python: implement reverse lookup function

[nominatim.git] / nominatim / api / core.py

diff --git a/nominatim/api/core.py b/nominatim/api/core.py
index 159229dd89d67d99383787bd0ccd1a1055c8e020..116a2625c76028a4e4d3de1d9358b82b509b3653 100644 (file)
--- a/nominatim/api/core.py
+++ b/nominatim/api/core.py
@@ -7,7 +7,7 @@
 """
 Implementation of classes for API access via libraries.
 """
-from typing import Mapping, Optional, Any, AsyncIterator
+from typing import Mapping, Optional, Any, AsyncIterator, Dict
 import asyncio
 import contextlib
 from pathlib import Path
@@ -16,8 +16,15 @@ import sqlalchemy as sa
 import sqlalchemy.ext.asyncio as sa_asyncio
 import asyncpg
 
+from nominatim.db.sqlalchemy_schema import SearchTables
 from nominatim.config import Configuration
+from nominatim.api.connection import SearchConnection
 from nominatim.api.status import get_status, StatusResult
+from nominatim.api.lookup import get_place_by_id
+from nominatim.api.reverse import ReverseGeocoder
+from nominatim.api.types import PlaceRef, LookupDetails, AnyPoint, DataLayer
+from nominatim.api.results import DetailedResult, ReverseResult
+
 
 class NominatimAPIAsync:
     """ API loader asynchornous version.
@@ -29,6 +36,8 @@ class NominatimAPIAsync:
 
         self._engine_lock = asyncio.Lock()
         self._engine: Optional[sa_asyncio.AsyncEngine] = None
+        self._tables: Optional[SearchTables] = None
+        self._property_cache: Dict[str, Any] = {'DB:server_version': 0}
 
 
     async def setup_database(self) -> None:
@@ -61,18 +70,21 @@ class NominatimAPIAsync:
             try:
                 async with engine.begin() as conn:
                     result = await conn.scalar(sa.text('SHOW server_version_num'))
-                    self.server_version = int(result)
+                    server_version = int(result)
             except asyncpg.PostgresError:
-                self.server_version = 0
+                server_version = 0
 
-            if self.server_version >= 110000:
-                @sa.event.listens_for(engine.sync_engine, "connect") # type: ignore[misc]
+            if server_version >= 110000:
+                @sa.event.listens_for(engine.sync_engine, "connect")
                 def _on_connect(dbapi_con: Any, _: Any) -> None:
                     cursor = dbapi_con.cursor()
                     cursor.execute("SET jit_above_cost TO '-1'")
                 # Make sure that all connections get the new settings
                 await self.close()
 
+            self._property_cache['DB:server_version'] = server_version
+
+            self._tables = SearchTables(sa.MetaData(), engine.name) # pylint: disable=no-member
             self._engine = engine
 
 
@@ -86,7 +98,7 @@ class NominatimAPIAsync:
 
 
     @contextlib.asynccontextmanager
-    async def begin(self) -> AsyncIterator[sa_asyncio.AsyncConnection]:
+    async def begin(self) -> AsyncIterator[SearchConnection]:
         """ Create a new connection with automatic transaction handling.
 
             This function may be used to get low-level access to the database.
@@ -97,9 +109,10 @@ class NominatimAPIAsync:
             await self.setup_database()
 
         assert self._engine is not None
+        assert self._tables is not None
 
         async with self._engine.begin() as conn:
-            yield conn
+            yield SearchConnection(conn, self._tables, self._property_cache)
 
 
     async def status(self) -> StatusResult:
@@ -114,6 +127,40 @@ class NominatimAPIAsync:
         return status
 
 
+    async def lookup(self, place: PlaceRef,
+                     details: Optional[LookupDetails] = None) -> Optional[DetailedResult]:
+        """ Get detailed information about a place in the database.
+
+            Returns None if there is no entry under the given ID.
+        """
+        async with self.begin() as conn:
+            return await get_place_by_id(conn, place, details or LookupDetails())
+
+
+    async def reverse(self, coord: AnyPoint, max_rank: Optional[int] = None,
+                      layer: Optional[DataLayer] = None,
+                      details: Optional[LookupDetails] = None) -> Optional[ReverseResult]:
+        """ Find a place by its coordinates. Also known as reverse geocoding.
+
+            Returns the closest result that can be found or None if
+            no place matches the given criteria.
+        """
+        # The following negation handles NaN correctly. Don't change.
+        if not abs(coord[0]) <= 180 or not abs(coord[1]) <= 90:
+            # There are no results to be expected outside valid coordinates.
+            return None
+
+        if layer is None:
+            layer = DataLayer.ADDRESS | DataLayer.POI
+
+        max_rank = max(0, min(max_rank or 30, 30))
+
+        async with self.begin() as conn:
+            geocoder = ReverseGeocoder(conn, max_rank, layer,
+                                       details or LookupDetails())
+            return await geocoder.lookup(coord)
+
+
 class NominatimAPI:
     """ API loader, synchronous version.
     """
@@ -133,7 +180,32 @@ class NominatimAPI:
         self._loop.close()
 
 
+    @property
+    def config(self) -> Configuration:
+        """ Return the configuration used by the API.
+        """
+        return self._async_api.config
+
     def status(self) -> StatusResult:
         """ Return the status of the database.
         """
         return self._loop.run_until_complete(self._async_api.status())
+
+
+    def lookup(self, place: PlaceRef,
+               details: Optional[LookupDetails] = None) -> Optional[DetailedResult]:
+        """ Get detailed information about a place in the database.
+        """
+        return self._loop.run_until_complete(self._async_api.lookup(place, details))
+
+
+    def reverse(self, coord: AnyPoint, max_rank: Optional[int] = None,
+                layer: Optional[DataLayer] = None,
+                details: Optional[LookupDetails] = None) -> Optional[ReverseResult]:
+        """ Find a place by its coordinates. Also known as reverse geocoding.
+
+            Returns the closest result that can be found or None if
+            no place matches the given criteria.
+        """
+        return self._loop.run_until_complete(
+                   self._async_api.reverse(coord, max_rank, layer, details))