/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jface.text.templates.persistence;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
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.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.xml.sax.InputSource;
import org.xml.sax.SAXException;

import org.eclipse.jface.text.Assert;
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 3.0
 */
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"; //$NON-NLS-1$
	
	/**
	 * 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 <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 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);
	}
	
	/**
	 * 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);
	}
	
	/**
	 * 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
	 * @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) throws IOException {
		try {
			Collection templates= new ArrayList();
			Set ids= new HashSet();
			
			DocumentBuilderFactory factory= DocumentBuilderFactory.newInstance();
			DocumentBuilder parser= factory.newDocumentBuilder();		
			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))
					throw new IOException(TemplatePersistenceMessages.getString("TemplateReaderWriter.duplicate.id")); //$NON-NLS-1$
				
				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(TemplatePersistenceMessages.getString("TemplateReaderWriter.error.missing_attribute")); //$NON-NLS-1$

				boolean enabled = getBooleanValue(attributes, ENABLED_ATTRIBUTE, true);
				
				StringBuffer buffer= new StringBuffer();
				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);
				TemplatePersistenceData data= new TemplatePersistenceData(template, enabled, id);
				data.setDeleted(deleted);
				
				templates.add(data);
			}
			
			return (TemplatePersistenceData[]) templates.toArray(new TemplatePersistenceData[templates.size()]);
			
		} catch (ParserConfigurationException e) {
			Assert.isTrue(false);
		} catch (SAXException e) {
			Throwable t= e.getCause();
			if (t instanceof IOException)
				throw (IOException) t;
			else
				throw new IOException(t.getMessage());
		}
		
		return null; // dummy
	}
	
	/**
	 * 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.
	 * 
	 * @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.
	 * 
	 * @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); //$NON-NLS-1$
			document.appendChild(root);
			
			for (int i= 0; i < templates.length; i++) {
				TemplatePersistenceData data= templates[i];
				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(template.getName());
					attributes.setNamedItem(name);
				}
	
				if (template != null) {
					Attr description= document.createAttribute(DESCRIPTION_ATTRIBUTE);
					description.setValue(template.getDescription());
					attributes.setNamedItem(description);
				}
	
				if (template != null) {
					Attr context= document.createAttribute(CONTEXT_ATTRIBUTE);
					context.setValue(template.getContextTypeId());
					attributes.setNamedItem(context);
				}
				
				Attr enabled= document.createAttribute(ENABLED_ATTRIBUTE);
				enabled.setValue(data.isEnabled() ? Boolean.toString(true) : Boolean.toString(false)); //$NON-NLS-1$ //$NON-NLS-2$
				attributes.setNamedItem(enabled);
				
				Attr deleted= document.createAttribute(DELETED_ATTRIBUTE);
				deleted.setValue(data.isDeleted() ? Boolean.toString(true) : Boolean.toString(false)); //$NON-NLS-1$ //$NON-NLS-2$
				attributes.setNamedItem(deleted);
				
				if (template != null) {
					Text pattern= document.createTextNode(template.getPattern());
					node.appendChild(pattern);			
				}
			}		
			
			
			Transformer transformer=TransformerFactory.newInstance().newTransformer();
			transformer.setOutputProperty(OutputKeys.METHOD, "xml"); //$NON-NLS-1$
			transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8"); //$NON-NLS-1$
			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);
		}		
	}

	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(TemplatePersistenceMessages.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(TemplatePersistenceMessages.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;
		}
		StringBuffer buf= new StringBuffer();
		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 + '!';
			}
		} else
			return TemplatePersistenceMessages.getString(key); // default messages
	}
}

