#!/usr/bin/env python

#  This software code is made available "AS IS" without warranties of any
#  kind.  You may copy, display, modify and redistribute the software
#  code either by itself or as incorporated into your code; provided that
#  you do not remove any proprietary notices.  Your use of this software
#  code is at your own risk and you waive any claim against Amazon
#  Digital Services, Inc. or its affiliates with respect to your use of
#  this software code. (c) 2006-2007 Amazon Digital Services, Inc. or its
#  affiliates.

# modified by davew to use urlfetch.fetch

import base64
import hmac
import httplib
import re
import sha
import sys
import time
import urllib
import urlparse
import xml.sax

from google.appengine.ext import webapp
from google.appengine.api import urlfetch

DEFAULT_HOST = 's3.amazonaws.com'
PORTS_BY_SECURITY = { True: 443, False: 80 }
METADATA_PREFIX = 'x-amz-meta-'
AMAZON_HEADER_PREFIX = 'x-amz-'

# generates the aws canonical string for the given parameters
def canonical_string(method, bucket="", key="", query_args={}, headers={}, expires=None):
    interesting_headers = {}
    for header_key in headers:
        lk = header_key.lower()
        if lk in ['content-md5', 'content-type', 'date'] or lk.startswith(AMAZON_HEADER_PREFIX):
            interesting_headers[lk] = headers[header_key].strip()

    # these keys get empty strings if they don't exist
    if not interesting_headers.has_key('content-type'):
        interesting_headers['content-type'] = ''
    if not interesting_headers.has_key('content-md5'):
        interesting_headers['content-md5'] = ''

    # just in case someone used this.  it's not necessary in this lib.
    if interesting_headers.has_key('x-amz-date'):
        interesting_headers['date'] = ''

    # if you're using expires for query string auth, then it trumps date
    # (and x-amz-date)
    if expires:
        interesting_headers['date'] = str(expires)

    sorted_header_keys = interesting_headers.keys()
    sorted_header_keys.sort()

    buf = "%s\n" % method
    for header_key in sorted_header_keys:
        if header_key.startswith(AMAZON_HEADER_PREFIX):
            buf += "%s:%s\n" % (header_key, interesting_headers[header_key])
        else:
            buf += "%s\n" % interesting_headers[header_key]

    # append the bucket if it exists
    if bucket != "":
        buf += "/%s" % bucket

    # add the key.  even if it doesn't exist, add the slash
    buf += "/%s" % urllib.quote_plus(key)

    # handle special query string arguments

    if query_args.has_key("acl"):
        buf += "?acl"
    elif query_args.has_key("torrent"):
        buf += "?torrent"
    elif query_args.has_key("logging"):
        buf += "?logging"
    elif query_args.has_key("location"):
        buf += "?location"

    return buf

# computes the base64'ed hmac-sha hash of the canonical string and the secret
# access key, optionally urlencoding the result
def encode(aws_secret_access_key, str, urlencode=False):
    b64_hmac = base64.encodestring(hmac.new(aws_secret_access_key, str, sha).digest()).strip()
    if urlencode:
        return urllib.quote_plus(b64_hmac)
    else:
        return b64_hmac

def merge_meta(headers, metadata):
    final_headers = headers.copy()
    for k in metadata.keys():
        final_headers[METADATA_PREFIX + k] = metadata[k]

    return final_headers

# builds the query arg string
def query_args_hash_to_string(query_args):
    query_string = ""
    pairs = []
    for k, v in query_args.items():
        piece = k
        if v != None:
            piece += "=%s" % urllib.quote_plus(str(v))
        pairs.append(piece)

    return '&'.join(pairs)


class CallingFormat:
    PATH = 1
    SUBDOMAIN = 2
    VANITY = 3

    def build_url_base(protocol, server, port, bucket, calling_format):
        url_base = '%s://' % protocol

        if bucket == '':
            url_base += server
        elif calling_format == CallingFormat.SUBDOMAIN:
            url_base += "%s.%s" % (bucket, server)
        elif calling_format == CallingFormat.VANITY:
            url_base += bucket
        else:
            url_base += server

        url_base += ":%s" % port

        if (bucket != '') and (calling_format == CallingFormat.PATH):
            url_base += "/%s" % bucket

        return url_base

    build_url_base = staticmethod(build_url_base)



class Location:
    DEFAULT = None
    EU = 'EU'



class AWSAuthConnection:
    def __init__(self, aws_access_key_id, aws_secret_access_key, is_secure=True,
            server=DEFAULT_HOST, port=None, calling_format=CallingFormat.SUBDOMAIN):

        if not port:
            port = PORTS_BY_SECURITY[is_secure]

        self.aws_access_key_id = aws_access_key_id
        self.aws_secret_access_key = aws_secret_access_key
        self.is_secure = is_secure
        self.server = server
        self.port = port
        self.calling_format = calling_format

    def create_bucket(self, bucket, headers={}):
        return Response(self._make_request('PUT', bucket, '', {}, headers))

    def create_located_bucket(self, bucket, location=Location.DEFAULT, headers={}):
        if location == Location.DEFAULT:
            body = ""
        else:
            body = "<CreateBucketConstraint><LocationConstraint>" + \
                   location + \
                   "</LocationConstraint></CreateBucketConstraint>"
        return Response(self._make_request('PUT', bucket, '', {}, headers, body))

    def check_bucket_exists(self, bucket):
        return self._make_request('HEAD', bucket, '', {}, {})

    def list_bucket(self, bucket, options={}, headers={}):
        return ListBucketResponse(self._make_request('GET', bucket, '', options, headers))

    def delete_bucket(self, bucket, headers={}):
        return Response(self._make_request('DELETE', bucket, '', {}, headers))

    def put(self, bucket, key, object, headers={}):
        if not isinstance(object, S3Object):
            object = S3Object(object)

        return Response(
                self._make_request(
                    'PUT',
                    bucket,
                    key,
                    {},
                    headers,
                    object.data,
                    object.metadata))

    def get(self, bucket, key, headers={}):
        return GetResponse(
                self._make_request('GET', bucket, key, {}, headers))

    def delete(self, bucket, key, headers={}):
        return Response(
                self._make_request('DELETE', bucket, key, {}, headers))

    def get_bucket_logging(self, bucket, headers={}):
        return GetResponse(self._make_request('GET', bucket, '', { 'logging': None }, headers))

    def put_bucket_logging(self, bucket, logging_xml_doc, headers={}):
        return Response(self._make_request('PUT', bucket, '', { 'logging': None }, headers, logging_xml_doc))

    def get_bucket_acl(self, bucket, headers={}):
        return self.get_acl(bucket, '', headers)

    def get_acl(self, bucket, key, headers={}):
        return GetResponse(
                self._make_request('GET', bucket, key, { 'acl': None }, headers))

    def put_bucket_acl(self, bucket, acl_xml_document, headers={}):
        return self.put_acl(bucket, '', acl_xml_document, headers)

    def put_acl(self, bucket, key, acl_xml_document, headers={}):
        return Response(
                self._make_request(
                    'PUT',
                    bucket,
                    key,
                    { 'acl': None },
                    headers,
                    acl_xml_document))

    def list_all_my_buckets(self, headers={}):
        return ListAllMyBucketsResponse(self._make_request('GET', '', '', {}, headers))

    def get_bucket_location(self, bucket):
        return LocationResponse(self._make_request('GET', bucket, '', {'location' : None}))

    # end public methods

    def _make_request(self, method, bucket='', key='', query_args={}, headers={}, data='', metadata={}):

        server = ''
        if bucket == '':
            server = self.server
        elif self.calling_format == CallingFormat.SUBDOMAIN:
            server = "%s.%s" % (bucket, self.server)
        elif self.calling_format == CallingFormat.VANITY:
            server = bucket
        else:
            server = self.server

        path = ''

        if (bucket != '') and (self.calling_format == CallingFormat.PATH):
            path += "/%s" % bucket

        # add the slash after the bucket regardless
        # the key will be appended if it is non-empty
        path += "/%s" % urllib.quote_plus(key)


        # build the path_argument string
        # add the ? in all cases since 
        # signature and credentials follow path args
        if len(query_args):
            path += "?" + query_args_hash_to_string(query_args)

        is_secure = self.is_secure
        host = "%s:%d" % (server, self.port)

        final_headers = merge_meta(headers, metadata);

        # add auth header
        self._add_aws_auth_header(final_headers, method, bucket, key, query_args)
                
        if is_secure :
            url = "https://%s%s" % (host, path)
        else :
            url = "http://%s%s" % (host, path)
        
        # convert method str to urlfetch method int id
        methodId = urlfetch.GET
        if method == 'POST':
            methodId = urlfetch.POST
        elif method == 'HEAD':
            methodId = urlfetch.HEAD
        elif method == 'PUT':
            methodId = urlfetch.PUT
        elif method == 'DELETE':
            methodId = urlfetch.DELETE
        
        # fetch(url, payload=None, method=GET, headers={}, allow_truncated=False)
        return urlfetch.fetch(url, data, methodId, final_headers, False)


    def _add_aws_auth_header(self, headers, method, bucket, key, query_args):
        #if not headers.has_key('Date'):
        #    headers['Date'] = time.strftime("%a, %d %b %Y %X GMT", time.gmtime())

        if not headers.has_key('x-amz-date'):
            headers['x-amz-date'] = time.strftime("%a, %d %b %Y %X GMT", time.gmtime())

        c_string = canonical_string(method, bucket, key, query_args, headers)
        headers['Authorization'] = \
            "AWS %s:%s" % (self.aws_access_key_id, encode(self.aws_secret_access_key, c_string))


class QueryStringAuthGenerator:
    # by default, expire in 1 minute
    DEFAULT_EXPIRES_IN = 60

    def __init__(self, aws_access_key_id, aws_secret_access_key, is_secure=True,
                 server=DEFAULT_HOST, port=None, calling_format=CallingFormat.SUBDOMAIN):

        if not port:
            port = PORTS_BY_SECURITY[is_secure]

        self.aws_access_key_id = aws_access_key_id
        self.aws_secret_access_key = aws_secret_access_key
        if (is_secure):
            self.protocol = 'https'
        else:
            self.protocol = 'http'

        self.is_secure = is_secure
        self.server = server
        self.port = port
        self.calling_format = calling_format
        self.__expires_in = QueryStringAuthGenerator.DEFAULT_EXPIRES_IN
        self.__expires = None

        # for backwards compatibility with older versions
        self.server_name = "%s:%s" % (self.server, self.port)

    def set_expires_in(self, expires_in):
        self.__expires_in = expires_in
        self.__expires = None

    def set_expires(self, expires):
        self.__expires = expires
        self.__expires_in = None

    def create_bucket(self, bucket, headers={}):
        return self.generate_url('PUT', bucket, '', {}, headers)

    def list_bucket(self, bucket, options={}, headers={}):
        return self.generate_url('GET', bucket, '', options, headers)

    def delete_bucket(self, bucket, headers={}):
        return self.generate_url('DELETE', bucket, '', {}, headers)

    def put(self, bucket, key, object, headers={}):
        if not isinstance(object, S3Object):
            object = S3Object(object)

        return self.generate_url(
                'PUT',
                bucket,
                key,
                {},
                merge_meta(headers, object.metadata))

    def get(self, bucket, key, headers={}):
        return self.generate_url('GET', bucket, key, {}, headers)

    def delete(self, bucket, key, headers={}):
        return self.generate_url('DELETE', bucket, key, {}, headers)

    def get_bucket_logging(self, bucket, headers={}):
        return self.generate_url('GET', bucket, '', { 'logging': None }, headers)

    def put_bucket_logging(self, bucket, logging_xml_doc, headers={}):
        return self.generate_url('PUT', bucket, '', { 'logging': None }, headers)

    def get_bucket_acl(self, bucket, headers={}):
        return self.get_acl(bucket, '', headers)

    def get_acl(self, bucket, key='', headers={}):
        return self.generate_url('GET', bucket, key, { 'acl': None }, headers)

    def put_bucket_acl(self, bucket, acl_xml_document, headers={}):
        return self.put_acl(bucket, '', acl_xml_document, headers)

    # don't really care what the doc is here.
    def put_acl(self, bucket, key, acl_xml_document, headers={}):
        return self.generate_url('PUT', bucket, key, { 'acl': None }, headers)

    def list_all_my_buckets(self, headers={}):
        return self.generate_url('GET', '', '', {}, headers)

    def make_bare_url(self, bucket, key=''):
        full_url = self.generate_url(self, bucket, key)
        return full_url[:full_url.index('?')]

    def generate_url(self, method, bucket='', key='', query_args={}, headers={}):
        expires = 0
        if self.__expires_in != None:
            expires = int(time.time() + self.__expires_in)
        elif self.__expires != None:
            expires = int(self.__expires)
        else:
            raise "Invalid expires state"

        canonical_str = canonical_string(method, bucket, key, query_args, headers, expires)
        encoded_canonical = encode(self.aws_secret_access_key, canonical_str)

        url = CallingFormat.build_url_base(self.protocol, self.server, self.port, bucket, self.calling_format)

        url += "/%s" % urllib.quote_plus(key)

        query_args['Signature'] = encoded_canonical
        query_args['Expires'] = expires
        query_args['AWSAccessKeyId'] = self.aws_access_key_id

        url += "?%s" % query_args_hash_to_string(query_args)

        return url


class S3Object:
    def __init__(self, data, metadata={}):
        self.data = data
        self.metadata = metadata

class Owner:
    def __init__(self, id='', display_name=''):
        self.id = id
        self.display_name = display_name

class ListEntry:
    def __init__(self, key='', last_modified=None, etag='', size=0, storage_class='', owner=None):
        self.key = key
        self.last_modified = last_modified
        self.etag = etag
        self.size = size
        self.storage_class = storage_class
        self.owner = owner

class CommonPrefixEntry:
    def __init(self, prefix=''):
        self.prefix = prefix

class Bucket:
    def __init__(self, name='', creation_date=''):
        self.name = name
        self.creation_date = creation_date

class Response:
    def __init__(self, http_response):
        self.http_response = http_response
        # you have to do this read, even if you don't expect a body.
        # otherwise, the next request fails.
        #self.body = http_response.read()
        self.body = http_response.content
        if http_response.status_code >= 300 and self.body:
            self.message = self.body
        else:
            self.message = "%03d %s" % (http_response.status_code, http_response.content)



class ListBucketResponse(Response):
    def __init__(self, http_response):
        Response.__init__(self, http_response)
        if http_response.status_code < 300:
            handler = ListBucketHandler()
            xml.sax.parseString(self.body, handler)
            self.entries = handler.entries
            self.common_prefixes = handler.common_prefixes
            self.name = handler.name
            self.marker = handler.marker
            self.prefix = handler.prefix
            self.is_truncated = handler.is_truncated
            self.delimiter = handler.delimiter
            self.max_keys = handler.max_keys
            self.next_marker = handler.next_marker
        else:
            self.entries = []

class ListAllMyBucketsResponse(Response):
    def __init__(self, http_response):
        Response.__init__(self, http_response)
        if http_response.status_code < 300: 
            handler = ListAllMyBucketsHandler()
            xml.sax.parseString(self.body, handler)
            self.entries = handler.entries
        else:
            self.entries = []

class GetResponse(Response):
    def __init__(self, http_response):
        Response.__init__(self, http_response)
        #response_headers = http_response.msg   # older pythons don't have getheaders
        response_headers = http_response.headers   # older pythons don't have getheaders
        metadata = self.get_aws_metadata(response_headers)
        self.object = S3Object(self.body, metadata)

    def get_aws_metadata(self, headers):
        metadata = {}
        for hkey in headers.keys():
            if hkey.lower().startswith(METADATA_PREFIX):
                metadata[hkey[len(METADATA_PREFIX):]] = headers[hkey]
                del headers[hkey]

        return metadata

class LocationResponse(Response):
    def __init__(self, http_response):
        Response.__init__(self, http_response)
        if http_response.status_code < 300: 
            handler = LocationHandler()
            xml.sax.parseString(self.body, handler)
            self.location = handler.location

class ListBucketHandler(xml.sax.ContentHandler):
    def __init__(self):
        self.entries = []
        self.curr_entry = None
        self.curr_text = ''
        self.common_prefixes = []
        self.curr_common_prefix = None
        self.name = ''
        self.marker = ''
        self.prefix = ''
        self.is_truncated = False
        self.delimiter = ''
        self.max_keys = 0
        self.next_marker = ''
        self.is_echoed_prefix_set = False

    def startElement(self, name, attrs):
        if name == 'Contents':
            self.curr_entry = ListEntry()
        elif name == 'Owner':
            self.curr_entry.owner = Owner()
        elif name == 'CommonPrefixes':
            self.curr_common_prefix = CommonPrefixEntry()


    def endElement(self, name):
        if name == 'Contents':
            self.entries.append(self.curr_entry)
        elif name == 'CommonPrefixes':
            self.common_prefixes.append(self.curr_common_prefix)
        elif name == 'Key':
            self.curr_entry.key = self.curr_text
        elif name == 'LastModified':
            self.curr_entry.last_modified = self.curr_text
        elif name == 'ETag':
            self.curr_entry.etag = self.curr_text
        elif name == 'Size':
            self.curr_entry.size = int(self.curr_text)
        elif name == 'ID':
            self.curr_entry.owner.id = self.curr_text
        elif name == 'DisplayName':
            self.curr_entry.owner.display_name = self.curr_text
        elif name == 'StorageClass':
            self.curr_entry.storage_class = self.curr_text
        elif name == 'Name':
            self.name = self.curr_text
        elif name == 'Prefix' and self.is_echoed_prefix_set:
            self.curr_common_prefix.prefix = self.curr_text
        elif name == 'Prefix':
            self.prefix = self.curr_text
            self.is_echoed_prefix_set = True
        elif name == 'Marker':
            self.marker = self.curr_text
        elif name == 'IsTruncated':
            self.is_truncated = self.curr_text == 'true'
        elif name == 'Delimiter':
            self.delimiter = self.curr_text
        elif name == 'MaxKeys':
            self.max_keys = int(self.curr_text)
        elif name == 'NextMarker':
            self.next_marker = self.curr_text

        self.curr_text = ''

    def characters(self, content):
        self.curr_text += content


class ListAllMyBucketsHandler(xml.sax.ContentHandler):
    def __init__(self):
        self.entries = []
        self.curr_entry = None
        self.curr_text = ''

    def startElement(self, name, attrs):
        if name == 'Bucket':
            self.curr_entry = Bucket()

    def endElement(self, name):
        if name == 'Name':
            self.curr_entry.name = self.curr_text
        elif name == 'CreationDate':
            self.curr_entry.creation_date = self.curr_text
        elif name == 'Bucket':
            self.entries.append(self.curr_entry)

    def characters(self, content):
        self.curr_text = content


class LocationHandler(xml.sax.ContentHandler):
    def __init__(self):
        self.location = None
        self.state = 'init'

    def startElement(self, name, attrs):
        if self.state == 'init':
            if name == 'LocationConstraint':
                self.state = 'tag_location'
                self.location = ''
            else: self.state = 'bad'
        else: self.state = 'bad'

    def endElement(self, name):
        if self.state == 'tag_location' and name == 'LocationConstraint':
            self.state = 'done'
        else: self.state = 'bad'

    def characters(self, content):
        if self.state == 'tag_location':
            self.location += content