Refactor filter arguments outside tile handler

api/obs/api/routes/tiles.py

@@ -1,6 +1,7 @@
 from gzip import decompress
 from sqlite3 import connect
 from datetime import datetime, time, timedelta
+from typing import Optional, Tuple
 
 import dateutil.parser
 from sanic.exceptions import Forbidden, InvalidUsage
@@ -54,12 +55,17 @@ def round_date(date, to="weeks", up=False):
 TILE_CACHE_MAX_AGE = 3600 * 24
 
 
-@app.route(r"/tiles/<zoom:int>/<x:int>/<y:(\d+)\.pbf>")
+def get_filter_options(
-async def tiles(req, zoom: int, x: int, y: str):
+    req,
-    if app.config.get("TILES_FILE"):
+) -> Tuple[Optional[str], Optional[datetime], Optional[datetime]]:
-        tile = get_tile(req.app.config.TILES_FILE, int(zoom), int(x), int(y))
+    """
+    Returns parsed, validated and normalized options for filtering map data, a
+    tuple of
 
-    else:
+        * user_id (str|None)
+        * start (datetime|None)
+        * end (datetime|None)
+    """
     user_id = None
     username = req.ctx.get_single_arg("user", default=None)
     if username is not None:
@@ -79,6 +85,17 @@ async def tiles(req, zoom: int, x: int, y: str):
             "end date must be later than start date (note: dates are rounded to weeks)"
         )
 
+    return user_id, start, end
+
+
+@app.route(r"/tiles/<zoom:int>/<x:int>/<y:(\d+)\.pbf>")
+async def tiles(req, zoom: int, x: int, y: str):
+    if app.config.get("TILES_FILE"):
+        tile = get_tile(req.app.config.TILES_FILE, int(zoom), int(x), int(y))
+
+    else:
+        user_id, start, end = get_filter_options(req)
+
         tile = await req.ctx.db.scalar(
             text(
                 f"select data from getmvt(:zoom, :x, :y, :user_id, :min_time, :max_time) as b(data, key);"