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/*
 * Copyright (c) 2008-2017 akquinet tech@spree GmbH
 *
 * This file is part of Hibersap.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this software 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 org.hibersap.execution.jca.cci;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import javax.resource.cci.ConnectionSpec;
import org.hibersap.InternalHiberSapException;
import org.hibersap.mapping.ReflectionHelper;

/**
 * Offers methods to help accessing and instantiating the ConnectionSpec implementation. May be used
 * to implement a new ConnectionSpecFactory.
 *
 * @author Carsten Erker
 */
public abstract class AbstractConnectionSpecFactory
        implements ConnectionSpecFactory {

    /**
     * Looks up and returns the specified class. First, it will try to get the class from the
     * context class loader, if not found, it will try to get it from the current class loader.
     *
     * @param connectionSpecClass The fully qualified class name of the ConnectionSpec
     * implementation.
     * @return The Class object of the ConnectionSpec implementation
     * @throws ClassNotFoundException - if the class could not be found.
     * @throws IllegalArgumentException - if the class does not implement
     * javax.resource.cci.ConnectionSpec.
     */
    protected Class getConnectionSpecClass(final String connectionSpecClass)
            throws ClassNotFoundException {
        Class connSpecClass = ReflectionHelper.getClassForName(connectionSpecClass);

        if (!ConnectionSpec.class.isAssignableFrom(connSpecClass)) {
            throw new IllegalArgumentException(
                    connSpecClass.getName() + " does not implement " + ConnectionSpec.class);
        }

        //noinspection unchecked
        return (Class) connSpecClass;
    }

    /**
     * Creates a new instance of the specified ConnectionSpec implementation class via reflection.
     *
     * @param connectionSpecClass The class to instantiate. Must implement
     * javax.resource.cci.ConnectionSpec.
     * @param constructorParameterTypes The types of the constructor's parameters. Used to determine
     * which constructor should be used.
     * @param constructorArguments The constructor's arguments used when creating a new instance of
     * the class. Must match the constructorParameterTypes.
     * @return The instance of the ConnectionSpec implementation
     * @throws InternalHiberSapException - if the class could not be accessed or instantiated,
     * see cause for the actual reason.
     */
    protected ConnectionSpec newConnectionSpecInstance(final Class connectionSpecClass,
                                                       final Class[] constructorParameterTypes,
                                                       final Object[] constructorArguments) {
        Object connSpecImpl = null;
        try {
            Constructor constructor = connectionSpecClass.getConstructor(constructorParameterTypes);
            connSpecImpl = constructor.newInstance(constructorArguments);
        } catch (SecurityException e) {
            final String msg = "Can not access declared constructor: ";
            throwInternalHibersapException(connectionSpecClass, constructorParameterTypes, e, msg);
        } catch (NoSuchMethodException e) {
            final String msg = "No such constructor: ";
            return throwInternalHibersapException(connectionSpecClass, constructorParameterTypes, e, msg);
        } catch (IllegalArgumentException e) {
            throw new InternalHiberSapException("No such constructor: "
                    + getSignature(connectionSpecClass, constructorArguments), e);
        } catch (InstantiationException e) {
            final String msg = "Cannot create new instance of: ";
            throwInternalHibersapException(connectionSpecClass, constructorParameterTypes, e, msg);
        } catch (IllegalAccessException e) {
            final String msg = "Cannot create new instance of: ";
            throwInternalHibersapException(connectionSpecClass, constructorParameterTypes, e, msg);
        } catch (InvocationTargetException e) {
            final String msg = "Constructor threw an Exception: ";
            throwInternalHibersapException(connectionSpecClass, constructorParameterTypes, e, msg);
        }

        if (!ConnectionSpec.class.isAssignableFrom(connSpecImpl.getClass())) {
            throw new InternalHiberSapException(connectionSpecClass + " does not implement " + ConnectionSpec.class);
        }
        return (ConnectionSpec) connSpecImpl;
    }

    private ConnectionSpec throwInternalHibersapException(final Class connectionSpecClass,
                                                          final Class[] constructorParameterTypes, Exception e,
                                                          final String msg) {
        throw new InternalHiberSapException(msg + getSignature(connectionSpecClass, constructorParameterTypes), e);
    }

    private String getSignature(final Class clazz, final Object[] arguments) {
        Class[] classes = new Class[arguments.length];

        for (int i = 0; i < arguments.length; i++) {
            Class argClass = arguments[i] == null ? null : arguments[i].getClass();
            classes[i] = argClass;
        }

        return getSignature(clazz, classes);
    }

    private String getSignature(final Class clazz, final Class[] argClasses) {
        StringBuilder sb = new StringBuilder(clazz.getName());
        sb.append('(');

        for (int i = 0; i < argClasses.length; i++) {
            if (i > 0) {
                sb.append(",");
            }
            Class argClass = argClasses[i];
            sb.append(argClass == null ? "null" : argClass.getName());
        }

        sb.append(')');
        return sb.toString();
    }
}