mcl_structures.registered_structures = {}

function mcl_structures.place_structure(pos, def, pr)
	if not def then	return end
	local logging = not def.terrain_feature
	local y_offset = 0
	if type(def.y_offset) == "function" then
		y_offset = def.y_offset(pr)
	elseif def.y_offset then
		y_offset = def.y_offset
	end
	local pp = vector.offset(pos,0,y_offset,0)
	if def.solid_ground and def.sidelen then
		local bn = minetest.get_biome_name(minetest.get_biome_data(pos).biome)
		local node_top = minetest.registered_biomes[bn].node_top
		local node_fill = minetest.registered_biomes[bn].node_filler
		local ground_p1 = vector.offset(pos,-def.sidelen/2,-1,-def.sidelen/2)
		local ground_p2 = vector.offset(pos,def.sidelen/2,-1,def.sidelen/2)
		local solid = minetest.find_nodes_in_area(ground_p1,ground_p2,{"group:solid"})
		if #solid < ( def.sidelen * def.sidelen ) then
			if def.make_foundation then
				minetest.bulk_set_node(minetest.find_nodes_in_area(ground_p1,ground_p2,{"air","group:liquid"}),{name=node_top})
				minetest.bulk_set_node(minetest.find_nodes_in_area(vector.offset(ground_p1,0,-1,0),vector.offset(ground_p2,0,-30,0),{"air","group:liquid"}),{name=node_fill})
			else
				if logging then
					minetest.log("warning","[mcl_structures] "..def.name.." at "..minetest.pos_to_string(pos).." not placed. No solid ground.")
				end
				return false
			end
		end
	end
	if def.on_place and not def.on_place(pos,def,pr) then
		if logging then
			minetest.log("warning","[mcl_structures] "..def.name.." at "..minetest.pos_to_string(pos).." not placed. Conditions not satisfied.")
		end
		return false
	end
	if def.filenames then
		table.shuffle(def.filenames)
		local file = def.filenames[1]
		if file then
			local ap = function(pos,def,pr) end
			if def.after_place then ap = def.after_place  end

			mcl_structures.place_schematic(pp, file, "random", nil, true, "place_center_x,place_center_z",function(p) return ap(pos,def,pr) end,pr)
			if logging then
				minetest.log("action","[mcl_structures] "..def.name.." placed at "..minetest.pos_to_string(pos))
			end
			return true
		end
	elseif def.place_func and def.place_func(pos,def,pr) then
		if not def.after_place or ( def.after_place  and def.after_place(pos,def,pr) ) then
			if logging then
				minetest.log("action","[mcl_structures] "..def.name.." placed at "..minetest.pos_to_string(pos))
			end
			return true
		end
	end
	if logging then
		minetest.log("warning","[mcl_structures] placing "..def.name.." failed at "..minetest.pos_to_string(pos))
	end
end

function mcl_structures.register_structure(name,def,nospawn) --nospawn means it will be placed by another (non-nospawn) structure that contains it's structblock i.e. it will not be placed by mapgen directly
	local structblock = "mcl_structures:structblock_"..name
	local flags = "place_center_x, place_center_z, force_placement"
	local y_offset = 0
	local sbgroups = { structblock = 1, not_in_creative_inventory=1 }
	if def.flags then flags = def.flags end
	def.name = name
	if nospawn then
		sbgroups.structblock = nil
		sbgroups.structblock_lbm = 1
	else
		minetest.register_on_mods_loaded(function() --make sure all previous decorations and biomes have been registered
			def.deco = minetest.register_decoration({
				name = "mcl_structures:deco_"..name,
				decoration = structblock,
				deco_type = "simple",
				place_on = def.place_on,
				spawn_by = def.spawn_by,
				num_spawn_by = def.num_spawn_by,
				sidelen = 80,
				fill_ratio = def.fill_ratio,
				noise_params = def.noise_params,
				flags = flags,
				biomes = def.biomes,
				y_max = def.y_max,
				y_min = def.y_min
			})
			def.deco_id = minetest.get_decoration_id("mcl_structures:deco_"..name)
			minetest.set_gen_notify({decoration=true}, { def.deco_id })
			--catching of gennotify happens in mcl_mapgen_core
		end)
	end
	minetest.register_node(":"..structblock, {drawtype="airlike", walkable = false, pointable = false,groups = sbgroups})
	def.structblock = structblock
	mcl_structures.registered_structures[name] = def
end

--lbm for secondary structures (structblock included in base structure)
minetest.register_lbm({
	name = "mcl_structures:struct_lbm",
	run_at_every_load = true,
	nodenames = {"group:structblock_lbm"},
	action = function(pos, node)
		minetest.remove_node(pos)
		local name = node.name:gsub("mcl_structures:structblock_","")
		local def = mcl_structures.registered_structures[name]
		if not def then return end
		mcl_structures.place_structure(pos)
	end
})