using System;
using SoundAnalysis;
using SoundCapture;

namespace FrequencyDetection
{
	public class SoundFrequencyInfoSource : FrequencyInfoSource
	{
		readonly SoundCaptureDevice _device;
		Adapter _adapter;

		public SoundFrequencyInfoSource(SoundCaptureDevice device)
		{
			_device = device;
		}

		public override void Listen()
		{
			_adapter = new Adapter(this, _device);
			_adapter.Start();
		}

		public override void Stop()
		{
			_adapter.Stop();
		}

		class Adapter : SoundCaptureBase
		{
			readonly SoundFrequencyInfoSource _owner;

			const double MinFreq = 60;
			const double MaxFreq = 1300;

			internal Adapter(SoundFrequencyInfoSource owner, SoundCaptureDevice device)
				: base(device)
			{
				_owner = owner;
			}

			protected override void ProcessData(short[] data)
			{
				double[] x = new double[data.Length];
				for (int i = 0; i < x.Length; i++)
				{
					x[i] = data[i];
				}

				double[] spectr = FftAlgorithm.Calculate(x);
				int index = 0;
				double max = spectr[0];
				int usefullMaxSpectr = Math.Min(spectr.Length,
				                                (int)(MaxFreq * spectr.Length / SampleRate) + 1);
				for (int i = 1; i < usefullMaxSpectr; i++)
				{
					if (max < spectr[i])
					{
						max = spectr[i]; index = i;
					}
				}

				double freq = (double)SampleRate * index / spectr.Length;
				if (freq < MinFreq) freq = 0;

				_owner.OnFrequencyDetected(new FrequencyDetectedEventArgs(freq));
			}
		}
	}
}