using System;
using System.Runtime.InteropServices;

namespace TimePlease
{
    class App
    {

        static void Main(string[] args)
        {
            var app = new App();
            app.run();
        }

        Otter.Game engine;
        Otter.Scene scene;
        long counter;
        public float lastTimePerformance;
        public DateTime lastTimeMedia;

        void run()
        {
            engine = new Otter.Game("Otter time and framerate", 640, 480, 60, false);
            engine.SetWindow(640, 480, false, true);
            scene = new Otter.Scene();
            scene.OnUpdate = update;
            lastTimePerformance = PerformanceTimer.time;
            lastTimeMedia = MediaTimer.UtcNow;
            engine.Start(scene);
        }

        string f(float x)
        {
            return x.ToString("00.000");
        }

        void update()
        {
            var performanceTime = PerformanceTimer.time;
            var performanceDeltaTime = performanceTime - lastTimePerformance;
            lastTimePerformance = performanceTime;

            var engineRealDeltaTime = engine.RealDeltaTime / 1000;

            var mediaTime = MediaTimer.UtcNow;
            var mediaDeltaTime = Convert.ToSingle((MediaTimer.UtcNow - lastTimeMedia).TotalMilliseconds / 1000);
            lastTimeMedia = mediaTime;

            if (counter % 3 == 0)
            {
                Console.WriteLine("engine-fps = " + f(engine.Framerate)
                    + "; engine-real-dt = " + f(engineRealDeltaTime)
                    + "; performance-dt = " + f(performanceDeltaTime)
                    + "; media-dt = " + f(mediaDeltaTime)
                    + "; " + performanceTime);
            }
            counter++;
        }

    }

    static class MediaTimer
    {
        public static bool IsAvailable { get; private set; }

        [DllImport("Kernel32.dll", CallingConvention = CallingConvention.Winapi)]
        private static extern void GetSystemTimePreciseAsFileTime(out long filetime);

        public static DateTime UtcNow
        {
            get
            {
                if (!IsAvailable)
                {
                    throw new InvalidOperationException(
                        "High resolution clock isn't available.");
                }

                long filetime;
                GetSystemTimePreciseAsFileTime(out filetime);

                return DateTime.FromFileTimeUtc(filetime);
            }
        }

        static MediaTimer()
        {
            try
            {
                long filetime;
                GetSystemTimePreciseAsFileTime(out filetime);
                IsAvailable = true;
            }
            catch (EntryPointNotFoundException)
            {
                // Not running Windows 8 or higher.
                IsAvailable = false;
            }
        }
    }

    static class PerformanceTimer
    {
        [DllImport("Kernel32.dll")]
        private static extern bool QueryPerformanceCounter(
            out long lpPerformanceCount);

        [DllImport("Kernel32.dll")]
        private static extern bool QueryPerformanceFrequency(
            out long lpFrequency);

        static private float freqency;

        // Constructor
        static PerformanceTimer()
        {
            long performanceFrequency;
            if (QueryPerformanceFrequency(out performanceFrequency))
            {
                freqency = performanceFrequency;
                Console.WriteLine("frequency = " + freqency);
            }
            else
            {
                throw new Exception("High-performance counter not supported");
            }
        }

        public static float time
        {
            get
            {
                long performanceTime;
                QueryPerformanceCounter(out performanceTime);
                return (float)performanceTime / freqency;
            }
        }
    }

}