CREATE OR REPLACE VIEW landuse_z4 AS (
    SELECT NULL::bigint AS osm_id, geom AS geometry, 'residential' AS landuse, 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
    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
    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
    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
    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
    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
    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
);

CREATE OR REPLACE FUNCTION layer_landuse(bbox geometry, zoom_level int)
RETURNS TABLE(osm_id bigint, geometry geometry, landuse text) AS $$
    SELECT osm_id, geometry, landuse FROM (
        SELECT * FROM landuse_z4
        WHERE zoom_level = 4
        UNION ALL
        SELECT * FROM landuse_z5
        WHERE zoom_level = 5
        UNION ALL
        SELECT * FROM landuse_z6
        WHERE zoom_level BETWEEN 6 AND 10 AND scalerank-1 <= zoom_level
        UNION ALL
        SELECT * FROM landuse_z10 WHERE zoom_level = 10
        UNION ALL
        SELECT * FROM landuse_z11 WHERE zoom_level = 11
        UNION ALL
        SELECT * FROM landuse_z12 WHERE zoom_level = 12
        UNION ALL
        SELECT * FROM landuse_z13 WHERE zoom_level = 13
        UNION ALL
        SELECT * FROM landuse_z14 WHERE zoom_level >= 14
    ) AS zoom_levels;
$$ LANGUAGE SQL IMMUTABLE;