local ofs = {
	neighbors = {
		{x =  1, y =  0, z =  0};
		{x = -1, y =  0, z =  0};
		{x =  0, y =  1, z =  0};
		{x =  0, y = -1, z =  0};
		{x =  0, y =  0, z =  1};
		{x =  0, y =  0, z = -1};
	};
	planecorners = {
		{x =  1, y =  0, z =  1};
		{x = -1, y =  0, z =  1};
		{x = -1, y =  0, z = -1};
		{x =  1, y =  0, z = -1};

		{x =  1, y =  1, z =  0};
		{x = -1, y =  1, z =  0};
		{x = -1, y = -1, z =  0};
		{x =  1, y = -1, z =  0};
	};
	cubecorners = {
		{x =  1, y =  1, z =  1};
		{x = -1, y =  1, z =  1};
		{x = -1, y = -1, z =  1};
		{x = -1, y = -1, z = -1};
		{x =  1, y = -1, z = -1};
		{x =  1, y =  1, z = -1};
		{x =  1, y = -1, z =  1};
		{x = -1, y =  1, z = -1};
	};
	nextto = {
		{x =  1, y =  0, z =  0};
		{x = -1, y =  0, z =  0};
		{x =  0, y =  0, z =  1};
		{x =  0, y =  0, z = -1};
	};
}

ofs.adjoining = sorcery.lib.tbl.append(sorcery.lib.tbl.append(
	ofs.neighbors,ofs.planecorners),ofs.cubecorners)

return {
	offsets = ofs;
	purge_container = function(pos,node,meta,user)
		local offset = function(pos,range)
			local r = function(min,max)
				return (math.random() * (max - min)) + min
			end
			return {
				x = pos.x + r(0 - range, range);
				y = pos.y;
				z = pos.z + r(0 - range, range);
			}
		end
		for name, inv in pairs(meta.inventory) do
			for _, item in pairs(inv) do
				if not item:is_empty() then
					minetest.add_item(offset(pos,0.4), item)
				end
			end
		end
	end;

	amass = function(startpoint,names,directions)
		if not directions then directions = ofs.neighbors end
		local nodes, positions, checked = {},{},{}
		local checkedp = function(pos)
			for _,v in pairs(checked) do
				if vector.equals(pos,v) then return true end
			end
			return false
		end
		local i,stack = 1,{startpoint} repeat
			local pos = stack[i]
			local n = minetest.get_node(pos).name
			if sorcery.lib.tbl.has(names, n) then -- match found
				-- record the find
				nodes[pos] = n
				if positions[n] then positions[n][#positions[n]] = pos
				else positions[n] = {pos} end

				-- check selected neighbors to see if any need scanning
				for _,d in pairs(directions) do
					local sum = vector.add(pos, d)
					if not checkedp(sum) then
						stack[#stack + 1] = sum
					end
				end
			end
			checked[#checked+1] = pos
			i = i + 1
		until i > #stack
		return nodes, positions
	end;
}
