/*
 * Copyright (c) 2012, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.jersey.server.model;

import java.lang.annotation.Annotation;
import java.util.HashSet;
import java.util.Set;

import javax.inject.Singleton;

import org.glassfish.jersey.internal.Errors;
import org.glassfish.jersey.internal.inject.PerLookup;
import org.glassfish.jersey.internal.inject.Providers;
import org.glassfish.jersey.server.internal.LocalizationMessages;

Validator ensuring that invocable and constructor is correctly defined (for example correctly annotated with scope annotation). This validator is stateful and therefore new instance must be created for each resource model validation. 
Author:
Miroslav Fuksa/**
 * Validator ensuring that {@link Invocable invocable} and {@link HandlerConstructor constructor} is correctly defined (for
 * example correctly annotated with scope annotation). This validator is stateful and therefore new instance must be created
 * for each resource model validation.
 *
 * @author Miroslav Fuksa
 *
 */
class InvocableValidator extends AbstractResourceModelVisitor {
    private static final Set<Class<?>> SCOPE_ANNOTATIONS = getScopeAnnotations();
    
Classes that have been checked already.
/**
     * Classes that have been checked already.
     */
    protected final Set<Class<?>> checkedClasses = new HashSet<Class<?>>();

    private static Set<Class<?>> getScopeAnnotations() {
        Set<Class<?>> scopeAnnotations = new HashSet<Class<?>>();
        scopeAnnotations.add(Singleton.class);
        scopeAnnotations.add(PerLookup.class);
        return scopeAnnotations;
    }

    @Override
    public void visitInvocable(final Invocable invocable) {
        // TODO: check invocable.
        Class resClass = invocable.getHandler().getHandlerClass();
        if (resClass != null && !checkedClasses.contains(resClass)) {
            checkedClasses.add(resClass);
            final boolean provider = Providers.isProvider(resClass);
            int counter = 0;
            for (Annotation annotation : resClass.getAnnotations()) {
                if (SCOPE_ANNOTATIONS.contains(annotation.annotationType())) {
                    counter++;
                }
            }
            if (counter == 0 && provider) {
                Errors.warning(resClass, LocalizationMessages.RESOURCE_IMPLEMENTS_PROVIDER(resClass,
                        Providers.getProviderContracts(resClass)));
            } else if (counter > 1) {
                Errors.fatal(resClass, LocalizationMessages.RESOURCE_MULTIPLE_SCOPE_ANNOTATIONS(resClass));
            }
        }


    }

    
Check if the resource class is declared to be a singleton.
Params:
resourceClass – resource class.
Returns:
true if the resource class is a singleton, false otherwise./**
     * Check if the resource class is declared to be a singleton.
     *
     * @param resourceClass resource class.
     * @return {@code true} if the resource class is a singleton, {@code false} otherwise.
     */
    public static boolean isSingleton(Class<?> resourceClass) {
        return resourceClass.isAnnotationPresent(Singleton.class)
                || (Providers.isProvider(resourceClass) && !resourceClass.isAnnotationPresent(PerLookup.class));
    }


    @Override
    public void visitResourceHandlerConstructor(final HandlerConstructor constructor) {
        Class<?> resClass = constructor.getConstructor().getDeclaringClass();
        boolean isSingleton = isSingleton(resClass);
        int paramCount = 0;
        for (Parameter p : constructor.getParameters()) {
            ResourceMethodValidator.validateParameter(p, constructor.getConstructor(), constructor.getConstructor()
                    .toGenericString(),
                    Integer.toString(++paramCount), isSingleton);
        }
    }


    // TODO: validate also method handler.


}