using System;
using System.Runtime.InteropServices;

namespace MoonWorks.Audio
{
    public class AudioDevice
    {
        public IntPtr Handle { get; }
        public byte[] Handle3D { get; }
        public IntPtr MasteringVoice { get; }
        public FAudio.FAudioDeviceDetails DeviceDetails { get; }
        public IntPtr ReverbVoice { get; }

        public float CurveDistanceScalar = 1f;
        public float DopplerScale = 1f;
        public float SpeedOfSound = 343.5f;

        private FAudio.FAudioVoiceSends reverbSends;

        public unsafe AudioDevice()
        {
            FAudio.FAudioCreate(out var handle, 0, 0);
            Handle = handle;

            /* Find a suitable device */

            FAudio.FAudio_GetDeviceCount(Handle, out var devices);

            if (devices == 0)
            {
                Logger.LogError("No audio devices found!");
                Handle = IntPtr.Zero;
                FAudio.FAudio_Release(Handle);
                return;
            }

            FAudio.FAudioDeviceDetails deviceDetails;

            uint i = 0;
            for (i = 0; i < devices; i++)
            {
                FAudio.FAudio_GetDeviceDetails(
                    Handle,
                    i,
                    out deviceDetails
                );
                if ((deviceDetails.Role & FAudio.FAudioDeviceRole.FAudioDefaultGameDevice) == FAudio.FAudioDeviceRole.FAudioDefaultGameDevice)
                {
                    DeviceDetails = deviceDetails;
                    break;
                }
            }

            if (i == devices)
            {
                i = 0; /* whatever we'll just use the first one I guess */
                FAudio.FAudio_GetDeviceDetails(
                    Handle,
                    i,
                    out deviceDetails
                );
                DeviceDetails = deviceDetails;
            }

            /* Init Mastering Voice */
            IntPtr masteringVoice;

            if (FAudio.FAudio_CreateMasteringVoice(
                Handle,
                out masteringVoice,
                FAudio.FAUDIO_DEFAULT_CHANNELS,
                FAudio.FAUDIO_DEFAULT_SAMPLERATE,
                0,
                i,
                IntPtr.Zero
            ) != 0)
            {
                Logger.LogError("No mastering voice found!");
                Handle = IntPtr.Zero;
                FAudio.FAudio_Release(Handle);
                return;
            }

            MasteringVoice = masteringVoice;

            /* Init 3D Audio */

            Handle3D = new byte[FAudio.F3DAUDIO_HANDLE_BYTESIZE];
            FAudio.F3DAudioInitialize(
                DeviceDetails.OutputFormat.dwChannelMask,
                SpeedOfSound,
                Handle3D
            );

            /* Init reverb */

            IntPtr reverbVoice;

            IntPtr reverb;
            FAudio.FAudioCreateReverb(out reverb, 0);

            IntPtr chainPtr;
            chainPtr = Marshal.AllocHGlobal(
                Marshal.SizeOf<FAudio.FAudioEffectChain>()
            );

            FAudio.FAudioEffectChain* reverbChain = (FAudio.FAudioEffectChain*) chainPtr;
            reverbChain->EffectCount = 1;
            reverbChain->pEffectDescriptors = Marshal.AllocHGlobal(
                Marshal.SizeOf<FAudio.FAudioEffectDescriptor>()
            );

            FAudio.FAudioEffectDescriptor* reverbDescriptor =
                (FAudio.FAudioEffectDescriptor*) reverbChain->pEffectDescriptors;

            reverbDescriptor->InitialState = 1;
            reverbDescriptor->OutputChannels = (uint) (
                (DeviceDetails.OutputFormat.Format.nChannels == 6) ? 6 : 1
            );
            reverbDescriptor->pEffect = reverb;

            FAudio.FAudio_CreateSubmixVoice(
                Handle,
                out reverbVoice,
                1, /* omnidirectional reverb */
                DeviceDetails.OutputFormat.Format.nSamplesPerSec,
                0,
                0,
                IntPtr.Zero,
                chainPtr
            );
            FAudio.FAPOBase_Release(reverb);

            Marshal.FreeHGlobal(reverbChain->pEffectDescriptors);
            Marshal.FreeHGlobal(chainPtr);

            ReverbVoice = reverbVoice;

            /* Init reverb params */
            // Defaults based on FAUDIOFX_I3DL2_PRESET_GENERIC

            IntPtr reverbParamsPtr = Marshal.AllocHGlobal(
                Marshal.SizeOf<FAudio.FAudioFXReverbParameters>()
            );

            FAudio.FAudioFXReverbParameters* reverbParams = (FAudio.FAudioFXReverbParameters*) reverbParamsPtr;
            reverbParams->WetDryMix = 100.0f;
            reverbParams->ReflectionsDelay = 7;
            reverbParams->ReverbDelay = 11;
            reverbParams->RearDelay = FAudio.FAUDIOFX_REVERB_DEFAULT_REAR_DELAY;
            reverbParams->PositionLeft = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION;
            reverbParams->PositionRight = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION;
            reverbParams->PositionMatrixLeft = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION_MATRIX;
            reverbParams->PositionMatrixRight = FAudio.FAUDIOFX_REVERB_DEFAULT_POSITION_MATRIX;
            reverbParams->EarlyDiffusion = 15;
            reverbParams->LateDiffusion = 15;
            reverbParams->LowEQGain = 8;
            reverbParams->LowEQCutoff = 4;
            reverbParams->HighEQGain = 8;
            reverbParams->HighEQCutoff = 6;
            reverbParams->RoomFilterFreq = 5000f;
            reverbParams->RoomFilterMain = -10f;
            reverbParams->RoomFilterHF = -1f;
            reverbParams->ReflectionsGain = -26.0200005f;
            reverbParams->ReverbGain = 10.0f;
            reverbParams->DecayTime = 1.49000001f;
            reverbParams->Density = 100.0f;
            reverbParams->RoomSize = FAudio.FAUDIOFX_REVERB_DEFAULT_ROOM_SIZE;
            FAudio.FAudioVoice_SetEffectParameters(
                ReverbVoice,
                0,
                reverbParamsPtr,
                (uint) Marshal.SizeOf<FAudio.FAudioFXReverbParameters>(),
                0
            );
            Marshal.FreeHGlobal(reverbParamsPtr);

            /* Init reverb sends */

            reverbSends = new FAudio.FAudioVoiceSends();
            reverbSends.SendCount = 2;
            reverbSends.pSends = Marshal.AllocHGlobal(
                2 * Marshal.SizeOf<FAudio.FAudioSendDescriptor>()
            );
            FAudio.FAudioSendDescriptor* sendDesc = (FAudio.FAudioSendDescriptor*) reverbSends.pSends;
            sendDesc[0].Flags = 0;
            sendDesc[0].pOutputVoice = MasteringVoice;
            sendDesc[1].Flags = 0;
            sendDesc[1].pOutputVoice = ReverbVoice;
        }
    }
}