~azzar1/unity/add-show-desktop-key

# IVLE - Informatics Virtual Learning Environment

# Copyright (C) 2009 The University of Melbourne

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

# Author: William Grant

'''Media file support for the framework.'''

import os

import time

import inspect

import mimetypes

import email.utils

import ivle.conf

from ivle.config import Config

from ivle.webapp.base.views import BaseView

from ivle.webapp.base.plugins import ViewPlugin, MediaPlugin

from ivle.webapp.errors import NotFound, Forbidden

def media_url(req, plugin, path):

    '''Generates a URL to a media file.

    Plugin can be a string, in which case it is put into the path literally,

    or a plugin object, in which case its name is looked up.

    If a version is specified in the IVLE configuration, a versioned URL will

    be generated.

    '''

    if not isinstance(plugin, basestring):

        plugin = req.config.reverse_plugins[plugin]

    config = Config()

    media_path = os.path.join('+media', '+' + config['media']['version']) if \

                              config['media']['version'] else '+media'

    return os.path.join(ivle.conf.root_dir, media_path, plugin, path)

class BaseMediaFileView(BaseView):

    '''A view for media files.

    This serves static files from directories registered by plugins.

    Plugins wishing to export media should declare a 'media' attribute,

    pointing to the directory to serve (relative to the module's directory).

    The contents of that directory will then be available under

    /+media/python.path.to.module.

    '''

    def __init__(self, req, ns, path):

        self.ns = ns

        self.path = path

    def _make_filename(self, req):

        raise NotImplementedError()

    def render(self, req):

        # If it begins with ".." or separator, it's illegal. Die.

        if self.path.startswith("..") or self.path.startswith('/'):

            raise Forbidden()

        filename = self._make_filename(req)

        # Find an appropriate MIME type.

        (type, _) = mimetypes.guess_type(filename)

        if type is None:

            type = 'application/octet-stream'

        # Get out if it is unreadable or a directory.

        if not os.access(filename, os.F_OK):

            raise NotFound()

        if not os.access(filename, os.R_OK) or os.path.isdir(filename):

            raise Forbidden()

        req.content_type = type

        req.sendfile(filename)

class MediaFileView(BaseMediaFileView):

    '''A view for media files.

    This serves static files from directories registered by plugins.

    Plugins wishing to export media should declare a 'media' attribute,

    pointing to the directory to serve (relative to the module's directory).

    The contents of that directory will then be available under

    /+media/python.path.to.module.

    '''

    permission = None

    def _make_filename(self, req):

        try:

            plugin = req.config.plugins[self.ns]

        except KeyError:

            raise NotFound()

        if not issubclass(plugin, MediaPlugin):

            raise NotFound()

        mediadir = plugin.media

        plugindir = os.path.dirname(inspect.getmodule(plugin).__file__)

        return os.path.join(plugindir, mediadir, self.path)

    def get_permissions(self, user):

        return set()

class VersionedMediaFileView(MediaFileView):

    '''A view for versioned media files, with aggressive caching.

    This serves static media files with a version string, and requests that

    browsers cache them for a long time.

    '''

    def __init__(self, req, ns, path, version):

        super(VersionedMediaFileView, self).__init__(req, ns, path)

        self.version = version

    def _make_filename(self, req):

        if self.version != Config()['media']['version']:

            raise NotFound()

        # Don't expire for a year.

        req.headers_out['Expires'] = email.utils.formatdate(

                                    timeval=time.time() + (60*60*24*365),

                                    localtime=False,

                                    usegmt=True)

        return super(VersionedMediaFileView, self)._make_filename(req)

class Plugin(ViewPlugin):

    urls = [

        ('+media/+:version/:ns/*path', VersionedMediaFileView),

        ('+media/:ns/*path', MediaFileView),

    ]