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/*
 * 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;

import java.lang.reflect.Array;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.util.StringUtils;
import org.springframework.validation.Errors;
import org.springframework.validation.Validator;
import org.springmodules.validation.bean.conf.BeanValidationConfiguration;
import org.springmodules.validation.bean.conf.CascadeValidation;
import org.springmodules.validation.bean.conf.loader.BeanValidationConfigurationLoader;
import org.springmodules.validation.bean.conf.loader.xml.DefaultXmlBeanValidationConfigurationLoader;
import org.springmodules.validation.bean.converter.ErrorCodeConverter;
import org.springmodules.validation.bean.converter.ModelAwareErrorCodeConverter;
import org.springmodules.validation.bean.rule.ValidationRule;
import org.springmodules.validation.util.condition.Condition;

/**
 * An {@link org.springmodules.validation.validator.AbstractTypeSpecificValidator} implementation that applies all validation rules
 * on a bean of a specific type, based on an appropriate {@link org.springmodules.validation.bean.conf.BeanValidationConfiguration}. The validation
 * configuration is loaded per bean type by the configured {@link BeanValidationConfigurationLoader}.
 *
 * @author Uri Boness
 */
public class BeanValidator extends RuleBasedValidator {

    private final static Log logger = LogFactory.getLog(BeanValidator.class);

    private final static String PROPERTY_KEY_PREFIX = "[";
    private final static String PROPERTY_KEY_SUFFIX = "]";

    private BeanValidationConfigurationLoader configurationLoader;
    private ErrorCodeConverter errorCodeConverter;

    /**
     * Constructs a new BeanValidator. By default the
     * {@link org.springmodules.validation.bean.conf.loader.SimpleBeanValidationConfigurationLoader} is
     * used as the bean validation configuration loader.
     */
    public BeanValidator() {
        this(new DefaultXmlBeanValidationConfigurationLoader());
    }

    /**
     * Constructs a new BeanValidator for the given bean class using the given validation configuration loader.
     *
     * @param configurationLoader The {@link org.springmodules.validation.bean.conf.loader.BeanValidationConfigurationLoader} that is used to load the bean validation
     *        configuration.
     */
    public BeanValidator(BeanValidationConfigurationLoader configurationLoader) {
        this.configurationLoader = configurationLoader;
        errorCodeConverter = new ModelAwareErrorCodeConverter();
    }

    /**
     * This validator supports only those classes that are supported by the validation configuration loader it uses.
     *
     * @see org.springmodules.validation.bean.RuleBasedValidator#supports(Class)
     * @see org.springmodules.validation.bean.conf.loader.BeanValidationConfigurationLoader#supports(Class)
     */
    public boolean supports(Class clazz) {
        return configurationLoader.supports(clazz) || super.supports(clazz);
    }

    /**
     * Applies all validation rules as defined in the {@link org.springmodules.validation.bean.conf.BeanValidationConfiguration} retrieved for the given
     * bean from the configured {@link org.springmodules.validation.bean.conf.loader.BeanValidationConfigurationLoader}.
     *
     * @see Validator#validate(Object, org.springframework.validation.Errors)
     */
    public void validate(Object obj, Errors errors) {

        // validation the object graph using the class validation manager.
        validateObjectGraphConstraints(obj, obj, errors, new HashSet());

        // applying the registered validation rules.
        super.validate(obj, errors);
    }

    //============================================== Setter/Getter =====================================================

    /**
     * Sets the error code converter this validator will use to resolve the error codes to be registered with the
     * {@link Errors} object.
     *
     * @param errorCodeConverter The error code converter this validator will use to resolve the error
     *        different error codes.
     */
    public void setErrorCodeConverter(ErrorCodeConverter errorCodeConverter) {
        this.errorCodeConverter = errorCodeConverter;
    }

    /**
     * Sets the bean validation configuration loader this validator will use to load the bean validation configurations.
     *
     * @param configurationLoader The loader this validator will use to load the bean validation configurations.
     */
    public void setConfigurationLoader(BeanValidationConfigurationLoader configurationLoader) {
        this.configurationLoader = configurationLoader;
    }

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

    /**
     * The heart of this validator. This is a recursive method that validates the given object (object) under the
     * context of the given object graph root (root). The validation rules to be applied are loaded using the
     * configured {@link org.springmodules.validation.bean.conf.loader.BeanValidationConfigurationLoader}. All errors are registered with the given {@link Errors}
     * object under the context of the object graph root.
     *
     * @param root The root of the object graph.
     * @param obj The object to be validated
     * @param errors The {@link Errors} instance where the validation errors will be registered.
     * @param validatedObjects keeps track of all the validated objects (to prevent revalidating the same objects when
     *        a circular relationship exists).
     */
    protected void validateObjectGraphConstraints(Object root, Object obj, Errors errors, Set validatedObjects) {

        // cannot load any validation rules for null values
        if (obj == null) {
            return;
        }

        // if this object was already validated, the skipping this valiation.
        if (validatedObjects.contains(obj)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Skipping validation of object in path '" + errors.getObjectName() +
                    "' for it was already validated");
            }
            return;
        }

        if (logger.isDebugEnabled()) {
            logger.debug("Validating object in path '" + errors.getNestedPath() + "'");
        }

        // loading the bean validation configuration based on the validated object class.
        Class clazz = obj.getClass();
        BeanValidationConfiguration configuration = configurationLoader.loadConfiguration(clazz);

        if (configuration == null) {
            return; // no validation configuration for this object, then there's nothing to validate.
        }

        // applying all the validation rules for the object and registering the object as "validated"
        applyBeanValidation(configuration, obj, errors);
        validatedObjects.add(obj);

        // after all the validation rules where applied, checking what properties of the object require their own
        // validation and recursively calling this method on them.
        CascadeValidation[] cascadeValidations = configuration.getCascadeValidations();
        BeanWrapper wrapper = wrapBean(obj);
        for (int i=0; i