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/*

 * Geotools 2 - OpenSource mapping toolkit

 * (C) 2005, Geotools Project Managment Committee (PMC)

 *

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

 *    modify it under the terms of the GNU Lesser General Public

 *    License as published by the Free Software Foundation; either

 *    version 2.1 of the License, or (at your option) any later version.

 *

 *    This library 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

 *    Lesser General Public License for more details.

 *

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

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

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

 */

package org.geotools.referencing.factory.epsg;

// J2SE dependencies

import java.io.File;

import java.io.IOException;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.sql.ResultSet;

import java.sql.Statement;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.logging.Logger;

// Geotools dependencies

import org.geotools.factory.Hints;

import org.geotools.referencing.factory.FactoryGroup;

import org.geotools.referencing.factory.AbstractAuthorityFactory;

// HSQL dependencies

import org.hsqldb.jdbc.jdbcDataSource;

/**

 * Connection to the EPSG database in HSQL database engine format using JDBC. The EPSG

 * database can be downloaded from <A HREF="http://www.epsg.org">http://www.epsg.org</A>.

 * The SQL scripts (modified for the HSQL syntax as <A HREF="doc-files/HSQL.html">explained

 * here</A>) are bundled into this plugin. The database version is given in the

 * {@linkplain org.opengis.metadata.citation.Citation#getEdition edition attribute}

 * of the {@linkplain org.opengis.referencing.AuthorityFactory#getAuthority authority}.

 * The HSQL database is read only.

 * <P>

 * <H3>Implementation note</H3>

 * The SQL scripts are executed the first time a connection is required. The database

 * is then created as cached tables ({@code HSQL.properties} and {@code HSQL.data} files)

 * in a temporary directory. Future connections to the EPSG database while reuse the cached

 * tables, if available. Otherwise, the scripts will be executed again in order to recreate

 * them.

 *

 * @version $Id: HSQLDataSource.java 14624 2005-06-29 02:19:08Z desruisseaux $

 * @author Martin Desruisseaux

 * @author Didier Richard

 *

 * @since 2.2

 */

public class HSQLDataSource extends jdbcDataSource implements DataSource {

        // 20090518 cmartinez: Use a different tmp dir for each geotools instance

        private static File tmpDir = null;

    /**

     * Creates a new instance of this data source

     */

    public HSQLDataSource() {

        File directory = getGtTmpDir();

        if (directory.isDirectory() || directory.mkdir()) {

            directory = new File(directory, "Cached databases");

            if (directory.isDirectory() || directory.mkdir()) {

                /*

                 * Constructs the full path to the HSQL database. Note: we do not use

                 * File.toURI() because HSQL doesn't seem to expect an encoded URL

                 * (e.g. "%20" instead of spaces).

                 */

                final StringBuffer url = new StringBuffer("jdbc:hsqldb:file:");

                final String path = directory.getAbsolutePath().replace(File.separatorChar, '/');

                if (path.length()==0 || path.charAt(0)!='/') {

                    url.append('/');

                }

                url.append(path);

                if (url.charAt(url.length()-1) != '/') {

                    url.append('/');

                }

                url.append("EPSG");

                setDatabase(url.toString());

            }

            /*

             * If the temporary directory do not exists or can't be created,

             * lets the 'database' attribute unset. If the user do not set it

             * explicitly (for example through JNDI), an exception will be thrown

             * when 'getConnection()' will be invoked.

             */

        }

        setUser("SA"); // System administrator. No password.

    }

    private static File getGtTmpDir() {

            if (tmpDir == null) {

                    tmpDir = new File(System.getProperty("java.io.tmpdir", "."), "Geotools-"+System.currentTimeMillis());

            }

            return tmpDir;

    }

    /**

     * Returns the priority for this data source. This priority is set to a lower value than

     * the {@linkplain AccessDataSource}'s one in order to give the priority to the Access-backed

     * database, if presents. Priorities are set that way because:

     * <ul>

     *   <li>The MS-Access format is the primary EPSG database format.</li>

     *   <li>If a user downloads the MS-Access database himself, he probably wants to use it.</li>

     * </ul>

     */

    public int getPriority() {

        return NORMAL_PRIORITY - 30;

    }

    /**

     * Returns {@code true} if the database contains data. This method returns {@code false}

     * if an empty EPSG database has been automatically created by HSQL and not yet populated.

     */

    private static boolean dataExists(final Connection connection) throws SQLException {

        final ResultSet tables = connection.getMetaData().getTables(

                null, null, "EPSG_%", new String[] {"TABLE"});

        final boolean exists = tables.next();

        tables.close();

        return exists;

    }

    /**

     * Opens a connection to the database. If the cached tables are not available,

     * they will be created now from the SQL scripts bundled in this plugin.

     */

    public Connection getConnection() throws SQLException {

        final String database = getDatabase();

        if (database==null || database.trim().length()==0) {

            /*

             * The 'database' attribute is unset if the constructor has been unable

             * to locate the temporary directory, or to create the subdirectory.

             */

            // TODO: localize

            throw new SQLException("Can't write to the temporary directory.");

        }

        Connection connection = super.getConnection();

        if (!dataExists(connection)) {

            /*

             * HSQL has created automatically an empty database. We need to populate it.

             * Executes the SQL scripts bundled in the JAR. In theory, each line contains

             * a full SQL statement. For this plugin however, we have compressed "INSERT

             * INTO" statements using Compactor class in this package.

             */

            Logger.getLogger("org.geotools.referencing.factory").config("Creating cached EPSG database."); // TODO: localize

            final Statement statement = connection.createStatement();

            try {

                final BufferedReader in = new BufferedReader(new InputStreamReader(

                        HSQLDataSource.class.getResourceAsStream("EPSG.sql"), "ISO-8859-1"));

                StringBuffer insertStatement = null;

                String line;

                while ((line=in.readLine()) != null) {

                    line = line.trim();

                    final int length = line.length();

                    if (length != 0) {

                        if (line.startsWith("INSERT INTO")) {

                            /*

                             * We are about to insert many rows into a single table.

                             * The row values appear in next lines; the current line

                             * should stop right after the VALUES keyword.

                             */

                            insertStatement = new StringBuffer(line);

                            continue;

                        }

                        if (insertStatement != null) {

                            /*

                             * We are about to insert a row. Prepend the "INSERT INTO"

                             * statement and check if we will have more rows to insert

                             * after this one.

                             */

                            final int values = insertStatement.length();

                            insertStatement.append(line);

                            final boolean hasMore = (line.charAt(length-1) == ',');

                            if (hasMore) {

                                insertStatement.setLength(insertStatement.length()-1);

                            }

                            line = insertStatement.toString();

                            insertStatement.setLength(values);

                            if (!hasMore) {

                                insertStatement = null;

                            }

                        }

                        statement.execute(line);

                    }

                }

                in.close();

            } catch (IOException exception) {

                statement.close();

                SQLException e = new SQLException("Can't read the SQL script."); // TODO: localize

                e.initCause(exception);

                throw e;

            }

            statement.close();

            connection.close();

            connection = super.getConnection();

            assert dataExists(connection);

        }

        return connection;

    }

    /**

     * Open a connection and creates an {@linkplain FactoryUsingSQL EPSG factory} for it.

     *

     * @param  factories The low-level factories to use for CRS creation.

     * @return The EPSG factory using HSQLDB SQL syntax.

     * @throws SQLException if connection to the database failed.

     */

    public AbstractAuthorityFactory createFactory(final FactoryGroup factories) throws SQLException {

        return new FactoryUsingHSQL(factories, getConnection());

    }

}