using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TrackerBridge.DSP
{
    public class GazeDecimatorFixedLength : IGazeFilter
    {
        private GazeData[] buffer;
        private Int32 currentValueIndex;
        private Single inputFrequency;
        private GazeData? output;
        private Single outputFrequency;

        private Object outputLock = new Object();
        private Object inputLock = new Object();

        public event EventHandler<GazeData> OutputAvailable;

        public Single InputFrequency {
            get { return inputFrequency; }
            set {
                inputFrequency = value;
                Reset();
            }
        }
        public GazeData? Output {
            get {
                lock (outputLock)
                {
                    GazeData? temp = null;
                    if (output.HasValue)
                    {
                        temp = output.Value;
                        output = null;

                    }
                    return temp;
                }
            }
        }

        public Single OutputFrequency {
            get { return outputFrequency; }
            set {
                outputFrequency = value;
                Reset();
            }
        }

        public GazeDecimatorFixedLength(Single outputFrequency, Single inputFrequency)
        {
            this.outputFrequency = outputFrequency;
            this.inputFrequency = inputFrequency;
            Reset();
        }

        public void Input(GazeData input)
        {
            lock (inputLock)
            {
                currentValueIndex = (currentValueIndex + 1) % buffer.Length;
            }
            buffer[currentValueIndex] = input;

            if (currentValueIndex == buffer.Length-1)
            {
                GazeData sum = buffer[0];
                for (Int32 index = 1; index < buffer.Length; index++)
                {
                    sum += buffer[index];
                }
                sum /= buffer.Length;

                lock (outputLock)
                {
                    output = sum;
                }
            }

        }

        public void Reset()
        {
            Int32 bufferLength = Convert.ToInt32(InputFrequency / OutputFrequency);
            buffer = new GazeData[bufferLength];
            currentValueIndex = -1;
            output = null;
        }
    }
}