import tarfile, StringIO, re, json, os

class dirfs(object):
	"""
	author:Martin Robinson
	mail:nornibor.nitram@gmail.com
	minimal use case of directory as storage
	will list, open and add file
	"""
	def __init__(self, dirname):
		self.dirname = dirname

	def ls(self):
		"""
		will list file available
		"""
		for name in os.listdir(self.dirname):
			if os.path.isfile(os.path.join(self.dirname, name)):
				yield name

	def open(self,name):
		"""
		will try to open a file inside tar file and return content as string
		"""
		with open(name) as file:
			return file.read()

	def add(self,name,data):
		"""
		will try to add a file in the tar file
		"""
		with open(name,'wb') as file:
			file.write(data)

class targzfs(object):
	"""
	author:Martin Robinson
	mail:nornibor.nitram@gmail.com
	minimal use case of tar file as storage
	will list, open and add file
	"""
	def __init__(self, filename):
		self.compression = 'gz'
		self.readmode = 'r'+self.compression
		self.writemode = 'w'+self.compression
		tarfile.open(self.filename, self.writemode).close()

	def ls(self):
		"""
		will list file available
		"""
		with tarfile.open(self.filename, self.readmode) as tar:
			for name in tar.getnames():
				yield name

	def open(self,name):
		"""
		will try to open a file inside tar file and return content as string
		"""
		with tarfile.open(self.filename, self.readmode) as tar:
			return tar.extractfile(name).read()

	def add(self,name,data):
		"""
		will try to add a file in the tar file
		"""
		try:
			with tarfile.open(self.filename, self.writemode) as tar:
				info = tarfile.TarInfo(name)
				info.size = len(data)
				tar.addfile(info,StringIO.StringIO(data))
				return True
		except IOError:
			return False

class jsonForFs(object):
	"""
	author:Martin Robinson
	mail:nornibor.nitram@gmail.com
	forwarding decorator
	will encode or decode every object in tar file as json
	"""
	def __init__(self,fs=dirfs(os.getcwd())):
		self.fs = fs

	def ls(self):
		"""
		list files
		"""
		return self.fs.ls()

	def open(self,name):
		"""
		open and decode json file
		"""
		if not re.match('^.+\.json$',name):
			name += '.json'
		return json.JSONDecoder().decode(self.fs.open(name))

	def add(self,name,data):
		"""
		encode and add json file
		"""
		if not re.match('^.+\.json$',name):
			name += '.json'
		return self.fs.add(name, json.JSONEncoder().encode(data))

if __name__ == '__main__':
	test = dirfs(os.getcwd())
	print 'first'
	for name in test.ls():
		print name
	test.add('hello',str(['hello','world']))
	print 'then'
	for name in test.ls():
		if name=='hello':
			print name
			print test.open(name)