Repository: apache/airflow

Issue:
Add integration with Google Calendar API


**Description**

I ask for operator to create events table from the Google Calendar API
https://developers.google.com/calendar/v3/reference/events/import

**Use case / motivation**

we have calendar where we save events that has business impact and we need this data available for our analysts in tables.

I would also be nice if the hook will be able to insert events into the calendar based on logic from the pipeline.



Discussion:
Can I try to handle that task?
Of course. Go ahead and start work. I will gladly help you if you have questions. 🇵🇱 
Here is GCP integration guide: 
https://docs.google.com/document/d/1_rTdJSLCt0eyrAylmmgYc3yZr-_h51fVlnvMmWqhCkY/edit
Many topics are common between Google and GCP.
@JeffryMAC @mik-laj Would you help me to specify tasks more? I wonder if operator should only fetch calendar events, organize into table structure (maybe CSV format?) and return into next pipe or should persist data into some SQL table? 
> I would also be nice if the hook will be able to insert events into the calendar based on logic from the pipeline.

It's not clear at all for me. Need to clarify. Does it mean that hook should be able to update/insert event conditionally? For example - if there is at least one event available in particular day, then do not add next one? 
@wojtek2kdev the idea is to be able to pull events from Calendar. This is useful to make analysis if some events have effect on data (like: on 2.10.19 office closed due to employ trip). So we want our automatic process to consider events from calendar when making calculations and analysis.

On the other hand we want also the ability to post event into calendar. For example if ETL discovered issues we want to be able to call `hook.post_event(recipients, title)` this will create event in the recipients calander.
@JeffryMAC So, it would be fine to pull events and organize them into CSV format? Then it would be easy to load to e.g pandas in further pipe. It's not about saving events into particular SQL database? Then it should looks like:
[Some task] >> [Calendar operator: return events in csv] >> [Analysis]
@wojtek2kdev In my opinion, JSONL is a best format in this case. 
It should save data to GCS - Data Lake. If you have data in GCS, you can use many tool to analyze this data including BigQuery. 
@mik-laj Ok, I'll try that way. It sounds good. 
@wojtek2kdev Can you check if we can use operator `airflow.providers.amazon.aws.operators.google_api_to_s3_transfer.GoogleApiToS3Transfer` to fetch calendar events? If yes, then we just need to write a new variant that will allow us to download data to GCS.
@mik-laj I think we can. We just only need to choose calendar service and prepare desired query. So should we create Google API to GCS transfer operator? Will it be sufficient for case described in issue + calendar hook for events create/update/remove? 

Additionaly, I have a few notes, one - I know that's more art than science, but I think it would be better if operators was organize by type, use-case packages e.g having s3_to_gcs or bigquery_to_gcs or bigquery_to_mysql and so on, those should be in e.g **operators.transfer** package, operators which only executes api CRUD operations should be in **operators.api**, etc. I think we can extract more operation types, and create packages to keep order, instead of having so many different operators in single folder. Just proposition.

Two - why we create hooks which only wraps API calls? For example [sheets.py](https://github.com/apache/airflow/blob/5f3774aebdce8fe7bdcc478ea0b05d95c37c9440/airflow/providers/google/suite/hooks/sheets.py). Also, why we must implement get_conn method in all hooks/operators using google services, instead of inherit that or make some smart decorator?
@mik-laj Yes. One generic operator is more useful. I think it is also worth creating an operator that adds a calendar entry. Some organizations do not use hooks but only operators.

We had a lot of discussions on this subject. https://cwiki.apache.org/confluence/display/AIRFLOW/AIP-21%3A+Changes+in+import+paths
https://lists.apache.org/thread.html/f9262d9faa45fce6523bf85b7a5295a44cac419eb7fafeaeef1c7755%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/b461c5d03c2f32d3379a1f9ddacc36e5ef077dccda0e37843064e409%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/bdc1a070295121782e2e054ae62cac363ef84540b48f750916eae88a%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/2c9559184045e772acd21cbdd7435f6bf89c76eb9311311d58d16e5f%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/b07a93c9114e3d3c55d4ee514955bac79bc012c7a00db627c6b4c55f%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/0a2bccd52e7a303c2191d072029e1c1647dba76d8aae2ccef28d9780%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/df4340c1972952de5f3f69336db3c1f5064d145863f8223fda0c8137%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/d28fdba79b226c4b5e85e84a28da6ff318797b063c3990254a1a79bc%40%3Cdev.airflow.apache.org%3E
https://lists.apache.org/thread.html/4e648d9421c792d4537f5ac66f1a16dce468f816fc5221a9f9db9433%40%3Cdev.airflow.apache.org%3E
and other....

Not every hook method is just a wrapper. Some methods introduce other minor improvements, e.g. fallback for project ID or wait for result These changes most often result from a better library adaptation for Airflow.  You just need to update one class and all operators will still work.
We often try to respect [the KISS rule](https://pl.wikipedia.org/wiki/KISS_(regu%C5%82a)).
A separate layer in the form of a handle also makes it easier to maintain backward compatibility.

@wojtek2kdev  Do you need any help? Do you have any questions?
@mik-laj , is this something I can take on, Im trying to find a good first issue, I have been using airflow for a few years and have written custom operators. Just thought will start contributing.
@wojtek2kdev  are you working on this?
@mik-laj if @subkanthi is interested can he start working on it?
@subkanthi @JeffryMAC  @wojtek2kdev I assigned you to this ticket. I wish you a nice work together. :-D
Since no PR raised since August I'm clearing all Assignees.
The issue is open for anyone who wants to pick it up.
Hey @eladkal Im back working on this, should have a PR soon.
Hi @eladkal -  I am new to Airflow and would like to try and take a pass at this if no one else is working on this..
Fell freee  - just ask @subkanthi if he is also OK
Thanks for checking  , @rsg17 please go for it, I have some code in the branch for inserting event to the calendar(if its helpful)

https://github.com/subkanthi/airflow/tree/subkanthi/google_calendar_api_8471

> Fell freee - just ask @subkanthi if he is also OK



Resolving patch:
diff --git a/airflow/providers/google/suite/hooks/calendar.py b/airflow/providers/google/suite/hooks/calendar.py
new file mode 100644
--- /dev/null
+++ b/airflow/providers/google/suite/hooks/calendar.py
@@ -0,0 +1,239 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+#
+"""This module contains a Google Calendar API hook"""
+
+from datetime import datetime
+from typing import Any, Dict, Optional, Sequence, Union
+
+from googleapiclient.discovery import build
+
+from airflow.exceptions import AirflowException
+from airflow.providers.google.common.hooks.base_google import GoogleBaseHook
+
+
+class GoogleCalendarHook(GoogleBaseHook):
+    """
+    Interact with Google Calendar via Google Cloud connection
+    Reading and writing cells in Google Sheet:
+    https://developers.google.com/calendar/api/v3/reference
+
+    :param gcp_conn_id: The connection ID to use when fetching connection info.
+    :type gcp_conn_id: str
+    :param api_version: API Version. For example v3
+    :type api_version: str
+    :param delegate_to: The account to impersonate using domain-wide delegation of authority,
+        if any. For this to work, the service account making the request must have
+        domain-wide delegation enabled.
+    :type delegate_to: str
+    :param impersonation_chain: Optional service account to impersonate using short-term
+        credentials, or chained list of accounts required to get the access_token
+        of the last account in the list, which will be impersonated in the request.
+        If set as a string, the account must grant the originating account
+        the Service Account Token Creator IAM role.
+        If set as a sequence, the identities from the list must grant
+        Service Account Token Creator IAM role to the directly preceding identity, with first
+        account from the list granting this role to the originating account.
+    :type impersonation_chain: Union[str, Sequence[str]]
+    """
+
+    def __init__(
+        self,
+        api_version: str,
+        gcp_conn_id: str = 'google_cloud_default',
+        delegate_to: Optional[str] = None,
+        impersonation_chain: Optional[Union[str, Sequence[str]]] = None,
+    ) -> None:
+        super().__init__(
+            gcp_conn_id=gcp_conn_id,
+            delegate_to=delegate_to,
+            impersonation_chain=impersonation_chain,
+        )
+        self.gcp_conn_id = gcp_conn_id
+        self.api_version = api_version
+        self.delegate_to = delegate_to
+        self._conn = None
+
+    def get_conn(self) -> Any:
+        """
+        Retrieves connection to Google Calendar.
+
+        :return: Google Calendar services object.
+        :rtype: Any
+        """
+        if not self._conn:
+            http_authorized = self._authorize()
+            self._conn = build('calendar', self.api_version, http=http_authorized, cache_discovery=False)
+
+        return self._conn
+
+    def get_events(
+        self,
+        calendar_id: str = 'primary',
+        i_cal_uid: Optional[str] = None,
+        max_attendees: Optional[int] = None,
+        max_results: Optional[int] = None,
+        order_by: Optional[str] = None,
+        private_extended_property: Optional[str] = None,
+        q: Optional[str] = None,
+        shared_extended_property: Optional[str] = None,
+        show_deleted: Optional[bool] = False,
+        show_hidden_invitation: Optional[bool] = False,
+        single_events: Optional[bool] = False,
+        sync_token: Optional[str] = None,
+        time_max: Optional[datetime] = None,
+        time_min: Optional[datetime] = None,
+        time_zone: Optional[str] = None,
+        updated_min: Optional[datetime] = None,
+    ) -> list:
+        """
+        Gets events from Google Calendar from a single calendar_id
+        https://developers.google.com/calendar/api/v3/reference/events/list
+
+        :param calendar_id: The Google Calendar ID to interact with
+        :type calendar_id: str
+        :param i_cal_uid: Optional. Specifies event ID in the ``iCalendar`` format in the response.
+        :type i_cal_uid: str
+        :param max_attendees: Optional. If there are more than the specified number of attendees,
+            only the participant is returned.
+        :type max_attendees: int
+        :param max_results: Optional. Maximum number of events returned on one result page.
+            Incomplete pages can be detected by a non-empty ``nextPageToken`` field in the response.
+            By default the value is 250 events. The page size can never be larger than 2500 events
+        :type max_results: int
+        :param order_by: Optional. Acceptable values are ``"startTime"`` or "updated"
+        :type order_by: str
+        :param private_extended_property: Optional. Extended properties constraint specified as
+            ``propertyName=value``. Matches only private properties. This parameter might be repeated
+            multiple times to return events that match all given constraints.
+        :type private_extended_property: str
+        :param q: Optional. Free text search.
+        :type q: str
+        :param shared_extended_property: Optional. Extended properties constraint specified as
+            ``propertyName=value``. Matches only shared properties. This parameter might be repeated
+            multiple times to return events that match all given constraints.
+        :type shared_extended_property: str
+        :param show_deleted: Optional. False by default
+        :type show_deleted: bool
+        :param show_hidden_invitation: Optional. False by default
+        :type show_hidden_invitation: bool
+        :param single_events: Optional. False by default
+        :type single_events: bool
+        :param sync_token: Optional. Token obtained from the ``nextSyncToken`` field returned
+        :type sync_token: str
+        :param time_max: Optional. Upper bound (exclusive) for an event's start time to filter by.
+            Default is no filter
+        :type time_max: datetime
+        :param time_min: Optional. Lower bound (exclusive) for an event's end time to filter by.
+            Default is no filter
+        :type time_min: datetime
+        :param time_zone: Optional. Time zone used in response. Default is calendars time zone.
+        :type time_zone: str
+        :param updated_min: Optional. Lower bound for an event's last modification time
+        :type updated_min: datetime
+        :rtype: List
+        """
+        service = self.get_conn()
+        page_token = None
+        events = []
+        while True:
+            response = (
+                service.events()
+                .list(
+                    calendarId=calendar_id,
+                    iCalUID=i_cal_uid,
+                    maxAttendees=max_attendees,
+                    maxResults=max_results,
+                    orderBy=order_by,
+                    pageToken=page_token,
+                    privateExtendedProperty=private_extended_property,
+                    q=q,
+                    sharedExtendedProperty=shared_extended_property,
+                    showDeleted=show_deleted,
+                    showHiddenInvitations=show_hidden_invitation,
+                    singleEvents=single_events,
+                    syncToken=sync_token,
+                    timeMax=time_max,
+                    timeMin=time_min,
+                    timeZone=time_zone,
+                    updatedMin=updated_min,
+                )
+                .execute(num_retries=self.num_retries)
+            )
+            events.extend(response["items"])
+            page_token = response.get("nextPageToken")
+            if not page_token:
+                break
+        return events
+
+    def create_event(
+        self,
+        event: Dict[str, Any],
+        calendar_id: str = 'primary',
+        conference_data_version: Optional[int] = 0,
+        max_attendees: Optional[int] = None,
+        send_notifications: Optional[bool] = False,
+        send_updates: Optional[str] = 'false',
+        supports_attachments: Optional[bool] = False,
+    ) -> dict:
+        """
+        Create event on the specified calendar
+        https://developers.google.com/calendar/api/v3/reference/events/insert
+
+        :param calendar_id: The Google Calendar ID to interact with
+        :type calendar_id: str
+        :param conference_data_version: Optional. Version number of conference data
+            supported by the API client.
+        :type conference_data_version: int
+        :param max_attendees: Optional. If there are more than the specified number of attendees,
+            only the participant is returned.
+        :type max_attendees: int
+        :param send_notifications: Optional. Default is False
+        :type send_notifications: bool
+        :param send_updates: Optional. Default is "false". Acceptable values as "all", "none",
+            ``"externalOnly"``
+        :type send_updates: str
+        :type supports_attachments: Optional. Default is False
+        :type supports_attachments: bool
+        :type event: Required. Request body of Events resource. Start and End are required
+            https://developers.google.com/calendar/api/v3/reference/events#resource
+        :type event: dict
+        :rtype: Dict
+        """
+        if "start" not in event or "end" not in event:
+            raise AirflowException(
+                f"start and end must be specified in the event body while creating an event. API docs:"
+                f"https://developers.google.com/calendar/api/{self.api_version}/reference/events/insert "
+            )
+        service = self.get_conn()
+
+        response = (
+            service.events()
+            .insert(
+                calendarId=calendar_id,
+                conferenceDataVersion=conference_data_version,
+                maxAttendees=max_attendees,
+                sendNotifications=send_notifications,
+                sendUpdates=send_updates,
+                supportsAttachments=supports_attachments,
+                body=event,
+            )
+            .execute(num_retries=self.num_retries)
+        )
+
+        return response


Test patch:
diff --git a/tests/providers/google/suite/hooks/test_calendar.py b/tests/providers/google/suite/hooks/test_calendar.py
new file mode 100644
--- /dev/null
+++ b/tests/providers/google/suite/hooks/test_calendar.py
@@ -0,0 +1,100 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+#
+"""
+Unit Tests for the Google Calendar Hook
+"""
+
+import unittest
+from unittest import mock
+
+from airflow.providers.google.suite.hooks.calendar import GoogleCalendarHook
+from tests.providers.google.cloud.utils.base_gcp_mock import mock_base_gcp_hook_default_project_id
+
+API_VERSION = 'api_version'
+GCP_CONN_ID = 'test'
+CALENDAR_ID = 'test12345'
+EVENT = {
+    'summary': 'Calendar Test Event',
+    'description': 'A chance to test creating an event from airflow.',
+    'start': {
+        'dateTime': '2021-12-28T09:00:00-07:00',
+        'timeZone': 'America/Los_Angeles',
+    },
+    'end': {
+        'dateTime': '2021-12-28T17:00:00-07:00',
+        'timeZone': 'America/Los_Angeles',
+    },
+}
+NUM_RETRIES = 5
+API_RESPONSE = {'test': 'response'}
+
+
+class TestGoogleCalendarHook(unittest.TestCase):
+    def setUp(self):
+        with mock.patch(
+            'airflow.providers.google.common.hooks.base_google.GoogleBaseHook.__init__',
+            new=mock_base_gcp_hook_default_project_id,
+        ):
+            self.hook = GoogleCalendarHook(api_version=API_VERSION, gcp_conn_id=GCP_CONN_ID)
+
+    @mock.patch("airflow.providers.google.suite.hooks.calendar.GoogleCalendarHook.get_conn")
+    def test_get_events(self, get_conn):
+        get_method = get_conn.return_value.events.return_value.list
+        execute_method = get_method.return_value.execute
+        execute_method.return_value = {"kind": "calendar#events", "nextPageToken": None, "items": [EVENT]}
+        result = self.hook.get_events(calendar_id=CALENDAR_ID)
+        self.assertEqual(result, [EVENT])
+        execute_method.assert_called_once_with(num_retries=NUM_RETRIES)
+        get_method.assert_called_once_with(
+            calendarId=CALENDAR_ID,
+            iCalUID=None,
+            maxAttendees=None,
+            maxResults=None,
+            orderBy=None,
+            pageToken=None,
+            privateExtendedProperty=None,
+            q=None,
+            sharedExtendedProperty=None,
+            showDeleted=False,
+            showHiddenInvitations=False,
+            singleEvents=False,
+            syncToken=None,
+            timeMax=None,
+            timeMin=None,
+            timeZone=None,
+            updatedMin=None,
+        )
+
+    @mock.patch("airflow.providers.google.suite.hooks.calendar.GoogleCalendarHook.get_conn")
+    def test_create_event(self, mock_get_conn):
+        create_mock = mock_get_conn.return_value.events.return_value.insert
+        create_mock.return_value.execute.return_value = API_RESPONSE
+
+        result = self.hook.create_event(calendar_id=CALENDAR_ID, event=EVENT)
+
+        create_mock.assert_called_once_with(
+            body=EVENT,
+            calendarId=CALENDAR_ID,
+            conferenceDataVersion=0,
+            maxAttendees=None,
+            sendNotifications=False,
+            sendUpdates='false',
+            supportsAttachments=False,
+        )
+        assert result == API_RESPONSE