package ca.uhn.fhir.model.primitive;

/*
 * #%L
 * HAPI FHIR - Core Library
 * %%
 * Copyright (C) 2014 - 2017 University Health Network
 * %%
 * 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%
 */

import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

import javax.xml.stream.FactoryConfigurationError;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLEventWriter;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.XMLEvent;

import ca.uhn.fhir.context.ConfigurationException;
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.XmlUtil;

@DatatypeDef(name = "xhtml")
public class XhtmlDt extends BasePrimitive<List<XMLEvent>> {

	private static final String DECL_XMLNS = " xmlns=\"http://www.w3.org/1999/xhtml\"";
	private 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(List<XMLEvent> theValue) {
		try {
			StringWriter w = new StringWriter();
			XMLEventWriter ew = XmlUtil.createXmlFragmentWriter(w);

			for (XMLEvent next : getValue()) {
				if (next.isCharacters()) {
					ew.add(next);
				} else {
					ew.add(next);
				}
			}
			ew.close();
			return w.toString();
		} catch (XMLStreamException e) {
			throw new DataFormatException("Problem with the contained XML events", e);
		} catch (FactoryConfigurationError e) {
			throw new ConfigurationException(e);
		}
	}

	public boolean hasContent() {
		return getValue() != null && getValue().size() > 0;
	}

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

	@Override
	protected List<XMLEvent> parse(String theValue) {
		String val = theValue.trim();
		if (!val.startsWith("<")) {
			val = DIV_OPEN_FIRST + val + "</div>";
		}
		boolean hasProcessingInstruction = val.startsWith("<?");
		if (hasProcessingInstruction && val.endsWith("?>")) {
			return null;
		}

		
		try {
			ArrayList<XMLEvent> value = new ArrayList<XMLEvent>();
			StringReader reader = new StringReader(val);
			XMLEventReader er = XmlUtil.createXmlReader(reader);
			boolean first = true;
			while (er.hasNext()) {
				XMLEvent next = er.nextEvent();
				if (first) {
					first = false;
					continue;
				}
				if (er.hasNext()) {
					// don't add the last event
					value.add(next);
				}
			}
			return value;

		} catch (XMLStreamException e) {
			throw new DataFormatException("String does not appear to be valid XML/XHTML (error is \"" + e.getMessage() + "\"): " + theValue, e);
		} catch (FactoryConfigurationError e) {
			throw new ConfigurationException(e);
		}
	}

	/**
	 * 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 (&foo;) which are not a part of the entities defined in core XML (e.g. &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;
	}

}