## Amazon SimpleDB library
## Author: Michal Ludvig <michal@logix.cz>
##         http://www.logix.cz/michal
## License: GPL Version 2

"""
Low-level class for working with Amazon SimpleDB
"""

import time
import urllib
import base64
import hmac
import sha
import httplib
from logging import debug, info, warning, error

from Utils import convertTupleListToDict
from SortedDict import SortedDict
from Exceptions import *

class SimpleDB(object):
	# API Version
	# See http://docs.amazonwebservices.com/AmazonSimpleDB/2007-11-07/DeveloperGuide/
	Version = "2007-11-07"
	SignatureVersion = 1

	def __init__(self, config):
		self.config = config

	## ------------------------------------------------
	## Methods implementing SimpleDB API
	## ------------------------------------------------

	def ListDomains(self, MaxNumberOfDomains = 100):
		'''
		Lists all domains associated with our Access Key. Returns 
		domain names up to the limit set by MaxNumberOfDomains.
		'''
		parameters = SortedDict()
		parameters['MaxNumberOfDomains'] = MaxNumberOfDomains
		return self.send_request("ListDomains", DomainName = None, parameters = parameters)

	def CreateDomain(self, DomainName):
		return self.send_request("CreateDomain", DomainName = DomainName)

	def DeleteDomain(self, DomainName):
		return self.send_request("DeleteDomain", DomainName = DomainName)

	def PutAttributes(self, DomainName, ItemName, Attributes):
		parameters = SortedDict()
		parameters['ItemName'] = ItemName
		seq = 0
		for attrib in Attributes:
			if type(Attributes[attrib]) == type(list()):
				for value in Attributes[attrib]:
					parameters['Attribute.%d.Name' % seq] = attrib
					parameters['Attribute.%d.Value' % seq] = unicode(value)
					seq += 1
			else:
				parameters['Attribute.%d.Name' % seq] = attrib
				parameters['Attribute.%d.Value' % seq] = unicode(Attributes[attrib])
				seq += 1
		## TODO:
		## - support for Attribute.N.Replace
		## - support for multiple values for one attribute
		return self.send_request("PutAttributes", DomainName = DomainName, parameters = parameters)

	def GetAttributes(self, DomainName, ItemName, Attributes = []):
		parameters = SortedDict()
		parameters['ItemName'] = ItemName
		seq = 0
		for attrib in Attributes:
			parameters['AttributeName.%d' % seq] = attrib
			seq += 1
		return self.send_request("GetAttributes", DomainName = DomainName, parameters = parameters)

	def DeleteAttributes(self, DomainName, ItemName, Attributes = {}):
		"""
		Remove specified Attributes from ItemName.
		Attributes parameter can be either:
		- not specified, in which case the whole Item is removed
		- list, e.g. ['Attr1', 'Attr2'] in which case these parameters are removed
		- dict, e.g. {'Attr' : 'One', 'Attr' : 'Two'} in which case the 
		  specified values are removed from multi-value attributes.
		"""
		parameters = SortedDict()
		parameters['ItemName'] = ItemName
		seq = 0
		for attrib in Attributes:
			parameters['Attribute.%d.Name' % seq] = attrib
			if type(Attributes) == type(dict()):
				parameters['Attribute.%d.Value' % seq] = unicode(Attributes[attrib])
			seq += 1
		return self.send_request("DeleteAttributes", DomainName = DomainName, parameters = parameters)

	def Query(self, DomainName, QueryExpression = None, MaxNumberOfItems = None, NextToken = None):
		parameters = SortedDict()
		if QueryExpression:
			parameters['QueryExpression'] = QueryExpression
		if MaxNumberOfItems:
			parameters['MaxNumberOfItems'] = MaxNumberOfItems
		if NextToken:
			parameters['NextToken'] = NextToken
		return self.send_request("Query", DomainName = DomainName, parameters = parameters)
		## Handle NextToken? Or maybe not - let the upper level do it

	## ------------------------------------------------
	## Low-level methods for handling SimpleDB requests
	## ------------------------------------------------

	def send_request(self, *args, **kwargs):
		request = self.create_request(*args, **kwargs)
		#debug("Request: %s" % repr(request))
		conn = self.get_connection()
		conn.request("GET", self.format_uri(request['uri_params']))
		http_response = conn.getresponse()
		response = {}
		response["status"] = http_response.status
		response["reason"] = http_response.reason
		response["headers"] = convertTupleListToDict(http_response.getheaders())
		response["data"] =  http_response.read()
		conn.close()

		if response["status"] < 200 or response["status"] > 299:
			debug("Response: " + str(response))
			raise S3Error(response)

		return response

	def create_request(self, Action, DomainName, parameters = None):
		if not parameters:
			parameters = SortedDict()
		parameters['AWSAccessKeyId'] = self.config.access_key
		parameters['Version'] = self.Version
		parameters['SignatureVersion'] = self.SignatureVersion
		parameters['Action'] = Action
		parameters['Timestamp'] = time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime())
		if DomainName:
			parameters['DomainName'] = DomainName
		parameters['Signature'] = self.sign_request(parameters)
		parameters.keys_return_lowercase = False
		uri_params = urllib.urlencode(parameters)
		request = {}
		request['uri_params'] = uri_params
		request['parameters'] = parameters
		return request

	def sign_request(self, parameters):
		h = ""
		parameters.keys_sort_lowercase = True
		parameters.keys_return_lowercase = False
		for key in parameters:
			h += "%s%s" % (key, parameters[key])
		#debug("SignRequest: %s" % h)
		return base64.encodestring(hmac.new(self.config.secret_key, h, sha).digest()).strip()

	def get_connection(self):
		if self.config.proxy_host != "":
			return httplib.HTTPConnection(self.config.proxy_host, self.config.proxy_port)
		else:
			if self.config.use_https:
				return httplib.HTTPSConnection(self.config.simpledb_host)
			else:
				return httplib.HTTPConnection(self.config.simpledb_host)

	def format_uri(self, uri_params):
		if self.config.proxy_host != "":
			uri = "http://%s/?%s" % (self.config.simpledb_host, uri_params)
		else:
			uri = "/?%s" % uri_params
		#debug('format_uri(): ' + uri)
		return uri
