Free Timeslots Endpoint

backend/app/models.py

@@ -19,6 +19,21 @@ def toJSON(self):
             "user_id": self.user_id
         })
 
+class Interval:
+    def __init__(self, start, end, id, duration):
+        self.start = start
+        self.end = end
+        self.id = id
+        self.duration = duration
+
+    def toJSON(self):
+        return jsonify({
+            "start": self.start,
+            "end": self.end,
+            "id": self.id,
+            "duration": self.duration
+        })
+
 class Error(Exception):
     status_code = 400
 

backend/app/routes.py

@@ -6,8 +6,9 @@
 from dateutil import parser
 from google.auth.transport import requests
 from .models import User, Error
-from .util import convertDateToRFC3339
-import os.path, json
+from .util import convertDateToRFC3339, convertDateTimeToRFC3339, formulate_open_timeslots
+import os.path, json, time, datetime, pytz
+from pytz import timezone
 
 routes_blueprint = Blueprint('routes', __name__)
 
@@ -57,6 +58,44 @@ def login():
         # Invalid token
         raise Error(e, status_code = 400)
 
+@routes_blueprint.route('/free_intervals/id=<id>')
+@cross_origin(supports_credentials=True)
+def get_free_intervals(id):
+    user = User.objects(user_id = id).first()
+    if not user:
+        raise Error("No existing user with the associated user ID", status_code = 400)
+    else:
+        access_token = user.access_token
+
+
+    credentials = AccessTokenCredentials(access_token, 'my-user-agent/1.0')
+
+
+    try: 
+        service = build('calendar', 'v3', credentials=credentials)
+
+        local_timezone = timezone('US/Pacific')
+        now = datetime.datetime.now(tz=local_timezone)
+        today = now.date()
+        today_7am = local_timezone.localize(datetime.datetime.combine(today, datetime.time(7,0)))
+        tomorrow = today + datetime.timedelta(days=1)
+        tomorrow_start = local_timezone.localize(datetime.datetime.combine(tomorrow, datetime.time(0,0)))
+
+        events_result = service.events().list(calendarId='primary', timeMin=convertDateTimeToRFC3339(today_7am), timeMax=convertDateTimeToRFC3339(tomorrow_start), singleEvents=True, orderBy='startTime').execute()
+        if not events_result:
+            raise ValueError("Could not get events from Calendar API", status_code = 500)
+        events = events_result.get('items', [])
+
+        return jsonify([timeslot.__dict__ for timeslot in formulate_open_timeslots(events, today)]), 200
+
+
+    except ValueError as e:
+        raise Error(e, status_code = 500)
+
+    except Exception as e:
+        raise Error("Could not connect to calendar API, perhaps due to invalid credentials/access_token --> Returned Error: {}".format(e), status_code = 400)
+
+
 
 @routes_blueprint.route('/calendar/id=<id>&start=<start_date>&end=<end_date>', methods=['GET'])
 @cross_origin(supports_credentials=True)

backend/app/util.py

@@ -1,9 +1,48 @@
 from dateutil import parser
-import datetime, time
+from .models import Interval
+from pytz import timezone
+import datetime, time, pytz
+
+
 
 def convertDateToRFC3339(date):
     # Parse date into datetime object
     date_time = parser.parse(date)
 
     # Return RFC3339 date after switching to UTC format
-    return datetime.datetime.utcfromtimestamp(time.mktime(date_time.timetuple())).isoformat('T') + 'Z'
+    return date_time.astimezone(tz=pytz.utc).strftime('%Y-%m-%dT%H:%M:%S.%fZ')
+
+def convertDateTimeToRFC3339(date_time):
+    return date_time.astimezone(tz=pytz.utc).strftime('%Y-%m-%dT%H:%M:%S.%fZ')
+
+def duration(start, end):
+    difference_seconds = (end - start).total_seconds()
+    hours, leftover_seconds = divmod(difference_seconds, 3600)
+    return float(hours) + float(leftover_seconds/3600)
+
+def formulate_open_timeslots(events, current_date):
+    time_slots = []
+    local_timezone = timezone('US/Pacific')
+    start_time = local_timezone.localize(datetime.datetime.combine(current_date, datetime.time(7, 0)))   # beginning of first interval is 7am day 1
+    end_time = local_timezone.localize(datetime.datetime.combine(current_date + datetime.timedelta(days = 1), datetime.time(0, 0))) #end of first interval is beginning of next day
+    curr_interval = (start_time, end_time)
+    i = 1
+
+    for event in events:
+        event_start = parser.parse(event['start']['dateTime']).astimezone(local_timezone) #assume event time is PST timezone
+        event_end = parser.parse(event['end']['dateTime']).astimezone(local_timezone) #assume event time is PST timezone
+
+        if event_start > curr_interval[0]:
+            new_interval = (event_end, curr_interval[1])
+            changed_curr_interval = (curr_interval[0], event_start)
+            time_slots.append(Interval(changed_curr_interval[0], changed_curr_interval[1], i, duration(changed_curr_interval[0], changed_curr_interval[1])))
+
+            i += 1
+            curr_interval = new_interval
+        elif event_end > curr_interval[0]:
+            new_interval = (event_end, curr_interval[1])
+            curr_interval = new_interval
+
+    time_slots.append(Interval(curr_interval[0], curr_interval[1], i, duration(curr_interval[0], curr_interval[1])))
+
+    return time_slots

backend/requirements.txt

@@ -21,6 +21,7 @@ pyasn1==0.4.5
 pyasn1-modules==0.2.4
 pymongo==3.7.2
 python-dateutil==2.8.0
+pytz==2019.1
 requests==2.21.0
 requests-oauthlib==1.2.0
 rsa==4.0