/*
 * 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.validation.validator;

import java.io.Serializable;
import java.util.Locale;

import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.validation.IValidatable;
import org.apache.wicket.validation.IValidationError;
import org.apache.wicket.validation.IValidator;
import org.apache.wicket.validation.ValidationError;

/**
 * Base class for validators that check if a given value falls within [min,max] range.
 * 
 * If either min or max are {@code null} they are not checked.
 * 
 * <p>
 * Resource keys:
 * <ul>
 * <li>{@code <class.simpleName>.exact} if min==max</li>
 * <li>{@code <class.simpleName>.range} if both min and max are not {@code null}</li>
 * <li>{@code <class.simpleName>.minimum} if max is {@code null}</li>
 * <li>{@code <class.simpleName>.maximum} if min is {@code null}</li>
 * </ul>
 * </p>
 * 
 * <p>
 * Error Message Variables:
 * <ul>
 * <li>{@code name}: the id of {@code Component} that failed</li>
 * <li>{@code label}: the label of the {@code Component} (either comes from
 * {@code FormComponent.labelModel} or resource key {@code <form-id>.<form-component-id>}</li>
 * <li>{@code input}: the input value</li>
 * <li>{@code minimum}: the minimum allowed value</li>
 * <li>{@code maximum}: the maximum allowed value</li>
 * </ul>
 * </p>
 * 
 * @param <R>
 *            type of range value
 * @param <V>
 *            type of validatable
 * 
 * @author igor
 */
public abstract class AbstractRangeValidator<R extends Comparable<? super R> & Serializable, V extends Serializable>
        extends Behavior implements IValidator<V>
{
        private static final long serialVersionUID = 1L;
        private R minimum;
        private R maximum;

        /**
         * Constructor that sets the minimum and maximum values.
         * 
         * @param minimum
         *            the minimum value
         * @param maximum
         *            the maximum value
         */
        public AbstractRangeValidator(R minimum, R maximum)
        {
                setRange(minimum, maximum);
        }

        /**
         * Constructor used for subclasses who want to set the range using
         * {@link #setRange(Comparable, Comparable)}
         */
        protected AbstractRangeValidator()
        {
        }

        /**
         * Sets validator range
         * 
         * @param minimum
         * @param maximum
         */
        protected final void setRange(R minimum, R maximum)
        {
                if (minimum == null && maximum == null)
                {
                        throw new IllegalArgumentException("Both minimum and maximum values cannot be null");
                }
                this.minimum = minimum;
                this.maximum = maximum;
        }

        @Override
        public void validate(IValidatable<V> validatable)
        {
                R value = getValue(validatable);
                final R min = getMinimum();
                final R max = getMaximum();
                if ((min != null && value.compareTo(min) < 0) || (max != null && value.compareTo(max) > 0))
                {
                        Mode mode = getMode();
                        ValidationError error = new ValidationError(this, mode.getVariation());
                        if (min != null)
                        {
                                error.setVariable("minimum", min);
                        }
                        if (max != null)
                        {
                                error.setVariable("maximum", max);
                        }
                        if (mode == Mode.EXACT)
                        {
                                error.setVariable("exact", max);
                        }
                        validatable.error(decorate(error, validatable));
                }
        }

        /**
         * Gets the value that should be validated against the range
         * 
         * @param validatable
         * @return value to validate
         */
        protected abstract R getValue(IValidatable<V> validatable);

        /**
         * Gets the minimum value.
         * 
         * @return minimum value
         */
        public R getMinimum()
        {
                return minimum;
        }

        /**
         * Gets the maximum value.
         * 
         * @return maximum value
         */
        public R getMaximum()
        {
                return maximum;
        }

        /**
         * Allows subclasses to decorate reported errors
         * 
         * @param error
         * @param validatable
         * @return decorated error
         */
        protected IValidationError decorate(IValidationError error, IValidatable<V> validatable)
        {
                return error;
        }

        /**
         * Gets validation mode which is determined by whether min, max, or both values are provided
         * 
         * @return validation mode
         */
        public final Mode getMode()
        {
                final R min = getMinimum();
                final R max = getMaximum();

                if (min == null && max != null)
                {
                        return Mode.MAXIMUM;
                }
                else if (max == null && min != null)
                {
                        return Mode.MINIMUM;
                }
                else if ((min == null && max == null) || max.equals(min))
                {
                        return Mode.EXACT;
                }
                else
                {
                        return Mode.RANGE;
                }
        }

        /**
         * Validator mode
         * 
         * @author igor
         */
        public static enum Mode {
                MINIMUM, MAXIMUM, RANGE, EXACT;

                public String getVariation()
                {
                        return name().toLowerCase(Locale.ROOT);
                }
        }

}