/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuProcessSectionView.NT.cpp
    Date: 2022-08-09
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuProcessSectionView.NT.hpp"
#include "Process.hpp"
#include <Source/IO/FS/FileStream.NT.hpp>
#include "AuProcessSectionFileMapView.NT.hpp"
#include <Source/IO/IPC/AuIPCHandle.hpp>
#include <Windows.h>

namespace Aurora::Process
{
    AuUInt ProcessSectionView::GetStart()
    {
        return AuNumericLimits<AuUInt>::min();
    }

    AuUInt ProcessSectionView::GetEnd()
    {
        return AuNumericLimits<AuUInt>::max();
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::Allocate(AuUInt uLength)
    {
        PageTable table {};
        table.NX = true;
        table.readable = true;
        table.writable = true;
        return this->AllocateEx2(uLength, 0, table);
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::MapFileByPath(const AuString &str,
                                                                     AuUInt64 uOffset,
                                                                     AuUInt uLength,
                                                                     AuFS::EFileOpenMode mode,
                                                                     AuFS::EFileAdvisoryLockLevel sectionLock)
    {
        auto pHandle = AuIO::IOHandleShared();
        if (!pHandle)
        {
            SysPushErrorMemory();
            return nullptr;
        }

        AuIO::IIOHandle::HandleCreate createhandle(str);
        createhandle.eAdvisoryLevel = AuFS::EFileAdvisoryLockLevel::eNoSafety;
        createhandle.eMode = mode;
        createhandle.bFailIfNonEmptyFile = false;
        createhandle.bDirectIOMode = false;
        createhandle.bAsyncHandle = false;

        if (!pHandle->InitFromPath(createhandle))
        {
            return nullptr;
        }

        return this->MapFileByObject(pHandle, uOffset, uLength, mode, sectionLock);
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::MapFileByObject(const AuSPtr<IO::IIOHandle> &pIOHandle,
                                                                       AuUInt64 uOffset,
                                                                       AuUInt uLength,
                                                                       AuFS::EFileOpenMode mode,
                                                                       AuFS::EFileAdvisoryLockLevel processLockLevel)
    {
        HANDLE hFileMap;
        ULONG desiredAccess {}, pageAttributes {};

        if (!pIOHandle)
        {
            SysPushErrorArg();
            return {};
        }

        if (!uLength)
        {
            SysPushErrorArg("invalid uLength");
            return {};
        }

        if (processLockLevel != AuFS::EFileAdvisoryLockLevel::eNoSafety)
        {
            DWORD dwFlags {};
            OVERLAPPED overlapped {};

            if (processLockLevel == AuFS::EFileAdvisoryLockLevel::eBlockReadWrite)
            {
                dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
            }

            dwFlags |= LOCKFILE_FAIL_IMMEDIATELY;

            overlapped.Offset = AuBitsToLower(uOffset);
            overlapped.OffsetHigh = AuBitsToHigher(uOffset);

            if (!::LockFileEx((HANDLE)pIOHandle->GetOSHandle(),
                              dwFlags,
                              0,
                              AuBitsToLower(uLength),
                              AuBitsToHigher(uLength),
                              &overlapped))
            {
                SysPushErrorIO("No Lock");
                return {};
            }
        }
   
        switch (mode)
        {
        case AuFS::EFileOpenMode::eRead:
        {
            desiredAccess  = SECTION_MAP_READ;
            pageAttributes = PAGE_READONLY;
            break;
        }
        case AuFS::EFileOpenMode::eWrite:
        case AuFS::EFileOpenMode::eReadWrite:
        {
            desiredAccess  = SECTION_MAP_READ | SECTION_MAP_WRITE;
            pageAttributes = PAGE_READWRITE;
            break;
        }
        default:
            SysPushErrorGeneric();
            return {};
        };

        hFileMap = ::CreateFileMappingA((HANDLE)pIOHandle->GetOSHandle(),
                                        nullptr,
                                        pageAttributes,
                                     #if defined(AURORA_IS_64BIT)
                                        AuBitsToHigher(uLength),
                                        AuBitsToLower(uLength),
                                     #else
                                        0,
                                        uLength,
                                     #endif
                                        nullptr);
        if ((hFileMap == INVALID_HANDLE_VALUE) ||
            (!hFileMap))
        {
            SysPushErrorIO("Couldn't create file map. Is the requeted access mode too high for the given object?");
            return {};
        }

        auto map = ::MapViewOfFile(hFileMap,
                                   desiredAccess,
                                   AuBitsToHigher(uOffset),
                                   AuBitsToLower(uOffset),
                                   uLength);
        if (!map)
        {
            SysPushErrorIO("Couldn't create map of section");
            AuWin32CloseHandle(hFileMap);
            return {};
        }

        auto pNewObject = AuMakeShared<ProcessSectionFileMapView>(AuUInt(map), hFileMap);
        if (!pNewObject)
        {
            SysPushErrorMem();
            AuWin32CloseHandle(hFileMap);
            ::UnmapViewOfFile(map);
            return {};
        }

        pNewObject->pProcessGlobalHint = this;
        pNewObject->uLength = uLength;

        return pNewObject;
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::MapIPCMemory(const AuString &handleString,
                                                                    AuUInt64 uOffset,
                                                                    AuUInt uLength,
                                                                    AuFS::EFileOpenMode mode)
    {
        AuIPC::IPCHandle handle;
        HANDLE hFileMap;
        ULONG desiredAccess {}, pageAttributes {};

        if (!uLength)
        {
            SysPushErrorArg("invalid uLength");
            return {};
        }

        if (!handle.FromString(handleString))
        {
            SysPushErrorParseError("{}", handleString);
            return {};
        }

        auto token = handle.GetToken(AuIPC::EIPCHandleType::eIPCMemory, 0);
        if (!token)
        {
            SysPushErrorParseError();
            return {};
        }

        auto actualLength = token->token.word;
        auto path         = token->token.ToNTPath();

        if (actualLength < uOffset + uLength)
        {
            SysPushErrorIO("Out of range");
            return {};
        }

        switch (mode)
        {
        case AuFS::EFileOpenMode::eRead:
        {
            desiredAccess  = SECTION_MAP_READ;
            pageAttributes = PAGE_READONLY;
            break;
        }
        case AuFS::EFileOpenMode::eWrite:
        case AuFS::EFileOpenMode::eReadWrite:
        {
            desiredAccess  = SECTION_MAP_READ | SECTION_MAP_WRITE;
            pageAttributes = PAGE_READWRITE;
            break;
        }
        default:
            SysPushErrorGeneric();
            return {};
        };

        hFileMap = ::OpenFileMappingA(desiredAccess,
                                       FALSE,
                                       path.c_str());
        if ((hFileMap == INVALID_HANDLE_VALUE) ||
            (!hFileMap))
        {
            SysPushErrorIO("Couldn't create IPC map (handle: {})", handleString);
            return {};
        }

        auto map = ::MapViewOfFile(hFileMap,
                                   desiredAccess,
                                   AuBitsToHigher(uOffset),
                                   AuBitsToLower(uOffset),
                                   uLength);
        if (!map)
        {
            SysPushErrorIO("Couldn't create map of IPC section (handle: {})", handleString);
            AuWin32CloseHandle(hFileMap);
            return {};
        }

        auto pNewObject = AuMakeShared<ProcessSectionFileMapView>(AuUInt(map), hFileMap);
        if (!pNewObject)
        {
            SysPushErrorMem();
            AuWin32CloseHandle(hFileMap);
            ::UnmapViewOfFile(map);
            return {};
        }

        pNewObject->pProcessGlobalHint = this;
        pNewObject->uLength = uLength;

        return pNewObject;
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::AllocateEx(AuUInt uLength,
                                                                  AuUInt uOffset)
    {
        SysAssert(this->bPanicOnEx, "Windows 7/8 called a Windows 10 RS4 memory management routine. "
                                    "Applications requiring explicit and pre-reserved memory maps cannot run on unmodified unsupported versions of Windows."
                                    "We lied about reserving a region of bytes with a ProcessSectionView. Unable to gurantee uOffset.");
        return this->Allocate(uLength);
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::AllocateEx2(AuUInt uLength,
                                                                   AuUInt uOffset,
                                                                   PageTable permissions)
    {
        SysAssert(this->bPanicOnEx, "Windows 7/8 called a Windows 10 RS4 memory management routine. "
                                    "Applications requiring explicit and pre-reserved memory maps cannot run on unmodified unsupported versions of Windows."
                                    "We lied about reserving a region of bytes with a ProcessSectionView. Unable to gurantee uOffset.");

        HANDLE hFileMap;

        if (!uLength)
        {
            SysPushErrorArg("invalid uLength");
            return {};
        }

        DWORD uPageFlags {};
        if (permissions.writable && permissions.NX)
        {
            uPageFlags = PAGE_READWRITE;
        }
        else if (permissions.readable && permissions.NX)
        {
            uPageFlags = PAGE_READONLY;
        }
        else if (permissions.writable)
        {
            uPageFlags = PAGE_EXECUTE_READWRITE;
        }
        else if (permissions.readable)
        {
            uPageFlags = PAGE_EXECUTE_READ;
        }

        hFileMap = ::CreateFileMappingA(INVALID_HANDLE_VALUE,
                                        nullptr,
                                        uPageFlags,
                                     #if defined(AURORA_IS_64BIT)
                                        AuBitsToHigher(uLength),
                                        AuBitsToLower(uLength),
                                     #else
                                        0,
                                        uLength,
                                     #endif
                                        nullptr);
        if ((hFileMap == INVALID_HANDLE_VALUE) ||
            (!hFileMap))
        {
            SysPushErrorIO("Couldn't create file map");
            return {};
        }

        DWORD sectionPermission {};
        if (permissions.readable)
        {
            sectionPermission = SECTION_MAP_READ;
        }

        if (permissions.writable)
        {
            sectionPermission |= SECTION_MAP_WRITE;
        }

        if (!permissions.NX)
        {
            sectionPermission |= SECTION_MAP_EXECUTE;
        }

        auto map = ::MapViewOfFile(hFileMap,
                                   sectionPermission,
                                   0,
                                   0,
                                   uLength);
        if (!map)
        {
            SysPushErrorIO("Couldn't create allocation of section");
            AuWin32CloseHandle(hFileMap);
            return {};
        }

        auto pNewObject = AuMakeShared<ProcessSectionFileMapView>(AuUInt(map), hFileMap);
        if (!pNewObject)
        {
            SysPushErrorMem();
            AuWin32CloseHandle(hFileMap);
            return {};
        }

        pNewObject->pProcessGlobalHint = this;
        pNewObject->uLength = uLength;

        return pNewObject;
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::MapFileByPathEx(AuUInt viewOffset,
                                                                       const AuString &str,
                                                                       AuUInt64 uOffset,
                                                                       AuUInt uLength,
                                                                       Aurora::IO::FS::EFileOpenMode mode,
                                                                       Aurora::IO::FS::EFileAdvisoryLockLevel processLockLevel)
    {
        SysAssert(this->bPanicOnEx, "Windows 7/8 called a Windows 10 RS4 memory management routine. "
                                    "Applications requiring explicit and pre-reserved memory maps cannot run on unmodified unsupported versions of Windows."
                                    "We lied about reserving a region of bytes with a ProcessSectionView. Unable to gurantee uOffset.");
        return this->MapFileByPath(str, uOffset, uLength, mode, processLockLevel);
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::MapFileByObjectEx(AuUInt viewOffset,
                                                                         const AuSPtr<IO::IIOHandle> &pIOHandle,
                                                                         AuUInt64 uOffset,
                                                                         AuUInt uLength,
                                                                         Aurora::IO::FS::EFileOpenMode mode,
                                                                         Aurora::IO::FS::EFileAdvisoryLockLevel processLockLevel)
    {
        SysAssert(this->bPanicOnEx, "Windows 7/8 called a Windows 10 RS4 memory management routine. "
                                    "Applications requiring explicit and pre-reserved memory maps cannot run on unmodified unsupported versions of Windows."
                                    "We lied about reserving a region of bytes with a ProcessSectionView. Unable to gurantee uOffset.");
        return this->MapFileByObject(pIOHandle, uOffset, uLength, mode, processLockLevel);
    }

    AuSPtr<IProcessSectionMapView> ProcessSectionView::MapIPCMemoryEx(AuUInt viewOffset,
                                                                      const AuString &handle,
                                                                      AuUInt64 uOffset,
                                                                      AuUInt uLength,
                                                                      Aurora::IO::FS::EFileOpenMode mode)
    {
        SysAssert(this->bPanicOnEx, "Windows 7/8 called a Windows 10 RS4 memory management routine. "
                                    "Applications requiring explicit and pre-reserved memory maps cannot run on unmodified unsupported versions of Windows."
                                    "We lied about reserving a region of bytes with a ProcessSectionView. Unable to gurantee uOffset.");
        return this->MapIPCMemory(handle, uOffset, uLength, mode);
    }

    AuList<AuPair<AuUInt, AuUInt>> ProcessSectionView::GetAllocations()
    {
        AU_LOCK_GUARD(this->spinlock);
        return this->allocations;
    }

    void ProcessSectionView::DoVanillaDriverlessExtesionWin7Test()
    {
    #if defined(AURORA_PLATFORM_WIN32)

    #define WIN_7_WARN "WARNING: ADDRESS SPACE CANNOT BE RESERVED ON OLDER NT KERNELS. \r\n" \
                       "AuProcess::ReserveAddressSpace(AuUInt uOffset) is about to lie about reserving the address space, yield the entire address space, and leave a note to terminate the application if an explicit fixed-offset request is made."

        SysPushErrorUnimplemented("Win7_ReserveAddressSpace_RS4_REQ");

        AuUInt uEnvSize {};
        ::getenv_s(&uEnvSize, nullptr, 0, "AURORA_FORCE_RANDOM_ADDRESS_WITHOUT_VIRTALLOC2");
        if (uEnvSize)
        {
            // bah
            // enjoy return not respecting what was provided as the expected offset.
            // this is not a workaround for missing functionality in the operating systems userland and kernel abstraction.
            // this will just prevent us from panicing preemptively.
            this->bPanicOnEx = true;
        }
        else
        {
            AuLogWarn(WIN_7_WARN);
            this->bPanicOnEx = false;
        }
    #else
        AuLogWarn("I don't know this platform - AuProcess");
        this->bPanicOnEx = true;
    #endif
    }

    AUKN_SYM AuSPtr<IProcessSectionView> GetGlobalProcessSpace()
    {
        static ProcessSectionView gSingleton;
        gSingleton.DoVanillaDriverlessExtesionWin7Test();
        return AuUnsafeRaiiToShared(&gSingleton);
    }
}