Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that implements session utility methods 

 *  Copyright: 2008 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Michael Daigle

 * 

 *   '$Author: daigle $'

 *     '$Date: 2008-08-22 16:23:38 -0700 (Fri, 22 Aug 2008) $'

 * '$Revision: 4297 $'

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

package edu.ucsb.nceas.metacat.service;

import java.io.IOException;

import java.io.StringReader;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.Vector;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import org.apache.log4j.Logger;

import edu.ucsb.nceas.metacat.DBConnection;

import edu.ucsb.nceas.metacat.DBConnectionPool;

import edu.ucsb.nceas.metacat.DocumentImpl;

import edu.ucsb.nceas.metacat.MetaCatServlet;

import edu.ucsb.nceas.utilities.FileUtil;

import edu.ucsb.nceas.utilities.PropertyNotFoundException;

import edu.ucsb.nceas.utilities.StringUtil;

public class XMLSchemaService implements ServiceInterface {

	public static final String NAMESPACEKEYWORD = "xmlns";

	public static final String SCHEMA_DIR = "/schema/";

	private static XMLSchemaService xmlSchemaService = null;

	private static Logger logMetacat = Logger.getLogger(XMLSchemaService.class);

	private static boolean useFullSchemaValidation = false;

	private static String documentNamespace = null;

	// all schema objects that represent schemas registered in the db that 

	// actually have files on disk.

	private static Vector<XMLSchema> registeredSchemaList = new Vector<XMLSchema>();

	// a convenience list that holds the names of registered namespaces.

    private static Vector<String> nameSpaceList = new Vector<String>();

    // a convenience string that holds all name spaces and locations in a space

    // delimited format

    private static String nameSpaceAndLocationString = ""; 

	/**

	 * private constructor since this is a singleton

	 */

	private XMLSchemaService() {

		try {

			setUseFullSchemaValidation();

			populateRegisteredSchemaList();

			createRegisteredNameSpaceList();

			createRegisteredNameSpaceAndLocationString();

		} catch (PropertyNotFoundException pnfe) {

			logMetacat.error("Could not find property: xml.useFullSchemaValidation. " + 

					"Setting to false.");

		}

	}

	/**

	 * Get the single instance of XMLService.

	 * 

	 * @return the single instance of XMLService

	 */

	public static XMLSchemaService getInstance() {

		if (xmlSchemaService == null) {

			xmlSchemaService = new XMLSchemaService();

		}

		return xmlSchemaService;

	}

	/**

	 * refresh the persistant values in this service.

	 */

	public static void refresh() {

		try {

			populateRegisteredSchemaList();

			setUseFullSchemaValidation();

			createRegisteredNameSpaceList();

			createRegisteredNameSpaceAndLocationString();

		} catch (PropertyNotFoundException pnfe) {

			logMetacat.error("Could not find property: xml.useFullSchemaValidation. " + 

					"Setting to false.");

		}

	}

	/**

	 * Gets the registered schema list. This list holds schemas that exist in

	 * the xml_catalog table that also have associated files in the schema

	 * directory.

	 * 

	 * @return a list of XMLSchema objects holding registered schema information

	 */

	public static Vector<XMLSchema> getRegisteredSchemaList() {

		return registeredSchemaList;

	}

	/**

	 * Gets the name space and location string. This is a convenience method.

	 * The string will have space delimited namespaces and locations that are

	 * held in the registered schema list.

	 * 

	 * @return a string that holds space delimited registered namespaces and

	 *         locations.

	 */

	public static String getNameSpaceAndLocationString() {

		return nameSpaceAndLocationString;

	}

	/**

	 * Gets a list of name spaces. This is a convenience method. The list will 

	 * have all namespaces that are held in the registered schema list.

	 * 

	 * @return a list that holds registered namespaces.

	 */

	public static Vector<String> getNameSpaceList() {

		return nameSpaceList;

	}

	/**

	 * Report whether xml parsing is set to use full schema parsing. If full

	 * schema parsing is true, new schemas will be validated before being

	 * entered into the database and file system.

	 * 

	 * @return true if the xml.useFullSchemaValidation property is set to true,

	 *         false otherwise.

	 */

	public static boolean useFullSchemaValidation() {

		return useFullSchemaValidation;

	}

	/**

	 * sets the UseFullSchemaValidation variable.  The only way this should be

	 * set is in the constructor or the refresh methods.

	 */

	private static void setUseFullSchemaValidation() throws PropertyNotFoundException {

		String strUseFullSchemaValidation = 

			PropertyService.getProperty("xml.useFullSchemaValidation");

		useFullSchemaValidation = Boolean.valueOf(strUseFullSchemaValidation);

	}

	/**

	 * Populate the list of registered schemas. This reads all schemas in the

	 * xml_catalog table and then makes sure the schema actually exists and is

	 * readable on disk.

	 */

	public static void populateRegisteredSchemaList() {

		DBConnection conn = null;

		int serialNumber = -1;

		PreparedStatement pstmt = null;

		ResultSet resultSet = null;

		registeredSchemaList = new Vector<XMLSchema>();

		// get the system id from the xml_catalog table for all schemas.

		String sql = "SELECT public_id, system_id FROM xml_catalog where "

				+ "entry_type ='" + DocumentImpl.SCHEMA + "'";

		try {

			// check out DBConnection

			conn = DBConnectionPool

					.getDBConnection("XMLService.populateRegisteredSchemaList");

			serialNumber = conn.getCheckOutSerialNumber();

			pstmt = conn.prepareStatement(sql);

			pstmt.execute();

			resultSet = pstmt.getResultSet();

			// make sure the schema actually exists on the file system. If so,

			// add it

			// to the registered schema list.

			while (resultSet.next()) {

				String fileNamespace = resultSet.getString(1);

				String fileLocation = resultSet.getString(2);

				XMLSchema xmlSchema = new XMLSchema(fileNamespace);

				xmlSchema.setFileName(fileLocation);

				if (FileUtil.getFileStatus(xmlSchema.getLocalFileDir()) >= FileUtil.EXISTS_READABLE) {

					registeredSchemaList.add(xmlSchema);

				} else {

					logMetacat.warn("Schema file: " + fileLocation + " is registered "

							+ " in the database but does not exist on the file system.");

				}

			}

		} catch (SQLException e) {

			logMetacat.error("XMLService.populateRegisteredSchemaList(): "

					+ e.getMessage());

		} finally {

			try {

				pstmt.close();

			}// try

			catch (SQLException sqlE) {

				logMetacat.error("Error in XMLService.populateRegisteredSchemaList(): "

						+ sqlE.getMessage());

			}

			DBConnectionPool.returnDBConnection(conn, serialNumber);

		}

	}	

	/**

	 * create a space delimited string of all namespaces and locations

	 * in the registered schema list.

	 */

	private static void createRegisteredNameSpaceAndLocationString() {

		boolean firstRow = true;

		for (XMLSchema xmlSchema : registeredSchemaList) {

			if (!firstRow) {

				nameSpaceAndLocationString += " ";

			}

			nameSpaceAndLocationString += xmlSchema.getFileNamespace() + " "

					+ xmlSchema.getLocalFileUri();

			firstRow = false;

		}

	}

	/**

	 * create a lsit of all namespaces in the registered schema list.

	 */

	private static void createRegisteredNameSpaceList() {

		for (XMLSchema xmlSchema : registeredSchemaList) {

			nameSpaceList.add(xmlSchema.getFileNamespace());

		}

	}

	/**

	 * Checks to see that all schemas are registered. If a single one in the

	 * list is not, this will return false.

	 * 

	 * @param schemaList

	 *            a list of schemas as they appear in xml.

	 * @return true if all schemas are registered.

	 */

	public static boolean areAllSchemasRegistered(Vector<XMLSchema> schemaList) {			

		for (XMLSchema xmlSchema : schemaList) {

			if ( ! isSchemaRegistered(xmlSchema)) {

				return false;

			}

		}		

		return true;

	}

	/**

	 * Returns true if the schema is registered.

	 * 

	 * @param schema

	 *            a single schema as it appears in xml

	 * @return true if the schema is registered, false otherwise.

	 */

	public static boolean isSchemaRegistered(XMLSchema xmlSchema) {

		for (XMLSchema registeredXmlSchema : registeredSchemaList) {

			if (registeredXmlSchema.getLocalFileUri().equals(

						xmlSchema.getLocalFileUri())

					&& registeredXmlSchema.getFileNamespace().equals(

							xmlSchema.getFileNamespace())) {

				return true;

			}

		}

		return false;

	}

    /**

	 * See if schemas have been specified in the xml:schemalocation attribute.

	 * If so, return a vector of the system ids.

	 * 

	 * @param xml

	 *            the document we want to look in for schema location

	 * @return a vector of XMLSchema objects, or an empty vector if none are

	 *         found

	 */

	public static Vector<XMLSchema> findSchemasInXML(StringReader xml) throws IOException {

		Logger logMetacat = Logger.getLogger(MetaCatServlet.class);

		Vector<XMLSchema> schemaList = new Vector<XMLSchema>();

		// no xml. return empty vector

		if (xml == null) {

			logMetacat.debug("Returning empty schemaList.");

			return schemaList;

		}

		// Get the "second line" from the xml

		String targetLine = getSchemaLine(xml);

		// see if there is a match for xsi.schemaLocation. If so, extract the

		// schemas.

		if (targetLine != null) {

			String regex = "(\\p{Graph}*):schemaLocation=\"(.*)\"";

			Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE

					| Pattern.DOTALL);

			Matcher matcher = pattern.matcher(targetLine);

			int i = 0;

			while (i < targetLine.length()) {

				if (!matcher.find(i)) {

					break;

				}

				String uri = matcher.group(2);

				uri = StringUtil.replaceTabsNewLines(uri);

				uri = StringUtil.replaceDuplicateSpaces(uri);

				// each namespace could have several schema locations. parsedUri

				// will hold a list of uri and files.

				Vector<String> parsedUri = StringUtil.toVector(uri, ' ');

				for (int j = 0; j < parsedUri.size(); j = j + 2) {

					if (j + 1 >= parsedUri.size()) {

						throw new IOException(

								"Odd number of elements found when parsing schema location: "

										+ targetLine

										+ ". There should be an even number of uri/files in location.");

					}

					XMLSchema xmlSchema = new XMLSchema(parsedUri.get(j), parsedUri

							.get(j + 1));

					schemaList.add(xmlSchema);

				}

				i = matcher.end();

			}

		}

		logMetacat.debug("Schemas for eml are " + schemaList.toString());

		return schemaList;

	}    

    /**

	 * Returns all the namespace for an xml document.  This is done by getting

	 * the internal namespace declaration (prefix) and looking for xmlns:<prefix>

	 * 

	 * @param xml

	 *            the document to search

	 * @return a string holding the namespace

	 */

	public static String findDocumentNamespace(StringReader xml) throws IOException {

		String namespace = null;

		String eml2_0_0NameSpace = DocumentImpl.EML2_0_0NAMESPACE;

		String eml2_0_1NameSpace = DocumentImpl.EML2_0_1NAMESPACE;

		String eml2_1_0NameSpace = DocumentImpl.EML2_1_0NAMESPACE;

		if (xml == null) {

			logMetacat.debug("XML doc is null.  There is no namespace.");

			return namespace;

		}

		String targetLine = getSchemaLine(xml);

		// the prefix is at the beginning of the doc

		String prefix = null;

		String regex1 = "^\\s*(.+):.* ";

		Pattern pattern = Pattern.compile(regex1, Pattern.CASE_INSENSITIVE);

		Matcher matcher = pattern.matcher(targetLine);

		if (matcher.find()) {

			prefix = matcher.group(1).trim();

		}

		// if a prefix was found, we are looking for xmlns:<prefix>="namespace"

		// if no prefix was found, we grab the first namespace.

		String regex2;

		if (prefix != null) {

			regex2 = "xmlns:" + prefix + "=\"(.*)\"";

		} else {

			regex2 = "xmlns:.*=\"(.*)\"";

		}

		Pattern pattern2 = Pattern.compile(regex2, Pattern.CASE_INSENSITIVE);

		Matcher matcher2 = pattern2.matcher(targetLine);

		if (matcher2.find()) {

			namespace = matcher2.group(1);

			if (namespace.indexOf(eml2_0_0NameSpace) != -1) {

				namespace = eml2_0_0NameSpace;

			} else if (namespace.indexOf(eml2_0_1NameSpace) != -1) {

				namespace = eml2_0_1NameSpace;

			} else if (namespace.indexOf(eml2_1_0NameSpace) != -1) {

				namespace = eml2_1_0NameSpace;

			}

		}

		return namespace;

	}

    /**

	 * Return the line from xml that holds the metadata like namespace and

	 * schema location

	 * 

	 * @param xml

	 *            the document to parse

	 * @return the "second" line of the document

	 */

    private static String getSchemaLine(StringReader xml) throws IOException {

        Logger logMetacat = Logger.getLogger(MetaCatServlet.class);

        // find the line

        String secondLine = null;

        int count = 0;

        final int TARGETNUM = 1;

        StringBuffer buffer = new StringBuffer();

        boolean comment = false;

        boolean processingInstruction = false;

        char thirdPreviousCharacter = '?';

        char secondPreviousCharacter = '?';

        char previousCharacter = '?';

        char currentCharacter = '?';

        int tmp = xml.read();

        while (tmp != -1) {

            currentCharacter = (char)tmp;

            //in a comment

            if (currentCharacter == '-' && previousCharacter == '-'

                    && secondPreviousCharacter == '!'

                    && thirdPreviousCharacter == '<') {

                comment = true;

            }

            //out of comment

            if (comment && currentCharacter == '>' && previousCharacter == '-'

                    && secondPreviousCharacter == '-') {

                comment = false;

            }

            //in a processingInstruction

            if (currentCharacter == '?' && previousCharacter == '<') {

                processingInstruction = true;

            }

            //out of processingInstruction

            if (processingInstruction && currentCharacter == '>'

                    && previousCharacter == '?') {

                processingInstruction = false;

            }

            //this is not comment or a processingInstruction

            if (currentCharacter != '!' && previousCharacter == '<'

                    && !comment && !processingInstruction) {

                count++;

            }

            // get target line

            if (count == TARGETNUM && currentCharacter != '>') {

                buffer.append(currentCharacter);

            }

            if (count == TARGETNUM && currentCharacter == '>') {

                break;

            }

            thirdPreviousCharacter = secondPreviousCharacter;

            secondPreviousCharacter = previousCharacter;

            previousCharacter = currentCharacter;

            tmp = xml.read();

        }

        secondLine = buffer.toString();

        logMetacat.debug("the second line string is: " + secondLine);

        xml.reset();

        return secondLine;

    }

    /**

	 * Get a schema file name from the schema uri.

	 * 

	 * @param uri

	 *            the uri from which to extract the file name

	 * @return a string holding the file name

	 */

    public static String getSchemaFileNameFromUri(String uri) {

		// get filename from systemId

		String filename = uri;

		if (filename != null && !(filename.trim()).equals("")) {

			int slash = Math.max(filename.lastIndexOf('/'), filename.lastIndexOf('\\'));

			if (slash > -1) {

				filename = filename.substring(slash + 1);

			}

		}

		return filename;

	}

}