local buildings = osm2pgsql.define_area_table('buildings', {
  { column = 'osm_id', type = 'bigint', not_null = true },
  { column = 'geom', type = 'multipolygon', projection = 4326, not_null = true },
  { column = 'height_m', type = 'real', not_null = true },
  { column = 'levels', type = 'int' },
  { column = 'building_type', type = 'text' },
  { column = 'source', type = 'text', not_null = true },
})

local function parse_number(value)
  if value == nil then
    return nil
  end
  local normalized = tostring(value):gsub(',', '.')
  local number = normalized:match('[-+]?%d+%.?%d*')
  if number == nil then
    return nil
  end
  return tonumber(number)
end

local function default_height(building_type)
  if building_type == 'garage' or building_type == 'garages' or building_type == 'shed' then
    return 3.0
  end
  if building_type == 'industrial' or building_type == 'warehouse' then
    return 8.0
  end
  if building_type == 'church' or building_type == 'cathedral' then
    return 12.0
  end
  return 9.0
end

local function building_height(tags)
  local height = parse_number(tags.height)
  if height ~= nil and height > 0 then
    return height, parse_number(tags['building:levels']), 'measured'
  end

  local levels = parse_number(tags['building:levels'])
  if levels ~= nil and levels > 0 then
    return levels * 3.0, levels, 'estimated'
  end

  return default_height(tags.building), nil, 'estimated'
end

local function add_building(object, geom)
  if object.tags.building == nil or object.tags.building == 'no' then
    return
  end

  local height_m, levels, source = building_height(object.tags)
  buildings:add_row({
    osm_id = object.id,
    geom = geom,
    height_m = height_m,
    levels = levels,
    building_type = object.tags.building,
    source = source,
  })
end

function osm2pgsql.process_way(object)
  if object.is_closed then
    add_building(object, object:as_multipolygon())
  end
end

function osm2pgsql.process_relation(object)
  if object.tags.type == 'multipolygon' or object.tags.type == 'boundary' then
    add_building(object, object:as_multipolygon())
  end
end