io.fluxcapacitor.javaclient.tracking.handling.MutableHandler Maven / Gradle / Ivy

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Default Java client library for interfacing with Flux Capacitor.
There is a newer version: v0.1
/*
 * Copyright (c) Flux Capacitor IP B.V. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *     http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.fluxcapacitor.javaclient.tracking.handling;

import io.fluxcapacitor.common.ObjectUtils;
import io.fluxcapacitor.common.Registration;
import io.fluxcapacitor.common.handling.Handler;
import io.fluxcapacitor.common.handling.HandlerInvoker;
import io.fluxcapacitor.common.handling.HandlerMatcher;
import io.fluxcapacitor.common.reflection.ReflectionUtils;
import lombok.AllArgsConstructor;
import lombok.Getter;

import java.lang.reflect.Method;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.BiFunction;

@AllArgsConstructor
public class MutableHandler implements Handler {
    @Getter
    private final Class targetClass;
    private final HandlerMatcher handlerMatcher;
    private final boolean returnTargetInstance;

    private final Set onDeleteCallbacks = ConcurrentHashMap.newKeySet();

    @Getter
    private volatile Object target;

    @Override
    public Optional getInvoker(M message) {
        return handlerMatcher.getInvoker(target, message)
                .map(h -> new HandlerInvoker.DelegatingHandlerInvoker(h) {
                    @Override
                    public Object invoke(BiFunction combiner) {
                        Object result = delegate.invoke(combiner);
                        if (targetClass.isInstance(result)) {
                            target = result;
                            if (!returnTargetInstance) {
                                return null;
                            }
                        } else if (result == null && expectResult() && getMethod() instanceof Method m
                                   && (targetClass.isAssignableFrom(m.getReturnType())
                                       || m.getReturnType().isAssignableFrom(targetClass))) {
                            target = null;
                            onDeleteCallbacks.forEach(ObjectUtils::tryRun);
                        }
                        return result;
                    }
                });
    }

    public MutableHandler instantiateTarget() {
        target = ReflectionUtils.asInstance(targetClass);
        return this;
    }

    public boolean isEmpty() {
        return target == null;
    }

    public Registration onDelete(Runnable callback) {
        onDeleteCallbacks.add(callback);
        return () -> onDeleteCallbacks.remove(callback);
    }
}