add python implementation of reverse

This adds an additional layer parameter and slightly changes the
queries to do more efficient lookups for large area features.

nominatim/api/results.py

@@ -19,7 +19,7 @@ import datetime as dt
 import sqlalchemy as sa
 
 from nominatim.typing import SaSelect, SaRow
-from nominatim.api.types import Point, LookupDetails
+from nominatim.api.types import Point, Bbox, LookupDetails
 from nominatim.api.connection import SearchConnection
 from nominatim.api.logging import log
 
@@ -46,6 +46,8 @@ class AddressLine:
     names: Dict[str, str]
     extratags: Optional[Dict[str, str]]
 
+    local_name: Optional[str] = None
+
     admin_level: Optional[int]
     fromarea: bool
     isaddress: bool
@@ -136,6 +138,14 @@ class DetailedResult(BaseResult):
     indexed_date: Optional[dt.datetime] = None
 
 
+@dataclasses.dataclass
+class ReverseResult(BaseResult):
+    """ A search result for reverse geocoding.
+    """
+    distance: Optional[float] = None
+    bbox: Optional[Bbox] = None
+
+
 def _filter_geometries(row: SaRow) -> Dict[str, str]:
     return {k[9:]: v for k, v in row._mapping.items() # pylint: disable=W0212
             if k.startswith('geometry_')}