using System;
using System.IO;
using System.Runtime.InteropServices;

namespace Mono.Audio {

	/* these are the values used by alsa */
#if PUBLIC_API
	public
#else
	internal
#endif
	enum AudioFormat {
		S8,
		U8,
		S16_LE,
		S16_BE,
		U16_LE,
		U16_BE,
		S24_LE,
		S24_BE,
		U24_LE,
		U24_BE,
		S32_LE,
		S32_BE,
		U32_LE,
		U32_BE,
		FLOAT_LE,
		FLOAT_BE,
		FLOAT64_LE,
		FLOAT64_BE,
		IEC958_SUBFRAME_LE,
		IEC958_SUBFRAME_BE,
		MU_LAW,
		A_LAW,
		IMA_ADPCM,
		MPEG,
		GSM
	}

#if PUBLIC_API
	public
#else
	internal
#endif
	class AudioDevice {

		static AudioDevice TryAlsa (string name) {
			AudioDevice dev;
			try {
				dev = new AlsaDevice (name);
				return dev;
			} catch {
				return null;
			}
		}

		public static AudioDevice CreateDevice (string name) {
			AudioDevice dev;

			dev = TryAlsa (name);
			/* if no option is found, return a silent device */
			if (dev == null)
				dev = new AudioDevice ();
			return dev;
		}

		public virtual bool SetFormat (AudioFormat format, int channels, int rate) {
			return true;
		}

		public virtual int PlaySample (byte[] buffer, int num_frames) {
			return num_frames;
		}
		
		public virtual void Wait () {
		}
	}

	class AlsaDevice: AudioDevice, IDisposable {
		IntPtr handle;

		[DllImport ("libasound.so.2")]
		static extern int snd_pcm_open (ref IntPtr handle, string pcm_name, int stream, int mode);

		[DllImport ("libasound.so.2")]
		static extern int snd_pcm_close (IntPtr handle);

		[DllImport ("libasound.so.2")]
		static extern int snd_pcm_drain (IntPtr handle);

		[DllImport ("libasound.so.2")]
		static extern int snd_pcm_writei (IntPtr handle, byte[] buf, int size);

		[DllImport ("libasound.so.2")]
		static extern int snd_pcm_set_params (IntPtr handle, int format, int access, int channels, int rate, int soft_resample, int latency);

		public AlsaDevice (string name) {
			if (name == null)
				name = "default";
			int err = snd_pcm_open (ref handle, name, 0, 0);
			if (err < 0)
				throw new Exception ("no open " + err);
		}

		~AlsaDevice () {
			Dispose (false);
		}

		public void Dispose () {
			Dispose (true);
			GC.SuppressFinalize (this);
		}

		protected virtual void Dispose (bool disposing) {
			if (disposing) {
				
			}
			if (handle != IntPtr.Zero)
				snd_pcm_close (handle);
			handle = IntPtr.Zero;
		}

		public override bool SetFormat (AudioFormat format, int channels, int rate) {
			int err = snd_pcm_set_params (handle, (int)format, 3, channels, rate, 1, 500000);
			return err == 0;
		}

		public override int PlaySample (byte[] buffer, int num_frames) {
			int frames = snd_pcm_writei (handle, buffer, num_frames);
			return frames;
		}
		
		public override void Wait () {
			snd_pcm_drain (handle);
		}
	}

}