/*
 * Copyright 2022 Google LLC
 *
 * 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 com.example.cloudsql;

// [START cloud_sql_mysql_servlet_connect_connector]
// [START cloud_sql_mysql_servlet_connect_unix]

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class ConnectorConnectionPoolFactory extends ConnectionPoolFactory {

  // Note: Saving credentials in environment variables is convenient, but not
  // secure - consider a more secure solution such as
  // Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
  // keep secrets safe.
  private static final String INSTANCE_CONNECTION_NAME =
      System.getenv("INSTANCE_CONNECTION_NAME");
  private static final String INSTANCE_UNIX_SOCKET = System.getenv("INSTANCE_UNIX_SOCKET");
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:mysql:///<DB_NAME>?cloudSqlInstance=<INSTANCE_CONNECTION_NAME>&
    // socketFactory=com.google.cloud.sql.mysql.SocketFactory&user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:mysql:///%s", DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", "mysql"
    config.setPassword(DB_PASS); // e.g. "my-password"

    config.addDataSourceProperty("socketFactory", "com.google.cloud.sql.mysql.SocketFactory");
    config.addDataSourceProperty("cloudSqlInstance", INSTANCE_CONNECTION_NAME);

    // [END cloud_sql_mysql_servlet_connect_connector]
    // Unix sockets are not natively supported in Java, so it is necessary to use the Cloud SQL
    // Java Connector to connect. When setting INSTANCE_UNIX_SOCKET, the connector will 
    // call an external package that will enable Unix socket connections.
    // Note: For Java users, the Cloud SQL Java Connector can provide authenticated connections
    // which is usually preferable to using the Cloud SQL Proxy with Unix sockets.
    // See https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory for details.
    if (INSTANCE_UNIX_SOCKET != null) {
      config.addDataSourceProperty("unixSocketPath", INSTANCE_UNIX_SOCKET);
    }
    // [START cloud_sql_mysql_servlet_connect_connector]

    // [END cloud_sql_mysql_servlet_connect_unix]
    // The ipTypes argument can be used to specify a comma delimited list of preferred IP types
    // for connecting to a Cloud SQL instance. The argument ipTypes=PRIVATE will force the
    // SocketFactory to connect with an instance's associated private IP.
    config.addDataSourceProperty("ipTypes", "PUBLIC,PRIVATE");
    // [START cloud_sql_mysql_servlet_connect_unix]

    // cloudSqlRefreshStrategy set to "lazy" is used to perform a
    // refresh when needed, rather than on a scheduled interval.
    // This is recommended for serverless environments to
    // avoid background refreshes from throttling CPU.
    config.addDataSourceProperty("cloudSqlRefreshStrategy", "lazy");
    
    // ... Specify additional connection properties here.
    // [START_EXCLUDE]
    configureConnectionPool(config);
    // [END_EXCLUDE]

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}
// [END cloud_sql_mysql_servlet_connect_connector]
// [END cloud_sql_mysql_servlet_connect_unix]
