# Copyright (c) 2010 Mitch Garnaat http://garnaat.org/
# Copyright 2010 Google Inc.
# Copyright (c) 2010, Eucalyptus Systems, Inc.
# Copyright (c) 2011, Nexenta Systems Inc.
# All rights reserved.
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish, dis-
# tribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the fol-
# lowing conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.
"""
This class encapsulates the provider-specific header differences.
"""

import os
from boto.compat import six
from datetime import datetime

import boto
from boto import config
from boto.compat import expanduser
from boto.pyami.config import Config
from boto.exception import InvalidInstanceMetadataError
from boto.gs.acl import ACL
from boto.gs.acl import CannedACLStrings as CannedGSACLStrings
from boto.s3.acl import CannedACLStrings as CannedS3ACLStrings
from boto.s3.acl import Policy


HEADER_PREFIX_KEY = 'header_prefix'
METADATA_PREFIX_KEY = 'metadata_prefix'

AWS_HEADER_PREFIX = 'x-amz-'
GOOG_HEADER_PREFIX = 'x-goog-'

ACL_HEADER_KEY = 'acl-header'
AUTH_HEADER_KEY = 'auth-header'
COPY_SOURCE_HEADER_KEY = 'copy-source-header'
COPY_SOURCE_VERSION_ID_HEADER_KEY = 'copy-source-version-id-header'
COPY_SOURCE_RANGE_HEADER_KEY = 'copy-source-range-header'
DELETE_MARKER_HEADER_KEY = 'delete-marker-header'
DATE_HEADER_KEY = 'date-header'
METADATA_DIRECTIVE_HEADER_KEY = 'metadata-directive-header'
RESUMABLE_UPLOAD_HEADER_KEY = 'resumable-upload-header'
SECURITY_TOKEN_HEADER_KEY = 'security-token-header'
STORAGE_CLASS_HEADER_KEY = 'storage-class'
MFA_HEADER_KEY = 'mfa-header'
SERVER_SIDE_ENCRYPTION_KEY = 'server-side-encryption-header'
VERSION_ID_HEADER_KEY = 'version-id-header'
RESTORE_HEADER_KEY = 'restore-header'

STORAGE_COPY_ERROR = 'StorageCopyError'
STORAGE_CREATE_ERROR = 'StorageCreateError'
STORAGE_DATA_ERROR = 'StorageDataError'
STORAGE_PERMISSIONS_ERROR = 'StoragePermissionsError'
STORAGE_RESPONSE_ERROR = 'StorageResponseError'
NO_CREDENTIALS_PROVIDED = object()


class ProfileNotFoundError(ValueError):
    pass


class Provider(object):

    CredentialMap = {
        'aws':    ('aws_access_key_id', 'aws_secret_access_key',
                   'aws_security_token', 'aws_profile'),
        'google': ('gs_access_key_id',  'gs_secret_access_key',
                   None, None),
    }

    AclClassMap = {
        'aws':    Policy,
        'google': ACL
    }

    CannedAclsMap = {
        'aws':    CannedS3ACLStrings,
        'google': CannedGSACLStrings
    }

    HostKeyMap = {
        'aws':    's3',
        'google': 'gs'
    }

    ChunkedTransferSupport = {
        'aws':    False,
        'google': True
    }

    MetadataServiceSupport = {
        'aws': True,
        'google': False
    }

    # If you update this map please make sure to put "None" for the
    # right-hand-side for any headers that don't apply to a provider, rather
    # than simply leaving that header out (which would cause KeyErrors).
    HeaderInfoMap = {
        'aws': {
            HEADER_PREFIX_KEY: AWS_HEADER_PREFIX,
            METADATA_PREFIX_KEY: AWS_HEADER_PREFIX + 'meta-',
            ACL_HEADER_KEY: AWS_HEADER_PREFIX + 'acl',
            AUTH_HEADER_KEY: 'AWS',
            COPY_SOURCE_HEADER_KEY: AWS_HEADER_PREFIX + 'copy-source',
            COPY_SOURCE_VERSION_ID_HEADER_KEY: AWS_HEADER_PREFIX +
                                                'copy-source-version-id',
            COPY_SOURCE_RANGE_HEADER_KEY: AWS_HEADER_PREFIX +
                                           'copy-source-range',
            DATE_HEADER_KEY: AWS_HEADER_PREFIX + 'date',
            DELETE_MARKER_HEADER_KEY: AWS_HEADER_PREFIX + 'delete-marker',
            METADATA_DIRECTIVE_HEADER_KEY: AWS_HEADER_PREFIX +
                                            'metadata-directive',
            RESUMABLE_UPLOAD_HEADER_KEY: None,
            SECURITY_TOKEN_HEADER_KEY: AWS_HEADER_PREFIX + 'security-token',
            SERVER_SIDE_ENCRYPTION_KEY: AWS_HEADER_PREFIX +
                                         'server-side-encryption',
            VERSION_ID_HEADER_KEY: AWS_HEADER_PREFIX + 'version-id',
            STORAGE_CLASS_HEADER_KEY: AWS_HEADER_PREFIX + 'storage-class',
            MFA_HEADER_KEY: AWS_HEADER_PREFIX + 'mfa',
            RESTORE_HEADER_KEY: AWS_HEADER_PREFIX + 'restore',
        },
        'google': {
            HEADER_PREFIX_KEY: GOOG_HEADER_PREFIX,
            METADATA_PREFIX_KEY: GOOG_HEADER_PREFIX + 'meta-',
            ACL_HEADER_KEY: GOOG_HEADER_PREFIX + 'acl',
            AUTH_HEADER_KEY: 'GOOG1',
            COPY_SOURCE_HEADER_KEY: GOOG_HEADER_PREFIX + 'copy-source',
            COPY_SOURCE_VERSION_ID_HEADER_KEY: GOOG_HEADER_PREFIX +
                                                'copy-source-version-id',
            COPY_SOURCE_RANGE_HEADER_KEY: None,
            DATE_HEADER_KEY: GOOG_HEADER_PREFIX + 'date',
            DELETE_MARKER_HEADER_KEY: GOOG_HEADER_PREFIX + 'delete-marker',
            METADATA_DIRECTIVE_HEADER_KEY: GOOG_HEADER_PREFIX  +
                                            'metadata-directive',
            RESUMABLE_UPLOAD_HEADER_KEY: GOOG_HEADER_PREFIX + 'resumable',
            SECURITY_TOKEN_HEADER_KEY: GOOG_HEADER_PREFIX + 'security-token',
            SERVER_SIDE_ENCRYPTION_KEY: None,
            # Note that this version header is not to be confused with
            # the Google Cloud Storage 'x-goog-api-version' header.
            VERSION_ID_HEADER_KEY: GOOG_HEADER_PREFIX + 'version-id',
            STORAGE_CLASS_HEADER_KEY: GOOG_HEADER_PREFIX + 'storage-class',
            MFA_HEADER_KEY: None,
            RESTORE_HEADER_KEY: None,
        }
    }

    ErrorMap = {
        'aws': {
            STORAGE_COPY_ERROR: boto.exception.S3CopyError,
            STORAGE_CREATE_ERROR: boto.exception.S3CreateError,
            STORAGE_DATA_ERROR: boto.exception.S3DataError,
            STORAGE_PERMISSIONS_ERROR: boto.exception.S3PermissionsError,
            STORAGE_RESPONSE_ERROR: boto.exception.S3ResponseError,
        },
        'google': {
            STORAGE_COPY_ERROR: boto.exception.GSCopyError,
            STORAGE_CREATE_ERROR: boto.exception.GSCreateError,
            STORAGE_DATA_ERROR: boto.exception.GSDataError,
            STORAGE_PERMISSIONS_ERROR: boto.exception.GSPermissionsError,
            STORAGE_RESPONSE_ERROR: boto.exception.GSResponseError,
        }
    }

    def __init__(self, name, access_key=None, secret_key=None,
                 security_token=None, profile_name=None):
        self.host = None
        self.port = None
        self.host_header = None
        self.access_key = access_key
        self.secret_key = secret_key
        self.security_token = security_token
        self.profile_name = profile_name
        self.name = name
        self.acl_class = self.AclClassMap[self.name]
        self.canned_acls = self.CannedAclsMap[self.name]
        self._credential_expiry_time = None

        # Load shared credentials file if it exists
        shared_path = os.path.join(expanduser('~'), '.' + name, 'credentials')
        self.shared_credentials = Config(do_load=False)
        if os.path.isfile(shared_path):
            self.shared_credentials.load_from_path(shared_path)

        self.get_credentials(access_key, secret_key, security_token, profile_name)
        self.configure_headers()
        self.configure_errors()

        # Allow config file to override default host and port.
        host_opt_name = '%s_host' % self.HostKeyMap[self.name]
        if config.has_option('Credentials', host_opt_name):
            self.host = config.get('Credentials', host_opt_name)
        port_opt_name = '%s_port' % self.HostKeyMap[self.name]
        if config.has_option('Credentials', port_opt_name):
            self.port = config.getint('Credentials', port_opt_name)
        host_header_opt_name = '%s_host_header' % self.HostKeyMap[self.name]
        if config.has_option('Credentials', host_header_opt_name):
            self.host_header = config.get('Credentials', host_header_opt_name)

    def get_access_key(self):
        if self._credentials_need_refresh():
            self._populate_keys_from_metadata_server()
        return self._access_key

    def set_access_key(self, value):
        self._access_key = value

    access_key = property(get_access_key, set_access_key)

    def get_secret_key(self):
        if self._credentials_need_refresh():
            self._populate_keys_from_metadata_server()
        return self._secret_key

    def set_secret_key(self, value):
        self._secret_key = value

    secret_key = property(get_secret_key, set_secret_key)

    def get_security_token(self):
        if self._credentials_need_refresh():
            self._populate_keys_from_metadata_server()
        return self._security_token

    def set_security_token(self, value):
        self._security_token = value

    security_token = property(get_security_token, set_security_token)

    def _credentials_need_refresh(self):
        if self._credential_expiry_time is None:
            return False
        else:
            # The credentials should be refreshed if they're going to expire
            # in less than 5 minutes.
            delta = self._credential_expiry_time - datetime.utcnow()
            # python2.6 does not have timedelta.total_seconds() so we have
            # to calculate this ourselves.  This is straight from the
            # datetime docs.
            seconds_left = (
                (delta.microseconds + (delta.seconds + delta.days * 24 * 3600)
                 * 10 ** 6) / 10 ** 6)
            if seconds_left < (5 * 60):
                boto.log.debug("Credentials need to be refreshed.")
                return True
            else:
                return False

    def get_credentials(self, access_key=None, secret_key=None,
                        security_token=None, profile_name=None):
        access_key_name, secret_key_name, security_token_name, \
            profile_name_name = self.CredentialMap[self.name]

        # Load profile from shared environment variable if it was not
        # already passed in and the environment variable exists
        if profile_name is None and profile_name_name is not None and \
           profile_name_name.upper() in os.environ:
            profile_name = os.environ[profile_name_name.upper()]

        shared = self.shared_credentials

        if access_key is not None:
            self.access_key = access_key
            boto.log.debug("Using access key provided by client.")
        elif access_key_name.upper() in os.environ:
            self.access_key = os.environ[access_key_name.upper()]
            boto.log.debug("Using access key found in environment variable.")
        elif profile_name is not None:
            if shared.has_option(profile_name, access_key_name):
                self.access_key = shared.get(profile_name, access_key_name)
                boto.log.debug("Using access key found in shared credential "
                               "file for profile %s." % profile_name)
            elif config.has_option("profile %s" % profile_name,
                                   access_key_name):
                self.access_key = config.get("profile %s" % profile_name,
                                             access_key_name)
                boto.log.debug("Using access key found in config file: "
                               "profile %s." % profile_name)
            else:
                raise ProfileNotFoundError('Profile "%s" not found!' %
                                           profile_name)
        elif shared.has_option('default', access_key_name):
            self.access_key = shared.get('default', access_key_name)
            boto.log.debug("Using access key found in shared credential file.")
        elif config.has_option('Credentials', access_key_name):
            self.access_key = config.get('Credentials', access_key_name)
            boto.log.debug("Using access key found in config file.")

        if secret_key is not None:
            self.secret_key = secret_key
            boto.log.debug("Using secret key provided by client.")
        elif secret_key_name.upper() in os.environ:
            self.secret_key = os.environ[secret_key_name.upper()]
            boto.log.debug("Using secret key found in environment variable.")
        elif profile_name is not None:
            if shared.has_option(profile_name, secret_key_name):
                self.secret_key = shared.get(profile_name, secret_key_name)
                boto.log.debug("Using secret key found in shared credential "
                               "file for profile %s." % profile_name)
            elif config.has_option("profile %s" % profile_name, secret_key_name):
                self.secret_key = config.get("profile %s" % profile_name,
                                             secret_key_name)
                boto.log.debug("Using secret key found in config file: "
                               "profile %s." % profile_name)
            else:
                raise ProfileNotFoundError('Profile "%s" not found!' %
                                           profile_name)
        elif shared.has_option('default', secret_key_name):
            self.secret_key = shared.get('default', secret_key_name)
            boto.log.debug("Using secret key found in shared credential file.")
        elif config.has_option('Credentials', secret_key_name):
            self.secret_key = config.get('Credentials', secret_key_name)
            boto.log.debug("Using secret key found in config file.")
        elif config.has_option('Credentials', 'keyring'):
            keyring_name = config.get('Credentials', 'keyring')
            try:
                import keyring
            except ImportError:
                boto.log.error("The keyring module could not be imported. "
                               "For keyring support, install the keyring "
                               "module.")
                raise
            self.secret_key = keyring.get_password(
                keyring_name, self.access_key)
            boto.log.debug("Using secret key found in keyring.")

        if security_token is not None:
            self.security_token = security_token
            boto.log.debug("Using security token provided by client.")
        elif ((security_token_name is not None) and
              (access_key is None) and (secret_key is None)):
            # Only provide a token from the environment/config if the
            # caller did not specify a key and secret.  Otherwise an
            # environment/config token could be paired with a
            # different set of credentials provided by the caller
            if security_token_name.upper() in os.environ:
                self.security_token = os.environ[security_token_name.upper()]
                boto.log.debug("Using security token found in environment"
                               " variable.")
            elif shared.has_option(profile_name or 'default',
                                   security_token_name):
                self.security_token = shared.get(profile_name or 'default',
                                                 security_token_name)
                boto.log.debug("Using security token found in shared "
                               "credential file.")
            elif profile_name is not None:
                if config.has_option("profile %s" % profile_name,
                                     security_token_name):
                    boto.log.debug("config has option")
                    self.security_token = config.get("profile %s" % profile_name,
                                                     security_token_name)
                    boto.log.debug("Using security token found in config file: "
                                   "profile %s." % profile_name)
            elif config.has_option('Credentials', security_token_name):
                self.security_token = config.get('Credentials',
                                                 security_token_name)
                boto.log.debug("Using security token found in config file.")

        if ((self._access_key is None or self._secret_key is None) and
                self.MetadataServiceSupport[self.name]):
            self._populate_keys_from_metadata_server()
        self._secret_key = self._convert_key_to_str(self._secret_key)

    def _populate_keys_from_metadata_server(self):
        # get_instance_metadata is imported here because of a circular
        # dependency.
        boto.log.debug("Retrieving credentials from metadata server.")
        from boto.utils import get_instance_metadata
        timeout = config.getfloat('Boto', 'metadata_service_timeout', 1.0)
        attempts = config.getint('Boto', 'metadata_service_num_attempts', 1)
        # The num_retries arg is actually the total number of attempts made,
        # so the config options is named *_num_attempts to make this more
        # clear to users.
        metadata = get_instance_metadata(
            timeout=timeout, num_retries=attempts,
            data='meta-data/iam/security-credentials/')
        if metadata:
            creds = self._get_credentials_from_metadata(metadata)
            self._access_key = creds[0]
            self._secret_key = creds[1]
            self._security_token = creds[2]
            expires_at = creds[3]
            # I'm assuming there's only one role on the instance profile.
            self._credential_expiry_time = datetime.strptime(
                expires_at, "%Y-%m-%dT%H:%M:%SZ")
            boto.log.debug("Retrieved credentials will expire in %s at: %s",
                           self._credential_expiry_time - datetime.now(),
                           expires_at)

    def _get_credentials_from_metadata(self, metadata):
        # Given metadata, return a tuple of (access, secret, token, expiration)
        # On errors, an InvalidInstanceMetadataError will be raised.
        # The "metadata" is a lazy loaded dictionary means that it's possible
        # to still encounter errors as we traverse through the metadata dict.
        # We try to be careful and raise helpful error messages when this
        # happens.
        creds = list(metadata.values())[0]
        if not isinstance(creds, dict):
            # We want to special case a specific error condition which is
            # where get_instance_metadata() returns an empty string on
            # error conditions.
            if creds == '':
                msg = 'an empty string'
            else:
                msg = 'type: %s' % creds
            raise InvalidInstanceMetadataError("Expected a dict type of "
                                               "credentials instead received "
                                               "%s" % (msg))
        try:
            access_key = creds['AccessKeyId']
            secret_key = self._convert_key_to_str(creds['SecretAccessKey'])
            security_token = creds['Token']
            expires_at = creds['Expiration']
        except KeyError as e:
            raise InvalidInstanceMetadataError(
                "Credentials from instance metadata missing "
                "required key: %s" % e)
        return access_key, secret_key, security_token, expires_at

    def _convert_key_to_str(self, key):
        if isinstance(key, six.text_type):
            # the secret key must be bytes and not unicode to work
            #  properly with hmac.new (see http://bugs.python.org/issue5285)
            return str(key)
        return key

    def configure_headers(self):
        header_info_map = self.HeaderInfoMap[self.name]
        self.metadata_prefix = header_info_map[METADATA_PREFIX_KEY]
        self.header_prefix = header_info_map[HEADER_PREFIX_KEY]
        self.acl_header = header_info_map[ACL_HEADER_KEY]
        self.auth_header = header_info_map[AUTH_HEADER_KEY]
        self.copy_source_header = header_info_map[COPY_SOURCE_HEADER_KEY]
        self.copy_source_version_id = header_info_map[
            COPY_SOURCE_VERSION_ID_HEADER_KEY]
        self.copy_source_range_header = header_info_map[
            COPY_SOURCE_RANGE_HEADER_KEY]
        self.date_header = header_info_map[DATE_HEADER_KEY]
        self.delete_marker = header_info_map[DELETE_MARKER_HEADER_KEY]
        self.metadata_directive_header = (
            header_info_map[METADATA_DIRECTIVE_HEADER_KEY])
        self.security_token_header = header_info_map[SECURITY_TOKEN_HEADER_KEY]
        self.resumable_upload_header = (
            header_info_map[RESUMABLE_UPLOAD_HEADER_KEY])
        self.server_side_encryption_header = header_info_map[SERVER_SIDE_ENCRYPTION_KEY]
        self.storage_class_header = header_info_map[STORAGE_CLASS_HEADER_KEY]
        self.version_id = header_info_map[VERSION_ID_HEADER_KEY]
        self.mfa_header = header_info_map[MFA_HEADER_KEY]
        self.restore_header = header_info_map[RESTORE_HEADER_KEY]

    def configure_errors(self):
        error_map = self.ErrorMap[self.name]
        self.storage_copy_error = error_map[STORAGE_COPY_ERROR]
        self.storage_create_error = error_map[STORAGE_CREATE_ERROR]
        self.storage_data_error = error_map[STORAGE_DATA_ERROR]
        self.storage_permissions_error = error_map[STORAGE_PERMISSIONS_ERROR]
        self.storage_response_error = error_map[STORAGE_RESPONSE_ERROR]

    def get_provider_name(self):
        return self.HostKeyMap[self.name]

    def supports_chunked_transfer(self):
        return self.ChunkedTransferSupport[self.name]


# Static utility method for getting default Provider.
def get_default():
    return Provider('aws')