/*
 * #%L
 * HAPI FHIR - Core Library
 * %%
 * Copyright (C) 2014 - 2023 Smile CDR, Inc.
 * %%
 * 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
 *
 *      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.
 * #L%
 */
package ca.uhn.fhir.model.primitive;

import ca.uhn.fhir.model.api.BasePrimitive;
import ca.uhn.fhir.model.api.annotation.DatatypeDef;
import ca.uhn.fhir.model.api.annotation.SimpleSetter;
import ca.uhn.fhir.parser.DataFormatException;
import ca.uhn.fhir.util.XmlDetectionUtil;
import ca.uhn.fhir.util.XmlUtil;

import java.util.List;

import static org.apache.commons.lang3.StringUtils.isNotBlank;

/**
 * Note that as of HAPI FHIR 3.1.0, this method no longer uses
 * the StAX XMLEvent type as the XML representation, and uses a
 * String instead. If you need to work with XML as StAX events, you
 * can use the {@link XmlUtil#parse(String)} and {@link XmlUtil#encode(List)}
 * methods to do so.
 */
@DatatypeDef(name = "xhtml")
public class XhtmlDt extends BasePrimitive<String> {

        private static final String DECL_XMLNS = " xmlns=\"http://www.w3.org/1999/xhtml\"";
        public static final String DIV_OPEN_FIRST = "<div" + DECL_XMLNS + ">";
        private static final long serialVersionUID = 1L;

        /**
         * Constructor
         */
        public XhtmlDt() {
                // nothing
        }

        /**
         * Constructor which accepts a string code
         *
         * @see #setValueAsString(String) for a description of how this value is applied
         */
        @SimpleSetter()
        public XhtmlDt(@SimpleSetter.Parameter(name = "theTextDiv") String theTextDiv) {
                setValueAsString(theTextDiv);
        }

        @Override
        protected String encode(String theValue) {
                return theValue;
        }

        public boolean hasContent() {
                return isNotBlank(getValue());
        }

        @Override
        public boolean isEmpty() {
                return super.isBaseEmpty() && (getValue() == null || getValue().isEmpty());
        }

        @Override
        protected String parse(String theValue) {
                if (XmlDetectionUtil.isStaxPresent()) {
                        // for validation
                        XmlUtil.parse(theValue);
                }
                return theValue;
        }


        /**
         * Note that as of HAPI FHIR 3.1.0, this method no longer uses
         * the StAX XMLEvent type as the XML representation, and uses a
         * String instead. If you need to work with XML as StAX events, you
         * can use the {@link XmlUtil#parse(String)} and {@link XmlUtil#encode(List)}
         * methods to do so.
         */
        @Override
        public String getValue() {
                return super.getValue();
        }

        /**
         * Note that as of HAPI FHIR 3.1.0, this method no longer uses
         * the StAX XMLEvent type as the XML representation, and uses a
         * String instead. If you need to work with XML as StAX events, you
         * can use the {@link XmlUtil#parse(String)} and {@link XmlUtil#encode(List)}
         * methods to do so.
         */
        @Override
        public BasePrimitive<String> setValue(String theValue) throws DataFormatException {
                return super.setValue(theValue);
        }

        /**
         * Accepts a textual DIV and parses it into XHTML events which are stored internally.
         * <p>
         * <b>Formatting note:</b> The text will be trimmed {@link String#trim()}. If the text does not start with an HTML tag (generally this would be a div tag), a div tag will be automatically placed
         * surrounding the text.
         * </p>
         * <p>
         * Also note that if the parsed text contains any entities (&amp;foo;) which are not a part of the entities defined in core XML (e.g. &amp;sect; which is valid in XHTML 1.0 but not in XML 1.0) they
         * will be parsed and converted to their equivalent unicode character.
         * </p>
         */
        @Override
        public void setValueAsString(String theValue) throws DataFormatException {
                if (theValue == null || theValue.isEmpty()) {
                        super.setValueAsString(null);
                } else {
                        String value = theValue.trim();
                        value = preprocessXhtmlNamespaceDeclaration(value);

                        super.setValueAsString(value);
                }
        }

        public static String preprocessXhtmlNamespaceDeclaration(String value) {
                if (value.charAt(0) != '<') {
                        value = DIV_OPEN_FIRST + value + "</div>";
                }

                boolean hasProcessingInstruction = value.startsWith("<?");
                int firstTagIndex = value.indexOf("<", hasProcessingInstruction ? 1 : 0);
                if (firstTagIndex != -1) {
                        int firstTagEnd = value.indexOf(">", firstTagIndex);
                        int firstSlash = value.indexOf("/", firstTagIndex);
                        if (firstTagEnd != -1) {
                                if (firstSlash > firstTagEnd) {
                                        String firstTag = value.substring(firstTagIndex, firstTagEnd);
                                        if (!firstTag.contains(" xmlns")) {
                                                value = value.substring(0, firstTagEnd) + DECL_XMLNS + value.substring(firstTagEnd);
                                        }
                                }
                        }
                }
                return value;
        }

}