using System;
using System.Collections.Generic;
using System.Threading;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;

namespace Ticker.Animation
{
  public class Ticker<T> where T : FrameworkElement
  {
    private static int DISPLAY_TIMER_SPEED_SECONDS=40;                        // This is the speed used to traverse the display from right to left
    private static int DISPLAY_TIMER_INTERVAL_MILLISECONDS=1000;              // This is the interval of time between displaying successive items
    private readonly DispatcherTimer displayTimer=new DispatcherTimer(DispatcherPriority.Normal);    // new DispatcherTimer();
    public EventHandler<ItemEventArgs<T>> ItemDisplayed;
    public Ticker(Panel container)
    {
      SeperatorSize = 25;
      Container = container;
      Container.Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
      Container.Arrange(new Rect(Container.DesiredSize));
      Speed = new TimeSpan(0, 0, 0, DISPLAY_TIMER_SPEED_SECONDS);
      Items = new Queue<T>();
      displayTimer.Tick += displayTimer_Tick;
      displayTimer.Start();
      IsRunning = true;
    }
    public virtual void Dispose()
    {
      Stop();
    }
    public bool IsRunning { get; set; }
    public void Stop()
    {
      if(!IsRunning)return;
      if(null!=displayTimer)displayTimer.Stop();
      IsRunning = false;
    }
    public void Start()
    {
      if(IsRunning)return;
      if(null==displayTimer)return;
      displayTimer.Start();
      displayTimer.Interval = new TimeSpan(0,0,0,0,DISPLAY_TIMER_INTERVAL_MILLISECONDS);
      IsRunning = true;
    }
    public double SeperatorSize { get; set; }
    public TimeSpan Speed { get; set; }
    public Queue<T> Items { get; set; }
    public Panel Container { get; private set; }
    private void displayTimer_Tick(object sender, EventArgs e)
    {
        DisplayNextItem();
    }
    private void DisplayNextItem()
    {
      if (Items.Count == 0)return;
      T item = Items.Dequeue();
      Container.Children.Add(item);
      AnimateMove(item);
      if (ItemDisplayed != null) ItemDisplayed(this, new ItemEventArgs<T>(item));
    }
    private void AnimateMove(FrameworkElement e)
    {
      e.Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
      e.Arrange(new Rect(e.DesiredSize));
      double from = Container.ActualWidth;
      double to = -500;
      int unitsPerSec = Convert.ToInt32(Math.Abs(from - to)/Speed.TotalSeconds);
      int nextFire = Convert.ToInt32((e.ActualWidth + SeperatorSize)/unitsPerSec);
      displayTimer.Stop();
      displayTimer.Interval = new TimeSpan(0, 0, nextFire);
//      displayTimer.Dispatcher.Thread.Priority=ThreadPriority.AboveNormal;
      displayTimer.Start();
      TaggedDoubleAnimation animation = new TaggedDoubleAnimation();
      animation.From = from;
      animation.To = to;
      animation.Duration = new Duration(Speed);
      animation.TargetElement = e;
      animation.Completed += ani_Completed;
      TranslateTransform translateTransform = new TranslateTransform();
      e.RenderTransform = translateTransform;
      translateTransform.BeginAnimation(TranslateTransform.XProperty, animation, HandoffBehavior.Compose);
    }
    private void ani_Completed(object sender, EventArgs e)
    {
      Clock clock = (Clock) sender;
      TaggedDoubleAnimation animation = (TaggedDoubleAnimation) clock.Timeline;
      FrameworkElement element = animation.TargetElement;
      Container.Children.Remove(element);
    }
  }
}