Add state from Natural Earth

schema/layers/state.sql

@@ -0,0 +1,44 @@
+CREATE TABLE IF NOT EXISTS state_label AS (
+    SELECT topoint(geom) AS geom,
+           name_local, fix_win1252_shp_encoding(name) AS name_en,
+           abbrev, postal,
+           scalerank, labelrank,
+           shape_area, datarank, type
+    FROM ne_10m_admin_1_states_provinces_shp
+    WHERE type IN ('State', 'Avtonomnyy Okrug', 'Sheng', 'Estado')
+    AND scalerank <= 3 AND labelrank <= 2
+);
+CREATE INDEX IF NOT EXISTS state_label_geom_idx ON state_label USING gist(geom);
+
+CREATE OR REPLACE FUNCTION fix_win1252_shp_encoding(str TEXT) RETURNS TEXT
+AS $$
+BEGIN
+    RETURN convert_from(convert_to(str, 'WIN1252'), 'UTF-8');
+    EXCEPTION WHEN others THEN RETURN str;
+END;
+$$ LANGUAGE plpgsql IMMUTABLE;
+
+CREATE OR REPLACE VIEW state_z3 AS (
+    SELECT * FROM state_label
+    WHERE (scalerank <= 2 AND labelrank <= 1) OR type = 'Avtonomnyy Okrug'
+);
+
+CREATE OR REPLACE VIEW state_z4 AS (
+    SELECT * FROM state_label
+);
+
+CREATE OR REPLACE FUNCTION layer_state(bbox geometry, zoom_level int)
+RETURNS TABLE(geom geometry, name text, name_en text, abbrev text, postal text, scalerank int, labelrank int) AS $$
+    WITH zoom_levels AS (
+        SELECT * FROM state_z3
+        WHERE zoom_level = 3
+        UNION ALL
+        SELECT * FROM state_z4
+        WHERE zoom_level >= 4
+    )
+    SELECT geom,
+    COALESCE(name_local, name_en) AS name_local, name_en,
+    abbrev, postal, scalerank::int, labelrank::int FROM zoom_levels
+    WHERE geom && bbox
+    ORDER BY scalerank ASC, labelrank ASC, shape_area DESC;
+$$ LANGUAGE SQL IMMUTABLE;