~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

from ivle.webapp.base.views import BaseView

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

from ivle.webapp.errors import NotFound, Forbidden

from ivle.webapp.publisher import INF

from ivle.webapp import ApplicationRoot

# This maps a media namespace to an external dependency directory (in this

# case specified by the configuration option media/externals/jquery) and a

# list of permitted subpaths.

EXTERNAL_MEDIA_MAP = {'jquery': ('jquery', ['jquery.js'])}

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]

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

                    if req.config['media']['version'] else '+media'

    return req.make_path(os.path.join(media_path, plugin, path))

class MediaFile(object):

    def __init__(self, root, external, version, ns, path):

        self.root = root

        self.external = external

        self.version = version

        self.ns = ns

        self.path = path

    @property

    def filename(self):

        if self.external:

            try:

                extern = EXTERNAL_MEDIA_MAP[self.ns]

            except KeyError:

                return None

            # Unless it's a whitelisted path, we don't want to hear about it.

            if self.path not in extern[1]:

                return None

            # Grab the admin-configured path for this particular external dep.

            externdir = self.root.config['media']['externals'][extern[0]]

            assert isinstance(externdir, basestring)

            return os.path.join(externdir, self.path)

        else:

            try:

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

            except KeyError:

                return None

            if not issubclass(plugin, MediaPlugin):

                return None

            mediadir = plugin.media

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

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

class MediaFileView(BaseView):

    def authorize(self, req):

        return True

    def render(self, req):

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

        if self.context.path.startswith("..") or \

           self.context.path.startswith('/'):

            raise Forbidden()

        filename = self.get_filename(req)

        if filename is None:

            raise NotFound()

        # 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()

        if self.context.version is not None:

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

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

                                localtime=False,

                                usegmt=True)

        req.content_type = type

        req.sendfile(filename)

    def get_filename(self, req):

        return self.context.filename

def root_to_media(root, *segments):

    if segments[0].startswith('+'):

        if segments[0] == '+external':

            external = True

            version = None

            path = segments[1:]

        else:

            version = segments[0][1:]

            if segments[1] == '+external':

                external = True

                path = segments[2:]

            else:

                external = False

                path = segments[1:]

    else:

        external = False

        version = None

        path = segments

    if version is not None and version != root.config['media']['version']:

        return None

    ns = path[0]

    path = os.path.normpath(os.path.join(*path[1:]))

    return MediaFile(root, external, version, ns, path)

class Plugin(ViewPlugin, PublicViewPlugin):

    forward_routes = [(ApplicationRoot, '+media', root_to_media, INF)]

    views = [(MediaFile, '+index', MediaFileView)]

    public_forward_routes = forward_routes

    public_views = views