Introduce landuse classes

layers/landuse/landuse.sql

@@ -1,46 +1,57 @@
+CREATE OR REPLACE FUNCTION landuse_class(landuse TEXT, amenity TEXT) RETURNS TEXT AS $$
+    SELECT CASE
+         WHEN amenity IN ('school', 'university', 'kindergarten', 'college', 'library') THEN 'school'
+         WHEN landuse IN('hospital', 'railway', 'cemetery', 'military', 'residential') THEN landuse
+        ELSE NULL
+	 END;
+$$ LANGUAGE SQL IMMUTABLE;
+
 CREATE OR REPLACE VIEW landuse_z4 AS (
-    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, scalerank
+    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, NULL::text AS amenity, scalerank
     FROM ne_50m_urban_areas
     WHERE scalerank <= 2
 );
 
 CREATE OR REPLACE VIEW landuse_z5 AS (
-    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, scalerank
+    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, NULL::text AS amenity, scalerank
     FROM ne_50m_urban_areas
 );
 
 CREATE OR REPLACE VIEW landuse_z6 AS (
-    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, scalerank
+    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, NULL::text AS amenity, scalerank
     FROM ne_10m_urban_areas
 );
 
 CREATE OR REPLACE VIEW landuse_z10 AS (
-    SELECT osm_id, geometry, landuse, NULL::int as scalerank FROM osm_landuse_polygon_gen2
+    SELECT osm_id, geometry, landuse, amenity, NULL::int as scalerank FROM osm_landuse_polygon_gen2
     WHERE ST_Area(geometry) > 1200000
 );
 
 CREATE OR REPLACE VIEW landuse_z11 AS (
-    SELECT osm_id, geometry, landuse, NULL::int as scalerank FROM osm_landuse_polygon_gen2
+    SELECT osm_id, geometry, landuse, amenity, NULL::int as scalerank FROM osm_landuse_polygon_gen2
     WHERE ST_Area(geometry) > 480000
 );
 
 CREATE OR REPLACE VIEW landuse_z12 AS (
-    SELECT osm_id, geometry, landuse, NULL::int as scalerank FROM osm_landuse_polygon_gen1
+    SELECT osm_id, geometry, landuse, amenity, NULL::int as scalerank FROM osm_landuse_polygon_gen1
     WHERE ST_Area(geometry) > 240000
 );
 
 CREATE OR REPLACE VIEW landuse_z13 AS (
-    SELECT osm_id, geometry, landuse, NULL::int as scalerank FROM osm_landuse_polygon
+    SELECT osm_id, geometry, landuse, amenity, NULL::int as scalerank FROM osm_landuse_polygon
     WHERE ST_Area(geometry) > 60000
 );
 
 CREATE OR REPLACE VIEW landuse_z14 AS (
-    SELECT osm_id, geometry, landuse, NULL::int as scalerank FROM osm_landuse_polygon
+    SELECT osm_id, geometry, landuse, amenity, NULL::int as scalerank FROM osm_landuse_polygon
 );
 
 CREATE OR REPLACE FUNCTION layer_landuse(bbox geometry, zoom_level int)
-RETURNS TABLE(osm_id bigint, geometry geometry, landuse text) AS $$
-    SELECT osm_id, geometry, landuse FROM (
+RETURNS TABLE(osm_id bigint, geometry geometry, class text, subclass text) AS $$
+    SELECT osm_id, geometry,
+        landuse_class(landuse, amenity) AS class,
+        COALESCE(NULLIF(landuse, ''), NULLIF(amenity, '')) AS subclass
+        FROM (
         SELECT * FROM landuse_z4
         WHERE zoom_level = 4
         UNION ALL