add server glue for reverse API call

nominatim/api/v1/server_glue.py

@@ -8,7 +8,7 @@
 Generic part of the server implementation of the v1 API.
 Combine with the scaffolding provided for the various Python ASGI frameworks.
 """
-from typing import Optional, Any, Type, Callable, NoReturn
+from typing import Optional, Any, Type, Callable, NoReturn, TypeVar
 import abc
 
 from nominatim.config import Configuration
@@ -22,6 +22,7 @@ CONTENT_TYPE = {
   'debug': 'text/html; charset=utf-8'
 }
 
+ConvT = TypeVar('ConvT', int, float)
 
 class ASGIAdaptor(abc.ABC):
     """ Adapter class for the different ASGI frameworks.
@@ -106,9 +107,10 @@ class ASGIAdaptor(abc.ABC):
         raise self.error(msg, status)
 
 
-    def get_int(self, name: str, default: Optional[int] = None) -> int:
-        """ Return an input parameter as an int. Raises an exception if
-            the parameter is given but not in an integer format.
+    def _get_typed(self, name: str, dest_type: Type[ConvT], type_name: str,
+                   default: Optional[ConvT] = None) -> ConvT:
+        """ Return an input parameter as the type 'dest_type'. Raises an
+            exception if the parameter is given but not in the given format.
 
             If 'default' is given, then it will be returned when the parameter
             is missing completely. When 'default' is None, an error will be
@@ -123,12 +125,35 @@ class ASGIAdaptor(abc.ABC):
             self.raise_error(f"Parameter '{name}' missing.")
 
         try:
-            intval = int(value)
+            intval = dest_type(value)
         except ValueError:
-            self.raise_error(f"Parameter '{name}' must be a number.")
+            self.raise_error(f"Parameter '{name}' must be a {type_name}.")
 
         return intval
 
+
+    def get_int(self, name: str, default: Optional[int] = None) -> int:
+        """ Return an input parameter as an int. Raises an exception if
+            the parameter is given but not in an integer format.
+
+            If 'default' is given, then it will be returned when the parameter
+            is missing completely. When 'default' is None, an error will be
+            raised on a missing parameter.
+        """
+        return self._get_typed(name, int, 'number', default)
+
+
+    def get_float(self, name: str, default: Optional[float] = None) -> int:
+        """ Return an input parameter as a flaoting-point number. Raises an
+            exception if the parameter is given but not in an float format.
+
+            If 'default' is given, then it will be returned when the parameter
+            is missing completely. When 'default' is None, an error will be
+            raised on a missing parameter.
+        """
+        return self._get_typed(name, float, 'number', default)
+
+
     def get_bool(self, name: str, default: Optional[bool] = None) -> bool:
         """ Return an input parameter as bool. Only '0' is accepted as
             an input for 'false' all other inputs will be interpreted as 'true'.
@@ -169,6 +194,17 @@ class ASGIAdaptor(abc.ABC):
         return False
 
 
+    def get_layers(self) -> napi.DataLayer:
+        """ Return a parsed version of the layer parameter.
+        """
+        param = self.get('layer', None)
+        if param is None:
+            return None
+
+        return reduce(napi.DataLayer.__or__,
+                      (getattr(napi.DataLayer, s.upper()) for s in param.split(',')))
+
+
     def parse_format(self, result_type: Type[Any], default: str) -> str:
         """ Get and check the 'format' parameter and prepare the formatter.
             `result_type` is the type of result to be returned by the function
@@ -243,9 +279,83 @@ async def details_endpoint(api: napi.NominatimAPIAsync, params: ASGIAdaptor) ->
     return params.build_response(output)
 
 
+async def reverse_endpoint(api: napi.NominatimAPIAsync, params: ASGIAdaptor) -> Any:
+    """ Server glue for /reverse endpoint. See API docs for details.
+    """
+    fmt = params.parse_format(napi.ReverseResults, 'xml')
+    debug = params.setup_debugging()
+    coord = napi.Point(params.get_float('lon'), params.get_float('lat'))
+    locales = napi.Locales.from_accept_languages(params.get_accepted_languages())
+
+    zoom = max(0, min(18, params.get_int('zoom', 18)))
+
+    # Negation makes sure that NaN is handled. Don't change.
+    if not abs(coord[0]) <= 180 or not abs(coord[1]) <= 90:
+        params.raise_error('Invalid coordinates.')
+
+    details = napi.LookupDetails(address_details=True,
+                                 geometry_simplification=params.get_float('polygon_threshold', 0.0))
+    numgeoms = 0
+    if params.get_bool('polygon_geojson', False):
+        details.geometry_output |= napi.GeometryFormat.GEOJSON
+        numgeoms += 1
+    if fmt not in ('geojson', 'geocodejson'):
+        if params.get_bool('polygon_text', False):
+            details.geometry_output |= napi.GeometryFormat.TEXT
+            numgeoms += 1
+        if params.get_bool('polygon_kml', False):
+            details.geometry_output |= napi.GeometryFormat.KML
+            numgeoms += 1
+        if params.get_bool('polygon_svg', False):
+            details.geometry_output |= napi.GeometryFormat.SVG
+            numgeoms += 1
+
+    if numgeoms > params.config().get_int('POLYGON_OUTPUT_MAX_TYPES'):
+        params.raise_error(f'Too many polgyon output options selected.')
+
+    result = await api.reverse(coord, REVERSE_MAX_RANKS[zoom],
+                               params.get_layers() or
+                                 napi.DataLayer.ADDRESS | napi.DataLayer.POI,
+                               details)
+
+    if debug:
+        return params.build_response(loglib.get_and_disable())
+
+    fmt_options = {'locales': locales,
+                   'extratags': params.get_bool('extratags', False),
+                   'namedetails': params.get_bool('namedetails', False),
+                   'addressdetails': params.get_bool('addressdetails', True),
+                   'single_result': True}
+    if fmt == 'xml':
+        fmt_options['xml_roottag'] = 'reversegeocode'
+        fmt_options['xml_extra_info'] = {'querystring': 'TODO'}
+
+    output = formatting.format_result(napi.ReverseResults([result] if result else []),
+                                      fmt, fmt_options)
+
+    return params.build_response(output)
+
+
 EndpointFunc = Callable[[napi.NominatimAPIAsync, ASGIAdaptor], Any]
 
+REVERSE_MAX_RANKS = [2, 2, 2,   # 0-2   Continent/Sea
+                     4, 4,      # 3-4   Country
+                     8,         # 5     State
+                     10, 10,    # 6-7   Region
+                     12, 12,    # 8-9   County
+                     16, 17,    # 10-11 City
+                     18,        # 12    Town
+                     19,        # 13    Village/Suburb
+                     22,        # 14    Hamlet/Neighbourhood
+                     25,        # 15    Localities
+                     26,        # 16    Major Streets
+                     27,        # 17    Minor Streets
+                     30         # 18    Building
+                    ]
+
+
 ROUTES = [
     ('status', status_endpoint),
-    ('details', details_endpoint)
+    ('details', details_endpoint),
+    ('reverse', reverse_endpoint)
 ]

nominatim/server/falcon/server.py

@@ -7,7 +7,7 @@
 """
 Server implementation using the falcon webserver framework.
 """
-from typing import Optional, Mapping, cast
+from typing import Optional, Mapping, cast, Any
 from pathlib import Path
 
 import falcon
@@ -17,6 +17,22 @@ from nominatim.api import NominatimAPIAsync
 import nominatim.api.v1 as api_impl
 from nominatim.config import Configuration
 
+class HTTPNominatimError(Exception):
+    """ A special exception class for errors raised during processing.
+    """
+    def __init__(self, msg: str, status: int, content_type: str) -> None:
+        self.msg = msg
+        self.status = status
+        self.content_type = content_type
+
+
+async def nominatim_error_handler(req: Request, resp: Response,
+                                  exception: HTTPNominatimError,
+                                  _: Any) -> None:
+    resp.status = exception.status
+    resp.text = exception.msg
+    resp.content_type = exception.content_type
+
 
 class ParamWrapper(api_impl.ASGIAdaptor):
     """ Adaptor class for server glue to Falcon framework.
@@ -37,13 +53,8 @@ class ParamWrapper(api_impl.ASGIAdaptor):
         return cast(Optional[str], self.request.get_header(name, default=default))
 
 
-    def error(self, msg: str, status: int = 400) -> falcon.HTTPError:
-        if status == 400:
-            return falcon.HTTPBadRequest(description=msg)
-        if status == 404:
-            return falcon.HTTPNotFound(description=msg)
-
-        return falcon.HTTPError(status, description=msg)
+    def error(self, msg: str, status: int = 400) -> HTTPNominatimError:
+        return HTTPNominatimError(msg, status, self.content_type)
 
 
     def create_response(self, status: int, output: str) -> None:
@@ -78,6 +89,7 @@ def get_application(project_dir: Path,
     api = NominatimAPIAsync(project_dir, environ)
 
     app = App(cors_enable=api.config.get_bool('CORS_NOACCESSCONTROL'))
+    app.add_error_handler(HTTPNominatimError, nominatim_error_handler)
 
     legacy_urls = api.config.get_bool('SERVE_LEGACY_URLS')
     for name, func in api_impl.ROUTES:

nominatim/server/sanic/server.py

@@ -35,7 +35,10 @@ class ParamWrapper(api_impl.ASGIAdaptor):
 
 
     def error(self, msg: str, status: int = 400) -> SanicException:
-        return SanicException(msg, status_code=status)
+        exception = SanicException(msg, status_code=status)
+        exception.headers = {'content-type': self.content_type}
+
+        return exception
 
 
     def create_response(self, status: int, output: str) -> HTTPResponse:

nominatim/server/starlette/server.py

@@ -39,7 +39,8 @@ class ParamWrapper(api_impl.ASGIAdaptor):
 
 
     def error(self, msg: str, status: int = 400) -> HTTPException:
-        return HTTPException(status, detail=msg)
+        return HTTPException(status, detail=msg,
+                             headers={'content-type': self.content_type})
 
 
     def create_response(self, status: int, output: str) -> Response: