local output = osm2pgsql.define_table({
    name = 'osm_nature_features',
    schema = 'nature_next',
    ids = {
        type = 'any',
        id_column = 'osm_id',
        type_column = 'osm_type',
        create_index = 'always'
    },
    columns = {
        { column = 'name', type = 'text' },
        { column = 'tags', type = 'jsonb', not_null = true },
        { column = 'geom', type = 'geometry', projection = 4326, not_null = true },
        {
            column = 'area_m2',
            create_only = true,
            sql_type = [[double precision GENERATED ALWAYS AS (
                CASE
                    WHEN GeometryType(geom) IN ('POLYGON', 'MULTIPOLYGON')
                    THEN ST_Area(geom::geography)
                    ELSE NULL
                END
            ) STORED]]
        }
    }
})

local named_values = {
    amenity = { grave_yard = true },
    boundary = { forest = true, national_park = true, protected_area = true },
    landuse = { cemetery = true, forest = true, recreation_ground = true },
    leisure = { garden = true, nature_reserve = true, park = true },
    mountain_pass = { yes = true },
    place = { archipelago = true, island = true, islet = true },
    tourism = { viewpoint = true },
    water = {
        lake = true,
        lagoon = true,
        oxbow = true,
        pond = true,
        rapids = true,
        reservoir = true,
        river = true,
        stream = true,
        stream_pool = true
    },
    waterway = {
        rapids = true,
        river = true,
        stream = true,
        tidal_channel = true,
        waterfall = true
    }
}

local unnamed_natural = {
    arch = true,
    arete = true,
    atoll = true,
    bay = true,
    beach = true,
    blowhole = true,
    cape = true,
    cave = true,
    cave_entrance = true,
    cliff = true,
    coastline = true,
    crevasse = true,
    dune = true,
    fumarole = true,
    geyser = true,
    gorge = true,
    hill = true,
    hot_spring = true,
    isthmus = true,
    peak = true,
    peninsula = true,
    reef = true,
    ridge = true,
    rock = true,
    saddle = true,
    shoal = true,
    sinkhole = true,
    spring = true,
    stone = true,
    strait = true,
    valley = true,
    volcano = true,
    waterfall = true
}

local unnamed_geological = {
    fault = true,
    giants_kettle = true,
    glacial_erratic = true,
    geotope = true,
    inselberg = true,
    landslide = true,
    limestone_pavement = true,
    meteor_crater = true,
    moraine = true,
    nunatak = true,
    outcrop = true,
    palaeontological_site = true,
    rock_glacier = true,
    volcanic_caldera_rim = true,
    volcanic_lava_field = true,
    volcanic_lava_flow = true,
    volcanic_lava_tube = true,
    volcanic_vent = true
}

local function has_name(tags)
    return tags.name ~= nil and tags.name ~= ''
end

local function matches_values(tags, catalogue)
    for key, values in pairs(catalogue) do
        if tags[key] ~= nil and values[tags[key]] then
            return true
        end
    end
    return false
end

local function is_interesting(tags)
    if has_name(tags) then
        if tags.natural ~= nil or tags.geological ~= nil then
            return true
        end
        return matches_values(tags, named_values)
    end

    if tags.natural ~= nil and unnamed_natural[tags.natural] then
        return true
    end
    if tags.geological ~= nil and unnamed_geological[tags.geological] then
        return true
    end
    return matches_values(tags, {
        mountain_pass = named_values.mountain_pass,
        tourism = named_values.tourism,
        water = { rapids = true, stream_pool = true },
        waterway = { rapids = true, waterfall = true }
    })
end

local function insert_feature(object, geometry)
    if geometry == nil or geometry:is_null() then
        return
    end
    output:insert({
        name = object.tags.name,
        tags = object.tags,
        geom = geometry
    })
end

function osm2pgsql.process_node(object)
    if is_interesting(object.tags) then
        insert_feature(object, object:as_point())
    end
end

function osm2pgsql.process_way(object)
    if not is_interesting(object.tags) then
        return
    end
    if object.is_closed then
        insert_feature(object, object:as_polygon())
    else
        insert_feature(object, object:as_linestring())
    end
end

function osm2pgsql.process_relation(object)
    if not is_interesting(object.tags) then
        return
    end
    if object.tags.type == 'multipolygon' or object.tags.type == 'boundary' then
        insert_feature(object, object:as_multipolygon())
    elseif object.tags.type == 'route' then
        insert_feature(object, object:as_multilinestring())
    else
        insert_feature(object, object:as_geometrycollection())
    end
end