/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.test.extension.actors;

import static java.lang.String.format;
import static org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS;
import static org.junit.jupiter.api.TestInstance.Lifecycle.PER_METHOD;
import static org.neo4j.test.ReflectionUtil.getAllFields;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.List;
import java.util.Optional;
import org.junit.jupiter.api.TestInstance;
import org.junit.jupiter.api.extension.AfterAllCallback;
import org.junit.jupiter.api.extension.AfterEachCallback;
import org.junit.jupiter.api.extension.ExtensionConfigurationException;
import org.junit.jupiter.api.extension.ExtensionContext;
import org.junit.jupiter.api.extension.ExtensionContext.Namespace;
import org.junit.jupiter.api.extension.TestInstancePostProcessor;
import org.neo4j.test.extension.Inject;

public class ActorsSupportExtension implements TestInstancePostProcessor, AfterEachCallback, AfterAllCallback {
    private static final Namespace NAMESPACE = Namespace.create("neo4j", "actors");
    private static final String ACTOR_MANAGER = "ACTOR_MANAGER";

    @Override
    public void afterAll(ExtensionContext context) throws Exception {
        if (getLifecycle(context) == PER_CLASS) {
            tearDownActors(context);
        }
    }

    @Override
    public void afterEach(ExtensionContext context) throws Exception {
        if (getLifecycle(context) == PER_METHOD) {
            tearDownActors(context);
        }
    }

    private static TestInstance.Lifecycle getLifecycle(ExtensionContext context) {
        return context.getTestInstanceLifecycle().orElse(PER_METHOD);
    }

    private static void tearDownActors(ExtensionContext context) throws Exception {
        Optional<ExtensionContext> current = Optional.of(context);
        while (current.isPresent()) {
            ExtensionContext ctx = current.get();
            ActorsManager manager = (ActorsManager) getStore(ctx).remove(ACTOR_MANAGER);
            if (manager != null) {
                manager.stopAllActors();
            }
            current = ctx.getParent();
        }
    }

    @Override
    public void postProcessTestInstance(Object testInstance, ExtensionContext extensionContext) throws Exception {
        ActorsManager manager = (ActorsManager) getStore(extensionContext)
                .getOrComputeIfAbsent(ACTOR_MANAGER, k -> new ActorsManager(extensionContext.getDisplayName()));
        Class<?> clazz = testInstance.getClass();
        List<Field> declaredFields = getAllFields(clazz);
        for (Field declaredField : declaredFields) {
            if (declaredField.getType() == Actor.class && declaredField.isAnnotationPresent(Inject.class)) {
                if (Modifier.isStatic(declaredField.getModifiers())) {
                    throw new ExtensionConfigurationException(format(
                            "Actors cannot be inject into static field: %s.%s.",
                            clazz.getName(), declaredField.getName()));
                }
                declaredField.setAccessible(true);
                if (declaredField.get(testInstance) != null) {
                    throw new ExtensionConfigurationException(format(
                            "Field %s that is marked for injection in class %s is managed by extension container "
                                    + "and should not have any manually assigned value.",
                            declaredField.getName(), clazz.getName()));
                }
                declaredField.set(testInstance, manager.createActor(declaredField.getName()));
            }
        }
    }

    private static ExtensionContext.Store getStore(ExtensionContext extensionContext) {
        return extensionContext.getStore(NAMESPACE);
    }
}
