using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace WhiteMagic.Native;

/// <summary>
/// P/Invoke declarations for kernel32/ntdll/user32 APIs used by the high-level
/// PEB, TEB, windowing, and input helpers. These live in a separate partial file so
/// they can evolve independently of <see cref="NativeMethods"/>.
/// </summary>
internal static partial class NativeMethods
{
    // ── Natives used directly by public helpers ──────────────────────────────

    /// <summary>Queries information about the specified process.</summary>
    [LibraryImport("ntdll.dll")]
    internal static partial int NtQueryInformationProcess(
        SafeMemoryHandle processHandle,
        int processInformationClass,
        ref ProcessBasicInformation processInformation,
        uint processInformationLength,
        out uint returnLength);

    /// <summary>Queries information about the specified thread.</summary>
    [LibraryImport("ntdll.dll")]
    internal static partial int NtQueryInformationThread(
        SafeMemoryHandle threadHandle,
        int threadInformationClass,
        ref ThreadBasicInformation threadInformation,
        uint threadInformationLength,
        out uint returnLength);

    /// <summary>Enumerates all top-level windows on the screen.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    internal static partial int EnumWindows(
        nint lpEnumFunc,
        IntPtr lParam);

    /// <summary>Retrieves the identifier of the thread that created the window and the process id of the window.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    internal static partial uint GetWindowThreadProcessId(
        IntPtr hWnd,
        out uint lpdwProcessId);

    /// <summary>Retrieves the name of the class to which the specified window belongs.</summary>
    [LibraryImport("user32.dll", SetLastError = true, StringMarshalling = StringMarshalling.Utf16)]
    internal static partial int GetClassNameW(
        IntPtr hWnd,
        [Out] char[] lpClassName,
        int nMaxCount);

    /// <summary>Copies the text of the specified window's title bar into a buffer.</summary>
    [LibraryImport("user32.dll", SetLastError = true, StringMarshalling = StringMarshalling.Utf16)]
    internal static partial int GetWindowTextW(
        IntPtr hWnd,
        [Out] char[] lpString,
        int nMaxCount);

    /// <summary>Changes the text of the specified window's title bar.</summary>
    [LibraryImport("user32.dll", SetLastError = true, StringMarshalling = StringMarshalling.Utf16)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool SetWindowTextW(
        IntPtr hWnd,
        string lpString);

    /// <summary>Changes the size, position, and Z order of a child, pop-up, or top-level window.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool SetWindowPos(
        IntPtr hWnd,
        IntPtr hWndInsertAfter,
        int x,
        int y,
        int cx,
        int cy,
        uint uFlags);

    /// <summary>Retrieves a handle to the foreground window.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    internal static partial IntPtr GetForegroundWindow();

    /// <summary>Brings the thread that created the specified window into the foreground and activates the window.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool SetForegroundWindow(IntPtr hWnd);

    /// <summary>Flashes the specified window.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool FlashWindowEx(ref FlashWindowInfo pwfi);

    /// <summary>Attaches or detaches the input processing mechanism of one thread to that of another thread.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool AttachThreadInput(
        uint idAttach,
        uint idAttachTo,
        [MarshalAs(UnmanagedType.Bool)] bool fAttach);

    /// <summary>Places a message in the message queue associated with the thread that created the specified window.</summary>
    [LibraryImport("user32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool PostMessageW(
        IntPtr hWnd,
        uint msg,
        nuint wParam,
        nint lParam);

    // ── Window / input constants ───────────────────────────────────────────────

    internal const uint WmChar = 0x0102;
    internal const uint WmLButtonDown = 0x0201;
    internal const uint WmLButtonUp = 0x0202;
    internal const uint WmRButtonDown = 0x0204;
    internal const uint WmRButtonUp = 0x0205;

    // Mouse button state flags for WM_*BUTTONDOWN messages
    internal const uint MkLButton = 0x0001;
    internal const uint MkRButton = 0x0002;

    internal static readonly IntPtr HwndTop = IntPtr.Zero;

    internal const uint SwpShowWindow = 0x0040;
    internal const uint SwpNoActivate = 0x0010;

    internal const uint FlashwAll = 0x00000003;
    internal const uint FlashwCaption = 0x00000001;
    internal const uint FlashwTray = 0x00000002;
    internal const uint FlashwTimer = 0x00000004;
    internal const uint FlashwTimerNoFg = 0x0000000C;
}

/// <summary>
/// Layout matches <c>PROCESS_BASIC_INFORMATION</c> (ProcessBasicInformation = 0).
/// </summary>
[StructLayout(LayoutKind.Sequential)]
internal struct ProcessBasicInformation
{
    public int ExitStatus;
    public IntPtr PebBaseAddress;
    public UIntPtr AffinityMask;
    public int BasePriority;
    public UIntPtr UniqueProcessId;
    public UIntPtr InheritedFromUniqueProcessId;
}

/// <summary>
/// Layout matches <c>THREAD_BASIC_INFORMATION</c> (ThreadBasicInformation = 0).
/// </summary>
[StructLayout(LayoutKind.Sequential)]
internal struct ThreadBasicInformation
{
    public int ExitStatus;
    public IntPtr TebBaseAddress;
    public ClientId ClientId;
    public UIntPtr AffinityMask;
    public int Priority;
    public int BasePriority;
}

/// <summary>
/// Layout matches <c>CLIENT_ID</c>.
/// </summary>
[StructLayout(LayoutKind.Sequential)]
internal struct ClientId
{
    public IntPtr UniqueProcess;
    public IntPtr UniqueThread;
}

/// <summary>
/// Layout matches <c>FLASHWINFO</c> used by <see cref="NativeMethods.FlashWindowEx"/>.
/// </summary>
[StructLayout(LayoutKind.Sequential)]
internal struct FlashWindowInfo
{
    public uint cbSize;
    public IntPtr hwnd;
    public uint dwFlags;
    public uint uCount;
    public uint dwTimeout;
}