-- todo: move this mostly to the mcl_mobs module?
local mob_cap_player = tonumber(minetest.settings:get("mcl_mob_cap_player")) or 75
local mob_cap_animal = tonumber(minetest.settings:get("mcl_mob_cap_animal")) or 10
local mg_name = minetest.get_mapgen_setting("mg_name")
local vector_offset = vector.offset

local structure_spawns = {}
--- Structure spawns via ABM
-- @param def table: containing
--   @param name string: Name
--   @param y_min number: minimum height
--   @param y_max number: maximum height
--   @param spawnon table: Node types to spawn on, can also use group:names
--   @param biomes table: Biomes to spawn in
--   @param chance number: Spawn chance, default 5, will trigger 1/chance per-node per-interval
--   @param interval number: Spawn check interval in seconds, default 60.0
--   @param limit number: Local mob cap, default 7
function vl_structures.register_structure_spawn(def)
	minetest.register_abm({
		label = "Spawn "..def.name,
		nodenames = def.spawnon,
		min_y = def.y_min or -31000,
		max_y = def.y_max or 31000,
		interval = def.interval or 60,
		chance = def.chance or 5,
		action = function(pos, node, active_object_count, active_object_count_wider)
			-- FIXME: review this logic, legacy code
			local limit = def.limit or 7
			if active_object_count_wider > limit + mob_cap_animal then return end
			if active_object_count_wider > mob_cap_player then return end
			local p = vector_offset(pos, 0, 1, 0)
			local pname = minetest.get_node(p).name
			if def.type_of_spawning == "water" then
				if pname ~= "mcl_core:water_source" and pname ~= "mclx_core:river_water_source" then return end
			else
				if pname ~= "air" then return end -- FIXME: allow everything non-walkable, non-water, non-lava?
			end
			if minetest.get_meta(pos):get_string("spawnblock") == "" then return end
			if mg_name ~= "v6" and mg_name ~= "singlenode" and def.biomes then
				if table.indexof(def.biomes, minetest.get_biome_name(minetest.get_biome_data(p).biome)) == -1 then
					return
				end
			end
			local mobdef = minetest.registered_entities[def.name]
			if mobdef.can_spawn and not mobdef.can_spawn(p) then return end
			minetest.add_entity(p, def.name)
		end,
	})
end