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

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

namespace SharpEmu.Libs.Np;

public static class NpManagerExports
{
    private const int NpTitleIdSize = 16;
    private const int NpTitleSecretSize = 128;
    private const int NpReachabilityStateUnavailable = 0;

    [SysAbiExport(
        Nid = "3Zl8BePTh9Y",
        ExportName = "sceNpCheckCallback",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpCheckCallback(CpuContext ctx)
    {
        ctx[CpuRegister.Rax] = 0;
        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
    }

    [SysAbiExport(
        Nid = "S7QTn72PrDw",
        ExportName = "sceNpDeleteRequest",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpDeleteRequest(CpuContext ctx)
    {
        ctx[CpuRegister.Rax] = 0;
        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
    }

    [SysAbiExport(
        Nid = "JELHf4xPufo",
        ExportName = "sceNpCheckCallbackForLib",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpCheckCallbackForLib(CpuContext ctx)
    {
        ctx[CpuRegister.Rax] = 0;
        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
    }

    // Offline profile: the online id payload is left untouched and the call
    // reports success, matching the other offline NpManager stubs here.
    [SysAbiExport(
        Nid = "XDncXQIJUSk",
        ExportName = "sceNpGetOnlineId",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpGetOnlineId(CpuContext ctx)
    {
        // Gen5 ABI: user ID, then output structure.
        return WriteOfflineOnlineId(ctx, ctx[CpuRegister.Rsi]);
    }

    [SysAbiExport(
        Nid = "rbknaUjpqWo",
        ExportName = "sceNpGetAccountIdA",
        Target = Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpGetOnlineIdA(CpuContext ctx)
    {
        // The A variant takes a user ID before OnlineId.
        return WriteOfflineOnlineId(ctx, ctx[CpuRegister.Rsi]);
    }

    [SysAbiExport(
        Nid = "e-ZuhGEoeC4",
        ExportName = "sceNpGetNpReachabilityState",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpGetNpReachabilityState(CpuContext ctx)
    {
        var stateAddress = ctx[CpuRegister.Rsi];
        if (stateAddress == 0)
        {
            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        return ctx.TryWriteInt32(stateAddress, NpReachabilityStateUnavailable)
            ? ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK)
            : ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
    }

    [SysAbiExport(
        Nid = "VfRSmPmj8Q8",
        ExportName = "sceNpRegisterStateCallback",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpRegisterStateCallback(CpuContext ctx)
    {
        ctx[CpuRegister.Rax] = 0;
        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
    }

    [SysAbiExport(
        Nid = "qQJfO8HAiaY",
        ExportName = "sceNpRegisterStateCallbackA",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpRegisterStateCallbackA(CpuContext ctx)
    {
        ctx[CpuRegister.Rax] = 0;
        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
    }

    [SysAbiExport(
        Nid = "0c7HbXRKUt4",
        ExportName = "sceNpRegisterStateCallbackForToolkit",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManagerForToolkit")]
    public static int NpRegisterStateCallbackForToolkit(CpuContext ctx)
    {
        ctx[CpuRegister.Rax] = 0;
        return (int)OrbisGen2Result.ORBIS_GEN2_OK;
    }

    [SysAbiExport(
        Nid = "eQH7nWPcAgc",
        ExportName = "sceNpGetState",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpGetState(CpuContext ctx)
    {
        var stateAddress = ctx[CpuRegister.Rsi];
        if (stateAddress == 0)
        {
            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        Span<byte> stateBytes = stackalloc byte[sizeof(uint)];
        BinaryPrimitives.WriteUInt32LittleEndian(stateBytes, 1);
        return ctx.Memory.TryWrite(stateAddress, stateBytes)
            ? ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK)
            : ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
    }

    [SysAbiExport(
        Nid = "Ec63y59l9tw",
        ExportName = "sceNpSetNpTitleId",
        Target = Generation.Gen4 | Generation.Gen5,
        LibraryName = "libSceNpManager")]
    public static int NpSetNpTitleId(CpuContext ctx)
    {
        var titleIdAddress = ctx[CpuRegister.Rdi];
        var titleSecretAddress = ctx[CpuRegister.Rsi];
        if (titleIdAddress == 0 || titleSecretAddress == 0)
        {
            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        Span<byte> titleId = stackalloc byte[NpTitleIdSize];
        Span<byte> titleSecret = stackalloc byte[NpTitleSecretSize];
        if (!ctx.Memory.TryRead(titleIdAddress, titleId) ||
            !ctx.Memory.TryRead(titleSecretAddress, titleSecret))
        {
            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
        }

        TraceNp($"set_np_title_id title='{ReadTitleId(titleId)}'");
        return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK);
    }

    private static string ReadTitleId(ReadOnlySpan<byte> bytes)
    {
        var length = 0;
        while (length < 12 && length < bytes.Length && bytes[length] != 0)
        {
            length++;
        }

        return length == 0
            ? string.Empty
            : System.Text.Encoding.ASCII.GetString(bytes[..length]);
    }

    private static void TraceNp(string message)
    {
        if (!string.Equals(Environment.GetEnvironmentVariable("SHARPEMU_LOG_NP"), "1", StringComparison.Ordinal))
        {
            return;
        }

        Console.Error.WriteLine($"[LOADER][TRACE] np.{message}");
    }

    private static int WriteOfflineOnlineId(CpuContext ctx, ulong address)
    {
        if (address == 0)
        {
            return ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_INVALID_ARGUMENT);
        }

        // SceNpOnlineId is a 16-byte handle plus four trailing bytes.
        Span<byte> onlineId = stackalloc byte[20];
        "Player"u8.CopyTo(onlineId);
        return ctx.Memory.TryWrite(address, onlineId)
            ? ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_OK)
            : ctx.SetReturn(OrbisGen2Result.ORBIS_GEN2_ERROR_MEMORY_FAULT);
    }
}