## 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
