## Amazon S3 - Access Control List representation
 ## Author: Michal Ludvig <michal@logix.cz>
 ##         http://www.logix.cz/michal
 ## License: GPL Version 2
 
 import S3Uri
 from Exceptions import ParameterError
 from Utils import getTreeFromXml
 from ACL import GranteeAnonRead
 
 try:
 	import xml.etree.ElementTree as ET
 except ImportError:
 	import elementtree.ElementTree as ET
 
 __all__ = []
 class AccessLog(object):
 	LOG_DISABLED = "<BucketLoggingStatus></BucketLoggingStatus>"
 	LOG_TEMPLATE = "<LoggingEnabled><TargetBucket></TargetBucket><TargetPrefix></TargetPrefix></LoggingEnabled>"
 
 	def __init__(self, xml = None):
 		if not xml:
 			xml = self.LOG_DISABLED
 		self.tree = getTreeFromXml(xml)
 		self.tree.attrib['xmlns'] = "http://doc.s3.amazonaws.com/2006-03-01"
 	
 	def isLoggingEnabled(self):
 		return bool(self.tree.find(".//LoggingEnabled"))
 
 	def disableLogging(self):
 		el = self.tree.find(".//LoggingEnabled")
 		if el:
 			self.tree.remove(el)
 	
 	def enableLogging(self, target_prefix_uri):
 		el = self.tree.find(".//LoggingEnabled")
 		if not el:
 			el = getTreeFromXml(self.LOG_TEMPLATE)
 			self.tree.append(el)
 		el.find(".//TargetBucket").text = target_prefix_uri.bucket()
 		el.find(".//TargetPrefix").text = target_prefix_uri.object()
 
 	def targetPrefix(self):
 		if self.isLoggingEnabled():
 			el = self.tree.find(".//LoggingEnabled")
 			target_prefix = "s3://%s/%s" % (
 				self.tree.find(".//LoggingEnabled//TargetBucket").text, 
 				self.tree.find(".//LoggingEnabled//TargetPrefix").text)
 			return S3Uri.S3Uri(target_prefix)
 		else:
 			return ""
 
 	def setAclPublic(self, acl_public):
 		le = self.tree.find(".//LoggingEnabled")
 		if not le:
 			raise ParameterError("Logging not enabled, can't set default ACL for logs")
 		tg = le.find(".//TargetGrants")
 		if not acl_public:
 			if not tg:
 				## All good, it's not been there
 				return
 			else:
 				le.remove(tg)
 		else: # acl_public == True
 			anon_read = GranteeAnonRead().getElement()
 			if not tg:
 				tg = ET.SubElement(le, "TargetGrants")
 			## What if TargetGrants already exists? We should check if 
 			## AnonRead is there before appending a new one. Later...
 			tg.append(anon_read)
 
 	def isAclPublic(self):
 		raise NotImplementedError()
 
 	def __str__(self):
 		return ET.tostring(self.tree)
 __all__.append("AccessLog")
 
 if __name__ == "__main__":
 	from S3Uri import S3Uri
 	log = AccessLog()
 	print log
 	log.enableLogging(S3Uri("s3://targetbucket/prefix/log-"))
 	print log
 	log.setAclPublic(True)
 	print log
 	log.setAclPublic(False)
 	print log
 	log.disableLogging()
 	print log