/**
 * @file dll/dispatch.c
 *
 * @copyright 2015 Bill Zissimopoulos
 */

#include <dll/library.h>

enum
{
    FspFileSystemDispatcherThreadCountMin = 2,
};

static FSP_FILE_SYSTEM_INTERFACE FspFileSystemNullInterface;

FSP_API NTSTATUS FspFileSystemCreate(PWSTR DevicePath,
    const FSP_FSCTL_VOLUME_PARAMS *VolumeParams,
    const FSP_FILE_SYSTEM_INTERFACE *Interface,
    FSP_FILE_SYSTEM **PFileSystem)
{
    NTSTATUS Result;
    FSP_FILE_SYSTEM *FileSystem;

    *PFileSystem = 0;

    if (0 == Interface)
        Interface = &FspFileSystemNullInterface;

    FileSystem = MemAlloc(sizeof *FileSystem);
    if (0 == FileSystem)
        return STATUS_INSUFFICIENT_RESOURCES;
    memset(FileSystem, 0, sizeof *FileSystem);

    Result = FspFsctlCreateVolume(DevicePath, VolumeParams,
        FileSystem->VolumeName, sizeof FileSystem->VolumeName,
        &FileSystem->VolumeHandle);
    if (!NT_SUCCESS(Result))
    {
        MemFree(FileSystem);
        return Result;
    }

    FileSystem->Operations[FspFsctlTransactCreateKind] = FspFileSystemOpCreate;
    FileSystem->Operations[FspFsctlTransactOverwriteKind] = FspFileSystemOpOverwrite;
    FileSystem->Operations[FspFsctlTransactCleanupKind] = FspFileSystemOpCleanup;
    FileSystem->Operations[FspFsctlTransactCloseKind] = FspFileSystemOpClose;
    FileSystem->Operations[FspFsctlTransactQueryInformationKind] = FspFileSystemOpQueryInformation;
    FileSystem->Operations[FspFsctlTransactSetInformationKind] = FspFileSystemOpSetInformation;
    FileSystem->Operations[FspFsctlTransactQueryVolumeInformationKind] = FspFileSystemOpQueryVolumeInformation;
    FileSystem->Operations[FspFsctlTransactSetVolumeInformationKind] = FspFileSystemOpSetVolumeInformation;
    // !!!: ...
    FileSystem->Interface = Interface;

    *PFileSystem = FileSystem;

    return STATUS_SUCCESS;
}

FSP_API VOID FspFileSystemDelete(FSP_FILE_SYSTEM *FileSystem)
{
    CloseHandle(FileSystem->VolumeHandle);
    MemFree(FileSystem);
}

static DWORD WINAPI FspFileSystemDispatcherThread(PVOID FileSystem0)
{
    FSP_FILE_SYSTEM *FileSystem = FileSystem0;
    NTSTATUS Result;
    SIZE_T RequestSize;
    FSP_FSCTL_TRANSACT_REQ *Request = 0;
    FSP_FSCTL_TRANSACT_RSP *Response = 0;
    HANDLE DispatcherThread = 0;

    Request = MemAlloc(FSP_FSCTL_TRANSACT_BUFFER_SIZEMIN);
    Response = MemAlloc(FSP_FSCTL_TRANSACT_RSP_SIZEMAX);
    if (0 == Request || 0 == Response)
    {
        Result = STATUS_INSUFFICIENT_RESOURCES;
        goto exit;
    }

    if (1 < FileSystem->DispatcherThreadCount)
    {
        FileSystem->DispatcherThreadCount--;
        DispatcherThread = CreateThread(0, 0, FspFileSystemDispatcherThread, FileSystem, 0, 0);
        if (0 == DispatcherThread)
        {
            Result = FspNtStatusFromWin32(GetLastError());
            goto exit;
        }
    }

    memset(Response, 0, sizeof *Response);
    for (;;)
    {
        RequestSize = FSP_FSCTL_TRANSACT_BUFFER_SIZEMIN;
        Result = FspFsctlTransact(FileSystem->VolumeHandle,
            Response, Response->Size, Request, &RequestSize, FALSE);
        if (!NT_SUCCESS(Result))
            goto exit;

        memset(Response, 0, sizeof *Response);
        if (0 == RequestSize)
            continue;

#if 0
        FspDebugLog("FspFileSystemDispatcherThread: TID=%ld, Request={Kind=%d, Hint=%p}\n",
            GetCurrentThreadId(), Request->Kind, (PVOID)Request->Hint);
#endif

        Response->Size = sizeof *Response;
        Response->Kind = Request->Kind;
        Response->Hint = Request->Hint;
        if (FspFsctlTransactKindCount > Request->Kind && 0 != FileSystem->Operations[Request->Kind])
        {
            FspFileSystemEnterOperation(FileSystem, Request, Response);
            Response->IoStatus.Status =
                FileSystem->Operations[Request->Kind](FileSystem, Request, Response);
            FspFileSystemLeaveOperation(FileSystem, Request, Response);
        }
        else
            Response->IoStatus.Status = STATUS_INVALID_DEVICE_REQUEST;
    }

exit:
    MemFree(Response);
    MemFree(Request);

    FspFileSystemSetDispatcherResult(FileSystem, Result);

    FspFsctlStop(FileSystem->VolumeHandle);

    if (0 != DispatcherThread)
    {
        WaitForSingleObject(DispatcherThread, INFINITE);
        CloseHandle(DispatcherThread);
    }

    return Result;
}

FSP_API NTSTATUS FspFileSystemStartDispatcher(FSP_FILE_SYSTEM *FileSystem, ULONG ThreadCount)
{
    if (0 != FileSystem->DispatcherThread)
        return STATUS_INVALID_PARAMETER;

    if (0 == ThreadCount)
    {
        DWORD_PTR ProcessMask, SystemMask;

        if (!GetProcessAffinityMask(GetCurrentProcess(), &ProcessMask, &SystemMask))
            return FspNtStatusFromWin32(GetLastError());

        for (ThreadCount = 0; 0 != ProcessMask; ProcessMask >>= 1)
            ThreadCount += ProcessMask & 1;
    }

    if (ThreadCount < FspFileSystemDispatcherThreadCountMin)
        ThreadCount = FspFileSystemDispatcherThreadCountMin;

    FileSystem->DispatcherThreadCount = ThreadCount;
    FileSystem->DispatcherThread = CreateThread(0, 0,
        FspFileSystemDispatcherThread, FileSystem, 0, 0);
    if (0 == FileSystem->DispatcherThread)
        return FspNtStatusFromWin32(GetLastError());

    return STATUS_SUCCESS;
}

FSP_API VOID FspFileSystemStopDispatcher(FSP_FILE_SYSTEM *FileSystem)
{
    if (0 == FileSystem->DispatcherThread)
        return;

    FspFsctlStop(FileSystem->VolumeHandle);

    WaitForSingleObject(FileSystem->DispatcherThread, INFINITE);
    CloseHandle(FileSystem->DispatcherThread);
}