/*******************************************************************************
 * ============LICENSE_START==================================================
 * * org.onap.dmaap
 * * ===========================================================================
 * * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
 * * ===========================================================================
 * * 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.
 * * ============LICENSE_END====================================================
 * *
 * * ECOMP is a trademark and service mark of AT&T Intellectual Property.
 * *
 ******************************************************************************/


package org.onap.dmaap.datarouter.provisioning.utils;

import org.apache.log4j.Logger;

import java.io.*;
import java.sql.*;
import java.util.*;

/**
 * Load the DB JDBC driver, and manage a simple pool of connections to the DB.
 *
 * @author Robert Eby
 * @version $Id$
 */
public class DB {
    /**
     * The name of the properties file (in CLASSPATH)
     */
    private static final String CONFIG_FILE = "provserver.properties";

    private static String DB_URL;
    private static String DB_LOGIN;
    private static String DB_PASSWORD;
    private static Properties props;
    private static Logger intlogger = Logger.getLogger("org.onap.dmaap.datarouter.provisioning.internal");
    private static final Queue<Connection> queue = new LinkedList<>();

    public static String HTTPS_PORT;
    public static String HTTP_PORT;

    /**
     * Construct a DB object.  If this is the very first creation of this object, it will load a copy
     * of the properties for the server, and attempt to load the JDBC driver for the database.  If a fatal
     * error occurs (e.g. either the properties file or the DB driver is missing), the JVM will exit.
     */
    public DB() {
        if (props == null) {
            props = new Properties();
            try (InputStream inStream = getClass().getClassLoader().getResourceAsStream(CONFIG_FILE)) {
                props.load(inStream);
                String DB_DRIVER = (String) props.get("org.onap.dmaap.datarouter.db.driver");
                DB_URL = (String) props.get("org.onap.dmaap.datarouter.db.url");
                DB_LOGIN = (String) props.get("org.onap.dmaap.datarouter.db.login");
                DB_PASSWORD = (String) props.get("org.onap.dmaap.datarouter.db.password");
                HTTPS_PORT = (String) props.get("org.onap.dmaap.datarouter.provserver.https.port");
                HTTP_PORT = (String) props.get("org.onap.dmaap.datarouter.provserver.http.port");
                Class.forName(DB_DRIVER);
            } catch (IOException e) {
                intlogger.fatal("PROV9003 Opening properties: " + e.getMessage());
                e.printStackTrace();
                System.exit(1);
            } catch (ClassNotFoundException e) {
                intlogger.fatal("PROV9004 cannot find the DB driver: " + e);
                e.printStackTrace();
                System.exit(1);
            }
        }
    }

    /**
     * Get the provisioning server properties (loaded from provserver.properties).
     *
     * @return the Properties object
     */
    public Properties getProperties() {
        return props;
    }

    /**
     * Get a JDBC connection to the DB from the pool.  Creates a new one if none are available.
     *
     * @return the Connection
     * @throws SQLException
     */
    @SuppressWarnings("resource")
    public Connection getConnection() throws SQLException {
        Connection connection = null;
        while (connection == null) {
            synchronized (queue) {
                try {
                    connection = queue.remove();
                } catch (NoSuchElementException nseEx) {
                    int n = 0;
                    do {
                        // Try up to 3 times to get a connection
                        try {
                            connection = DriverManager.getConnection(DB_URL, DB_LOGIN, DB_PASSWORD);
                        } catch (SQLException sqlEx) {
                            if (++n >= 3)
                                throw sqlEx;
                        }
                    } while (connection == null);
                }
            }
            if (connection != null && !connection.isValid(1)) {
                connection.close();
                connection = null;
            }
        }
        return connection;
    }

    /**
     * Returns a JDBC connection to the pool.
     *
     * @param connection the Connection to return
     */
    public void release(Connection connection) {
        if (connection != null) {
            synchronized (queue) {
                if (!queue.contains(connection))
                    queue.add(connection);
            }
        }
    }

    /**
     * Run all necessary retrofits required to bring the database up to the level required for this version
     * of the provisioning server.  This should be run before the server itself is started.
     *
     * @return true if all retrofits worked, false otherwise
     */
    public boolean runRetroFits() {
        return retroFit1();
    }

    /**
     * Retrofit 1 - Make sure the expected tables are in DB and are initialized.
     * Uses sql_init_01.sql to setup the DB.
     *
     * @return true if the retrofit worked, false otherwise
     */
    private boolean retroFit1() {
        final String[] expectedTables = {
                "FEEDS", "FEED_ENDPOINT_ADDRS", "FEED_ENDPOINT_IDS", "PARAMETERS",
                "SUBSCRIPTIONS", "LOG_RECORDS", "INGRESS_ROUTES", "EGRESS_ROUTES",
                "NETWORK_ROUTES", "NODESETS", "NODES", "GROUPS"
        };
        Connection connection = null;
        try {
            connection = getConnection();
            Set<String> actualTables = getTableSet(connection);
            boolean initialize = false;
            for (String table : expectedTables) {
                initialize |= !actualTables.contains(table);
            }
            if (initialize) {
                intlogger.info("PROV9001: First time startup; The database is being initialized.");
                runInitScript(connection, 1);
            }
        } catch (SQLException e) {
            intlogger.fatal("PROV9000: The database credentials are not working: " + e.getMessage());
            return false;
        } finally {
            if (connection != null)
                release(connection);
        }
        return true;
    }

    /**
     * Get a set of all table names in the DB.
     *
     * @param connection a DB connection
     * @return the set of table names
     */
    private Set<String> getTableSet(Connection connection) {
        Set<String> tables = new HashSet<String>();
        try {
            DatabaseMetaData md = connection.getMetaData();
            ResultSet rs = md.getTables("datarouter", "", "", null);
            if (rs != null) {
                while (rs.next()) {
                    tables.add(rs.getString("TABLE_NAME"));
                }
                rs.close();
            }
        } catch (SQLException e) {
        }
        return tables;
    }

    /**
     * Initialize the tables by running the initialization scripts located in the directory specified
     * by the property <i>org.onap.dmaap.datarouter.provserver.dbscripts</i>.  Scripts have names of
     * the form sql_init_NN.sql
     *
     * @param connection a DB connection
     * @param scriptId   the number of the sql_init_NN.sql script to run
     */
    private void runInitScript(Connection connection, int scriptId) {
        String scriptDir = (String) props.get("org.onap.dmaap.datarouter.provserver.dbscripts");
        StringBuilder sb = new StringBuilder();
        try {
            String scriptFile = String.format("%s/sql_init_%02d.sql", scriptDir, scriptId);
            if (!(new File(scriptFile)).exists())
                return;

            LineNumberReader in = new LineNumberReader(new FileReader(scriptFile));
            String line;
            while ((line = in.readLine()) != null) {
                if (!line.startsWith("--")) {
                    line = line.trim();
                    sb.append(line);
                    if (line.endsWith(";")) {
                        // Execute one DDL statement
                        String sql = sb.toString();
                        sb.setLength(0);
                        Statement s = connection.createStatement();
                        s.execute(sql);
                        s.close();
                    }
                }
            }
            in.close();
            sb.setLength(0);
        } catch (Exception e) {
            intlogger.fatal("PROV9002 Error when initializing table: " + e.getMessage());
            System.exit(1);
        }
    }
}