-- For documentation of Lua tag transformations, see docs/lua.md.

-- Objects with any of the following keys will be treated as polygon
polygon_keys = { 'building', 'landuse', 'amenity', 'harbour', 'historic', 'leisure', 
      'man_made', 'military', 'natural', 'office', 'place', 'power',
      'public_transport', 'shop', 'sport', 'tourism', 'waterway',
      'wetland', 'water', 'aeroway' }

-- Objects without any of the following keys will be deleted
generic_keys = {'access','addr:housename','addr:housenumber','addr:interpolation','admin_level','aerialway','aeroway','amenity','area','barrier',
   'bicycle','brand','bridge','boundary','building','capital','construction','covered','culvert','cutting','denomination','disused','ele',
   'embarkment','foot','generation:source','harbour','highway','historic','hours','intermittent','junction','landuse','layer','leisure','lock',
   'man_made','military','motor_car','name','natural','office','oneway','operator','place','poi','population','power','power_source','public_transport',
   'railway','ref','religion','route','service','shop','sport','surface','toll','tourism','tower:type', 'tracktype','tunnel','water','waterway',
   'wetland','width','wood','type'}

-- The following keys will be deleted
delete_tags = { 'FIXME', 'note', 'source' }

-- Array used to specify z_order per key/value combination.
-- Each element has the form {key, value, z_order, is_road}.
-- If is_road=1, the object will be added to planet_osm_roads.
zordering_tags = {{ 'railway', nil, 5, 1}, { 'boundary', 'administrative', 0, 1}, 
   { 'bridge', 'yes', 10, 0 }, { 'bridge', 'true', 10, 0 }, { 'bridge', 1, 10, 0 },
   { 'tunnel', 'yes', -10, 0}, { 'tunnel', 'true', -10, 0}, { 'tunnel', 1, -10, 0}, 
   { 'highway', 'minor', 3, 0}, { 'highway', 'road', 3, 0 }, { 'highway', 'unclassified', 3, 0 },
   { 'highway', 'residential', 3, 0 }, { 'highway', 'tertiary_link', 4, 0}, { 'highway', 'tertiary', 4, 0},
   { 'highway', 'secondary_link', 6, 1}, { 'highway', 'secondary', 6, 1},
   { 'highway', 'primary_link', 7, 1}, { 'highway', 'primary', 7, 1},
   { 'highway', 'trunk_link', 8, 1}, { 'highway', 'trunk', 8, 1},
   { 'highway', 'motorway_link', 9, 1}, { 'highway', 'motorway', 9, 1},
}

function add_z_order(keyvalues)
   -- The default z_order is 0
   z_order = 0

   -- Add the value of the layer key times 10 to z_order
   if (keyvalues["layer"] ~= nil and tonumber(keyvalues["layer"])) then
      z_order = 10*keyvalues["layer"]
   end

   -- Increase or decrease z_order based on the specific key/value combination as specified in zordering_tags
   for i,k in ipairs(zordering_tags) do
      -- If the value in zordering_tags is specified, match key and value. Otherwise, match key only.
      if ((k[2]  and keyvalues[k[1]] == k[2]) or (k[2] == nil and keyvalues[k[1]] ~= nil)) then
         -- If the fourth component of the element of zordering_tags is 1, add the object to planet_osm_roads
         if (k[4] == 1) then
            roads = 1
         end
         z_order = z_order + k[3]
      end
   end

   -- Add z_order as key/value combination
   keyvalues["z_order"] = z_order

   return keyvalues, roads
end

-- Filtering on nodes, ways, and relations
function filter_tags_generic(keyvalues, numberofkeys)
   filter = 0   -- Will object be filtered out?

   -- Filter out objects with 0 tags
   if numberofkeys == 0 then
      filter = 1
      return filter, keyvalues
   end

   -- Delete tags listed in delete_tags
   for i,k in ipairs(delete_tags) do
      keyvalues[k] = nil
   end
   
   -- Filter out objects that do not have any of the keys in generic_keys
   tagcount = 0
   for k,v in pairs(keyvalues) do
      for i, k2 in ipairs(generic_keys) do if k2 == k then tagcount = tagcount + 1; end end
   end
   if tagcount == 0 then
      filter = 1
   end

   return filter, keyvalues
end

-- Filtering on nodes
function filter_tags_node (keyvalues, numberofkeys)
   return filter_tags_generic(keyvalues, numberofkeys)
end

-- Filtering on relations
function filter_basic_tags_rel (keyvalues, numberofkeys)
   -- Filter out objects that are filtered out by filter_tags_generic
   filter, keyvalues = filter_tags_generic(keyvalues, numberofkeys)
   if filter == 1 then
      return filter, keyvalues
   end

   -- Filter out all relations except route, multipolygon and boundary relations
   if ((keyvalues["type"] ~= "route") and (keyvalues["type"] ~= "multipolygon") and (keyvalues["type"] ~= "boundary")) then
      filter = 1
      return filter, keyvalues
   end

   return filter, keyvalues
end

-- Filtering on ways
function filter_tags_way (keyvalues, numberofkeys)
   filter = 0  -- Will object be filtered out?
   polygon = 0 -- Will object be treated as polygon?
   roads = 0   -- Will object be added to planet_osm_roads?

   -- Filter out objects that are filtered out by filter_tags_generic
   filter, keyvalues = filter_tags_generic(keyvalues, numberofkeys)
   if filter == 1 then
      return filter, keyvalues, polygon, roads
   end

  -- Treat objects with a key in polygon_keys as polygon
   for i,k in ipairs(polygon_keys) do
      if keyvalues[k] then
         polygon=1
         break
      end
   end
   
   -- Treat objects tagged as area=yes, area=1, or area=true as polygon,
   -- and treat objects tagged as area=no, area=0, or area=false not as polygon
   if ((keyvalues["area"] == "yes") or (keyvalues["area"] == "1") or (keyvalues["area"] == "true")) then
      polygon = 1;
   elseif ((keyvalues["area"] == "no") or (keyvalues["area"] == "0") or (keyvalues["area"] == "false")) then
      polygon = 0;
   end

   -- Add z_order key/value combination and determine if the object should also be added to planet_osm_roads
   keyvalues, roads = add_z_order(keyvalues)

   return filter, keyvalues, polygon, roads
end

function filter_tags_relation_member (keyvalues, keyvaluemembers, roles, membercount)
   filter = 0     -- Will object be filtered out?
   linestring = 0 -- Will object be treated as linestring?
   polygon = 0    -- Will object be treated as polygon?
   roads = 0      -- Will object be added to planet_osm_roads?
   membersuperseded = {}
   for i = 1, membercount do
      membersuperseded[i] = 0 -- Will member be ignored when handling areas?
   end

   type = keyvalues["type"]

   -- Remove type key
   keyvalues["type"] = nil
  
   -- Relations with type=boundary are treated as linestring
   if (type == "boundary") then
      linestring = 1
   end
   -- Relations with type=multipolygon and boundary=* are treated as linestring
   if ((type == "multipolygon") and keyvalues["boundary"]) then
      linestring = 1
   -- For multipolygons...
   elseif (type == "multipolygon") then
      -- Treat as polygon
      polygon = 1
      polytagcount = 0;
      -- Count the number of polygon tags of the object
      for i,k in ipairs(polygon_keys) do
         if keyvalues[k] then
            polytagcount = polytagcount + 1
         end
      end
      -- If there are no polygon tags, add tags from all outer elements to the multipolygon itself
      if (polytagcount == 0) then
         for i = 1,membercount do
            if (roles[i] == "outer") then
               for k,v in pairs(keyvaluemembers[i]) do
                  keyvalues[k] = v
               end
            end
         end
      end
      -- For any member of the multipolygon, set membersuperseded to 1 (i.e. don't deal with it as area as well),
      -- except when the member has a key/value combination such that
      --   1) the key occurs in generic_keys
      --   2) the key/value combination is not also a key/value combination of the multipolygon itself
      for i = 1,membercount do
         superseded = 1
         for k,v in pairs(keyvaluemembers[i]) do
            if ((keyvalues[k] == nil) or (keyvalues[k] ~= v)) then
               for j,k2 in ipairs(generic_keys) do
                  if (k == k2) then
                     superseded = 0;
                     break
                  end
               end
            end
         end
         membersuperseded[i] = superseded
      end
   end

   -- Add z_order key/value combination and determine if the object should also be added to planet_osm_roads
   keyvalues, roads = add_z_order(keyvalues)

   return filter, keyvalues, membersuperseded, linestring, polygon, roads
end
