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

namespace Yaulw.Thread
{
    /// <summary>
    /// Single Threaded Timer * only calls the elapsed event handler once and only
    /// will call it again, if the elapsed event handler returns
    /// </summary>
    public class SingleThreadTimer
    {
        #region Private Members

        private STElapsedEventHandler _elapsedHandler = null;
        private uint _IntervalMilliseconds = 0;
        private System.Threading.Thread _thread = null;

        #endregion

        #region Construction

        /// <summary>
        /// Creates a new Single-threaded System.Timer
        /// </summary>
        /// <param name="ElapsedHandler">Event Handler for Timer</param>
        /// <param name="IntervalMiliseconds">Interval in Miliseconds</param>
        /// <param name="StartEnabled">True to start the timer upon creation, false otherwise</param>
        /// <returns>A Timer Object, which should be Disposed by Caller</returns>
        public SingleThreadTimer(STElapsedEventHandler ElapsedHandler, uint IntervalMilliseconds, bool StartEnabled)
        {
            _elapsedHandler = ElapsedHandler;
            _IntervalMilliseconds = IntervalMilliseconds;
            if (_elapsedHandler == null || _IntervalMilliseconds == 0)
                throw new ArgumentException("Invalid ElapsedHandler or Milliseconds. ElapsedHandler can not be null. Milliseconds can not be 0.");

            if (StartEnabled)
                Start();
        }

        #endregion

        #region Private Helpers

        /// <summary>
        /// Main DoWork() Function, calls the ElapsedHandler at every interval
        /// * Single threaded * ElapsedHandler will only get called again, once it returns
        /// </summary>
        private void STimerThreadMethod()
        {
            do
            {
                if (_IntervalMilliseconds > 0)
                    System.Threading.Thread.Sleep((int)_IntervalMilliseconds);

                if (_elapsedHandler != null)
                    _elapsedHandler(this, new STElapsedEventArgs(DateTime.Now));
            }
            while (true);
        }

        #endregion

        #region Public Delegates

        /// <summary>
        /// ElapsedEvent Handler is called when the time interval elapsed
        /// </summary>
        /// <param name="sender">Sends the STimer Object</param>
        /// <param name="e">sends the Timestampe when the interval elapsed</param>
        public delegate void STElapsedEventHandler(object sender, STElapsedEventArgs e);

        /// <summary>
        /// ElapsedEventArgs are called with the time stamp when the Event was raised
        /// </summary>
        public class STElapsedEventArgs : EventArgs
        {
            public DateTime SignalTime { get; private set; }
            public STElapsedEventArgs(DateTime SignalTime) { this.SignalTime = SignalTime; }
        }

        #endregion

        #region Public Methods

        /// <summary>
        /// Manually Start the STimer
        /// </summary>
        public bool Start()
        {            
            Stop(); // First Stop(), an existing Timer
            return Start(_IntervalMilliseconds);
        }

        /// <summary>
        /// Manually Start the STimer at a new Interval
        /// </summary>
        /// <param name="tsInterval">Interval as a TimeSpan</param>
        public bool Start(TimeSpan tsInterval)
        {
            Stop(); // First Stop(), an existing Timer
            return Start((uint)tsInterval.TotalMilliseconds);
        }

        /// <summary>
        /// Manually Start the STimer at a new Interval
        /// </summary>
        /// <param name="IntervalMiliseconds">Interval in Miliseconds</param>
        public bool Start(uint IntervalMiliseconds)
        {
            try
            {
                Stop(); // First Stop(), an existing Timer
                if (IntervalMiliseconds > 0)
                    _IntervalMilliseconds = IntervalMiliseconds;
                if (_thread == null)
                    _thread = TStarter.StartThread(STimerThreadMethod, ("STimer-" + _elapsedHandler.Method.Name), System.Threading.ApartmentState.MTA, false, System.Threading.ThreadPriority.Normal);
                return ((_thread != null) && (_thread.IsAlive));
            }
            catch (Exception) { /* ignore */ }
            return false;
        }

        /// <summary>
        /// Manually Stop the STimer
        /// </summary>
        public void Stop()
        {
            try
            {
                if (_thread != null)
                    _thread.Abort();                    
            }
            catch (Exception) { /* ignore */ }
            _thread = null;
        }

        #endregion

    }
}