-- function to decide if a node has a wall that's in verticals_list{}
-- returns wall direction of valid node, or nil if invalid.

function biome_lib.find_adjacent_wall(pos, verticals, randomflag)
	local verts = dump(verticals)
	if randomflag then
		local walltab = {}
		
		if string.find(verts, minetest.get_node({ x=pos.x-1, y=pos.y, z=pos.z   }).name) then walltab[#walltab + 1] = 3 end
		if string.find(verts, minetest.get_node({ x=pos.x+1, y=pos.y, z=pos.z   }).name) then walltab[#walltab + 1] = 2 end
		if string.find(verts, minetest.get_node({ x=pos.x  , y=pos.y, z=pos.z-1 }).name) then walltab[#walltab + 1] = 5 end
		if string.find(verts, minetest.get_node({ x=pos.x  , y=pos.y, z=pos.z+1 }).name) then walltab[#walltab + 1] = 4 end

		if #walltab > 0 then return walltab[math.random(1, #walltab)] end

	else
		if string.find(verts, minetest.get_node({ x=pos.x-1, y=pos.y, z=pos.z   }).name) then return 3 end
		if string.find(verts, minetest.get_node({ x=pos.x+1, y=pos.y, z=pos.z   }).name) then return 2 end
		if string.find(verts, minetest.get_node({ x=pos.x  , y=pos.y, z=pos.z-1 }).name) then return 5 end
		if string.find(verts, minetest.get_node({ x=pos.x  , y=pos.y, z=pos.z+1 }).name) then return 4 end
	end
	return nil
end

-- Function to search downward from the given position, looking for the first
-- node that matches the ground table.  Returns the new position, or nil if
-- height limit is exceeded before finding it.

function biome_lib.search_downward(pos, heightlimit, ground)
	for i = 0, heightlimit do
		if string.find(dump(ground), minetest.get_node({x=pos.x, y=pos.y-i, z = pos.z}).name) then
			return {x=pos.x, y=pos.y-i, z = pos.z}
		end
	end
	return false
end

function biome_lib.find_open_side(pos)
	if minetest.get_node({ x=pos.x-1, y=pos.y, z=pos.z }).name == "air" then
		return {newpos = { x=pos.x-1, y=pos.y, z=pos.z }, facedir = 2}
	end
	if minetest.get_node({ x=pos.x+1, y=pos.y, z=pos.z }).name == "air" then
		return {newpos = { x=pos.x+1, y=pos.y, z=pos.z }, facedir = 3}
	end
	if minetest.get_node({ x=pos.x, y=pos.y, z=pos.z-1 }).name == "air" then
		return {newpos = { x=pos.x, y=pos.y, z=pos.z-1 }, facedir = 4}
	end
	if minetest.get_node({ x=pos.x, y=pos.y, z=pos.z+1 }).name == "air" then
		return {newpos = { x=pos.x, y=pos.y, z=pos.z+1 }, facedir = 5}
	end
	return nil
end

-- "Record" the map chunks being generated by the core mapgen,
-- split into individual mapblocks to reduce lag

minetest.register_on_generated(function(minp, maxp, blockseed)
	local timestamp = minetest.get_us_time()
	for y = 0, 4 do
		local miny = minp.y + y*16

		if miny >= biome_lib.mapgen_elevation_limit.min
		  and (miny + 15) <= biome_lib.mapgen_elevation_limit.max then

			for x = 0, 4 do
				local minx = minp.x + x*16

				for z = 0, 4 do
					local minz = minp.z + z*16

					local bmin = {x=minx, y=miny, z=minz}
					local bmax = {x=minx + 15, y=miny + 15, z=minz + 15}
					biome_lib.block_log[#biome_lib.block_log + 1] = { bmin, bmax, true, timestamp }
					biome_lib.block_log[#biome_lib.block_log + 1] = { bmin, bmax, false, timestamp }
				end
			end
		else
			biome_lib.dbg("Did not enqueue mapblocks at elevation "..miny.."m, they're out of range of any generate_plant() calls.", 4)
		end
	end
	biome_lib.run_block_recheck_list = true
end)