using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace DTS.Common.Utilities
{
    public sealed class KeywordAlert
    {
        public static KeywordAlert Instance { get; } = new KeywordAlert();

        private List<string> alerts = null;

        private const string KeywordFile = "Keywords.txt";
        private KeywordAlert()
        {
            try
            {
                if (System.IO.File.Exists(KeywordFile))
                {
                    alerts = new List<string>(System.IO.File.ReadAllLines(KeywordFile));
                }
            }
            catch (System.Exception) { }
        }

        public void ProcessMsg(string msg)
        {
            if (null != alerts)
            {
                System.Threading.ThreadPool.QueueUserWorkItem(new System.Threading.WaitCallback(DoWork), msg);
            }
        }
        private void DoWork(object o)
        {
            var msg = o as string;
            var keys = alerts.ToArray();//avoid accessing the list since many threads may be operating simultaneously

            var matches = from k in keys.AsParallel() where msg.Contains(k) select k;
            if (matches.Any())
            {
                var foundKeys = string.Join(", ", matches.ToArray());
            }
        }
    }
}