// (C) Copyright Gert-Jan de Vos and Jan Wilmans 2013.

// Distributed under the Boost Software License, Version 1.0.

// (See accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

#include <cassert>

#include <filesystem>

#include "CobaltFusion/stringbuilder.h"

#include "Win32/Win32Lib.h"

#include "DebugViewppLib/FileIO.h"

#include "DebugViewppLib/FileReader.h"

#include "DebugViewppLib/LineBuffer.h"

#include "DebugViewppLib/Line.h"

namespace fusion {

namespace debugviewpp {

namespace fs = std::filesystem;

FileReader::FileReader(Timer& timer, ILineBuffer& linebuffer, FileType::type filetype, const std::wstring& filename, bool keeptailing) :

LogSource(timer, SourceType::File, linebuffer),

m_filename(Str(filename).str()),

m_name(Str(fs::path(filename).filename().string()).str()),

m_fileType(filetype),

m_handle(FindFirstChangeNotification(fs::path(m_filename).parent_path().wstring().c_str(), 0, FILE_NOTIFY_CHANGE_SIZE)), //todo: maybe adding FILE_NOTIFY_CHANGE_LAST_WRITE could have benefits, not sure what though.

m_ifstream(m_filename, std::ios::in),

m_filenameOnly(std::filesystem::path(m_filename).filename().string()),

m_initialized(false),

m_keeptailing(keeptailing),

m_thread([this] { PollThread(); })

{

SetDescription(filename);

}

FileReader::~FileReader() = default;

void FileReader::Abort()

{

LogSource::Abort();

if (m_thread.joinable())

{

m_thread.join();

}

}

bool FileReader::GetAutoNewLine() const

{

return true;

}

void FileReader::PollThread()

{

// FILE_NOTIFY_CHANGE_SIZE is broken on windows vista and above in that it does not

// trigger this notification until a) a cache timeout of N? (unspecified on MSDN, but > 30 seconds) or b) someone queries the status of the file

// both are not useful when tailing a file.

// references:

// https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-writefile

// https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-findfirstchangenotificationa

// MSDN: 'For operating systems that use extensive caching, detection occurs only when the cache is sufficiently flushed.'

// affect: timestamps for lines read from logfiles have > 500ms accuracy and unittests are slow.

uintmax_t filesize = fs::file_size(fs::path(m_filename));

ReadUntilEof();

while (!AtEnd())

{

if (Win32::WaitForSingleObject(m_handle.get(), 500))

{

// we got a FILE_NOTIFY_CHANGE_SIZE event

ReadUntilEof();

FindNextChangeNotification(m_handle.get());

}

else

{

// timeout occurred, poll the filesize

uintmax_t newFilesize = fs::file_size(fs::path(m_filename));

if (filesize != newFilesize)

{

filesize = newFilesize;

ReadUntilEof();

}

}

}

}

void FileReader::Initialize()

{

//if (m_initialized)

// return;

//m_initialized = true;

//if (m_ifstream.is_open())

//{

// ReadUntilEof();

//}

}

boost::signals2::connection FileReader::SubscribeToUpdate(UpdateSignal::slot_type slot)

{

return m_update.connect(slot);

}

HANDLE FileReader::GetHandle() const

{

return INVALID_HANDLE_VALUE; // m_handle.get();

}

void FileReader::Notify()

{

//assert(m_handle);

//ReadUntilEof();

//if (!m_keeptailing)

//{

// Abort();

// return;

//}

//FindNextChangeNotification(m_handle.get());

}

void FileReader::ReadUntilEof()

{

std::string line;

int count = 0;

while (std::getline(m_ifstream, line))

{

m_line += line;

if ((++count % 5000) == 0)

{

m_update();

}

if (m_ifstream.eof())

{

// the line ended without a newline character

}

else

{

SafeAddLine(m_line);

m_line.clear();

}

}

m_update();

if (m_ifstream.eof())

{

m_ifstream.clear(); // clear EOF condition

// resync to end of file, even if the file shrunk

auto lastReadPosition = m_ifstream.tellg();

m_ifstream.seekg(0, std::ifstream::end);

auto length = m_ifstream.tellg();

if (length > lastReadPosition)

{

m_ifstream.seekg(lastReadPosition);

}

else if (length != lastReadPosition)

{

m_line.clear();

Add(stringbuilder() << "file shrank, resynced at offset " << length);

}

}

else

{

// Some error other then EOF occured

Add("Stopped tailing " + m_filename);

LogSource::Abort();

}

m_update();

}

void FileReader::SafeAddLine(const std::string& line)

{

try

{

AddLine(line);

}

catch (std::exception& e)

{

Add(stringbuilder() << "Error parsing line: " << e.what());

}

}

void FileReader::AddLine(const std::string& line)

{

// AnyFileReader and BinaryFileReader override this method

Add(line);

}

void FileReader::PreProcess(Line& line) const

{

line.processName = m_filenameOnly;

}

} // namespace debugviewpp

} // namespace fusion