universe@16: /*
universe@16:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
universe@34:  *
universe@24:  * Copyright 2018 Mike Becker. All rights reserved.
universe@34:  *
universe@16:  * Redistribution and use in source and binary forms, with or without
universe@16:  * modification, are permitted provided that the following conditions are met:
universe@16:  *
universe@16:  *   1. Redistributions of source code must retain the above copyright
universe@16:  *      notice, this list of conditions and the following disclaimer.
universe@16:  *
universe@16:  *   2. Redistributions in binary form must reproduce the above copyright
universe@16:  *      notice, this list of conditions and the following disclaimer in the
universe@16:  *      documentation and/or other materials provided with the distribution.
universe@16:  *
universe@16:  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
universe@16:  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
universe@16:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
universe@16:  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
universe@16:  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
universe@16:  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
universe@16:  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
universe@16:  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
universe@16:  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
universe@16:  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
universe@16:  * POSSIBILITY OF SUCH DAMAGE.
universe@34:  *
universe@16:  */
universe@16: package de.uapcore.lightpit;
universe@16: 
universe@33: import org.slf4j.Logger;
universe@33: import org.slf4j.LoggerFactory;
universe@33: 
universe@16: import javax.naming.Context;
universe@16: import javax.naming.InitialContext;
universe@16: import javax.naming.NamingException;
universe@16: import javax.servlet.ServletContext;
universe@16: import javax.servlet.ServletContextEvent;
universe@16: import javax.servlet.ServletContextListener;
universe@16: import javax.servlet.annotation.WebListener;
universe@16: import javax.sql.DataSource;
universe@33: import java.sql.Connection;
universe@33: import java.sql.DatabaseMetaData;
universe@33: import java.sql.SQLException;
universe@33: import java.util.Optional;
universe@16: 
universe@16: /**
universe@16:  * Provides access to different privilege layers within the database.
universe@16:  */
universe@16: @WebListener
universe@16: public final class DatabaseFacade implements ServletContextListener {
universe@33: 
universe@16:     private static final Logger LOG = LoggerFactory.getLogger(DatabaseFacade.class);
universe@33: 
universe@16:     /**
universe@16:      * Timeout in seconds for the validation test.
universe@16:      */
universe@16:     private static final int DB_TEST_TIMEOUT = 10;
universe@33: 
universe@34:     /**
universe@34:      * Specifies the database dialect.
universe@34:      */
universe@33:     public enum Dialect {
universe@33:         Postgres
universe@19:     }
universe@33: 
universe@19:     /**
universe@19:      * The database dialect to use.
universe@33:      * <p>
universe@34:      * May be overridden by context parameter.
universe@33:      *
universe@19:      * @see Constants#CTX_ATTR_DB_DIALECT
universe@19:      */
universe@19:     private Dialect dialect = Dialect.Postgres;
universe@34: 
universe@16:     /**
universe@16:      * The default schema to test against when validating the connection.
universe@34:      * <p>
universe@16:      * May be overridden by context parameter.
universe@34:      *
universe@19:      * @see Constants#CTX_ATTR_DB_SCHEMA
universe@16:      */
universe@16:     private static final String DB_DEFAULT_SCHEMA = "lightpit";
universe@34: 
universe@16:     /**
universe@19:      * The attribute name in the Servlet context under which an instance of this class can be found.
universe@16:      */
universe@16:     public static final String SC_ATTR_NAME = DatabaseFacade.class.getName();
universe@33: 
universe@19:     private static final String DS_JNDI_NAME = "jdbc/lightpit/app";
universe@33:     private DataSource dataSource;
universe@34: 
universe@16:     /**
universe@19:      * Returns the data source.
universe@34:      *
universe@19:      * @return a data source
universe@16:      */
universe@38:     public DataSource getDataSource() {
universe@38:         return dataSource;
universe@34:     }
universe@34: 
universe@19:     public Dialect getSQLDialect() {
universe@19:         return dialect;
universe@16:     }
universe@33: 
universe@33:     private static void checkConnection(DataSource ds, String testSchema) {
universe@16:         try (Connection conn = ds.getConnection()) {
universe@16:             if (!conn.isValid(DB_TEST_TIMEOUT)) {
universe@16:                 throw new SQLException("Validation check failed.");
universe@16:             }
universe@16:             if (conn.isReadOnly()) {
universe@16:                 throw new SQLException("Connection is read-only and thus unusable.");
universe@16:             }
universe@16:             if (!conn.getSchema().equals(testSchema)) {
universe@16:                 throw new SQLException(String.format("Connection is not configured to use the schema %s.", testSchema));
universe@16:             }
universe@16:             DatabaseMetaData metaData = conn.getMetaData();
universe@16:             LOG.info("Connections as {} to {}/{} ready to go.", metaData.getUserName(), metaData.getURL(), conn.getSchema());
universe@16:         } catch (SQLException ex) {
universe@33:             LOG.error("Checking database connection failed", ex);
universe@16:         }
universe@16:     }
universe@33: 
universe@33:     private static DataSource retrieveDataSource(Context ctx) {
universe@16:         DataSource ret = null;
universe@16:         try {
universe@33:             ret = (DataSource) ctx.lookup(DS_JNDI_NAME);
universe@19:             LOG.info("Data source retrieved.");
universe@16:         } catch (NamingException ex) {
universe@19:             LOG.error("Data source {} not available.", DS_JNDI_NAME);
universe@16:             LOG.error("Reason for the missing data source: ", ex);
universe@16:         }
universe@33:         return ret;
universe@16:     }
universe@16: 
universe@16:     @Override
universe@16:     public void contextInitialized(ServletContextEvent sce) {
universe@33:         ServletContext sc = sce.getServletContext();
universe@34: 
universe@19:         dataSource = null;
universe@34: 
universe@16:         final String dbSchema = Optional
universe@16:                 .ofNullable(sc.getInitParameter(Constants.CTX_ATTR_DB_SCHEMA))
universe@16:                 .orElse(DB_DEFAULT_SCHEMA);
universe@19:         final String dbDialect = sc.getInitParameter(Constants.CTX_ATTR_DB_DIALECT);
universe@19:         if (dbDialect != null) {
universe@19:             try {
universe@19:                 dialect = Dialect.valueOf(dbDialect);
universe@19:             } catch (IllegalArgumentException ex) {
universe@20:                 LOG.error("Unknown or unsupported database dialect {}. Defaulting to {}.", dbDialect, dialect);
universe@19:             }
universe@19:         }
universe@16: 
universe@16:         try {
universe@50:             LOG.debug("Trying to access JNDI context ...");
universe@16:             Context initialCtx = new InitialContext();
universe@50:             Context ctx = (Context) initialCtx.lookup("java:comp/env");
universe@33: 
universe@19:             dataSource = retrieveDataSource(ctx);
universe@33: 
universe@33:             if (dataSource != null) {
universe@33:                 checkConnection(dataSource, dbSchema);
universe@33:             }
universe@16:         } catch (NamingException | ClassCastException ex) {
universe@16:             LOG.error("Cannot access JNDI resources.", ex);
universe@16:         }
universe@34: 
universe@16:         sc.setAttribute(SC_ATTR_NAME, this);
universe@16:         LOG.info("Database facade injected into ServletContext.");
universe@16:     }
universe@16: 
universe@16:     @Override
universe@16:     public void contextDestroyed(ServletContextEvent sce) {
universe@19:         dataSource = null;
universe@34:     }
universe@16: }