using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Runtime.InteropServices;
using System.Text.RegularExpressions;
using System.Text;
using System.Windows.Forms;

namespace sharpsyntax
{
    public partial class SyntaxTextBox : RichTextBox
    {
        private Language language;

        private bool refreshing;

        public Language Language
        {
            get { return language; }
            set
            {
                language = value;
                Refresh();
            }
        }

        [DllImport("user32.dll")]
        static extern bool LockWindowUpdate(IntPtr hWndLock);

        public SyntaxTextBox()
        {
            InitializeComponent();

            refreshing = false;
        }

        private void SyntaxTextBox_TextChanged(object sender, EventArgs e)
        {
            if (!refreshing) Refresh();
        }

        private void SetColor(int index, int length, Color color)
        {
            int selectionStart = SelectionStart;
            int selectionLenght = SelectionLength;
            Select(index, length);
            SelectionColor = color;
            SelectionStart = selectionStart;
            SelectionLength = selectionLenght;
        }

        private void Reset()
        {
            int selectionStart = SelectionStart;
            int selectionLenght = SelectionLength;
            SelectAll();
            ResetFont();
            Font = DefaultFont;
            SelectionColor = Color.Black;
            SelectionCharOffset = 0;
            SelectionStart = selectionStart;
            SelectionLength = selectionLenght;
        }

        public override void Refresh()
        {
            refreshing = true;

            base.Refresh();

            if (language == null) return;

            try
            {
                LockWindowUpdate(Handle);

                Reset();

                foreach (MatchGroup group in language.Groups)
                {
                    if (group.Enabled)
                    {
                        foreach (Match match in language.Matches(group, Text))
                        {
                            SetColor(match.Index, match.Length, group.Color);
                        }
                    }
                }
            }
            finally
            {
                LockWindowUpdate(IntPtr.Zero);

                refreshing = false;
            }
        }
    }
}