public final class RestoreManager implements Runnable {

    private final Set<RestoreNode> nodes = Sets.newHashSet();

    public void restore(Block block, Material material) {
        restore(block, material, seconds);
    }

    public void restore(Block block, Material material, long delay) {
        RestoreNode node = new RestoreNode(block.getState(), material, delay);
        if (delay > 0L) {
            this.nodes.add(node);
            node.onStart();
        } else {
            node.transfer();
        }
    }

    @Override
    public void run() {
        if (!this.nodes.isEmpty()) {
            long time = System.currentTimeMillis();
            this.nodes.removeIf(node -> node.update(time));
        }
    }

    public static final class RestoreNode {

        private final BlockState state;
        private final Material material;
        private final long transferExpire;

        RestoreNode(BlockState state, Material material, long delay) {
            this.state = state;
            this.material = material;
            this.transferExpire = System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(delay);
        }

        boolean update(long time) {
            if (time >= getTransferExpire()) {
                transfer();
                return true;
            }
            return false;
        }

        void onStart() {
            this.state.setType(Material.BEDROCK);
            this.state.update(true);
        }

        void transfer() {
            this.state.setType(this.material);
            this.state.update(true);
        }

        long getTransferExpire() {
            return this.transferExpire;
        }

    }

}