using System.Runtime.InteropServices;

namespace WhiteMagic.Native;

/// <summary>
/// P/Invoke declarations for the Win32 process, memory, thread, and module
/// APIs that WhiteMagic uses. Every declaration uses <see cref="LibraryImportAttribute"/>
/// (source-generated interop). SetLastError is enabled on all calls that the
/// Win32 API documents as setting a thread-local last-error value.
/// </summary>
internal static partial class NativeMethods
{
    // ── Process ──────────────────────────────────────────────────────────────

    /// <summary>Opens an existing process and returns a handle to it.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial SafeMemoryHandle OpenProcess(
        ProcessAccess desiredAccess,
        [MarshalAs(UnmanagedType.Bool)] bool inheritHandle,
        int processId);

    /// <summary>Opens an existing thread and returns a handle to it.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial SafeMemoryHandle OpenThread(
        ThreadAccess desiredAccess,
        [MarshalAs(UnmanagedType.Bool)] bool inheritHandle,
        int threadId);

    /// <summary>Closes an open object handle.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool CloseHandle(IntPtr handle);

    /// <summary>Determines whether the specified process is running under WOW64.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool IsWow64Process(
        SafeMemoryHandle process,
        [MarshalAs(UnmanagedType.Bool)] out bool wow64Process);

    /// <summary>Retrieves the termination status of the specified thread.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool GetExitCodeThread(
        SafeMemoryHandle thread,
        out uint exitCode);

    // ── Memory ───────────────────────────────────────────────────────────────

    /// <summary>Reads memory from a process.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool ReadProcessMemory(
        SafeMemoryHandle process,
        IntPtr baseAddress,
        Span<byte> buffer,
        int size,
        out nint bytesRead);

    /// <summary>Writes memory to a process.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool WriteProcessMemory(
        SafeMemoryHandle process,
        IntPtr baseAddress,
        ReadOnlySpan<byte> buffer,
        int size,
        out nint bytesWritten);

    /// <summary>Reserves or commits a region of memory in a process.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial IntPtr VirtualAllocEx(
        SafeMemoryHandle process,
        IntPtr address,
        nint size,
        MemoryAllocationType allocationType,
        MemoryProtectionType protect);

    /// <summary>Changes the protection on a committed region of memory.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool VirtualProtectEx(
        SafeMemoryHandle process,
        IntPtr address,
        nint size,
        MemoryProtectionType newProtect,
        out MemoryProtectionType oldProtect);

    /// <summary>Releases or decommits a region of memory in a process.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool VirtualFreeEx(
        SafeMemoryHandle process,
        IntPtr address,
        nint size,
        MemoryFreeType freeType);

    // ── Threading ────────────────────────────────────────────────────────────

    /// <summary>Creates a thread that runs in the virtual address space of a process.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial SafeMemoryHandle CreateRemoteThread(
        SafeMemoryHandle process,
        IntPtr threadAttributes,
        nint stackSize,
        IntPtr startAddress,
        IntPtr parameter,
        ThreadCreationFlags creationFlags,
        out uint threadId);

    /// <summary>Suspends the specified thread.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial uint SuspendThread(SafeMemoryHandle thread);

    /// <summary>Resumes the specified thread.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial uint ResumeThread(SafeMemoryHandle thread);

    /// <summary>Returns the thread identifier of the specified thread.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial uint GetThreadId(SafeMemoryHandle thread);

    /// <summary>Returns the identifier of the calling thread.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial uint GetCurrentThreadId();

    /// <summary>Sets a 64-bit thread context (AMD64).</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool SetThreadContext(
        SafeMemoryHandle thread,
        ref Context64 context);

    /// <summary>Gets a 64-bit thread context (AMD64).</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool GetThreadContext(
        SafeMemoryHandle thread,
        ref Context64 context);

    /// <summary>Sets a 32-bit (WOW64) thread context.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool Wow64SetThreadContext(
        SafeMemoryHandle thread,
        ref Context32 context);

    /// <summary>Gets a 32-bit (WOW64) thread context.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    internal static partial bool Wow64GetThreadContext(
        SafeMemoryHandle thread,
        ref Context32 context);

    // ── Modules ──────────────────────────────────────────────────────────────

    /// <summary>Loads a module into the calling process.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true, EntryPoint = "LoadLibraryW")]
    internal static partial IntPtr LoadLibrary(
        [MarshalAs(UnmanagedType.LPWStr)] string lpFileName);

    /// <summary>Returns the address of a function or variable from a loaded module.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial IntPtr GetProcAddress(
        IntPtr hModule,
        [MarshalAs(UnmanagedType.LPStr)] string lpProcName);

    /// <summary>Waits until an object is signaled or the timeout elapses. Returns a
    /// <c>WAIT_*</c> status (DWORD); <c>WAIT_FAILED</c> is <c>0xFFFFFFFF</c>.</summary>
    [LibraryImport("kernel32.dll", SetLastError = true)]
    internal static partial uint WaitForSingleObject(
        SafeMemoryHandle handle,
        uint milliseconds);

}