import java.util.function.LongConsumer;

import java.util.function.LongSupplier;

import java.lang.ref.Cleaner.Cleanable;

import jdk.internal.ref.CleanerFactory;

/**

 * A reference to the native zlib's z_stream structure. It also

 * serves as the "cleaner" to clean up the native resource when

 * the deflater or infalter is ended, closed or cleaned.

 */

class ZStreamRef implements Runnable {

    private LongConsumer end;

    private long address;

    private final Cleanable cleanable;

    private ZStreamRef (Object owner, LongSupplier addr, LongConsumer end) {

        this.cleanable = CleanerFactory.cleaner().register(owner, this);

        this.end = end;

        this.address = addr.getAsLong();

    void clean() {

        cleanable.clean();

    }

    public synchronized void run() {

        long addr = address;

        if (addr != 0) {

            end.accept(addr);

        }

    }

    private ZStreamRef (LongSupplier addr, LongConsumer end) {

        this.cleanable = null;

        this.end = end;

        this.address = addr.getAsLong();

    }

    /*

     * If {@code Inflater/Deflater} has been subclassed and the {@code end} method

     * is overridden, uses {@code finalizer} mechanism for resource cleanup. So

     * {@code end} method can be called when the {@code Inflater/Deflater} is

     * unreachable. This mechanism will be removed when the {@code finalize} method

     * is removed from {@code Inflater/Deflater}.

     */

    static ZStreamRef get(Object owner, LongSupplier addr, LongConsumer end) {

        Class<?> clz = owner.getClass();

        while (clz != Deflater.class && clz != Inflater.class) {

            try {

                clz.getDeclaredMethod("end");

                return new FinalizableZStreamRef(owner, addr, end);

            } catch (NoSuchMethodException nsme) {}

            clz = clz.getSuperclass();

        }

        return new ZStreamRef(owner, addr, end);

    }

    private static class FinalizableZStreamRef extends ZStreamRef {

        final Object owner;

        FinalizableZStreamRef (Object owner, LongSupplier addr, LongConsumer end) {

            super(addr, end);

            this.owner = owner;

        }

        @Override

        void clean() {

            run();

        }

        @Override

        @SuppressWarnings("deprecation")

        protected void finalize() {

            if (owner instanceof Inflater)

                ((Inflater)owner).end();

            else

                ((Deflater)owner).end();

        }