/*
 * Copyright 2004-2005 the original author or authors.
 *
 * 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 org.springmodules.validation.bean.conf.loader.annotation.handler;

import java.lang.annotation.Annotation;

import org.springmodules.validation.bean.conf.MutableBeanValidationConfiguration;

/**
 * A {@link ClassValidationAnnotationHandler} that handles {@link Validators} annotations.
 *
 * @author Uri Boness
 */
public class ValidatorsClassValidationAnnotationHandler implements ClassValidationAnnotationHandler {

    /**
     * Returns <code>true</code> if the given annotation is of type <code>{@link Validators}</code>.
     *
     * @see org.springmodules.validation.bean.conf.loader.annotation.handler.ClassValidationAnnotationHandler#supports(java.lang.annotation.Annotation, Class)
     */
    public boolean supports(Annotation annotation, Class clazz) {
        return Validators.class.isInstance(annotation);
    }

    /**
     * Handles the given class level annotation and manipulates the given bean validation configuration appropriately.
     * This method assumes that {@link #supports(java.lang.annotation.Annotation, Class)} returns <code>true</code> for the
     * given annotation.
     *
     * @param annotation    The annotation to handle.
     * @param clazz         The annotated class.
     * @param configuration The bean validation configuration to manipulate.
     */
    public void handleAnnotation(Annotation annotation, Class clazz, MutableBeanValidationConfiguration configuration) {
        Validator[] validators = ((Validators)annotation).value();
        configuration.setCustomValidators(createValidators(validators));
    }


    //=============================================== Helper Methods ===================================================

    /**
     * Creates a list of validator from the given list of validator annnotations.
     */
    protected org.springframework.validation.Validator[] createValidators(Validator[] validatorAnnotations) {
        org.springframework.validation.Validator[] validators =
            new org.springframework.validation.Validator[validatorAnnotations.length];
        for (int i=0; i<validatorAnnotations.length; i++) {
            validators[i] = createValidator(validatorAnnotations[i].value());
        }
        return validators;
    }

    /**
     * Creates a new validator from the given validator class.
     */
    protected org.springframework.validation.Validator createValidator(Class<? extends org.springframework.validation.Validator> validatorClass) {
        try {
            return validatorClass.newInstance();
        } catch (IllegalAccessException iae) {
            throw new ValidationAnnotationConfigurationException("Could not instantiate validator class '" +
                validatorClass.getName() + "'", iae);
        } catch (InstantiationException ie) {
            throw new ValidationAnnotationConfigurationException("Could not instantiate validator class '" +
                validatorClass.getName() + "'", ie);
        }
    }
}