# -*- coding: utf-8 -*-
from __future__ import unicode_literals
# Erik Stein <code@classlibrary.net>, 2016

import os
import warnings

from django.core.files.storage import FileSystemStorage
from django.conf import settings
from django.utils._os import safe_join
from django.utils.deconstruct import deconstructible
from django.utils.encoding import filepath_to_uri
from django.utils.six.moves.urllib.parse import urljoin


__all__ = ('MediaAssetStorage',)


ORIGINAL_FILE_PREFIX = 'original'
CACHED_VARIANT_PREFIX = 'cache'
MANUAL_VARIANT_PREFIX = 'manual'


"""
Storage setup:

    /<asset_uuid>/original/filename.ext
                 /cache/<format_slug>/<hash>.<variant_ext>
                 /manual/<format_slug>/<hash>.<variant_ext>

TODO Add snapshot (versioning) to path after asset_uuid.

"""


class BaseVariantSubStorage(FileSystemStorage):
    def delete(self, parent_storage, name):
        """
        Deletes the whole storage path
        """
        raise NotImplemented


@deconstructible
class MediaAssetStorage(FileSystemStorage):
    """
    Standard media assets filesystem storage
    """

    def __init__(self, location=None, base_url=None, file_permissions_mode=None,
            directory_permissions_mode=None):
        if location is None:
            location = getattr(settings, 'MEDIA_ASSETS_ROOT', settings.MEDIA_ROOT)
        if base_url is None:
            base_url = getattr(settings, 'MEDIA_ASSETS_URL', settings.MEDIA_URL)
        if not base_url.endswith('/'):
            base_url += '/'
        super(MediaAssetStorage, self).__init__(self)

    def delete(self, name):
        super(MediaAssetStorage, self).delete(name)
        # FIXME Delete all cached files, too
        warnings.warn("Cached files for asset \"%s\" are not deleted." % name)

    def path(self, name):
        """
        `name` must already contain the whole asset filesystem path.
        """
        return safe_join(self.location, ORIGINAL_FILE_PREFIX, name)

    def size(self, name):
        return os.path.getsize(self.path(name))

    def url(self, name):
        if self.base_url is None:
            raise ValueError("This file is not accessible via a URL.")
        return urljoin(self.base_url, ORIGINAL_FILE_PREFIX, filepath_to_uri(name))