/*
 * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.mdsal.binding.dom.codec.impl;

import static java.util.Objects.requireNonNull;

import com.google.common.base.Throwables;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Method;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

final class UnionValueOptionContext {
    private static final MethodType OBJECT_TYPE = MethodType.methodType(Object.class, Object.class);
    private static final Logger LOG = LoggerFactory.getLogger(UnionValueOptionContext.class);

    private final Class<?> bindingType;
    private final ValueCodec<Object,Object> codec;
    private final MethodHandle getter;
    private final MethodHandle unionCtor;

    UnionValueOptionContext(final Class<?> unionType, final Class<?> valueType, final Method getter,
            final ValueCodec<Object, Object> codec) {
        bindingType = requireNonNull(valueType);
        this.codec = requireNonNull(codec);

        try {
            this.getter = MethodHandles.publicLookup().unreflect(getter).asType(OBJECT_TYPE);
        } catch (IllegalAccessException e) {
            throw new IllegalStateException("Failed to access method " + getter, e);
        }

        try {
            unionCtor = MethodHandles.publicLookup().findConstructor(unionType,
                MethodType.methodType(void.class, valueType)).asType(OBJECT_TYPE);
        } catch (IllegalAccessException | NoSuchMethodException e) {
            throw new IllegalStateException(String.format("Failed to access constructor for %s in type %s", valueType,
                    unionType), e);
        }
    }

    Object serialize(final Object input) {
        final Object baValue = getValueFrom(input);
        return baValue == null ? null : codec.serialize(baValue);
    }

    @SuppressWarnings("checkstyle:illegalCatch")
    Object deserializeUnion(final Object input) {
        // Side-step potential exceptions by checking the type if it is available
        if (codec instanceof EncapsulatedValueCodec && !((EncapsulatedValueCodec) codec).canAcceptObject(input)) {
            return null;
        }

        final Object value;
        try {
            value = codec.deserialize(input);
        } catch (Exception e) {
            LOG.debug("Codec {} failed to deserialize input {}", codec, input, e);
            return null;
        }

        try {
            return unionCtor.invokeExact(value);
        } catch (ClassCastException e) {
            // This case can happen. e.g. NOOP_CODEC
            LOG.debug("Failed to instantiate {} for input {} value {}", bindingType, input, value, e);
            return null;
        } catch (Throwable e) {
            throw new IllegalArgumentException("Failed to construct union for value " + value, e);
        }
    }

    @SuppressWarnings("checkstyle:illegalCatch")
    Object getValueFrom(final Object input) {
        try {
            return getter.invokeExact(input);
        } catch (Throwable e) {
            Throwables.throwIfUnchecked(e);
            throw new IllegalStateException(e);
        }
    }

    @Override
    public int hashCode() {
        return bindingType.hashCode();
    }

    @Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof UnionValueOptionContext other)) {
            return false;
        }

        return bindingType.equals(other.bindingType);
    }
}