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

using SharpEmu.HLE;
using System.Buffers.Binary;
using System.Diagnostics;

namespace SharpEmu.Libs.Pad;

public static class PadExports
{
    private const int OrbisPadErrorInvalidHandle = unchecked((int)0x80920003);
    private const int OrbisPadErrorNotInitialized = unchecked((int)0x80920005);
    private const int OrbisPadErrorDeviceNotConnected = unchecked((int)0x80920007);
    private const int OrbisPadErrorDeviceNoHandle = unchecked((int)0x80920008);
    private const int PrimaryUserId = 1;
    private const int StandardPortType = 0;
    private const int PrimaryPadHandle = 1;
    private const int ControllerInformationSize = 0x1C;
    private const int PadDataSize = 0x78;

    private static bool _initialized;

    [SysAbiExport(
        Nid = "hv1luiJrqQM",
        ExportName = "scePadInit",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libScePad")]
    public static int PadInit(CpuContext ctx)
    {
        _initialized = true;
        return SetReturn(ctx, 0);
    }

    [SysAbiExport(
        Nid = "xk0AcarP3V4",
        ExportName = "scePadOpen",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libScePad")]
    public static int PadOpen(CpuContext ctx)
    {
        var userId = unchecked((int)ctx[CpuRegister.Rdi]);
        var type = unchecked((int)ctx[CpuRegister.Rsi]);
        var index = unchecked((int)ctx[CpuRegister.Rdx]);
        var parameterAddress = ctx[CpuRegister.Rcx];
        if (!_initialized)
        {
            return SetReturn(ctx, OrbisPadErrorNotInitialized);
        }

        if (userId == -1)
        {
            return SetReturn(ctx, OrbisPadErrorDeviceNoHandle);
        }

        if (userId != PrimaryUserId || type != StandardPortType || index != 0 || parameterAddress != 0)
        {
            return SetReturn(ctx, OrbisPadErrorDeviceNotConnected);
        }

        return SetReturn(ctx, PrimaryPadHandle);
    }

    [SysAbiExport(
        Nid = "clVvL4ZDntw",
        ExportName = "scePadSetMotionSensorState",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libScePad")]
    public static int PadSetMotionSensorState(CpuContext ctx)
    {
        var handle = unchecked((int)ctx[CpuRegister.Rdi]);
        return handle == PrimaryPadHandle
            ? SetReturn(ctx, 0)
            : SetReturn(ctx, OrbisPadErrorInvalidHandle);
    }

    [SysAbiExport(
        Nid = "gjP9-KQzoUk",
        ExportName = "scePadGetControllerInformation",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libScePad")]
    public static int PadGetControllerInformation(CpuContext ctx)
    {
        var handle = unchecked((int)ctx[CpuRegister.Rdi]);
        var informationAddress = ctx[CpuRegister.Rsi];
        if (handle != PrimaryPadHandle)
        {
            return SetReturn(ctx, OrbisPadErrorInvalidHandle);
        }

        if (informationAddress == 0)
        {
            return SetReturn(ctx, (int)OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        Span<byte> information = stackalloc byte[ControllerInformationSize];
        BinaryPrimitives.WriteSingleLittleEndian(information[0x00..], 44.86f);
        BinaryPrimitives.WriteUInt16LittleEndian(information[0x04..], 1920);
        BinaryPrimitives.WriteUInt16LittleEndian(information[0x06..], 943);
        information[0x08] = 30;
        information[0x09] = 30;
        information[0x0A] = StandardPortType;
        information[0x0B] = 1;
        information[0x0C] = 1;
        BinaryPrimitives.WriteInt32LittleEndian(information[0x10..], 0);

        return ctx.Memory.TryWrite(informationAddress, information)
            ? SetReturn(ctx, 0)
            : SetReturn(ctx, (int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
    }

    [SysAbiExport(
        Nid = "YndgXqQVV7c",
        ExportName = "scePadReadState",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libScePad")]
    public static int PadReadState(CpuContext ctx)
    {
        var handle = unchecked((int)ctx[CpuRegister.Rdi]);
        var dataAddress = ctx[CpuRegister.Rsi];
        if (handle != PrimaryPadHandle)
        {
            return SetReturn(ctx, OrbisPadErrorInvalidHandle);
        }

        if (dataAddress == 0)
        {
            return SetReturn(ctx, (int)OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        return WriteNeutralPadData(ctx, dataAddress)
            ? SetReturn(ctx, 0)
            : SetReturn(ctx, (int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
    }

    [SysAbiExport(
        Nid = "q1cHNfGycLI",
        ExportName = "scePadRead",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libScePad")]
    public static int PadRead(CpuContext ctx)
    {
        var handle = unchecked((int)ctx[CpuRegister.Rdi]);
        var dataAddress = ctx[CpuRegister.Rsi];
        var count = unchecked((int)ctx[CpuRegister.Rdx]);
        if (handle != PrimaryPadHandle)
        {
            return SetReturn(ctx, OrbisPadErrorInvalidHandle);
        }

        if (dataAddress == 0 || count < 1 || count > 64)
        {
            return SetReturn(ctx, (int)OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        return WriteNeutralPadData(ctx, dataAddress)
            ? SetReturn(ctx, 1)
            : SetReturn(ctx, (int)OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
    }

    private static bool WriteNeutralPadData(CpuContext ctx, ulong dataAddress)
    {
        Span<byte> data = stackalloc byte[PadDataSize];
        data.Clear();
        data[0x04] = 128;
        data[0x05] = 128;
        data[0x06] = 128;
        data[0x07] = 128;
        BinaryPrimitives.WriteSingleLittleEndian(data[0x18..], 1.0f);
        data[0x4C] = 1;
        var timestampTicks = Stopwatch.GetTimestamp();
        var timestampMicroseconds =
            ((ulong)(timestampTicks / Stopwatch.Frequency) * 1_000_000UL) +
            ((ulong)(timestampTicks % Stopwatch.Frequency) * 1_000_000UL / (ulong)Stopwatch.Frequency);
        BinaryPrimitives.WriteUInt64LittleEndian(
            data[0x50..],
            timestampMicroseconds);
        data[0x68] = 1;

        return ctx.Memory.TryWrite(dataAddress, data);
    }

    private static int SetReturn(CpuContext ctx, int result)
    {
        ctx[CpuRegister.Rax] = unchecked((ulong)result);
        return result;
    }
}