/*
 * 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.markup.html.form;

import org.apache.wicket.Component;
import org.apache.wicket.IGenericComponent;
import org.apache.wicket.WicketRuntimeException;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.html.WebMarkupContainer;
import org.apache.wicket.model.IModel;

/**
 * Component representing a single radio choice in a org.apache.wicket.markup.html.form.RadioGroup.
 * 
 * Must be attached to an <input type="radio" ... > markup.
 * <p>
 * STATELESS NOTES: By default this component cannot be used inside a stateless form. If it is
 * desirable to use this inside a stateless form then
 * <ul>
 * <li>
 * override #getValue() and return some stateless value to uniquely identify this radio (eg relative
 * component path from group to this radio)</li>
 * <li>
 * override {@link #getStatelessHint()} and return <code>true</code></li>
 * </ul>
 * </p>
 * 
 * @see org.apache.wicket.markup.html.form.RadioGroup
 * 
 * @author Igor Vaynberg
 * @author Sven Meier (svenmeier)
 * 
 * @param <T>
 *            The model object type
 */
public class Radio<T> extends LabeledWebMarkupContainer implements IGenericComponent<T, Radio<T>>
{
        private static final long serialVersionUID = 1L;

        private static final String ATTR_DISABLED = "disabled";

        /**
         * page-scoped uuid of this check. this property must not be accessed directly, instead
         * {@link #getValue()} must be used
         */
        private int uuid = -1;

        private final RadioGroup<T> group;

        /**
         * @see WebMarkupContainer#WebMarkupContainer(String)
         */
        public Radio(final String id)
        {
                this(id, null, null);
        }

        /**
         * @param id
         * @param model
         * @see WebMarkupContainer#WebMarkupContainer(String, IModel)
         */
        public Radio(final String id, final IModel<T> model)
        {
                this(id, model, null);
        }

        /**
         * @param id
         * @param group
         *            parent {@link RadioGroup}
         * @see WebMarkupContainer#WebMarkupContainer(String)
         */
        public Radio(final String id, final RadioGroup<T> group)
        {
                this(id, null, group);
        }

        /**
         * @param id
         * @param model
         * @param group
         *            parent {@link RadioGroup}
         * @see WebMarkupContainer#WebMarkupContainer(String, IModel)
         */
        public Radio(final String id, final IModel<T> model, final RadioGroup<T> group)
        {
                super(id, model);
                this.group = group;
                setOutputMarkupId(true);
        }

        /**
         * Form submission value used for the Html <code>value</code> attribute of the <code>input</code> tag.
         * <p>
         * If {@link Radio}s are recreated on each render of their {@link RadioGroup}, this method should
         * be overridden to return a 'stable' value, otherwise its selection will be lost after a {@link Form}
         * was submitted and resulted in {@link Form#hasError()}.
         * 
         * @return input value
         */
        public String getValue()
        {
                if (uuid < 0)
                {
                        uuid = getPage().getAutoIndex();
                }
                return "radio" + uuid;
        }

        /**
         * 
         * @return The associated radio group Component
         */
        @SuppressWarnings("unchecked")
        protected RadioGroup<T> getGroup()
        {
                RadioGroup<T> group = this.group;
                if (group == null)
                {
                        group = findParent(RadioGroup.class);
                        if (group == null)
                        {
                                throw new WicketRuntimeException(
                                        "Radio component [" +
                                                getPath() +
                                                "] cannot find its parent RadioGroup. All Radio components must be a child of or below in the hierarchy of a RadioGroup component.");
                        }
                }
                return group;
        }

        /**
         * @see Component#onComponentTag(ComponentTag)
         * @param tag
         *            the abstraction representing html tag of this component
         */
        @Override
        protected void onComponentTag(final ComponentTag tag)
        {
                // Default handling for component tag
                super.onComponentTag(tag);

                // must be attached to <input type="radio" .../> tag
                checkComponentTag(tag, "input");
                checkComponentTagAttribute(tag, "type", "radio");

                final String value = getValue();

                RadioGroup<?> group = getGroup();

                // assign name and value
                tag.put("name", group.getInputName());
                tag.put("value", value);

                // compare the model objects of the group and self, if the same add the
                // checked attribute, first check if there was a raw input on the group.
                if (group.hasRawInput())
                {
                        String rawInput = group.getRawInput();
                        if (rawInput != null && rawInput.equals(value))
                        {
                                tag.put("checked", "checked");
                        }
                }
                else if (group.getModelComparator().compare(group, getDefaultModelObject()))
                {
                        tag.put("checked", "checked");
                }

                if (!isEnabledInHierarchy())
                {
                        tag.put(ATTR_DISABLED, ATTR_DISABLED);
                }

        }

        /**
         * The value will be made available to the validator property by means of ${label}. It does not
         * have any specific meaning to Radio itself.
         * 
         * @param labelModel
         * @return this for chaining
         */
        @Override
        public Radio<T> setLabel(IModel<String> labelModel)
        {
                super.setLabel(labelModel);
                return this;
        }

        /** {@inheritDoc} */
        @Override
        protected boolean getStatelessHint()
        {
                // because we keep uuid this component cannot be stateless
                return false;
        }
}