// Copyright (C) 2026 SharpEmu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later

using System.Buffers.Binary;
using SharpEmu.HLE;
using SharpEmu.Libs.Audio;
using Xunit;

namespace SharpEmu.Libs.Tests.Audio;

public sealed class AudioOut2PortGetStateExportsTests
{
    private const ulong MemoryBase = 0x1_0000_0000;
    private const ulong StateAddress = MemoryBase + 0x100;

    private static CpuContext CreateContext(out FakeCpuMemory memory)
    {
        memory = new FakeCpuMemory(MemoryBase, 0x1000);
        return new CpuContext(memory, Generation.Gen5);
    }

    [Fact]
    public void PortGetState_WritesFixedSizeIgnoringPollutedR9()
    {
        var ctx = CreateContext(out var memory);
        // Paint the buffer so we can see the write footprint.
        Span<byte> paint = stackalloc byte[0x100];
        paint.Fill(0xAB);
        Assert.True(memory.TryWrite(StateAddress, paint));

        ctx[CpuRegister.Rdi] = 0xDE1FF6800001UL;
        ctx[CpuRegister.Rsi] = StateAddress;
        ctx[CpuRegister.Rdx] = StateAddress + 0x200;
        // Polluted GetSize leftover — must NOT enlarge the write.
        ctx[CpuRegister.R9] = 0x180;

        var result = AudioOut2Exports.AudioOut2PortGetState(ctx);

        Assert.Equal(0, result);
        Span<byte> state = stackalloc byte[0x100];
        Assert.True(memory.TryRead(StateAddress, state));
        Assert.Equal(1, BinaryPrimitives.ReadUInt16LittleEndian(state));
        Assert.Equal(2, state[2]);
        // Bytes past the fixed 0x20 header must remain untouched.
        Assert.Equal(0xAB, state[0x20]);
        Assert.Equal(0xAB, state[0x7F]);
    }

    [Fact]
    public void PortGetState_SkipsGuestStackOutBuffer()
    {
        var ctx = CreateContext(out _);
        const ulong stackOut = 0x00007FFFDE1FF688UL;
        ctx[CpuRegister.Rdi] = 0xDE1FF688004DUL;
        ctx[CpuRegister.Rsi] = stackOut;
        ctx[CpuRegister.Rdx] = 0;

        var result = AudioOut2Exports.AudioOut2PortGetState(ctx);

        Assert.Equal(0, result);
    }

    [Fact]
    public void GetSpeakerInfo_WritesFixedSizeToRdiNotRsiTypeFlag()
    {
        var ctx = CreateContext(out var memory);
        Span<byte> paint = stackalloc byte[0x80];
        paint.Fill(0xCD);
        Assert.True(memory.TryWrite(StateAddress, paint));

        ctx[CpuRegister.Rdi] = StateAddress;
        ctx[CpuRegister.Rsi] = 1;
        ctx[CpuRegister.Rdx] = StateAddress + 0x200;
        ctx[CpuRegister.R8] = 0x840;
        ctx[CpuRegister.R9] = 0x10C;

        var result = AudioOut2Exports.AudioOut2GetSpeakerInfo(ctx);

        Assert.Equal(0, result);
        Span<byte> info = stackalloc byte[0x80];
        Assert.True(memory.TryRead(StateAddress, info));
        Assert.Equal(2u, BinaryPrimitives.ReadUInt32LittleEndian(info));
        Assert.Equal(48000u, BinaryPrimitives.ReadUInt32LittleEndian(info[4..]));
        Assert.Equal(0xCD, info[0x20]);
    }
}