using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Tango.Core;
using Tango.Integration.Operation;
using Tango.Integration.ExternalBridge;
using Tango.MachineStudio.Common.StudioApplication;
using Tango.PMR.Diagnostics;
using System.Diagnostics;

namespace Tango.MachineStudio.Common.Diagnostics
{
    /// <summary>
    /// Represents the default diagnostics frame provider.
    /// </summary>
    /// <seealso cref="Tango.MachineStudio.Common.Diagnostics.IDiagnosticsFrameProvider" />
    public class DefaultDiagnosticsFrameProvider : ExtendedObject, IDiagnosticsFrameProvider
    {
        private IStudioApplicationManager _application;
        private Stopwatch _watch;
        private List<double> _rates;
        private DateTime _last_measure;
        private const int _min_rate_change = 4;

        private bool _disable;
        /// <summary>
        /// Disables the frame delivery from the current connected machine and enables the manual push frame method.
        /// </summary>
        public bool Disable
        {
            get { return _disable; }
            set
            {
                _disable = value;
            }
        }

        private double _frameRate;
        /// <summary>
        /// Gets the current diagnostics frame rate.
        /// </summary>
        public double FrameRate
        {
            get
            {
                return _frameRate;
            }
            private set
            {
                _frameRate = value;
                RaisePropertyChangedAuto();
            }
        }

        /// <summary>
        /// Occurs when a new data frame is available.
        /// </summary>
        public event EventHandler<StartDiagnosticsResponse> FrameReceived;

        /// <summary>
        /// Initializes a new instance of the <see cref="DefaultDiagnosticsFrameProvider"/> class.
        /// </summary>
        /// <param name="applicationManager">The application manager.</param>
        public DefaultDiagnosticsFrameProvider(IStudioApplicationManager applicationManager)
        {
            _rates = new List<double>();
            _watch = new Stopwatch();
            _application = applicationManager;
            applicationManager.ConnectedMachineChanged += ApplicationManager_ConnectedMachineChanged;
        }

        /// <summary>
        /// Applications the manager connected machine changed.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="machine">The machine.</param>
        private void ApplicationManager_ConnectedMachineChanged(object sender, IExternalBridgeClient machine)
        {
            if (machine != null)
            {
                _last_measure = DateTime.Now;
                _rates = new List<double>();
                _watch = new Stopwatch();
                machine.DiagnosticsDataAvailable += DefaultDiagnosticsFrameProvider_DiagnosticsDataAvailable;
            }
        }

        /// <summary>
        /// Defaults the diagnostics frame provider diagnostics data available.
        /// </summary>
        /// <param name="sender">The sender.</param>
        /// <param name="frame">The frame.</param>
        private void DefaultDiagnosticsFrameProvider_DiagnosticsDataAvailable(object sender, StartDiagnosticsResponse frame)
        {
            if (!Disable)
            {
                OnFrameReceived(frame);
            }
        }

        /// <summary>
        /// Push frames manual. (Only when Disable = true)
        /// </summary>
        /// <param name="frame">The frame.</param>
        public void PushFrame(StartDiagnosticsResponse frame)
        {
            if (Disable)
            {
                OnFrameReceived(frame);
            }
        }

        /// <summary>
        /// Raises the <see cref="FrameReceived"/> event.
        /// </summary>
        /// <param name="frame">The frame.</param>
        protected virtual void OnFrameReceived(StartDiagnosticsResponse frame)
        {
            if (DateTime.Now > _last_measure.AddSeconds(1) && _rates.Count > 0)
            {
                _last_measure = DateTime.Now;

                var rate = Math.Round(1000d / _rates.Average(), 2);

                if (rate > FrameRate + _min_rate_change || rate < FrameRate - _min_rate_change)
                {
                    FrameRate = rate;
                }

                _rates.Clear();
            }

            _rates.Add(_watch.ElapsedMilliseconds);

            _watch.Restart();

            FrameReceived?.Invoke(this, frame);
        }
    }
}