'''
manages logging events of the CryptoBox
'''
import sys
import os
import unittest

class CryptoBoxLogger:
	'''
	handles logging events and prints them e.g. to a logfile
	'''

	DebugLevels	= {"debug":0, "info":3, "warn":6, "error":9}
	DebugFacilities	= {"file":0}

	def __init__(self, level, facility, destination=None):
		"""create a CryptoBoxLogger object and connect it to an output facility

		level:		an integer (0..9) or string ('debug', 'info', 'warn' or 'error')
		facility:	for now only 'file'
		destination:	e.g. the name of the logfile or syslog facility

		"""
		try:
			try:
				facility = int(facility)
			except Exception:
				try:
					facility = self.DebugFacilities[facility]
				except KeyError:
					raise "LoggerError"
			if (facility != 0): raise "LoggerError"
		except "LoggerError":
			errorMsg = "Invalid debug facility: %s" % facility
			sys.stderr.write(errorMsg + "\n")
			raise "LoggerError", errorMsg
		try:
			try:
				level = int(level)
			except Exception:
				try:
					level = self.DebugLevels[level]
				except KeyError:
					raise "LoggerError"
			if (level < 0) or (level > 9): raise "LoggerError"
		except "LoggerError":
			errorMsg = "Invalid debug level: %s" % level
			sys.stderr.write(errorMsg + "\n")
			raise "LoggerError", errorMsg
		self.debug_level = level
		if facility == self.DebugFacilities["file"]:
			self.logFunc = self.message2file
			if destination is not None:
				self.logFile = destination
			else:
				self.logFile = '/var/log/cryptobox.log'
			try:
				fsock = open(self.logFile, "a")
				fsock.close()
			except IOError:
				errorMsg ="Unable to open logfile (%s) for writing." % (self.logFile,)
				sys.stderr.write(errorMsg + "\n")
				raise "LoggerError", errorMsg

		else:
			errorMsg = "Invalid logging facility: %d." % (facility, )
			sys.stderr.write(errorMsg + "\n")
			raise "LoggerError", errorMsg


	def printMessage(self, msg_level, text):
		if msg_level is None:	msg_level = self.DebugLevels["debug"]
		"convert debuglevel from string to int, if necessary"
		try:
			msg_level = int(msg_level)
		except ValueError:
			try:
				msg_level = self.DebugLevels[msg_level]
			except KeyError:
				errorMsg = "Invalid debug level: %s" % msg_level
				sys.stderr.write(errorMsg + "\n")
				raise "LoggerError", errorMsg
		if (msg_level < 0) or (msg_level > 9):
			errorMsg = "Invalid debug level: %s" % msg_level
			sys.stderr.write(errorMsg + "\n")
			raise "LoggerError", errorMsg
		if text is None:
			errorMsg = "Empty debug message - this is not allowed"
			sys.stderr.write(errorMsg + "\n")
			raise "LoggerError", errorMsg
		if msg_level >= self.debug_level:
			self.logFunc("[CryptoBox] - %s\n" % (text, ))
	

	def message2file(self, text):
		try:
			log_sock = open(self.logFile, "a")
			try:
				log_sock.writelines(text)
				log_sock.close()
				return
			except IOError:
				errorMsg = "Unable to write messages to logfile (%s)." % (self.logFile, )
				sys.stderr.write(errorMsg + "\n")
				raise "LoggerError", errorMsg
		except IOError:
			errorMsg = "Unable to open logfile (%s) for writing." % (self.logFile, )
			sys.stderr.write(errorMsg + "\n")
			raise "LoggerError", errorMsg


# ********************* test class **********************

class CryptoBoxLoggerTest(unittest.TestCase):

	logFile = "/tmp/cbox-test.log"

	def setUp(self):
		if os.path.exists(self.logFile): os.remove(self.logFile)

	def tearDown(self):
		if os.path.exists(self.logFile): os.remove(self.logFile)

	def testInit(self):
		try:
			CryptoBoxLogger(0, 0)
		except "LoggerError":
			CryptoBoxLogger(0, 0, self.logFile)
			os.remove(self.logFile)
		CryptoBoxLogger("info", "file", self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, "invalid", 0, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, 0, "invalid", self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, 10, 0, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, -1, 0, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, 0, 10, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, 0, -1, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, None, 0, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, 0, None, self.logFile)
		self.assertRaises("LoggerError", CryptoBoxLogger, 0, 0, "/no/existing/path")
		os.remove(self.logFile)
		
	def testMessage(self):
		cb = CryptoBoxLogger(3, 0, self.logFile)
		content1 = self.readFile()
		self.assertEquals(content1, "")
		cb.printMessage(3, "Ausgabe")
		content2 = self.readFile()
		self.assertNotEqual(content1, content2)
		self.assertRaises("LoggerError", cb.printMessage, 10, "Ausgabe")
		self.assertEquals(content2, self.readFile())
		self.assertRaises("LoggerError", cb.printMessage, -1, "Ausgabe")
		self.assertEquals(content2, self.readFile())
		self.assertRaises("LoggerError", cb.printMessage, "invalid", "Ausgabe")
		self.assertEquals(content2, self.readFile())
		self.assertRaises("LoggerError", cb.printMessage, 3, None)
		self.assertEquals(content2, self.readFile())
		cb.printMessage(2, "Ausgabe")
		self.assertEquals(content2, self.readFile())
		cb.printMessage(4, "Ausgabe")
		self.assertNotEqual(content2, self.readFile())
		os.remove(self.logFile)

	def readFile(self):
		fd = None
		try:
			fd = open(self.logFile, "r")
			text = fd.read()
			fd.close()
		except IOError:
			if fd is not None: fd.close()
			text = None
		return text


# *************** unit testing *********************

if __name__ == "__main__":
	try:
		devnull = open(os.devnull, "w")
		sys.stderr = devnull
	except IOError:
		pass
	unittest.main()