/*
 * 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 org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.support.BindStatus;
import org.springframework.web.util.TagUtils;

/**
 * Convenient tag that allows one to supply a collection of objects
 * that are to be rendered as '{@code option}' tags within a
 * '{@code select}' tag.
 *
 * <p><i>Must</i> be used within a {@link SelectTag 'select' tag}.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @author Scott Andrews
 * @since 2.0
 */
@SuppressWarnings("serial")
public class OptionsTag extends AbstractHtmlElementTag {

        /**
         * The {@link java.util.Collection}, {@link java.util.Map} or array of
         * objects used to generate the inner '{@code option}' tags.
         */
        private Object items;

        /**
         * The name of the property mapped to the '{@code value}' attribute
         * of the '{@code option}' tag.
         */
        private String itemValue;

        /**
         * The name of the property mapped to the inner text of the
         * '{@code option}' tag.
         */
        private String itemLabel;

        private boolean disabled;


        /**
         * Set the {@link java.util.Collection}, {@link java.util.Map} or array
         * of objects used to generate the inner '{@code option}' tags.
         * <p>Required when wishing to render '{@code option}' tags from an
         * array, {@link java.util.Collection} or {@link java.util.Map}.
         * <p>Typically a runtime expression.
         */
        public void setItems(Object items) {
                this.items = items;
        }

        /**
         * Get the {@link java.util.Collection}, {@link java.util.Map} or array
         * of objects used to generate the inner '{@code option}' tags.
         * <p>Typically a runtime expression.
         */
        protected Object getItems() {
                return this.items;
        }

        /**
         * Set the name of the property mapped to the '{@code value}'
         * attribute of the '{@code option}' tag.
         * <p>Required when wishing to render '{@code option}' tags from
         * an array or {@link java.util.Collection}.
         */
        public void setItemValue(String itemValue) {
                Assert.hasText(itemValue, "'itemValue' must not be empty");
                this.itemValue = itemValue;
        }

        /**
         * Return the name of the property mapped to the '{@code value}'
         * attribute of the '{@code option}' tag.
         */
        protected String getItemValue() {
                return this.itemValue;
        }

        /**
         * Set the name of the property mapped to the label (inner text) of the
         * '{@code option}' tag.
         */
        public void setItemLabel(String itemLabel) {
                Assert.hasText(itemLabel, "'itemLabel' must not be empty");
                this.itemLabel = itemLabel;
        }

        /**
         * Get the name of the property mapped to the label (inner text) of the
         * '{@code option}' tag.
         */
        protected String getItemLabel() {
                return this.itemLabel;
        }

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

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


        @Override
        protected int writeTagContent(TagWriter tagWriter) throws JspException {
                SelectTag selectTag = getSelectTag();
                Object items = getItems();
                Object itemsObject = null;
                if (items != null) {
                        itemsObject = (items instanceof String ? evaluate("items", items) : items);
                }
                else {
                        Class<?> selectTagBoundType = selectTag.getBindStatus().getValueType();
                        if (selectTagBoundType != null && selectTagBoundType.isEnum()) {
                                itemsObject = selectTagBoundType.getEnumConstants();
                        }
                }
                if (itemsObject != null) {
                        String selectName = selectTag.getName();
                        String itemValue = getItemValue();
                        String itemLabel = getItemLabel();
                        String valueProperty =
                                        (itemValue != null ? ObjectUtils.getDisplayString(evaluate("itemValue", itemValue)) : null);
                        String labelProperty =
                                        (itemLabel != null ? ObjectUtils.getDisplayString(evaluate("itemLabel", itemLabel)) : null);
                        OptionsWriter optionWriter = new OptionsWriter(selectName, itemsObject, valueProperty, labelProperty);
                        optionWriter.writeOptions(tagWriter);
                }
                return SKIP_BODY;
        }

        /**
         * Appends a counter to a specified id,
         * since we're dealing with multiple HTML elements.
         */
        @Override
        protected String resolveId() throws JspException {
                Object id = evaluate("id", getId());
                if (id != null) {
                        String idString = id.toString();
                        return (StringUtils.hasText(idString) ? TagIdGenerator.nextId(idString, this.pageContext) : null);
                }
                return null;
        }

        private SelectTag getSelectTag() {
                TagUtils.assertHasAncestorOfType(this, SelectTag.class, "options", "select");
                return (SelectTag) findAncestorWithClass(this, SelectTag.class);
        }

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


        /**
         * Inner class that adapts OptionWriter for multiple options to be rendered.
         */
        private class OptionsWriter extends OptionWriter {

                private final String selectName;

                public OptionsWriter(String selectName, Object optionSource, String valueProperty, String labelProperty) {
                        super(optionSource, getBindStatus(), valueProperty, labelProperty, isHtmlEscape());
                        this.selectName = selectName;
                }

                @Override
                protected boolean isOptionDisabled() throws JspException {
                        return isDisabled();
                }

                @Override
                protected void writeCommonAttributes(TagWriter tagWriter) throws JspException {
                        writeOptionalAttribute(tagWriter, "id", resolveId());
                        writeOptionalAttributes(tagWriter);
                }

                @Override
                protected String processOptionValue(String value) {
                        return processFieldValue(this.selectName, value, "option");
                }
        }

}