/*
 * Copyright 2002-2018 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
 *
 *      https://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.springframework.jdbc.datasource.embedded;

import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.UUID;
import java.util.logging.Logger;

import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.jdbc.datasource.SimpleDriverDataSource;
import org.springframework.jdbc.datasource.init.DatabasePopulator;
import org.springframework.jdbc.datasource.init.DatabasePopulatorUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * Factory for creating an {@link EmbeddedDatabase} instance.
 *
 * <p>Callers are guaranteed that the returned database has been fully
 * initialized and populated.
 *
 * <p>The factory can be configured as follows:
 * <ul>
 * <li>Call {@link #generateUniqueDatabaseName} to set a unique, random name
 * for the database.
 * <li>Call {@link #setDatabaseName} to set an explicit name for the database.
 * <li>Call {@link #setDatabaseType} to set the database type if you wish to
 * use one of the supported types.
 * <li>Call {@link #setDatabaseConfigurer} to configure support for a custom
 * embedded database type.
 * <li>Call {@link #setDatabasePopulator} to change the algorithm used to
 * populate the database.
 * <li>Call {@link #setDataSourceFactory} to change the type of
 * {@link DataSource} used to connect to the database.
 * </ul>
 *
 * <p>After configuring the factory, call {@link #getDatabase()} to obtain
 * a reference to the {@link EmbeddedDatabase} instance.
 *
 * @author Keith Donald
 * @author Juergen Hoeller
 * @author Sam Brannen
 * @since 3.0
 */
public class EmbeddedDatabaseFactory {

        /**
         * Default name for an embedded database: {@value}.
         */
        public static final String DEFAULT_DATABASE_NAME = "testdb";

        private static final Log logger = LogFactory.getLog(EmbeddedDatabaseFactory.class);

        private boolean generateUniqueDatabaseName = false;

        private String databaseName = DEFAULT_DATABASE_NAME;

        private DataSourceFactory dataSourceFactory = new SimpleDriverDataSourceFactory();

        @Nullable
        private EmbeddedDatabaseConfigurer databaseConfigurer;

        @Nullable
        private DatabasePopulator databasePopulator;

        @Nullable
        private DataSource dataSource;


        /**
         * Set the {@code generateUniqueDatabaseName} flag to enable or disable
         * generation of a pseudo-random unique ID to be used as the database name.
         * <p>Setting this flag to {@code true} overrides any explicit name set
         * via {@link #setDatabaseName}.
         * @since 4.2
         * @see #setDatabaseName
         */
        public void setGenerateUniqueDatabaseName(boolean generateUniqueDatabaseName) {
                this.generateUniqueDatabaseName = generateUniqueDatabaseName;
        }

        /**
         * Set the name of the database.
         * <p>Defaults to {@value #DEFAULT_DATABASE_NAME}.
         * <p>Will be overridden if the {@code generateUniqueDatabaseName} flag
         * has been set to {@code true}.
         * @param databaseName name of the embedded database
         * @see #setGenerateUniqueDatabaseName
         */
        public void setDatabaseName(String databaseName) {
                Assert.hasText(databaseName, "Database name is required");
                this.databaseName = databaseName;
        }

        /**
         * Set the factory to use to create the {@link DataSource} instance that
         * connects to the embedded database.
         * <p>Defaults to {@link SimpleDriverDataSourceFactory}.
         */
        public void setDataSourceFactory(DataSourceFactory dataSourceFactory) {
                Assert.notNull(dataSourceFactory, "DataSourceFactory is required");
                this.dataSourceFactory = dataSourceFactory;
        }

        /**
         * Set the type of embedded database to use.
         * <p>Call this when you wish to configure one of the pre-supported types.
         * <p>Defaults to HSQL.
         * @param type the database type
         */
        public void setDatabaseType(EmbeddedDatabaseType type) {
                this.databaseConfigurer = EmbeddedDatabaseConfigurerFactory.getConfigurer(type);
        }

        /**
         * Set the strategy that will be used to configure the embedded database instance.
         * <p>Call this when you wish to use an embedded database type not already supported.
         */
        public void setDatabaseConfigurer(EmbeddedDatabaseConfigurer configurer) {
                this.databaseConfigurer = configurer;
        }

        /**
         * Set the strategy that will be used to initialize or populate the embedded
         * database.
         * <p>Defaults to {@code null}.
         */
        public void setDatabasePopulator(DatabasePopulator populator) {
                this.databasePopulator = populator;
        }

        /**
         * Factory method that returns the {@linkplain EmbeddedDatabase embedded database}
         * instance, which is also a {@link DataSource}.
         */
        public EmbeddedDatabase getDatabase() {
                if (this.dataSource == null) {
                        initDatabase();
                }
                return new EmbeddedDataSourceProxy(this.dataSource);
        }


        /**
         * Hook to initialize the embedded database.
         * <p>If the {@code generateUniqueDatabaseName} flag has been set to {@code true},
         * the current value of the {@linkplain #setDatabaseName database name} will
         * be overridden with an auto-generated name.
         * <p>Subclasses may call this method to force initialization; however,
         * this method should only be invoked once.
         * <p>After calling this method, {@link #getDataSource()} returns the
         * {@link DataSource} providing connectivity to the database.
         */
        protected void initDatabase() {
                if (this.generateUniqueDatabaseName) {
                        setDatabaseName(UUID.randomUUID().toString());
                }

                // Create the embedded database first
                if (this.databaseConfigurer == null) {
                        this.databaseConfigurer = EmbeddedDatabaseConfigurerFactory.getConfigurer(EmbeddedDatabaseType.HSQL);
                }
                this.databaseConfigurer.configureConnectionProperties(
                                this.dataSourceFactory.getConnectionProperties(), this.databaseName);
                this.dataSource = this.dataSourceFactory.getDataSource();

                if (logger.isInfoEnabled()) {
                        if (this.dataSource instanceof SimpleDriverDataSource) {
                                SimpleDriverDataSource simpleDriverDataSource = (SimpleDriverDataSource) this.dataSource;
                                logger.info(String.format("Starting embedded database: url='%s', username='%s'",
                                                simpleDriverDataSource.getUrl(), simpleDriverDataSource.getUsername()));
                        }
                        else {
                                logger.info(String.format("Starting embedded database '%s'", this.databaseName));
                        }
                }

                // Now populate the database
                if (this.databasePopulator != null) {
                        try {
                                DatabasePopulatorUtils.execute(this.databasePopulator, this.dataSource);
                        }
                        catch (RuntimeException ex) {
                                // failed to populate, so leave it as not initialized
                                shutdownDatabase();
                                throw ex;
                        }
                }
        }

        /**
         * Hook to shutdown the embedded database. Subclasses may call this method
         * to force shutdown.
         * <p>After calling, {@link #getDataSource()} returns {@code null}.
         * <p>Does nothing if no embedded database has been initialized.
         */
        protected void shutdownDatabase() {
                if (this.dataSource != null) {
                        if (logger.isInfoEnabled()) {
                                if (this.dataSource instanceof SimpleDriverDataSource) {
                                        logger.info(String.format("Shutting down embedded database: url='%s'",
                                                ((SimpleDriverDataSource) this.dataSource).getUrl()));
                                }
                                else {
                                        logger.info(String.format("Shutting down embedded database '%s'", this.databaseName));
                                }
                        }
                        if (this.databaseConfigurer != null) {
                                this.databaseConfigurer.shutdown(this.dataSource, this.databaseName);
                        }
                        this.dataSource = null;
                }
        }

        /**
         * Hook that gets the {@link DataSource} that provides the connectivity to the
         * embedded database.
         * <p>Returns {@code null} if the {@code DataSource} has not been initialized
         * or if the database has been shut down. Subclasses may call this method to
         * access the {@code DataSource} instance directly.
         */
        @Nullable
        protected final DataSource getDataSource() {
                return this.dataSource;
        }


        private class EmbeddedDataSourceProxy implements EmbeddedDatabase {

                private final DataSource dataSource;

                public EmbeddedDataSourceProxy(DataSource dataSource) {
                        this.dataSource = dataSource;
                }

                @Override
                public Connection getConnection() throws SQLException {
                        return this.dataSource.getConnection();
                }

                @Override
                public Connection getConnection(String username, String password) throws SQLException {
                        return this.dataSource.getConnection(username, password);
                }

                @Override
                public PrintWriter getLogWriter() throws SQLException {
                        return this.dataSource.getLogWriter();
                }

                @Override
                public void setLogWriter(PrintWriter out) throws SQLException {
                        this.dataSource.setLogWriter(out);
                }

                @Override
                public int getLoginTimeout() throws SQLException {
                        return this.dataSource.getLoginTimeout();
                }

                @Override
                public void setLoginTimeout(int seconds) throws SQLException {
                        this.dataSource.setLoginTimeout(seconds);
                }

                @Override
                public <T> T unwrap(Class<T> iface) throws SQLException {
                        return this.dataSource.unwrap(iface);
                }

                @Override
                public boolean isWrapperFor(Class<?> iface) throws SQLException {
                        return this.dataSource.isWrapperFor(iface);
                }

                // getParentLogger() is required for JDBC 4.1 compatibility
                @Override
                public Logger getParentLogger() {
                        return Logger.getLogger(Logger.GLOBAL_LOGGER_NAME);
                }

                @Override
                public void shutdown() {
                        shutdownDatabase();
                }
        }

}