# -*- coding: utf-8 -*- #
# Copyright 2018 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""A library that is used to support Functions commands."""

from __future__ import absolute_import
from __future__ import division
from __future__ import unicode_literals

import itertools

import enum


UNADVERTISED_PROVIDER_LABEL = 'unadvertised'


@enum.unique
class Resources(enum.Enum):

  class Resource(object):

    def __init__(self, name, collection_id):
      self.name = name
      self.collection_id = collection_id
  TOPIC = Resource('topic', 'pubsub.projects.topics')
  BUCKET = Resource('bucket', 'cloudfunctions.projects.buckets')
  FIREBASE_DB = Resource('firebase database', 'google.firebase.database.ref')
  FIRESTORE_DOC = Resource('firestore document', 'google.firestore.document')
  FIREBASE_ANALYTICS_EVENT = Resource('firebase analytics',
                                      'google.firebase.analytics.event')
  PROJECT = Resource('project', 'cloudresourcemanager.projects')


class TriggerProvider(object):
  """Represents --trigger-provider flag value options."""

  def __init__(self, label, events):
    self.label = label
    self.events = events
    for event in self.events:
      # Used to access provider properties when listing event types
      event.provider = self

  @property
  def default_event(self):
    return self.events[0]


class TriggerEvent(object):
  """Represents --trigger-event flag value options."""

  # Currently only project resource is optional
  OPTIONAL_RESOURCE_TYPES = [Resources.PROJECT]

  def __init__(self, label, resource_type):
    self.label = label
    self.resource_type = resource_type

  @property
  def event_is_optional(self):
    return self.provider.default_event == self

  # TODO(b/33097692) Let TriggerEvent know how to handle optional resources.
  @property
  def resource_is_optional(self):
    return self.resource_type in TriggerEvent.OPTIONAL_RESOURCE_TYPES

# TODO (b/73062780): Event types should not be hard-coded.
# Don't use those structures directly. Use registry object instead.
# By convention, first event type is default.
_BETA_PROVIDERS = [
    TriggerProvider('cloud.pubsub', [
        TriggerEvent('google.pubsub.topic.publish', Resources.TOPIC),
        TriggerEvent('providers/cloud.pubsub/eventTypes/topic.publish',
                     Resources.TOPIC),
    ]),
    TriggerProvider('cloud.storage', [
        TriggerEvent('google.storage.object.finalize', Resources.BUCKET),
        TriggerEvent('providers/cloud.storage/eventTypes/object.change',
                     Resources.BUCKET),
        TriggerEvent('google.storage.object.archive', Resources.BUCKET),
        TriggerEvent('google.storage.object.delete', Resources.BUCKET),
        TriggerEvent('google.storage.object.metadataUpdate', Resources.BUCKET),
    ]),
    TriggerProvider('google.firebase.database.ref', [
        TriggerEvent('providers/google.firebase.database/eventTypes/ref.create',
                     Resources.FIREBASE_DB),
        TriggerEvent('providers/google.firebase.database/eventTypes/ref.update',
                     Resources.FIREBASE_DB),
        TriggerEvent('providers/google.firebase.database/eventTypes/ref.delete',
                     Resources.FIREBASE_DB),
        TriggerEvent('providers/google.firebase.database/eventTypes/ref.write',
                     Resources.FIREBASE_DB),
    ]),
    TriggerProvider('google.firestore.document', [
        TriggerEvent('providers/cloud.firestore/eventTypes/document.create',
                     Resources.FIRESTORE_DOC),
        TriggerEvent('providers/cloud.firestore/eventTypes/document.update',
                     Resources.FIRESTORE_DOC),
        TriggerEvent('providers/cloud.firestore/eventTypes/document.delete',
                     Resources.FIRESTORE_DOC),
        TriggerEvent('providers/cloud.firestore/eventTypes/document.write',
                     Resources.FIRESTORE_DOC),
    ]),
    TriggerProvider('google.firebase.analytics.event', [
        TriggerEvent('providers/google.firebase.analytics/eventTypes/event.log',
                     Resources.FIREBASE_ANALYTICS_EVENT),
    ]),
]

_ALPHA_PROVIDERS = [
    TriggerProvider('firebase.auth', [
        TriggerEvent('providers/firebase.auth/eventTypes/user.create',
                     Resources.PROJECT),
        TriggerEvent('providers/firebase.auth/eventTypes/user.delete',
                     Resources.PROJECT),
    ]),
    TriggerProvider('firebase.database', [
        TriggerEvent('providers/firebase.auth/eventTypes/data.write',
                     Resources.PROJECT),
    ])
]


class _TriggerProviderRegistry(object):
  """This class encapsulates all Event Trigger related functionality."""

  def __init__(self, all_providers):
    self.providers = all_providers
    self._unadvertised_provider = TriggerProvider(
        UNADVERTISED_PROVIDER_LABEL, [])

  def ProvidersLabels(self):
    return (p.label for p in self.providers)

  def Provider(self, provider):
    return next((p for p in self.providers if p.label == provider))

  def EventsLabels(self, provider):
    return (e.label for e in self.Provider(provider).events)

  def AllEventLabels(self):
    all_events = (self.EventsLabels(p.label) for p in self.providers)
    return itertools.chain.from_iterable(all_events)

  def Event(self, provider, event):
    return next((e for e in self.Provider(provider).events if e.label == event))

  def ProviderForEvent(self, event_label):
    for p in self.providers:
      if event_label in self.EventsLabels(p.label):
        return p
    return self._unadvertised_provider


OUTPUT_TRIGGER_PROVIDER_REGISTRY = _TriggerProviderRegistry(_BETA_PROVIDERS)
INPUT_TRIGGER_PROVIDER_REGISTRY = _TriggerProviderRegistry(
    _BETA_PROVIDERS + _ALPHA_PROVIDERS)
