using System.Runtime.InteropServices;

// Shared "walk a native array of owned-struct entries, convert to managed records, free the
// native list" pattern — identical shape for vc_device_list/vc_channel_list/vc_user_list/
// vc_stream_summary_list (all core-allocated, caller-freed; see voicecat.h's doc comments on
// each). The matching vc_free_*_list call happens INSIDE each ToManaged here, immediately
// after the conversion, so callers never need to remember to free anything themselves.
namespace VoiceCat.Interop;

internal static class Marshaling
{
    public static List<DeviceInfo> ToManaged(ref VcDeviceListNative native)
    {
        var result = new List<DeviceInfo>((int)native.Count);
        int size = Marshal.SizeOf<VcDeviceNative>();
        for (nuint i = 0; i < native.Count; i++)
        {
            var raw = Marshal.PtrToStructure<VcDeviceNative>(native.Items + (int)i * size);
            result.Add(new DeviceInfo(
                Marshal.PtrToStringUTF8(raw.Id) ?? string.Empty,
                Marshal.PtrToStringUTF8(raw.Name) ?? string.Empty,
                raw.IsDefault != 0));
        }
        NativeMethods.vc_free_device_list(ref native);
        return result;
    }

    public static List<ChannelInfo> ToManaged(ref VcChannelListNative native)
    {
        var result = new List<ChannelInfo>((int)native.Count);
        int size = Marshal.SizeOf<VcChannelNative>();
        for (nuint i = 0; i < native.Count; i++)
        {
            var raw = Marshal.PtrToStructure<VcChannelNative>(native.Items + (int)i * size);
            result.Add(new ChannelInfo(
                raw.Id,
                raw.ParentId,
                Marshal.PtrToStringUTF8(raw.Name) ?? string.Empty,
                raw.PasswordProtected != 0,
                raw.MaxUsers));
        }
        NativeMethods.vc_free_channel_list(ref native);
        return result;
    }

    public static List<UserInfo> ToManaged(ref VcUserListNative native)
    {
        var result = new List<UserInfo>((int)native.Count);
        int size = Marshal.SizeOf<VcUserNative>();
        for (nuint i = 0; i < native.Count; i++)
        {
            var raw = Marshal.PtrToStructure<VcUserNative>(native.Items + (int)i * size);
            result.Add(new UserInfo(
                raw.Id,
                Marshal.PtrToStringUTF8(raw.Nickname) ?? string.Empty,
                raw.IsGuest != 0,
                raw.ChannelId));
        }
        NativeMethods.vc_free_user_list(ref native);
        return result;
    }

    public static List<StreamSummary> ToManaged(ref VcStreamSummaryListNative native)
    {
        var result = new List<StreamSummary>((int)native.Count);
        int size = Marshal.SizeOf<VcStreamSummaryNative>();
        for (nuint i = 0; i < native.Count; i++)
        {
            var raw = Marshal.PtrToStructure<VcStreamSummaryNative>(native.Items + (int)i * size);
            result.Add(new StreamSummary(
                raw.StreamId,
                raw.Kind,
                Marshal.PtrToStringUTF8(raw.Label) ?? string.Empty));
        }
        NativeMethods.vc_free_stream_summary_list(ref native);
        return result;
    }

    public static AudioConfigInfo ToManaged(in VcAudioConfigNative native) => new(
        native.Codec,
        native.Mode != 0,
        native.SampleRate,
        native.BitrateBps,
        native.FrameMs,
        native.Application,
        native.Fec != 0,
        native.ExpectedPacketLoss,
        native.Dtx != 0,
        native.Complexity);
}