using System.Runtime.InteropServices;

namespace Robovoice.Tts.LibPiper;

[StructLayout(LayoutKind.Sequential)]
internal struct PiperSynthesizeOptions
{
    public int SpeakerId;
    public float LengthScale;
    public float NoiseScale;
    public float NoiseWScale;
}

[StructLayout(LayoutKind.Sequential)]
internal struct PiperAudioChunk
{
    public IntPtr Samples;
    public nuint NumSamples;
    public int SampleRate;

    [MarshalAs(UnmanagedType.U1)]
    public bool IsLast;

    public IntPtr Phonemes;
    public nuint NumPhonemes;
    public IntPtr PhonemeIds;
    public nuint NumPhonemeIds;
    public IntPtr Alignments;
    public nuint NumAlignments;
}

internal static class PiperNative
{
    private const string LibName = "piper";

    public const int PiperOk = 0;
    public const int PiperDone = 1;
    public const int PiperErrGeneric = -1;

    [DllImport(LibName, CallingConvention = CallingConvention.Cdecl)]
    public static extern IntPtr piper_create(
        IntPtr modelPath,
        IntPtr configPath,
        IntPtr espeakDataPath);

    [DllImport(LibName, CallingConvention = CallingConvention.Cdecl)]
    public static extern void piper_free(IntPtr synth);

    [DllImport(LibName, CallingConvention = CallingConvention.Cdecl)]
    public static extern PiperSynthesizeOptions piper_default_synthesize_options(IntPtr synth);

    [DllImport(LibName, CallingConvention = CallingConvention.Cdecl)]
    public static extern int piper_synthesize_start(
        IntPtr synth,
        IntPtr text,
        in PiperSynthesizeOptions options);

    [DllImport(LibName, CallingConvention = CallingConvention.Cdecl)]
    public static extern int piper_synthesize_next(
        IntPtr synth,
        out PiperAudioChunk chunk);

    [DllImport(LibName, CallingConvention = CallingConvention.Cdecl)]
    public static extern IntPtr piper_version();
}