/***
    Copyright (C) 2021 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: FS.NT.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "FS.hpp"
#include "FS.Generic.hpp"
#include <Source/Time/Time.hpp>

#if !defined(_AURUNTIME_GENERICFS)
namespace Aurora::IO::FS
{
    static const AuUInt64 kFileCopyBlock = 0xFFFF; // 64KiB

    bool _MkDir(const AuString &str)
    {
        return CreateDirectoryW(Locale::ConvertFromUTF8(str).c_str(), NULL);
    }

    struct ReadDirStructure : IReadDir
    {
        HANDLE hFind {INVALID_HANDLE_VALUE};
        WIN32_FIND_DATAW ffd;
        bool bFirstTick {true};
        bool bDead {false};
        StatEx stat;
        AuString sPath;

        ~ReadDirStructure()
        {
            ::FindClose(this->hFind);
        }

        virtual StatEx *Next() override
        {
            if (!AuExchange(this->bFirstTick, false))
            {
                if (::FindNextFileW(this->hFind, &this->ffd) == 0)
                {
                    return {};
                }
            }

            if (this->bDead)
            {
                return {};
            }

            if (this->ffd.cFileName == std::wstring(L".") ||
                this->ffd.cFileName == std::wstring(L".."))
            {
                return Next();
            }
            
            stat.bExists            = true;

            stat.fileName = Locale::ConvertFromWChar(this->ffd.cFileName);
            if (stat.fileName.empty())
            {
                this->bDead = true;
                return {};
            }

            stat.path               = NormalizePathRet(this->sPath + stat.fileName);
            if (stat.path.empty())
            {
                this->bDead = true;
                return {};
            }

            stat.bExistsDirectory   = this->ffd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
            stat.bExistsFile        = !stat.bExistsDirectory;
            stat.bSymLink           = this->ffd.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT;
                                   
            stat.uSize              = AuUInt64(this->ffd.nFileSizeLow) | (AuUInt64(this->ffd.nFileSizeHigh) << 32);
                                   
            stat.created            = Time::ConvertTimestamp(this->ffd.ftCreationTime);
            stat.modified           = Time::ConvertTimestamp(this->ffd.ftLastWriteTime);
            stat.accessed           = Time::ConvertTimestamp(this->ffd.ftLastAccessTime);

            return &stat;
        }
    };

    AUKN_SYM AuSPtr<IReadDir> ReadDir(const AuString &string)
    {
        auto pObj = AuMakeShared<ReadDirStructure>();
        if (!pObj)
        {
            SysPushErrorMem();
            return {};
        }

        if (!AuIOFS::NormalizePath(pObj->sPath, string))
        {
            SysPushErrorMem();
            return {};
        }

        if (!AuTryInsert(pObj->sPath, '\\'))
        {
            SysPushErrorMem();
            return {};
        }

        pObj->hFind = ::FindFirstFileW(AuLocale::ConvertFromUTF8(pObj->sPath + "*").c_str(), &pObj->ffd);
        if (INVALID_HANDLE_VALUE == pObj->hFind)
        {
            SysPushErrorIO();
            return {};
        }

        return pObj;
    }

    AUKN_SYM bool FilesInDirectory(const AuString &string, AuList<AuString> &files)
    {
        auto itr = ReadDir(string);
        if (!itr)
        {
            return false;
        }

        // SECURITY(): if next fails, its indistinguishable from end of file list, and will return true. it kinda sucks
        while (auto stat = itr->Next())
        {
            if (!stat->bExistsFile)
            {
                continue;
            }

            if (!AuTryInsert(files, stat->fileName))
            {
                return false;
            }
        }

        return true;
    }

    AUKN_SYM bool DirsInDirectory(const AuString &string, AuList<AuString> &dirs)
    {
        auto itr = ReadDir(string);
        if (!itr)
        {
            return false;
        }

        // SECURITY(): if next fails, its indistinguishable from end of file list, and will return true. it kinda sucks
        while (auto stat = itr->Next())
        {
            if (!stat->bExistsDirectory)
            {
                continue;
            }

            if (!AuTryInsert(dirs, stat->fileName))
            {
                return false;
            }
        }

        return true;
    }

    AUKN_SYM bool WriteFile(const AuString &path, const Memory::MemoryViewRead &blob)
    {
        bool status;
        size_t offset;
        HANDLE fileHandle;
        std::wstring win32Path;
        AuString pathNormalized;
        AuUInt length;
        
        status         = false;
        pathNormalized = NormalizePathRet(path);

        if (pathNormalized.empty())
        {
            return false;
        }

        win32Path = Locale::ConvertFromUTF8(pathNormalized);

        if (win32Path.empty())
        {
            return false;
        }

        CreateDirectories(pathNormalized, true);
        
        fileHandle = CreateFileW(win32Path.c_str(), GENERIC_WRITE, NULL, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
        if (fileHandle == INVALID_HANDLE_VALUE)
        {
            SysPushErrorIO("Couldn't open handle: {}", path);
            return false;
        }

        length = blob.length;
        offset = 0;
        while (length)
        {  
            DWORD written;

            int blockSize = AuMin(static_cast<AuUInt64>(kFileCopyBlock), static_cast<AuUInt64>(length));

            if (!::WriteFile(fileHandle, &reinterpret_cast<const char *>(blob.ptr)[offset], blockSize, &written, NULL))
            {
                SysPushErrorIO();
                goto out;
            }
            
            if (!written)
            {
                SysPushErrorIO();
                goto out;
            }

            offset += written;
            length -= written;
        }
        
        status = true;

    out:
        AuWin32CloseHandle(fileHandle);
        return status;
    }

    AUKN_SYM bool ReadFile(const AuString &path, AuByteBuffer &buffer)
    {
        std::wstring win32Path;
        LARGE_INTEGER length;
        bool status;
        AuMemoryViewWrite writeView;
        size_t offset;
        
        status    = false;
        offset    = 0;
        win32Path = Locale::ConvertFromUTF8(NormalizePathRet(path));

        if (win32Path.empty())
        {
            return false;
        }

        auto fileHandle = CreateFileW(win32Path.c_str(), GENERIC_READ, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
        if (fileHandle == INVALID_HANDLE_VALUE)
        {
            SysPushErrorIO("Couldn't open handle: {}", path);
            return false;
        }

        if (!GetFileSizeEx(fileHandle, &length))
        {
            SysPushErrorIO();
            goto out;
        }

        writeView = buffer.GetOrAllocateLinearWriteable(length.QuadPart);
        if (!writeView)
        {
            SysPushErrorMem();
            goto out;
        }

        while (length.QuadPart)
        {
            DWORD read;

            int blockSize = AuMin(static_cast<AuUInt64>(kFileCopyBlock), static_cast<AuUInt64>(length.QuadPart));

            if (!::ReadFile(fileHandle, buffer.writePtr, blockSize, &read, NULL))
            {
                AuLogWarn("ReadFile IO Error: 0x{:x} {}", GetLastError(), path);
                SysPushErrorIO();
                goto out;
            }

            buffer.writePtr += read;
            offset += read;
            length.QuadPart -= read;
        }
        
        status = true;

    out:
        AuWin32CloseHandle(fileHandle);
        return status;
    }

    AUKN_SYM bool FileExists(const AuString &path)
    {
        try
        {
            DWORD dwAttrib = GetFileAttributesW(Locale::ConvertFromUTF8(NormalizePathRet(path)).c_str());
            return ((dwAttrib != INVALID_FILE_ATTRIBUTES) &&
                   !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
        }
        catch (...)
        {
            return false;
        }
    }

    AUKN_SYM bool DirExists(const AuString &path)
    {
        try
        {
            DWORD dwAttrib = GetFileAttributesW(Locale::ConvertFromUTF8(NormalizePathRet(path)).c_str());
            return ((dwAttrib != INVALID_FILE_ATTRIBUTES) &&
                    (dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
        }
        catch (...)
        {
            return false;
        }
    }
    
    AUKN_SYM bool DirMk(const AuString &path)
    {
        try
        {
            return CreateDirectories(NormalizePathRet(path), false);
        }
        catch (...)
        {
            return false;
        }
    }

    AUKN_SYM bool Remove(const AuString &path)
    {
        try
        {
            auto translatedPath = Locale::ConvertFromUTF8(NormalizePathRet(path));
            if (::DeleteFileW(translatedPath.c_str()))
            {
                return true;
            }

            if (::RemoveDirectoryW(translatedPath.c_str()))
            {
                return true;
            }

            return false;
        }
        catch (...)
        {
            return false;
        }
    }

    AUKN_SYM bool Relink(const AuString &src, const AuString &dest)
    {
        try
        {
            auto srcPathNormalized  = NormalizePathRet(src);
            auto destPathNormalized = NormalizePathRet(dest);
            CreateDirectories(destPathNormalized, true);

            return MoveFileW(Locale::ConvertFromUTF8(srcPathNormalized).c_str(),
                             Locale::ConvertFromUTF8(destPathNormalized).c_str());
        }
        catch (...)
        {
            return false;
        }
    }

    AUKN_SYM bool Copy(const AuString &src, const AuString &dest)
    {
        try
        {
            auto srcPathNormalized  = NormalizePathRet(src);
            auto destPathNormalized = NormalizePathRet(dest);
            CreateDirectories(destPathNormalized, true);

            return CopyFileW(Locale::ConvertFromUTF8(srcPathNormalized).c_str(),
                             Locale::ConvertFromUTF8(destPathNormalized).c_str(), true);
        }
        catch (...)
        {
            return false;
        }
    }

    AUKN_SYM bool StatFile(const AuString &path, Stat &stat)
    {
        WIN32_FILE_ATTRIBUTE_DATA data;

        stat = {};

        if (!GetFileAttributesExW(Locale::ConvertFromUTF8(NormalizePathRet(path)).c_str(), GetFileExInfoStandard, &data))
        {
            stat.bExists = false;
            return false;
        }

        stat.bExists = true;
        stat.bExistsDirectory = data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
        stat.bExistsFile      = !stat.bExistsDirectory;
        stat.bSymLink         = data.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT;

        stat.uSize            = AuUInt64(data.nFileSizeLow) | (AuUInt64(data.nFileSizeHigh) << 32);
                              
        stat.created          = Time::ConvertTimestamp(data.ftCreationTime);
        stat.modified         = Time::ConvertTimestamp(data.ftLastWriteTime);
        stat.accessed         = Time::ConvertTimestamp(data.ftLastAccessTime);
        return true;
    }
}
#endif