Add timezone option

time_app/helpers/datetime.py

@@ -1,8 +1,21 @@
 from datetime import datetime
-from zoneinfo import ZoneInfo
+from zoneinfo import ZoneInfo, available_timezones
 
-utc = ZoneInfo('UTC')
+ALLOWED_TIMEZONES = available_timezones()
+DATETIME_FORMAT = '%Y-%m-%d %H:%M:%S'
+
+
+def tz_aware_now(zone: str) -> datetime:
+    """
+    :param str zone: Zone name in DB
+    :return: A timezone aware datetime object
+    :raises: ValueError When zone name is not supported
+    """
+    # ZoneInfo uses a weak cache, no need to implement a local cache
+    if zone not in ALLOWED_TIMEZONES:
+        raise ValueError(f'Unsupported timezone "{zone}"')
+    return datetime.now(tz=ZoneInfo(zone))
 
 
 def real_utc_now() -> datetime:
-    return datetime.now(tz=utc)
+    return tz_aware_now('UTC')

time_app/helpers/views.py

@@ -0,0 +1,11 @@
+from fastapi import HTTPException
+
+from .datetime import tz_aware_now
+
+
+def get_now_in_view(zone: str = 'UTC'):
+    try:
+        now = tz_aware_now(zone=zone)
+    except ValueError:
+        raise HTTPException(status_code=400, detail=f'Zone "{zone}" is unsupported')
+    return now

time_app/views/api.py

@@ -1,16 +1,16 @@
 from fastapi import APIRouter
 
-from time_app.helpers.datetime import real_utc_now
+from time_app.helpers.views import get_now_in_view
 from time_app.models.main import Now
 
 router = APIRouter()
 
 
-@router.get('/', name='Now', response_model=Now)
-def now_view() -> dict:
-    return {"time": real_utc_now().strftime('%Y-%m-%d %H:%M:%S')}
+@router.get('/now', name='Now', response_model=Now)
+def now_view(zone: str = 'UTC') -> dict:
+    return {"time": f'{get_now_in_view(zone):%Y-%m-%d %H:%M:%S}'}
 
 
 @router.get('/diy', name='Day in year', response_model=Now)
-def day_in_year_view() -> dict:
-    return {"time": real_utc_now().strftime('%y%j')[-4:]}
+def day_in_year_view(zone: str = 'UTC') -> dict:
+    return {"time": f'{get_now_in_view(zone):%y%j}'[-4:]}

time_app/views/main.py

@@ -1,15 +1,20 @@
 from fastapi import APIRouter
 
-from time_app.helpers.datetime import real_utc_now
+from time_app.helpers.views import get_now_in_view
 
 router = APIRouter()
 
 
 @router.get('/', name='Now')
 def now_view() -> str:
-    return real_utc_now().strftime('%Y-%m-%d %H:%M:%S')
+    return f'{get_now_in_view():%Y-%m-%d %H:%M:%S}'
+
+
+@router.get('/now', name='Now')
+def now_view(zone: str = 'UTC') -> str:
+    return f'{get_now_in_view(zone):%Y-%m-%d %H:%M:%S}'
 
 
 @router.get('/diy', name='Day in year')
-def day_in_year_view() -> str:
-    return real_utc_now().strftime('%y%j')[-4:]
+def day_in_year_view(zone: str = 'UTC') -> str:
+    return f'{get_now_in_view(zone):%y%j}'[-4:]