/*
 * 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.bval.jsr303;


import org.apache.bval.jsr303.util.NodeImpl;
import org.apache.bval.jsr303.util.PathImpl;
import org.apache.bval.model.Validation;
import org.apache.bval.model.ValidationContext;
import org.apache.bval.model.ValidationListener;
import org.apache.bval.util.AccessStrategy;

import javax.validation.ConstraintDefinitionException;
import javax.validation.ConstraintValidator;
import javax.validation.Payload;
import javax.validation.ValidationException;
import javax.validation.metadata.ConstraintDescriptor;

import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.util.*;

/**
 * Description: Adapter between Constraint (JSR303) and Validation (Core)<br/>
 * this instance is immutable!<br/>
 */
public class ConstraintValidation<T extends Annotation>
    implements Validation, ConstraintDescriptor<T> {
  private static final String ANNOTATION_MESSAGE = "message";

  private final ConstraintValidator<T, ?> validator;
  private T annotation; // for metadata request API
  private final AccessStrategy access;
  private final boolean reportFromComposite;
  private final Map<String, Object> attributes;

  private Set<ConstraintValidation<?>> composedConstraints;

  /**
   * the owner is the type where the validation comes from.
   * it is used to support implicit grouping.
   */
  private final Class<?> owner;
  private Set<Class<?>> groups;
  private Set<Class<? extends Payload>> payload;
  private Class<? extends ConstraintValidator<T, ?>>[] validatorClasses;

  /**
   * Create a new ConstraintValidation instance.
   * @param validatorClasses
   * @param validator  - the constraint validator
   * @param annotation - the annotation of the constraint
   * @param owner      - the type where the annotated element is placed
   *                   (class, interface, annotation type)
   * @param access     - how to access the value
   * @param reportFromComposite
   */
  public ConstraintValidation(
      Class<? extends ConstraintValidator<T, ?>>[] validatorClasses,
      ConstraintValidator<T, ?> validator, T annotation, Class<?> owner,
      AccessStrategy access, boolean reportFromComposite) {
    this.attributes = new HashMap<String, Object>();
    this.validatorClasses = validatorClasses;
    this.validator = validator;
    this.annotation = annotation;
    this.owner = owner;
    this.access = access;
    this.reportFromComposite = reportFromComposite;
  }

  /**
   * Return a {@link Serializable} {@link ConstraintDescriptor} capturing a snapshot of current state.
   * @return {@link ConstraintDescriptor}
   */
  public ConstraintDescriptor<T> asSerializableDescriptor() {
    return new ConstraintDescriptorImpl<T>(this);
  }

  /**
   * Set the applicable validation groups.
   * @param groups
   */
  void setGroups(Set<Class<?>> groups) {
    this.groups = groups;
    this.attributes.put("groups", groups.toArray(new Class[groups.size()]));
  }

  /**
   * Set the payload.
   * @param payload
   */
  void setPayload(Set<Class<? extends Payload>> payload) {
    this.payload = payload;
    this.attributes.put("payload", payload.toArray(new Class[payload.size()]));
  }

  /**
   * {@inheritDoc}
   */
  public boolean isReportAsSingleViolation() {
    return reportFromComposite;
  }

  /**
   * Add a composing constraint.
   * @param aConstraintValidation to add
   */
  public void addComposed(ConstraintValidation<?> aConstraintValidation) {
    if (composedConstraints == null) {
      composedConstraints = new HashSet<ConstraintValidation<?>>();
    }
    composedConstraints.add(aConstraintValidation);
  }

  /**
   * {@inheritDoc}
   */
  public <L extends ValidationListener> void validate(ValidationContext<L> context) {
    validate((GroupValidationContext<?>) context);
  }

  /**
   * Validate a {@link GroupValidationContext}.
   * @param context root
   */
  public void validate(GroupValidationContext<?> context) {
    context.setConstraintValidation(this);
    /**
     * execute unless the given validation constraint has already been processed
     * during this validation routine (as part of a previous group match)
     */
    if (!isMemberOf(context.getCurrentGroup().getGroup())) {
      return; // do not validate in the current group
    }
    if (context.getCurrentOwner() != null && this.owner != context.getCurrentOwner()) {
      return;
    }
    if (validator != null && !context.collectValidated(validator))
      return; // already done

    if (context.getMetaProperty() != null && !isReachable(context)) {
      return;
    }

    // process composed constraints
    if (isReportAsSingleViolation()) {
      ConstraintValidationListener<?> listener = context.getListener();
      listener.beginReportAsSingle();

      boolean failed = false;
      try {
          // stop validating when already failed and ReportAsSingleInvalidConstraint = true ?
          for (Iterator<ConstraintValidation<?>> composed = getComposingValidations().iterator(); !failed && composed.hasNext();) {
              composed.next().validate(context);
              failed = listener.hasViolations();
          }
      } finally {
          listener.endReportAsSingle();
          // Restore current constraint validation
          context.setConstraintValidation(this);
      }

      if (failed) {
        // TODO RSt - how should the composed constraint error report look like?
        ConstraintValidatorContextImpl jsrContext =
            new ConstraintValidatorContextImpl(context, this);
        addErrors(context, jsrContext); // add defaultErrorMessage only*/
        return;
      }
    } else {
      for (ConstraintValidation<?> composed : getComposingValidations()) {
        composed.validate(context);
      }

      // Restore current constraint validation
      context.setConstraintValidation(this);
    }

    if (validator != null) {
      ConstraintValidatorContextImpl jsrContext =
          new ConstraintValidatorContextImpl(context, this);
      @SuppressWarnings("unchecked")
      final ConstraintValidator<T, Object> objectValidator = (ConstraintValidator<T, Object>) validator;
      if (!objectValidator.isValid(context.getValidatedValue(), jsrContext)) {
        addErrors(context, jsrContext);
      }
    }
  }

  /**
   * Initialize the validator (if not <code>null</code>) with the stored
   * annotation.
   */
  public void initialize() {
    if (null != validator) {
      try {
        validator.initialize(annotation);
      } catch (RuntimeException e) {
        // Either a "legit" problem initializing the validator or a
        // ClassCastException if the validator associated annotation is
        // not a supertype of the validated annotation.
        throw new ConstraintDefinitionException(
            "Incorrect validator [" + validator.getClass().getCanonicalName() + "] for annotation " +
                annotation.annotationType().getCanonicalName(), e);
      }
    }
  }

  private boolean isReachable(GroupValidationContext<?> context) {
    PathImpl path = context.getPropertyPath();
    NodeImpl node = path.getLeafNode();
    PathImpl beanPath = path.getPathWithoutLeafNode();
    if (beanPath == null) {
      beanPath = PathImpl.create(null);
    }
    try {
      if (!context.getTraversableResolver()
          .isReachable(context.getBean(), node,
              context.getRootMetaBean().getBeanClass(), beanPath,
              access.getElementType())) return false;
    } catch (RuntimeException e) {
      throw new ValidationException(
          "Error in TraversableResolver.isReachable() for " + context.getBean(), e);
    }

    return true;
  }

  private void addErrors(GroupValidationContext<?> context,
                         ConstraintValidatorContextImpl jsrContext) {
    for (ValidationListener.Error each : jsrContext.getErrorMessages()) {
      context.getListener().addError(each, context);
    }
  }

  /**
   * {@inheritDoc}
   */
  public String toString() {
    return "ConstraintValidation{" + validator + '}';
  }

  /**
   * Get the message template used by this constraint.
   * @return String
   */
  public String getMessageTemplate() {
    return (String) attributes.get(ANNOTATION_MESSAGE);
  }

  /**
   * Get the {@link ConstraintValidator} invoked by this {@link ConstraintValidation}.
   * @return
   */
  public ConstraintValidator<T, ?> getValidator() {
    return validator;
  }

  /**
   * Learn whether this {@link ConstraintValidation} belongs to the specified group.
   * @param reqGroup
   * @return boolean
   */
  protected boolean isMemberOf(Class<?> reqGroup) {
    return groups.contains(reqGroup);
  }

  /**
   * Get the owning class of this {@link ConstraintValidation}.
   * @return Class
   */
  public Class<?> getOwner() {
    return owner;
  }

  /**
   * {@inheritDoc}
   */
  public T getAnnotation() {
    return annotation;
  }

  /**
   * Get the {@link AccessStrategy} used by this {@link ConstraintValidation}.
   * @return {@link AccessStrategy}
   */
  public AccessStrategy getAccess() {
    return access;
  }

  /**
   * Override the Annotation set at construction.
   * @param annotation
   */
  public void setAnnotation(T annotation) {
    this.annotation = annotation;
  }

  /////////////////////////// ConstraintDescriptor implementation

  /**
   * {@inheritDoc}
   */
  public Map<String, Object> getAttributes() {
    return attributes;
  }

  /**
   * {@inheritDoc}
   */
  @SuppressWarnings("unchecked")
  public Set<ConstraintDescriptor<?>> getComposingConstraints() {
    return composedConstraints == null ? Collections.EMPTY_SET : composedConstraints;
  }

  /**
   * Get the composing {@link ConstraintValidation} objects.  This is effectively
   * an implementation-specific analogue to {@link #getComposingConstraints()}.
   * @return {@link Set} of {@link ConstraintValidation}
   */
  @SuppressWarnings("unchecked")
  Set<ConstraintValidation<?>> getComposingValidations() {
    return composedConstraints == null ? Collections.EMPTY_SET : composedConstraints;
  }

  /**
   * {@inheritDoc}
   */
  public Set<Class<?>> getGroups() {
    return groups;
  }

  /**
   * {@inheritDoc}
   */
  public Set<Class<? extends Payload>> getPayload() {
    return payload;
  }

  /**
   * {@inheritDoc}
   */
  public List<Class<? extends ConstraintValidator<T, ?>>> getConstraintValidatorClasses() {
    if (validatorClasses == null) {
      return Collections.emptyList();
    }
    return Arrays.asList(validatorClasses);
  }

}