i = 0; i < matches.Count; i++)
            {
                var idx = matches[i].Index;
                var aa = text_box.Text.IndexOf(matches[i].Groups[1].Value, idx, StringComparison.Ordinal);
                var bb = text_box.Text.IndexOf(matches[i].Groups[2].Value, idx, StringComparison.Ordinal);
                var cc = text_box.Text.IndexOf(matches[i].Groups[3].Value, idx, StringComparison.Ordinal);

                //Namespace | Library
                text_box.SelectionStart = aa;  //plus 1 for the \s in the regex
                text_box.SelectionLength = matches[i].Groups[1].Value.Length;
                text_box.SelectionColor = Color.FromArgb(255, 220, 0);

                //Class | Method
                text_box.SelectionStart = bb;
                text_box.SelectionLength = matches[i].Groups[2].Value.Length;
                text_box.SelectionColor = Color.FromArgb(255, 128, 0);

                //Signature
                text_box.SelectionStart = cc;
                text_box.SelectionLength = matches[i].Groups[3].Value.Length;
                text_box.SelectionColor = Color.FromArgb(255, 54, 0);
            }
        }

        private void load(object sender, EventArgs e)
        {
            path.Text = Settings.Default.Path;
            if (Settings.Default.Maximised)
            {
                WindowState = FormWindowState.Maximized;
                Location = Settings.Default.Location;
                Size = Settings.Default.Size;
            }
            else if (Settings.Default.Minimised)
            {
                WindowState = FormWindowState.Minimized;
                Location = Settings.Default.Location;
                Size = Settings.Default.Size;
            }
            else
            {
                Location = Settings.Default.Location;
                Size = Settings.Default.Size;
            }
        }

        private void close(object sender, EventArgs e)
        {
            Settings.Default.Path = path.Text;
            if (WindowState == FormWindowState.Maximized)
            {
                Settings.Default.Location = RestoreBounds.Location;
                Settings.Default.Size = RestoreBounds.Size;
                Settings.Default.Maximised = true;
                Settings.Default.Minimised = false;
            }
            else if (WindowState == FormWindowState.Normal)
            {
                Settings.Default.Location = Location;
                Settings.Default.Size = Size;
                Settings.Default.Maximised = false;
                Settings.Default.Minimised = false;
            }
            else
            {
                Settings.Default.Location = RestoreBounds.Location;
                Settings.Default.Size = RestoreBounds.Size;
                Settings.Default.Maximised = false;
                Settings.Default.Minimised = true;
            }
            Settings.Default.Save();
        }

        private void btn_settings_Click(object sender, EventArgs e)
        {
            var frm = new System.Windows.Forms.Form()
            {

            };
            frm.Show();
        }
    }
}