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

    File: FileStream.Win32.cpp
    Date: 2021-6-12
    Author: Reece
***/
#include <RuntimeInternal.hpp>
#include "FS.hpp"
#include "FileStream.Win32.hpp"

#if !defined(_AURUNTIME_GENERICFILESTREAM)

namespace Aurora::IO::FS
{
    static const AuUInt64 kFileCopyBlock = 0x4000; // 16KiB

    WinFileStream::~WinFileStream()
    {
        Close();
    }

    void WinFileStream::Init(HANDLE handle)
    {
        handle_ = handle;
    }
    
    AuUInt64 WinFileStream::GetOffset()
    {
        LARGE_INTEGER distance {};
        LARGE_INTEGER pos {};

        if (handle_ == INVALID_HANDLE_VALUE)
        {
            SysPushErrorUninitialized();
            return 0;
        }

        if (SetFilePointerEx(handle_, distance, &pos, FILE_CURRENT) == INVALID_SET_FILE_POINTER)
        {
            LogWarn("SetFilePointerEx IO Error: 0x%x", GetLastError());
            SysPushErrorIO();
            return 0;
        }

        return pos.QuadPart;
    }

    bool WinFileStream::SetOffset(AuUInt64 offset)
    {
        LARGE_INTEGER distance {};
        LARGE_INTEGER pos {};

        if (handle_ == INVALID_HANDLE_VALUE)
        {
            SysPushErrorUninitialized();
            return false;
        }

        distance.QuadPart = offset;

        if (SetFilePointerEx(handle_, distance, &pos, FILE_CURRENT) == INVALID_SET_FILE_POINTER)
        {
            LogWarn("SetFilePointerEx IO Error: 0x%x", GetLastError());
            SysPushErrorIO();
            return false;
        }

        return true;
    }

    AuUInt64 WinFileStream::GetLength()
    {
        LARGE_INTEGER length;

        if (!GetFileSizeEx(handle_, &length))
        {
            SysPushErrorIO();
            return 0;
        }

        return length.QuadPart;
    }

    AuUInt64 WinFileStream::Read(void *in, AuUInt64 length)
    {
        if (handle_ == INVALID_HANDLE_VALUE)
        {
            SysPushErrorUninitialized();
            return 0;
        }

        AuUInt64 offset {0};
        while (length)
        {
            DWORD read;

            int blockSize = std::min(kFileCopyBlock, length);

            if (!::ReadFile(handle_, &reinterpret_cast<char *>(in)[offset], blockSize, &read, NULL))
            {
                LogWarn("ReadFile IO Error: 0x%x", GetLastError());
                SysPushErrorIO();
                goto out;
            }
            
        #if 0
            if (read != blockSize)
            {
                goto out;
            }
        #endif

            offset += read;
            length -= read;
        }
        
    out:
        if (handle_ != INVALID_HANDLE_VALUE) CloseHandle(handle_);
        return offset;
    }
    
    AuUInt64 WinFileStream::Write(const void *out, AuUInt64 length)
    {
        if (handle_ == INVALID_HANDLE_VALUE)
        {
            SysPushErrorUninitialized();
            return 0;
        }

        AuUInt64 offset {0};
        while (length)
        {
            DWORD written;

            int blockSize = std::min(kFileCopyBlock, length);

            if (!::WriteFile(handle_, &reinterpret_cast<const char *>(out)[offset], blockSize, &written, NULL))
            {
                LogWarn("WriteFileEx IO Error: 0x%x", GetLastError());
                SysPushErrorIO();
                return offset;
            }

            if (written != blockSize)
            {
                SysPushErrorIO();
                return offset;
            }

            offset += written;
            length -= written;
        }
        
        return offset;
    }

    void WinFileStream::Close()
    {
        HANDLE handle;

        if ((handle = std::exchange(handle_, INVALID_HANDLE_VALUE)) != INVALID_HANDLE_VALUE)
        {
            CloseHandle(handle);
        }
    }

    void WinFileStream::Flush()
    {
        FlushFileBuffers(handle_);
    }
    
    static IFileStream *OpenNew(const AuString &path, bool read)
    {
        auto pathex = NormalizePathRet(path);
        auto win32Path = Locale::ConvertFromUTF8(pathex);

        HANDLE fileHandle;
        if (read)
        {
            fileHandle = CreateFileW(win32Path.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
        }
        else
        {
            CreateDirectories(pathex, true);
            fileHandle = CreateFileW(win32Path.c_str(), GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
        }

        if (fileHandle == INVALID_HANDLE_VALUE)
        {
            LogWarn("Missing file: {}", path);
            SysPushErrorIO("Missing file: {}", path);
            return nullptr;
        }

        auto stream = _new WinFileStream();
        if (!stream)
        {
            CloseHandle(fileHandle);
            return nullptr;
        }

        stream->Init(fileHandle);
        return stream;
    }

    AUKN_SYM IFileStream *OpenReadNew(const AuString &path)
    {
        return OpenNew(path, true);
    }

    AUKN_SYM void OpenReadRelease(IFileStream * that)
    {
        SafeDelete<WinFileStream *>(that);
    }

    AUKN_SYM IFileStream *OpenWriteNew(const AuString &path)
    {
        return OpenNew(path, false);
    }
    
    AUKN_SYM void OpenWriteRelease(IFileStream * that)
    {
        SafeDelete<WinFileStream *>(that);
    }
}

#endif