/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.bean.validation;

import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.function.Supplier;

import javax.validation.Validator;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.validation.metadata.ConstraintDescriptor;

import org.apache.wicket.Application;
import org.apache.wicket.MetaDataKey;
import org.apache.wicket.markup.html.form.FormComponent;
import org.apache.wicket.util.lang.Args;

/**
 * Configures bean validation and integrates it with Wicket
 * 
 * @author igor
 * 
 */
public class BeanValidationConfiguration implements BeanValidationContext
{
        private static final MetaDataKey<BeanValidationConfiguration> KEY = new MetaDataKey<>()
        {
        };

        /**
         * Default list of annotations that make a component required.
         */
        static final List<Class<? extends Annotation>> REQUIRED_ANNOTATIONS;
        static
        {
                List<Class<? extends Annotation>> tmp = new ArrayList<>();
                tmp.add(NotNull.class);
                try
                {
                        tmp.add(Class.forName("javax.validation.constraints.NotBlank")
                                .asSubclass(Annotation.class));
                        tmp.add(Class.forName("javax.validation.constraints.NotEmpty")
                                .asSubclass(Annotation.class));
                }
                catch (ClassNotFoundException e)
                {
                        // ignore exception, we are using bean validation 1.1
                }
                REQUIRED_ANNOTATIONS = Collections.unmodifiableList(tmp);
        }

        private Supplier<Validator> validatorProvider = new DefaultValidatorProvider();

        private IViolationTranslator violationTranslator = new DefaultViolationTranslator();

        private List<IPropertyResolver> propertyResolvers = new CopyOnWriteArrayList<>();

        private Map<Class<?>, ITagModifier<? extends Annotation>> tagModifiers = new ConcurrentHashMap<>();

        public BeanValidationConfiguration()
        {
                add(new DefaultPropertyResolver());
                register(Size.class, new SizeTagModifier());
        }

        /**
         * Registers a tag modifier for a specific constraint annotation.
         * <p>
         * By default {@link Size} constraints are automatically mapped to <code>maxlength</code> of text inputs,
         * this can be disabled by registering a {@link ITagModifier#NO_OP} instead:
         * <code>
         * configuration.register(Size.class, ITagModifier.NO_OP});
         * </code>
         * 
         * @param annotationType
         *            constraint annotation such as {@link Size}
         * @param modifier
         *            tag modifier to use
         * @return {@code this}
         */
        public <T extends Annotation> BeanValidationConfiguration register(Class<T> annotationType,
                ITagModifier<T> modifier)
        {
                Args.notNull(annotationType, "annotationType");
                Args.notNull(modifier, "modifier");

                tagModifiers.put(annotationType, modifier);

                return this;
        }

        /**
         * Get the registered modifier for the given annotation.
         * 
         * @see #register(Class, ITagModifier)
         */
        @Override
        @SuppressWarnings("unchecked")
        public <T extends Annotation> ITagModifier<T> getTagModifier(Class<T> annotationType)
        {
                Args.notNull(annotationType, "annotationType");

                return (ITagModifier<T>)tagModifiers.get(annotationType);
        }

        /**
         * Adds a property resolver to the configuration. Property resolvers registered last are the
         * first to be allowed to resolve the property.
         * 
         * @param resolver
         * @return {@code this}
         */
        public BeanValidationConfiguration add(IPropertyResolver resolver)
        {
                Args.notNull(resolver, "resolver");

                // put newly added resolvers in the beginning so its possible to override previously added
                // resolvers with newer ones
                propertyResolvers.add(0, resolver);

                return this;
        }

        /**
         * @return validator
         */
        @Override
        public Validator getValidator()
        {
                return validatorProvider.get();
        }

        /**
         * Sets the provider used to retrieve {@link Validator} instances
         * 
         * @param validatorProvider
         */
        public void setValidatorProvider(Supplier<Validator> validatorProvider)
        {
                Args.notNull(validatorProvider, "validatorProvider");

                this.validatorProvider = validatorProvider;
        }

        /**
         * Binds this configuration to the application instance
         * 
         * @param application
         */
        public void configure(Application application)
        {
                application.setMetaData(KEY, this);
        }

        /** @return registered violation translator */
        @Override
        public IViolationTranslator getViolationTranslator()
        {
                return violationTranslator;
        }

        /**
         * Registers a violation translator
         *
         * @param violationTranslator
         *            A violation translator that will convert {@link javax.validation.ConstraintViolation}s into Wicket's
         *            {@link org.apache.wicket.validation.ValidationError}s
         */
        public void setViolationTranslator(IViolationTranslator violationTranslator)
        {
                Args.notNull(violationTranslator, "violationTranslator");

                this.violationTranslator = violationTranslator;
        }

        /**
         * Retrieves the validation context (read only version of the configuration). This is how
         * components retrieve the configuration.
         * 
         * @return validation context
         */
        public static BeanValidationContext get()
        {
                BeanValidationConfiguration config = Application.get().getMetaData(KEY);
                if (config == null)
                {
                        throw new IllegalStateException(
                                "Application instance has not yet been configured for bean validation. See BeanValidationConfiguration#configure(Application)");
                }
                return config;
        }

        @Override
        public Property resolveProperty(FormComponent<?> component)
        {
                for (IPropertyResolver resolver : propertyResolvers)
                {
                        Property property = resolver.resolveProperty(component);
                        if (property != null)
                        {
                                return property;
                        }
                }
                return null;
        }

        /**
         * By default {@link NotNull} and {@link NotEmpty} constraints make a component required.
         * 
         * @param constraint
         *            constraint 
         */
        @Override
        public boolean isRequiredConstraint(ConstraintDescriptor<?> constraint)
        {
                return REQUIRED_ANNOTATIONS.contains(constraint.getAnnotation().annotationType());
        }
}