using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;

namespace SoundIOSharp
{
	public struct SoundIOChannelLayout
	{
		public static int BuiltInCount {
			get { return Natives.soundio_channel_layout_builtin_count (); }
		}

		public static SoundIOChannelLayout GetBuiltIn (int index)
		{
			return new SoundIOChannelLayout (Natives.soundio_channel_layout_get_builtin (index));
		}

		public static SoundIOChannelLayout GetDefault (int channelCount)
		{
			var handle = Natives.soundio_channel_layout_get_default (channelCount);
			return new SoundIOChannelLayout (handle);
		}

		public static SoundIOChannelId ParseChannelId (string name)
		{
			var ptr = Marshal.StringToHGlobalAnsi (name);
			try {
				return (SoundIOChannelId)Natives.soundio_parse_channel_id (ptr, name.Length);
			} finally {
				Marshal.FreeHGlobal (ptr);
			}
		}

		// instance members

		internal SoundIOChannelLayout (Pointer<SoundIoChannelLayout> handle)
		{
			this.handle = handle;
		}

		readonly Pointer<SoundIoChannelLayout> handle;

		public bool IsNull {
			get { return handle.Handle == IntPtr.Zero;  }
		}

		internal IntPtr Handle {
			get { return handle; }
		}

		public int ChannelCount {
			get { return IsNull ? 0 : Marshal.ReadInt32 ((IntPtr) handle + channel_count_offset); }
		}
		static readonly int channel_count_offset = (int) Marshal.OffsetOf<SoundIoChannelLayout> ("channel_count");

		public string Name {
			get { return IsNull ? null : Marshal.PtrToStringAnsi (Marshal.ReadIntPtr ((IntPtr) handle + name_offset)); }
		}
		static readonly int name_offset = (int)Marshal.OffsetOf<SoundIoChannelLayout> ("name");

		public IEnumerable<SoundIOChannelId> Channels {
			get {
				if (IsNull)
					yield break;
				for (int i = 0; i < 24; i++)
					yield return (SoundIOChannelId) Marshal.ReadInt32 ((IntPtr) handle + channels_offset + sizeof (SoundIoChannelId) * i);
			}
		}
		static readonly int channels_offset = (int)Marshal.OffsetOf<SoundIoChannelLayout> ("channels");

		public override bool Equals (object other)
		{
			if (!(other is SoundIOChannelLayout))
				return false;
			var s = (SoundIOChannelLayout) other;
			return handle == s.handle || Natives.soundio_channel_layout_equal (handle, s.handle);
		}

		public override int GetHashCode ()
		{
			return handle.GetHashCode ();
		}

		public string DetectBuiltInName ()
		{
			if (IsNull)
				throw new InvalidOperationException ();
			return Natives.soundio_channel_layout_detect_builtin (handle) ? Name : null;
		}

		public int FindChannel (SoundIOChannelId channel)
		{
			if (IsNull)
				throw new InvalidOperationException ();
			return Natives.soundio_channel_layout_find_channel (handle, (SoundIoChannelId) channel);
		}
	}
}
