# Copyright (C) 2010 Google Inc. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

from datetime import datetime

from google.appengine.ext import db
from google.appengine.ext import webapp

from model.queues import Queue


class NextPatch(webapp.RequestHandler):
    # FIXME: This should probably be a post, or an explict lock_patch
    # since GET requests shouldn't really modify the datastore.
    def get(self, queue_name):
        queue = Queue.queue_with_name(queue_name)
        if not queue:
            self.error(404)
            return
        # FIXME: Patch assignment should probably move into Queue.
        patch_id = db.run_in_transaction(self._assign_patch, queue.active_work_items().key(), queue.work_items().item_ids)
        if not patch_id:
            self.error(404)
            return
        self.response.out.write(patch_id)

    @staticmethod
    def _assign_patch(key, work_item_ids):
        now = datetime.now()
        active_work_items = db.get(key)
        active_work_items.deactivate_expired(now)
        next_item = active_work_items.next_item(work_item_ids, now)
        active_work_items.put()
        return next_item