Copyright (c) 2000, 2018 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.text.templates;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import java.util.Set;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

import org.eclipse.osgi.util.NLS;

import org.eclipse.core.runtime.Assert;
import org.eclipse.core.runtime.ILog;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Platform;
import org.eclipse.core.runtime.Status;

import org.eclipse.jface.text.templates.Template;

Serializes templates as character or byte stream and reads the same format
back.

Clients may instantiate this class, it is not intended to be
subclassed.
Since:
3.7
@noextend
This class is not intended to be subclassed by clients./**
 * Serializes templates as character or byte stream and reads the same format
 * back.
 * <p>
 * Clients may instantiate this class, it is not intended to be
 * subclassed.</p>
 *
 * @since 3.7
 * @noextend This class is not intended to be subclassed by clients.
 */
public class TemplateReaderWriter {

	private static final String TEMPLATE_ROOT = "templates"; //$NON-NLS-1$
	private static final String TEMPLATE_ELEMENT = "template"; //$NON-NLS-1$
	private static final String NAME_ATTRIBUTE= "name"; //$NON-NLS-1$
	private static final String ID_ATTRIBUTE= "id"; //$NON-NLS-1$
	private static final String DESCRIPTION_ATTRIBUTE= "description"; //$NON-NLS-1$
	private static final String CONTEXT_ATTRIBUTE= "context"; //$NON-NLS-1$
	private static final String ENABLED_ATTRIBUTE= "enabled"; //$NON-NLS-1$
	private static final String DELETED_ATTRIBUTE= "deleted"; //$NON-NLS-1$
	
Since:
3.1/**
	 * @since 3.1
	 */
	private static final String AUTO_INSERTABLE_ATTRIBUTE= "autoinsert"; //$NON-NLS-1$

	
Create a new instance.
/**
	 * Create a new instance.
	 */
	public TemplateReaderWriter() {
	}

	
Reads templates from a reader and returns them. The reader must present
a serialized form as produced by the save method.
Params:
reader – the reader to read templates from
Throws:
IOException – if reading from the stream fails
Returns:
the read templates, encapsulated in instances of TemplatePersistenceData/**
	 * Reads templates from a reader and returns them. The reader must present
	 * a serialized form as produced by the <code>save</code> method.
	 *
	 * @param reader the reader to read templates from
	 * @return the read templates, encapsulated in instances of <code>TemplatePersistenceData</code>
	 * @throws IOException if reading from the stream fails
	 */
	public TemplatePersistenceData[] read(Reader reader) throws IOException {
		return read(reader, null);
	}

	
Reads the template with identifier id from a reader and
returns it. The reader must present a serialized form as produced by the
save method.
Params:
reader – the reader to read templates from
id – the id of the template to return
Throws:
IOException – if reading from the stream fails
Returns:
the read template, encapsulated in an instances of
        TemplatePersistenceData
Since:
3.1/**
	 * Reads the template with identifier <code>id</code> from a reader and
	 * returns it. The reader must present a serialized form as produced by the
	 * <code>save</code> method.
	 *
	 * @param reader the reader to read templates from
	 * @param id the id of the template to return
	 * @return the read template, encapsulated in an instances of
	 *         <code>TemplatePersistenceData</code>
	 * @throws IOException if reading from the stream fails
	 * @since 3.1
	 */
	public TemplatePersistenceData readSingle(Reader reader, String id) throws IOException {
		TemplatePersistenceData[] datas= read(new InputSource(reader), null, id);
		if (datas.length > 0)
			return datas[0];
		return null;
	}

	
Reads templates from a stream and adds them to the templates.
Params:
reader – the reader to read templates from
bundle – a resource bundle to use for translating the read templates, or null if no translation should occur
Throws:
IOException – if reading from the stream fails
Returns:
the read templates, encapsulated in instances of TemplatePersistenceData/**
	 * Reads templates from a stream and adds them to the templates.
	 *
	 * @param reader the reader to read templates from
	 * @param bundle a resource bundle to use for translating the read templates, or <code>null</code> if no translation should occur
	 * @return the read templates, encapsulated in instances of <code>TemplatePersistenceData</code>
	 * @throws IOException if reading from the stream fails
	 */
	public TemplatePersistenceData[] read(Reader reader, ResourceBundle bundle) throws IOException {
		return read(new InputSource(reader), bundle, null);
	}

	
Reads templates from a stream and adds them to the templates.
Params:
stream – the byte stream to read templates from
bundle – a resource bundle to use for translating the read templates, or null if no translation should occur
Throws:
IOException – if reading from the stream fails
Returns:
the read templates, encapsulated in instances of TemplatePersistenceData/**
	 * Reads templates from a stream and adds them to the templates.
	 *
	 * @param stream the byte stream to read templates from
	 * @param bundle a resource bundle to use for translating the read templates, or <code>null</code> if no translation should occur
	 * @return the read templates, encapsulated in instances of <code>TemplatePersistenceData</code>
	 * @throws IOException if reading from the stream fails
	 */
	public TemplatePersistenceData[] read(InputStream stream, ResourceBundle bundle) throws IOException {
		return read(new InputSource(stream), bundle, null);
	}

	
Reads templates from an InputSource and adds them to the templates.
Params:
source – the input source
bundle – a resource bundle to use for translating the read templates, or null if no translation should occur
singleId – the template id to extract, or null to read in all templates
Throws:
IOException – if reading from the stream fails
Returns:
the read templates, encapsulated in instances of TemplatePersistenceData/**
	 * Reads templates from an <code>InputSource</code> and adds them to the templates.
	 *
	 * @param source the input source
	 * @param bundle a resource bundle to use for translating the read templates, or <code>null</code> if no translation should occur
	 * @param singleId the template id to extract, or <code>null</code> to read in all templates
	 * @return the read templates, encapsulated in instances of <code>TemplatePersistenceData</code>
	 * @throws IOException if reading from the stream fails
	 */
	private TemplatePersistenceData[] read(InputSource source, ResourceBundle bundle, String singleId) throws IOException {
		try {
			Collection<TemplatePersistenceData> templates= new ArrayList<>();
			Set<String> ids= new HashSet<>();

			DocumentBuilderFactory factory= DocumentBuilderFactory.newInstance();
			DocumentBuilder parser= factory.newDocumentBuilder();
			parser.setErrorHandler(new DefaultHandler());
			Document document= parser.parse(source);

			NodeList elements= document.getElementsByTagName(TEMPLATE_ELEMENT);

			int count= elements.getLength();
			for (int i= 0; i != count; i++) {
				Node node= elements.item(i);
				NamedNodeMap attributes= node.getAttributes();

				if (attributes == null)
					continue;

				String id= getStringValue(attributes, ID_ATTRIBUTE, null);
				if (id != null && ids.contains(id)) {
					String PLUGIN_ID= "org.eclipse.jface.text"; //$NON-NLS-1$
					ILog log= Platform.getLog(Platform.getBundle(PLUGIN_ID));
					String message= NLS.bind(TextTemplateMessages.getString("TemplateReaderWriter.duplicate.id"), id); //$NON-NLS-1$
					log.log(new Status(IStatus.WARNING, PLUGIN_ID, IStatus.OK, message, null));
				} else {
					ids.add(id);
				}

				if (singleId != null && !singleId.equals(id))
					continue;

				boolean deleted = getBooleanValue(attributes, DELETED_ATTRIBUTE, false);

				String name= getStringValue(attributes, NAME_ATTRIBUTE);
				name= translateString(name, bundle);

				String description= getStringValue(attributes, DESCRIPTION_ATTRIBUTE, ""); //$NON-NLS-1$
				description= translateString(description, bundle);

				String context= getStringValue(attributes, CONTEXT_ATTRIBUTE);

				if (name == null || context == null)
					throw new IOException(TextTemplateMessages.getString("TemplateReaderWriter.error.missing_attribute")); //$NON-NLS-1$

				boolean enabled = getBooleanValue(attributes, ENABLED_ATTRIBUTE, true);
				boolean autoInsertable= getBooleanValue(attributes, AUTO_INSERTABLE_ATTRIBUTE, true);

				StringBuilder buffer= new StringBuilder();
				NodeList children= node.getChildNodes();
				for (int j= 0; j != children.getLength(); j++) {
					String value= children.item(j).getNodeValue();
					if (value != null)
						buffer.append(value);
				}
				String pattern= buffer.toString();
				pattern= translateString(pattern, bundle);

				Template template= new Template(name, description, context, pattern, autoInsertable);
				TemplatePersistenceData data= new TemplatePersistenceData(template, enabled, id);
				data.setDeleted(deleted);

				templates.add(data);

				if (singleId != null && singleId.equals(id))
					break;
			}

			return templates.toArray(new TemplatePersistenceData[templates.size()]);

		} catch (ParserConfigurationException e) {
			Assert.isTrue(false);
		} catch (SAXException e) {
			throw (IOException)new IOException("Could not read template file").initCause(e); //$NON-NLS-1$
		}

		return null; // dummy
	}

	
Saves the templates as XML, encoded as UTF-8 onto the given byte stream.
Params:
templates – the templates to save
stream – the byte output to write the templates to in XML
Throws:
IOException – if writing the templates fails/**
	 * Saves the templates as XML, encoded as UTF-8 onto the given byte stream.
	 *
	 * @param templates the templates to save
	 * @param stream the byte output to write the templates to in XML
	 * @throws IOException if writing the templates fails
	 */
	public void save(TemplatePersistenceData[] templates, OutputStream stream) throws IOException {
		save(templates, new StreamResult(stream));
	}

	
Saves the templates as XML.
Params:
templates – the templates to save
writer – the writer to write the templates to in XML
Throws:
IOException – if writing the templates fails/**
	 * Saves the templates as XML.
	 *
	 * @param templates the templates to save
	 * @param writer the writer to write the templates to in XML
	 * @throws IOException if writing the templates fails
	 */
	public void save(TemplatePersistenceData[] templates, Writer writer) throws IOException {
		save(templates, new StreamResult(writer));
	}

	
Saves the templates as XML.
Params:
templates – the templates to save
result – the stream result to write to
Throws:
IOException – if writing the templates fails/**
	 * Saves the templates as XML.
	 *
	 * @param templates the templates to save
	 * @param result the stream result to write to
	 * @throws IOException if writing the templates fails
	 */
	private void save(TemplatePersistenceData[] templates, StreamResult result) throws IOException {
		try {
			DocumentBuilderFactory factory= DocumentBuilderFactory.newInstance();
			DocumentBuilder builder= factory.newDocumentBuilder();
			Document document= builder.newDocument();

			Node root= document.createElement(TEMPLATE_ROOT);
			document.appendChild(root);

			for (TemplatePersistenceData data : templates) {
				Template template= data.getTemplate();

				Node node= document.createElement(TEMPLATE_ELEMENT);
				root.appendChild(node);

				NamedNodeMap attributes= node.getAttributes();

				String id= data.getId();
				if (id != null) {
					Attr idAttr= document.createAttribute(ID_ATTRIBUTE);
					idAttr.setValue(id);
					attributes.setNamedItem(idAttr);
				}

				if (template != null) {
					Attr name= document.createAttribute(NAME_ATTRIBUTE);
					name.setValue(validateXML(template.getName()));
					attributes.setNamedItem(name);
				}

				if (template != null) {
					Attr description= document.createAttribute(DESCRIPTION_ATTRIBUTE);
					description.setValue(validateXML(template.getDescription()));
					attributes.setNamedItem(description);
				}

				if (template != null) {
					Attr context= document.createAttribute(CONTEXT_ATTRIBUTE);
					context.setValue(validateXML(template.getContextTypeId()));
					attributes.setNamedItem(context);
				}

				Attr enabled= document.createAttribute(ENABLED_ATTRIBUTE);
				enabled.setValue(data.isEnabled() ? Boolean.toString(true) : Boolean.toString(false));
				attributes.setNamedItem(enabled);

				Attr deleted= document.createAttribute(DELETED_ATTRIBUTE);
				deleted.setValue(data.isDeleted() ? Boolean.toString(true) : Boolean.toString(false));
				attributes.setNamedItem(deleted);

				if (template != null) {
					Attr autoInsertable= document.createAttribute(AUTO_INSERTABLE_ATTRIBUTE);
					autoInsertable.setValue(template.isAutoInsertable() ? Boolean.toString(true) : Boolean.toString(false));
					attributes.setNamedItem(autoInsertable);
				}

				if (template != null) {
					Text pattern= document.createTextNode(validateXML(template.getPattern()));
					node.appendChild(pattern);
				}
			}


			Transformer transformer=TransformerFactory.newInstance().newTransformer();
			transformer.setOutputProperty(OutputKeys.METHOD, "xml"); //$NON-NLS-1$
			transformer.setOutputProperty(OutputKeys.ENCODING, StandardCharsets.UTF_8.name());
			DOMSource source = new DOMSource(document);

			transformer.transform(source, result);

		} catch (ParserConfigurationException e) {
			Assert.isTrue(false);
		} catch (TransformerException e) {
			if (e.getException() instanceof IOException)
				throw (IOException) e.getException();
			Assert.isTrue(false);
		}
	}

	
Validates whether the given string only contains valid XML characters.
Params:
string – the string to validate
Throws:
IOException – when the first invalid character is detected
Returns:
the input string
Since:
3.6/**
	 * Validates whether the given string only contains valid XML characters.
	 *
	 * @param string the string to validate
	 * @return the input string
	 * @throws IOException when the first invalid character is detected
	 * @since 3.6
	 */
	private static String validateXML(String string) throws IOException {
		for (int i= 0; i < string.length(); i++) {
			char ch= string.charAt(i);
			if (!(ch == 9 || ch == 10 || ch == 13 || ch >= 32))
				throw new IOException("Character reference \"&#" + Integer.toString(ch) + "\" is an invalid XML character."); //$NON-NLS-1$ //$NON-NLS-2$
		}
		return string;
	}

	private boolean getBooleanValue(NamedNodeMap attributes, String attribute, boolean defaultValue) throws SAXException {
		Node enabledNode= attributes.getNamedItem(attribute);
		if (enabledNode == null)
			return defaultValue;
		else if (enabledNode.getNodeValue().equals(Boolean.toString(true)))
			return true;
		else if (enabledNode.getNodeValue().equals(Boolean.toString(false)))
			return false;
		else
			throw new SAXException(TextTemplateMessages.getString("TemplateReaderWriter.error.illegal_boolean_attribute")); //$NON-NLS-1$
	}

	private String getStringValue(NamedNodeMap attributes, String name) throws SAXException {
		String val= getStringValue(attributes, name, null);
		if (val == null)
			throw new SAXException(TextTemplateMessages.getString("TemplateReaderWriter.error.missing_attribute")); //$NON-NLS-1$
		return val;
	}

	private String getStringValue(NamedNodeMap attributes, String name, String defaultValue) {
		Node node= attributes.getNamedItem(name);
		return node == null	? defaultValue : node.getNodeValue();
	}

	private String translateString(String str, ResourceBundle bundle) {
		if (bundle == null)
			return str;

		int idx= str.indexOf('%');
		if (idx == -1) {
			return str;
		}
		StringBuilder buf= new StringBuilder();
		int k= 0;
		while (idx != -1) {
			buf.append(str.substring(k, idx));
			for (k= idx + 1; k < str.length() && !Character.isWhitespace(str.charAt(k)); k++) {
				// loop
			}
			String key= str.substring(idx + 1, k);
			buf.append(getBundleString(key, bundle));
			idx= str.indexOf('%', k);
		}
		buf.append(str.substring(k));
		return buf.toString();
	}

	private String getBundleString(String key, ResourceBundle bundle) {
		if (bundle != null) {
			try {
				return bundle.getString(key);
			} catch (MissingResourceException e) {
				return '!' + key + '!';
			}
		}
		return TextTemplateMessages.getString(key); // default messages
	}
}