/*
 * Copyright 2005-2010 the original author or authors.
 * 
 * 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.
 */
package org.wamblee.support.persistence;

import java.io.File;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
import java.util.logging.Level;
import java.util.logging.Logger;

import junit.framework.TestCase;

import org.apache.derby.drda.NetworkServerControl;
import org.wamblee.io.FileSystemUtils;

/**
 * Derby database setup. The external JDBC url used to connect to a running
 * instance is
 * 
 * <pre>
 *     jdbc:derby:net://localhost:1527/testdb
 * </pre>
 * 
 * and the driver class is
 * 
 * <pre>
 * com.ibm.db2.jcc.DB2Driver
 * </pre>
 * 
 * The following jars will have to be used <code>db2jcc.jar</code> and
 * <code>db2jcc_license_c.jar</code>.
 */
public class DerbyDatabase extends AbstractDatabase {

    /**
     * Logger.
     */
    private static final Logger LOGGER = Logger.getLogger(DerbyDatabase.class
        .getName());

    /**
     * Database user name.
     */
    private static final String USERNAME = "sa";

    /**
     * Database password.
     */
    private static final String PASSWORD = "123";
    /**
     * Poll interval for the checking the server status.
     */
    private static final int POLL_INTERVAL = 100;

    /**
     * Maximum time to wait until the server has started or stopped.
     */
    private static final int MAX_WAIT_TIME = 10000;

    /**
     * Database name to use.
     */
    private static final String DATABASE_NAME = "testdb";

    /**
     * Path on the file system where derby files are stored.
     */
    private static final String DATABASE_PATH = "target/db/persistence/derby";

    /**
     * Derby property required to set the file system path
     * {@link #DATABASE_PATH}.
     */
    private static final String SYSTEM_PATH_PROPERTY = "derby.system.home";

    private boolean inmemory;

    /**
     * Constructs derby database class to allow creation of derby database
     * instances.
     */
    public DerbyDatabase() {
        inmemory = true;
    }

    public DerbyDatabase(boolean aInMemoryFlag) {
        inmemory = aInMemoryFlag;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.wamblee.persistence.Database#start()
     */
    public void doStart() {
        try {
            // just in case a previous run was killed without the
            // cleanup
            cleanPersistentStorage();

            if (!inmemory) {
                // set database path.
                Properties lProperties = System.getProperties();
                lProperties.put(SYSTEM_PATH_PROPERTY, DATABASE_PATH);
            }

            Class.forName("org.apache.derby.jdbc.EmbeddedDriver").newInstance();

            runDatabase();

            waitUntilStartedOrStopped(true);

            // Force creation of the database.
            Connection lConnection = createConnection();
            lConnection.close();

            LOGGER.info("Database started: \n    URL = " +
                getExternalJdbcUrl() + "\n    user = " + getUsername() +
                "\n    password = " + getPassword());

            createDataSource();

            Runtime.getRuntime().addShutdownHook(new Thread() {
                @Override
                public void run() {
                    if (isStarted()) {
                        LOGGER.warning("Shutting down db");
                        DerbyDatabase.this.stop();
                    }
                }
            });
        } catch (Exception e) {
            throw new RuntimeException("Problem starting database", e);
        }
    }

    /**
     * Waits until the database server has started or stopped.
     * 
     * @param aStarted
     *            If true, waits until the server is up, if false, waits until
     *            the server is down.
     * @throws InterruptedException
     */
    private void waitUntilStartedOrStopped(boolean aStarted)
        throws InterruptedException {
        long lWaited = 0;

        while (aStarted != isStarted()) {
            Thread.sleep(POLL_INTERVAL);
            lWaited += POLL_INTERVAL;

            if (lWaited > MAX_WAIT_TIME) {
                throw new RuntimeException(
                    "Derby database did not start within " + MAX_WAIT_TIME +
                        "ms");
            }
        }
    }

    /**
     * Checks if the database server has started or not.
     * 
     * @return True if started, false otherwise.
     */
    private boolean isStarted() {
        try {
            getControl().ping();

            return true;
        } catch (Exception e) {
            return false;
        }
    }

    /**
     * Gets the controller for the database server.
     * 
     * @return Controller.
     * @throws Exception
     */
    private NetworkServerControl getControl() throws Exception {
        return new NetworkServerControl();
    }

    /**
     * Runs the database.
     * 
     */
    private void runDatabase() {
        try {
            getControl().start(new PrintWriter(System.out));
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.wamblee.persistence.Database#getJdbcUrl()
     */
    public String getJdbcUrl() {
        return getBaseJdbcUrl() +
            ";create=true;retrieveMessagesFromServerOnGetMessage=true;";
    }

    private String getBaseJdbcUrl() {
        return (inmemory ? "jdbc:derby:memory:" : "jdbc:derby:") +
            DATABASE_NAME;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.wamblee.persistence.Database#getExternalJdbcUrl()
     */
    public String getExternalJdbcUrl() {
        return "jdbc:derby://localhost:1527/" + (inmemory ? "memory:" : "") +
            DATABASE_NAME;
    }

    /**
     * Shuts down the derby database and cleans up all created files.
     * 
     */
    private void shutdownDerby() {
        try {
            DriverManager.getConnection("jdbc:derby:;shutdown=true");
            throw new RuntimeException(
                "Derby did not shutdown, should always throw exception at shutdown");
        } catch (Exception e) {
            LOGGER.info("Derby has been shut down.");
        }
    }

    /**
     * Gets the user name.
     */
    public String getUsername() {
        return USERNAME;
    }

    /**
     * Gets the password.
     * 
     * @return
     */
    public String getPassword() {
        return PASSWORD;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.wamblee.persistence.Database#createConnection()
     */
    public Connection createConnection() throws SQLException {
        Connection c = DriverManager.getConnection(getJdbcUrl(), getUsername(),
            getPassword());

        return c;
    }

    /**
     * Stops the derby database and cleans up all derby files.
     */
    public void doStop() {
        try {
            // shutdown network server.
            getControl().shutdown();
            waitUntilStartedOrStopped(false);

            // shutdown inmemory access.
            shutdownDerby();
            cleanPersistentStorage();
        } catch (Exception e) {
            LOGGER.log(Level.WARNING, "Problem stopping database", e);
        }
    }

    /**
     * Cleans up persistent storage of Derby.
     */
    private void cleanPersistentStorage() {
        File lFile = new File(DATABASE_PATH);

        if (lFile.isFile()) {
            TestCase.fail("A regular file by the name " + DATABASE_PATH +
                " exists, clean this up first");
        }

        if (!lFile.isDirectory()) {
            return; // no-op already cleanup up.
        }
        FileSystemUtils.deleteDirRecursively(DATABASE_PATH);
    }
}