DirectoryMonitor.h
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	#ifndef ECHO_UTIL_DIRECTORY_MONITOR_H
	#define ECHO_UTIL_DIRECTORY_MONITOR_H

	#include <map>
	#include <efsw/efsw.hpp>
	#include <echo/cpp/functional>
	#include <boost/filesystem.hpp>

	namespace Echo
	{
	/**
	* A class to use efsw file watcher using callbacks.
	* @note You need to link libefsw with your project if you use this class as we do not include
	* it in Echo's build settings. This may change in the future.
	* @note This class is header only since it is not portable if the target platform does not
	* have an implementation (i.e. there would be no library to link against).
	*/
	class DirectoryMonitor : public efsw::FileWatchListener
	{
	public:
	typedef function<void(std::string, std::string)> DirectoryModifiedCallback;
	typedef function<void(std::string, std::string, std::string)> FileMovedCallback;

	DirectoryMonitor() : mIsWatching(false)
	{
	}

	~DirectoryMonitor()
	{
	for(auto it : mDirectoryWatches)
	{
	mFileWatcher.removeWatch(it.second);
	}
	for(auto it : mRecursiveDirectoryWatches)
	{
	mFileWatcher.removeWatch(it.second);
	}
	}

	void RegisterFileModifiedCallback(std::string filenameOrDirectory, DirectoryModifiedCallback callback)
	{
	mModifiedCallbacks[filenameOrDirectory] = callback;
	UpdateWatch(filenameOrDirectory, false);
	}

	void RegisterFileAddedCallback(std::string filenameOrDirectory, DirectoryModifiedCallback callback)
	{
	mAddedCallbacks[filenameOrDirectory] = callback;
	UpdateWatch(filenameOrDirectory, false);
	}

	void RegisterFileDeletedCallback(std::string filenameOrDirectory, DirectoryModifiedCallback callback)
	{
	mDeletedCallbacks[filenameOrDirectory] = callback;
	UpdateWatch(filenameOrDirectory, false);
	}

	void RegisterMovedCallback(std::string filenameOrDirectory, FileMovedCallback callback)
	{
	mMovedCallbacks[filenameOrDirectory] = callback;
	UpdateWatch(filenameOrDirectory, false);
	}

	void handleFileAction( efsw::WatchID watchid, const std::string& dir, const std::string& filename, efsw::Action action, std::string oldFilename = "" )
	{
	switch( action )
	{
	case efsw::Actions::Add:
	ProcessCallbacks(dir, filename, mAddedCallbacks);
	break;
	case efsw::Actions::Delete:
	ProcessCallbacks(dir, filename, mDeletedCallbacks);
	break;
	case efsw::Actions::Modified:
	ProcessCallbacks(dir, filename, mModifiedCallbacks);
	break;
	case efsw::Actions::Moved:
	ProcessCallbacks(dir, oldFilename, filename, mMovedCallbacks);
	break;
	default:
	std::cout << "Should never happen!" << std::endl;
	}
	}
	private:
	typedef std::map< std::string, DirectoryModifiedCallback > CallbackMap;
	typedef std::map< std::string, FileMovedCallback > FileMovedCallbackMap;
	void ProcessCallbacks(std::string directory, std::string filename, CallbackMap& callbackMap)
	{
	bool fileNameFound = false;
	auto it = callbackMap.find(filename);
	if(it!=callbackMap.end())
	{
	it->second(directory, filename);
	fileNameFound = true;
	}

	it = callbackMap.find(directory+filename);
	if(it!=callbackMap.end())
	{
	it->second(directory, filename);
	fileNameFound = true;
	}

	// It could be a funky name like filename.x12345, where the extra extension includes the
	// PID. I saw this behaviour on Linux and it seems to be coming directly from the system
	// not from efsw. I did not find any documentation on this naming behaviour.
	if(!fileNameFound)
	{
	size_t lastPeriod = filename.find_last_of(".");
	if(lastPeriod!=std::string::npos)
	{
	filename = filename.substr(0,lastPeriod);
	it = callbackMap.find(filename);
	if(it!=callbackMap.end())
	{
	it->second(directory, filename);
	}

	it = callbackMap.find(directory+filename);
	if(it!=callbackMap.end())
	{
	it->second(directory, filename);
	}
	}
	}
	}

	void ProcessCallbacks(std::string directory, std::string oldFilename, std::string newFilename, FileMovedCallbackMap& callbackMap)
	{
	auto it = callbackMap.find(oldFilename);
	if(it!=callbackMap.end())
	{
	it->second(directory, oldFilename, newFilename);
	}

	it = callbackMap.find(directory+oldFilename);
	if(it!=callbackMap.end())
	{
	it->second(directory, oldFilename, newFilename);
	}
	}

	void UpdateWatch(std::string filename, bool recursive)
	{
	// See if we need to create a watch for this filename since we can only monitor
	// directories we need to figure out the directory first.

	using boost::filesystem::path;
	path filepath(filename);

	if(!filepath.is_absolute())
	{
	filepath = boost::filesystem::current_path() / filepath;
	}
	boost::system::error_code ec;
	std::string directory;
	if(boost::filesystem::is_directory(filepath, ec))
	{
	directory = filepath.string();
	}else
	{
	directory = filepath.parent_path().string();
	}
	if(recursive)
	{
	if(mRecursiveDirectoryWatches.find(directory)==mRecursiveDirectoryWatches.end())
	{
	mRecursiveDirectoryWatches[directory] = mFileWatcher.addWatch(directory,this,true);
	}
	}else
	{
	if(mDirectoryWatches.find(directory)==mDirectoryWatches.end())
	{
	mDirectoryWatches[directory] = mFileWatcher.addWatch(directory,this,false);
	}
	}
	if(!mIsWatching)
	{
	mIsWatching = true;
	mFileWatcher.watch();
	}
	}
	CallbackMap mModifiedCallbacks;
	CallbackMap mAddedCallbacks;
	CallbackMap mDeletedCallbacks;
	FileMovedCallbackMap mMovedCallbacks;
	std::map< std::string, efsw::WatchID > mDirectoryWatches;
	std::map< std::string, efsw::WatchID > mRecursiveDirectoryWatches;
	efsw::FileWatcher mFileWatcher;
	bool mIsWatching;
	};
	}

	#endif

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