/*
 * Copyright 2002-2018 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
 *
 *      https://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.springframework.web.servlet.tags.form;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyContent;
import javax.servlet.jsp.tagext.BodyTag;

import org.springframework.lang.Nullable;
import org.springframework.web.servlet.support.BindStatus;
import org.springframework.web.util.TagUtils;

The <option> tag renders a single HTML 'option'. Sets 'selected' as appropriate based on bound value. 
Must be used nested inside a SelectTag.
Provides full support for databinding by marking an 'option' as 'selected' if the value matches the value bound to the out SelectTag. 
The value property is required and corresponds to the 'value' attribute of the rendered 'option'. 
An optional label property can be specified, the value of which corresponds to inner text of the rendered 'option' tag. If no label is specified then the value property will be used when rendering the inner text. 


Attribute Summary


Attribute
Required?
Runtime Expression?
Description




cssClass
false
true
HTML Optional Attribute


cssErrorClass
false
true
HTML Optional Attribute. Used when the bound field has
errors.


cssStyle
false
true
HTML Optional Attribute


dir
false
true
HTML Standard Attribute


disabled
false
true
HTML Optional Attribute. Setting the value of this attribute to 'true'
will disable the HTML element.


htmlEscape
false
true
Enable/disable HTML escaping of rendered values.


id
false
true
HTML Standard Attribute


label
false
true
HTML Optional Attribute


lang
false
true
HTML Standard Attribute


onclick
false
true
HTML Event Attribute


ondblclick
false
true
HTML Event Attribute


onkeydown
false
true
HTML Event Attribute


onkeypress
false
true
HTML Event Attribute


onkeyup
false
true
HTML Event Attribute


onmousedown
false
true
HTML Event Attribute


onmousemove
false
true
HTML Event Attribute


onmouseout
false
true
HTML Event Attribute


onmouseover
false
true
HTML Event Attribute


onmouseup
false
true
HTML Event Attribute


tabindex
false
true
HTML Standard Attribute


title
false
true
HTML Standard Attribute


value
true
true
HTML Optional Attribute



Author:
Rob Harrop, Juergen Hoeller
Since:
2.0/**
 * The {@code <option>} tag renders a single HTML 'option'. Sets 'selected' as
 * appropriate based on bound value.
 *
 * <p><b>Must be used nested inside a {@link SelectTag}.</b>
 *
 * <p>Provides full support for databinding by marking an
 * '{@code option}' as 'selected' if the {@link #setValue value}
 * matches the value bound to the out {@link SelectTag}.
 *
 * <p>The {@link #setValue value} property is required and corresponds to
 * the '{@code value}' attribute of the rendered '{@code option}'.
 *
 * <p>An optional {@link #setLabel label} property can be specified, the
 * value of which corresponds to inner text of the rendered
 * '{@code option}' tag. If no {@link #setLabel label} is specified
 * then the {@link #setValue value} property will be used when rendering
 * the inner text.
 *
 * <p>
 * <table>
 * <caption>Attribute Summary</caption>
 * <thead>
 * <tr>
 * <th class="colFirst">Attribute</th>
 * <th class="colOne">Required?</th>
 * <th class="colOne">Runtime Expression?</th>
 * <th class="colLast">Description</th>
 * </tr>
 * </thead>
 * <tbody>
 * <tr class="altColor">
 * <td><p>cssClass</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Optional Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>cssErrorClass</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Optional Attribute. Used when the bound field has
 * errors.</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>cssStyle</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Optional Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>dir</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Standard Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>disabled</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Optional Attribute. Setting the value of this attribute to 'true'
 * will disable the HTML element.</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>htmlEscape</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>Enable/disable HTML escaping of rendered values.</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>id</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Standard Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>label</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Optional Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>lang</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Standard Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>onclick</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>ondblclick</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>onkeydown</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>onkeypress</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>onkeyup</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>onmousedown</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>onmousemove</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>onmouseout</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>onmouseover</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>onmouseup</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Event Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>tabindex</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Standard Attribute</p></td>
 * </tr>
 * <tr class="altColor">
 * <td><p>title</p></td>
 * <td><p>false</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Standard Attribute</p></td>
 * </tr>
 * <tr class="rowColor">
 * <td><p>value</p></td>
 * <td><p>true</p></td>
 * <td><p>true</p></td>
 * <td><p>HTML Optional Attribute</p></td>
 * </tr>
 * </tbody>
 * </table>
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 */
@SuppressWarnings("serial")
public class OptionTag extends AbstractHtmlElementBodyTag implements BodyTag {

	
The name of the JSP variable used to expose the value for this tag.
/**
	 * The name of the JSP variable used to expose the value for this tag.
	 */
	public static final String VALUE_VARIABLE_NAME = "value";

	
The name of the JSP variable used to expose the display value for this tag.
/**
	 * The name of the JSP variable used to expose the display value for this tag.
	 */
	public static final String DISPLAY_VALUE_VARIABLE_NAME = "displayValue";

	
The name of the 'selected' attribute. /**
	 * The name of the '{@code selected}' attribute.
	 */
	private static final String SELECTED_ATTRIBUTE = "selected";

	
The name of the 'value' attribute. /**
	 * The name of the '{@code value}' attribute.
	 */
	private static final String VALUE_ATTRIBUTE = VALUE_VARIABLE_NAME;

	
The name of the 'disabled' attribute. /**
	 * The name of the '{@code disabled}' attribute.
	 */
	private static final String DISABLED_ATTRIBUTE = "disabled";


	
The 'value' attribute of the rendered HTML <option> tag. /**
	 * The 'value' attribute of the rendered HTML {@code <option>} tag.
	 */
	@Nullable
	private Object value;

	
The text body of the rendered HTML <option> tag. /**
	 * The text body of the rendered HTML {@code <option>} tag.
	 */
	@Nullable
	private String label;

	@Nullable
	private Object oldValue;

	@Nullable
	private Object oldDisplayValue;

	private boolean disabled;


	
Set the 'value' attribute of the rendered HTML <option> tag. /**
	 * Set the 'value' attribute of the rendered HTML {@code <option>} tag.
	 */
	public void setValue(Object value) {
		this.value = value;
	}

	
Get the 'value' attribute of the rendered HTML <option> tag. /**
	 * Get the 'value' attribute of the rendered HTML {@code <option>} tag.
	 */
	@Nullable
	protected Object getValue() {
		return this.value;
	}

	
Set the value of the 'disabled' attribute. /**
	 * Set the value of the '{@code disabled}' attribute.
	 */
	public void setDisabled(boolean disabled) {
		this.disabled = disabled;
	}

	
Get the value of the 'disabled' attribute. /**
	 * Get the value of the '{@code disabled}' attribute.
	 */
	protected boolean isDisabled() {
		return this.disabled;
	}

	
Set the text body of the rendered HTML <option> tag. 
May be a runtime expression.
/**
	 * Set the text body of the rendered HTML {@code <option>} tag.
	 * <p>May be a runtime expression.
	 */
	public void setLabel(String label) {
		this.label = label;
	}

	
Get the text body of the rendered HTML <option> tag. /**
	 * Get the text body of the rendered HTML {@code <option>} tag.
	 */
	@Nullable
	protected String getLabel() {
		return this.label;
	}


	@Override
	protected void renderDefaultContent(TagWriter tagWriter) throws JspException {
		Object value = this.pageContext.getAttribute(VALUE_VARIABLE_NAME);
		String label = getLabelValue(value);
		renderOption(value, label, tagWriter);
	}

	@Override
	protected void renderFromBodyContent(BodyContent bodyContent, TagWriter tagWriter) throws JspException {
		Object value = this.pageContext.getAttribute(VALUE_VARIABLE_NAME);
		String label = bodyContent.getString();
		renderOption(value, label, tagWriter);
	}

	
Make sure we are under a 'select' tag before proceeding. /**
	 * Make sure we are under a '{@code select}' tag before proceeding.
	 */
	@Override
	protected void onWriteTagContent() {
		assertUnderSelectTag();
	}

	@Override
	protected void exposeAttributes() throws JspException {
		Object value = resolveValue();
		this.oldValue = this.pageContext.getAttribute(VALUE_VARIABLE_NAME);
		this.pageContext.setAttribute(VALUE_VARIABLE_NAME, value);
		this.oldDisplayValue = this.pageContext.getAttribute(DISPLAY_VALUE_VARIABLE_NAME);
		this.pageContext.setAttribute(DISPLAY_VALUE_VARIABLE_NAME, getDisplayString(value, getBindStatus().getEditor()));
	}

	@Override
	protected BindStatus getBindStatus() {
		return (BindStatus) this.pageContext.getAttribute(SelectTag.LIST_VALUE_PAGE_ATTRIBUTE);
	}

	@Override
	protected void removeAttributes() {
		if (this.oldValue != null) {
			this.pageContext.setAttribute(VALUE_ATTRIBUTE, this.oldValue);
			this.oldValue = null;
		}
		else {
			this.pageContext.removeAttribute(VALUE_VARIABLE_NAME);
		}

		if (this.oldDisplayValue != null) {
			this.pageContext.setAttribute(DISPLAY_VALUE_VARIABLE_NAME, this.oldDisplayValue);
			this.oldDisplayValue = null;
		}
		else {
			this.pageContext.removeAttribute(DISPLAY_VALUE_VARIABLE_NAME);
		}
	}

	private void renderOption(Object value, String label, TagWriter tagWriter) throws JspException {
		tagWriter.startTag("option");
		writeOptionalAttribute(tagWriter, "id", resolveId());
		writeOptionalAttributes(tagWriter);
		String renderedValue = getDisplayString(value, getBindStatus().getEditor());
		renderedValue = processFieldValue(getSelectTag().getName(), renderedValue, "option");
		tagWriter.writeAttribute(VALUE_ATTRIBUTE, renderedValue);
		if (isSelected(value)) {
			tagWriter.writeAttribute(SELECTED_ATTRIBUTE, SELECTED_ATTRIBUTE);
		}
		if (isDisabled()) {
			tagWriter.writeAttribute(DISABLED_ATTRIBUTE, "disabled");
		}
		tagWriter.appendValue(label);
		tagWriter.endTag();
	}

	@Override
	protected String autogenerateId() throws JspException {
		return null;
	}

	
Return the value of the label for this 'option' element. 
If the label property is set then the resolved value of that property is used, otherwise the value of the resolvedValue argument is used. /**
	 * Return the value of the label for this '{@code option}' element.
	 * <p>If the {@link #setLabel label} property is set then the resolved value
	 * of that property is used, otherwise the value of the {@code resolvedValue}
	 * argument is used.
	 */
	private String getLabelValue(Object resolvedValue) throws JspException {
		String label = getLabel();
		Object labelObj = (label == null ? resolvedValue : evaluate("label", label));
		return getDisplayString(labelObj, getBindStatus().getEditor());
	}

	private void assertUnderSelectTag() {
		TagUtils.assertHasAncestorOfType(this, SelectTag.class, "option", "select");
	}

	private SelectTag getSelectTag() {
		return (SelectTag) findAncestorWithClass(this, SelectTag.class);
	}

	private boolean isSelected(Object resolvedValue) {
		return SelectedValueComparator.isSelected(getBindStatus(), resolvedValue);
	}

	@Nullable
	private Object resolveValue() throws JspException {
		return evaluate(VALUE_VARIABLE_NAME, getValue());
	}

}