/*
 * 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_postgres_servlet_auto_iam_authn]
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class ConnectorIamAuthnConnectionPoolFactory 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 DB_IAM_USER = System.getenv("DB_IAM_USER");
  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:postgresql:///<DB_NAME>?cloudSqlInstance=<INSTANCE_CONNECTION_NAME>&
    // socketFactory=com.google.cloud.sql.postgres.SocketFactory&user=<DB_IAM_USER>&
    // password=password
    // 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 to connect with.
    config.setJdbcUrl(String.format("jdbc:postgresql:///%s", DB_NAME));

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

    // If connecting using automatic database authentication, follow the instructions for
    // connecting using the connector, but set the DB_IAM_USER value to an IAM user or
    // service account that has been given access to the database.
    // See https://cloud.google.com/sql/docs/postgres/iam-logins for more details.
    config.addDataSourceProperty("enableIamAuth", "true");
    config.addDataSourceProperty("user", DB_IAM_USER);
    // Password must be set to a nonempty value to bypass driver validation errors.
    config.addDataSourceProperty("password", "password");
    // Explicitly set sslmode to disable to prevent driver from hanging.
    // The Java Connector will handle SSL so it is unneccesary to enable it at the driver level.
    config.addDataSourceProperty("sslmode", "disable");

    // 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_postgres_servlet_auto_iam_authn]
