CREATE OR REPLACE FUNCTION waterway_brunnel(is_bridge bool, is_tunnel bool) RETURNS text AS
$$
SELECT CASE
           WHEN is_bridge THEN 'bridge'
           WHEN is_tunnel THEN 'tunnel'
           END;
$$ LANGUAGE SQL IMMUTABLE
                STRICT
                PARALLEL SAFE;

-- etldoc: ne_110m_rivers_lake_centerlines ->  waterway_z3
CREATE OR REPLACE VIEW waterway_z3 AS
(
SELECT geometry,
       'river'::text AS class,
       NULL::text    AS name,
       NULL::text    AS name_en,
       NULL::text    AS name_de,
       NULL::hstore  AS tags,
       NULL::boolean AS is_bridge,
       NULL::boolean AS is_tunnel,
       NULL::boolean AS is_intermittent
FROM ne_110m_rivers_lake_centerlines
WHERE featurecla = 'River'
    );

-- etldoc: ne_50m_rivers_lake_centerlines ->  waterway_z4
CREATE OR REPLACE VIEW waterway_z4 AS
(
SELECT geometry,
       'river'::text AS class,
       NULL::text    AS name,
       NULL::text    AS name_en,
       NULL::text    AS name_de,
       NULL::hstore  AS tags,
       NULL::boolean AS is_bridge,
       NULL::boolean AS is_tunnel,
       NULL::boolean AS is_intermittent
FROM ne_50m_rivers_lake_centerlines
WHERE featurecla = 'River'
    );

-- etldoc: ne_10m_rivers_lake_centerlines ->  waterway_z6
CREATE OR REPLACE VIEW waterway_z6 AS
(
SELECT geometry,
       'river'::text AS class,
       NULL::text    AS name,
       NULL::text    AS name_en,
       NULL::text    AS name_de,
       NULL::hstore  AS tags,
       NULL::boolean AS is_bridge,
       NULL::boolean AS is_tunnel,
       NULL::boolean AS is_intermittent
FROM ne_10m_rivers_lake_centerlines
WHERE featurecla = 'River'
    );

-- etldoc: osm_important_waterway_linestring_gen3 ->  waterway_z9
CREATE OR REPLACE VIEW waterway_z9 AS
(
SELECT geometry,
       'river'::text AS class,
       name,
       name_en,
       name_de,
       tags,
       NULL::boolean AS is_bridge,
       NULL::boolean AS is_tunnel,
       NULL::boolean AS is_intermittent
FROM osm_important_waterway_linestring_gen3
    );

-- etldoc: osm_important_waterway_linestring_gen2 ->  waterway_z10
CREATE OR REPLACE VIEW waterway_z10 AS
(
SELECT geometry,
       'river'::text AS class,
       name,
       name_en,
       name_de,
       tags,
       NULL::boolean AS is_bridge,
       NULL::boolean AS is_tunnel,
       NULL::boolean AS is_intermittent
FROM osm_important_waterway_linestring_gen2
    );

-- etldoc:osm_important_waterway_linestring_gen1 ->  waterway_z11
CREATE OR REPLACE VIEW waterway_z11 AS
(
SELECT geometry,
       'river'::text AS class,
       name,
       name_en,
       name_de,
       tags,
       NULL::boolean AS is_bridge,
       NULL::boolean AS is_tunnel,
       NULL::boolean AS is_intermittent
FROM osm_important_waterway_linestring_gen1
    );

-- etldoc: osm_waterway_linestring ->  waterway_z12
CREATE OR REPLACE VIEW waterway_z12 AS
(
SELECT geometry,
       waterway::text AS class,
       name,
       name_en,
       name_de,
       tags,
       is_bridge,
       is_tunnel,
       is_intermittent
FROM osm_waterway_linestring
WHERE waterway IN ('river', 'canal')
    );

-- etldoc: osm_waterway_linestring ->  waterway_z13
CREATE OR REPLACE VIEW waterway_z13 AS
(
SELECT geometry,
       waterway::text AS class,
       name,
       name_en,
       name_de,
       tags,
       is_bridge,
       is_tunnel,
       is_intermittent
FROM osm_waterway_linestring
WHERE waterway IN ('river', 'canal', 'stream', 'drain', 'ditch')
    );

-- etldoc: osm_waterway_linestring ->  waterway_z14
CREATE OR REPLACE VIEW waterway_z14 AS
(
SELECT geometry,
       waterway::text AS class,
       name,
       name_en,
       name_de,
       tags,
       is_bridge,
       is_tunnel,
       is_intermittent
FROM osm_waterway_linestring
    );

-- etldoc: layer_waterway[shape=record fillcolor=lightpink, style="rounded,filled",
-- etldoc:     label="layer_waterway | <z3> z3 |<z4_5> z4-z5 |<z6_8> z6-8 | <z9> z9 |<z10> z10 |<z11> z11 |<z12> z12|<z13> z13|<z14> z14+" ];

CREATE OR REPLACE FUNCTION layer_waterway(bbox geometry, zoom_level int)
    RETURNS TABLE
            (
                geometry     geometry,
                class        text,
                name         text,
                name_en      text,
                name_de      text,
                brunnel      text,
                intermittent int,
                tags         hstore
            )
AS
$$
SELECT geometry,
       class,
       NULLIF(name, '')                             AS name,
       COALESCE(NULLIF(name_en, ''), name)          AS name_en,
       COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
       waterway_brunnel(is_bridge, is_tunnel)       AS brunnel,
       is_intermittent::int                         AS intermittent,
       tags
FROM (
         -- etldoc: waterway_z3 ->  layer_waterway:z3
         SELECT *
         FROM waterway_z3
         WHERE zoom_level = 3
         UNION ALL
         -- etldoc: waterway_z4 ->  layer_waterway:z4_5
         SELECT *
         FROM waterway_z4
         WHERE zoom_level BETWEEN 4 AND 5
         UNION ALL
         -- etldoc: waterway_z6 ->  layer_waterway:z6_8
         SELECT *
         FROM waterway_z6
         WHERE zoom_level BETWEEN 6 AND 8
         UNION ALL
         -- etldoc: waterway_z9 ->  layer_waterway:z9
         SELECT *
         FROM waterway_z9
         WHERE zoom_level = 9
         UNION ALL
         -- etldoc: waterway_z10 ->  layer_waterway:z10
         SELECT *
         FROM waterway_z10
         WHERE zoom_level = 10
         UNION ALL
         -- etldoc: waterway_z11 ->  layer_waterway:z11
         SELECT *
         FROM waterway_z11
         WHERE zoom_level = 11
         UNION ALL
         -- etldoc: waterway_z12 ->  layer_waterway:z12
         SELECT *
         FROM waterway_z12
         WHERE zoom_level = 12
         UNION ALL
         -- etldoc: waterway_z13 ->  layer_waterway:z13
         SELECT *
         FROM waterway_z13
         WHERE zoom_level = 13
         UNION ALL
         -- etldoc: waterway_z14 ->  layer_waterway:z14
         SELECT *
         FROM waterway_z14
         WHERE zoom_level >= 14
     ) AS zoom_levels
WHERE geometry && bbox;
$$ LANGUAGE SQL STABLE
                -- STRICT
                PARALLEL SAFE;