using System;
using System.Net.Security;
using System.Reflection;
using static System.Net.Mime.MediaTypeNames;

namespace Metoder
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btn_find_Click(object sender, EventArgs e)
        {
            string searchWord = txtbx_find.Text;
            Highlight(searchWord);
        }

        private void btn_clear_Click(object sender, EventArgs e)
        {
            lbl_found.Visible = false;
        }

        void UpdateFindResult(int foundCount)
        {
            lbl_found.Visible = true;
            string suffix;

            // correct grammar
            if (foundCount == 1)
                suffix = " item found";
            else
                suffix = " items found";

            lbl_found.Text = foundCount.ToString() + suffix;
        }

        (int start, int length) FindTextIndex(string text, int startIndex)
        {
            int start = (text.IndexOf(text, startIndex, StringComparison.OrdinalIgnoreCase));
            if (start == -1) return (-1, 0);

            return (start, text.Length);
        }

        void Highlight(string word)
        {
            if (word == "") return; // avoid errors, infinite loop

            RichTextBox richTextBox = txtbx_text;
            string text = richTextBox.Text;

            // reset old highlight
            richTextBox.SelectAll();
            richTextBox.SelectionBackColor = richTextBox.BackColor;

            int found = 0;
            int caret = richTextBox.SelectionStart; // set cursor

            var words = GetWords();
            int index = 0;

            while ((index = text.IndexOf(word, index, StringComparison.OrdinalIgnoreCase)) != -1)
            {
                richTextBox.Select(index, word.Length); // select word
                richTextBox.SelectionBackColor = Color.LightBlue;
                found++; // count found
                index = index + word.Length; // offset (ignore word next loop)
            }

            // reset cursor
            richTextBox.Select(caret, 0);

            // update find label
            UpdateFindResult(found);
        }

        List<string> GetWords() // get list of words separated by spaces
        {
            string text = txtbx_text.Text;
            string[] words = text.Split((char[])null, StringSplitOptions.RemoveEmptyEntries);

            return words.ToList();
        }

        private void btn_replace_Click(object sender, EventArgs e)
        {

        }
    }
}