from mimetypes import guess_type

import os

from django.core.exceptions import ImproperlyConfigured

from django.core.filestorage.base import Storage, RemoteFile

from django.core.filestorage.filesystem import FileSystemStorage

from django.utils.functional import curry

from django.conf import settings

ACCESS_KEY_NAME = 'AWS_ACCESS_KEY_ID'

SECRET_KEY_NAME = 'AWS_SECRET_ACCESS_KEY'

AWS_HEADERS = 'AWS_HEADERS'

try:

    from S3 import AWSAuthConnection, QueryStringAuthGenerator

except ImportError:

    raise ImproperlyConfigured, "Could not load amazon's S3 bindings.\

    \nSee http://developer.amazonwebservices.com/connect/entry.jspa?externalID=134"

class S3Storage(Storage):

    """Amazon Simple Storage Service"""

    def __init__(self, bucket=settings.AWS_STORAGE_BUCKET_NAME, 

            access_key=None, secret_key=None, acl='public-read', 

            calling_format=settings.AWS_CALLING_FORMAT):

        self.bucket = bucket

        self.acl = acl

        if not access_key and not secret_key:

             access_key, secret_key = self._get_access_keys()

        self.connection = AWSAuthConnection(access_key, secret_key, 

                            calling_format=calling_format)

        self.generator = QueryStringAuthGenerator(access_key, secret_key, 

                            calling_format=calling_format, is_secure=False)

        self.headers = getattr(settings, AWS_HEADERS, {})

    def _get_access_keys(self):

        access_key = getattr(settings, ACCESS_KEY_NAME, None)

        secret_key = getattr(settings, SECRET_KEY_NAME, None)

        if (access_key or secret_key) and (not access_key or not secret_key):

            access_key = os.environ.get(ACCESS_KEY_NAME)

            secret_key = os.environ.get(SECRET_KEY_NAME)

        if access_key and secret_key:

            # Both were provided, so use them

            return access_key, secret_key

        return None, None

    def _get_connection(self):

        return AWSAuthConnection(*self._get_access_keys())

    def _put_file(self, filename, raw_contents):

        content_type = guess_type(filename)[0] or "application/x-octet-stream"

        self.headers.update({'x-amz-acl':  self.acl, 'Content-Type': content_type})

        response = self.connection.put(self.bucket, filename, raw_contents, self.headers)

    def url(self, filename):

        return self.generator.make_bare_url(self.bucket, filename)

    path = url

    def filesize(self, filename):

        response = self.connection.make_request('HEAD', self.bucket, filename)

        return int(response.getheader('Content-Length'))

    def open(self, filename, mode='rb'):

        response = self.connection.get(self.bucket, filename)

        writer = curry(self._put_file, filename)

        return RemoteFile(self, response.object.data, mode, writer)

    def exists(self, filename):

        response = self.connection.make_request('HEAD', self.bucket, filename)

        return response.status == 200

    def save(self, filename, raw_contents):

        filename = self.get_available_filename(filename)

        self._put_file(filename, raw_contents)

        return filename

    ## UNCOMMENT BELOW IF NECESSARY

    #def delete(self, filename):

    #    """ Do not delete default images. """

    #    if not filename.endswith('default.jpg') and not filename.endswith('guest.jpg'):

    #        self.connection.delete(self.bucket, filename)

    #def get_available_filename(self, filename):

    #    """ Overwrite existing file with the same name. """

    #    return filename