using System;
using System.Collections.Generic;
using System.Threading;
using ln.http.api;

namespace ln.ethercat.service
{
    public delegate void RecordingWindowCompleted(EthercatProcessDataRecorder dataRecorder, EthercatProcessDataRecorder.RecordingWindow recordingWindow);
    public delegate void ProcessDataRecordingStartStopDelegate(EthercatProcessDataRecorder dataRecorder);

    public class EthercatProcessDataRecorder : IDisposable
    {
        public ECMaster ECMaster { get; }
        public event RecordingWindowCompleted OnRecordingWindowCompleted;
        public event ProcessDataRecordingStartStopDelegate OnStartRecording;
        public event ProcessDataRecordingStartStopDelegate OnStopRecording;

        public int RecordingWindowSize { get; set; } = 256;
        public int RecordingWindowCount { get; set; } = 10;


        PDO[] pdoMap;
        public PDO[] CurrentPDOMap => pdoMap;
        RecordingWindow[] recordingWindows;
        int currentWindow;

        public EthercatProcessDataRecorder(ECMaster ecMaster)
        {
            ECMaster = ecMaster;
        }

        [ESMethod]
        public void Start()
        {
            lock (this)
            {
                pdoMap = ECMaster.GetPDOMap();
                SetupRamStorage();
            }

            OnStartRecording?.Invoke(this);

            ECMaster.OnStateChange += MasterStateChanged;
            ECMaster.OnProcessDataExchanged += ProcessDataExchanged;
        }

        [ESMethod]
        public void Stop()
        {
            lock (this)
            {
                if (pdoMap != null)
                {
                    ECMaster.OnProcessDataExchanged -= ProcessDataExchanged;
                    ECMaster.OnStateChange -= MasterStateChanged;

                    OnStopRecording?.Invoke(this);

                    pdoMap = null;
                    recordingWindows = null;
                }
            }
        }

        void SetupRamStorage()
        {
            currentWindow = 0;
            recordingWindows = new RecordingWindow[RecordingWindowCount];
            for (int window=0; window < RecordingWindowCount; window++)
                recordingWindows[window] = new RecordingWindow(RecordingWindowSize, pdoMap.Length);
        }


        void ProcessDataExchanged(ECMaster ecMaster)
        {
            lock (this)
            {
                if (pdoMap != null)
                {
                    RecordingWindow recordingWindow = recordingWindows[currentWindow];
                    if (recordingWindow.GetNextRecordBuffer(out object[] currentRecord))
                    {
                        for (int n = 0; n < pdoMap.Length; n++)
                            currentRecord[n] = pdoMap[n].SDOValue.GetValue();
                    }

                    if (recordingWindow.Completed)
                    {
                        currentWindow++;
                        if (currentWindow >= recordingWindows.Length)
                            currentWindow = 0;

                        ThreadPool.QueueUserWorkItem((s)=>{
                            OnRecordingWindowCompleted?.Invoke(this, recordingWindow);
                        });
                    }
                }
            }
        }

        void MasterStateChanged(ECMaster ecMaster, ECSlaveState newState)
        {
            if (newState != ECSlaveState.OPERATIONAL)
                Stop();
        }

        public void Dispose()
        {
            Stop();
        }

        public class RecordingWindow
        {
            object[][] recordedData;
            int nextRecord;

            public bool Completed => nextRecord >= recordedData.Length;

            public RecordingWindow(int windowSize,int pdomapSize)
            {
                recordedData = new object[windowSize][];
                for (int pos=0 ; pos < windowSize ; pos++)
                {
                    recordedData[pos] = new object[pdomapSize];
                }

                Reset();
            }

            public void Reset()
            {
                nextRecord = 0;
            }

            public object[][] GetRecords() => recordedData;
            public object[] GetRecords(int record) => recordedData[record];

            public bool GetNextRecordBuffer(out object[] recordBuffer)
            {
                if (nextRecord < recordedData.Length)
                {
                    recordBuffer = recordedData[nextRecord++];
                    return true;
                }
                recordBuffer = null;
                return false;
            }

        }

    }

}