/*
    *    Copyright 2010-2022 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.apache.ibatis.migration;
  
  import java.sql.Connection;
  import java.sql.Driver;
  import java.sql.DriverManager;
  import java.sql.SQLException;
  import java.util.Enumeration;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.ibatis.migration.driver.DriverShim;
  
  public class JdbcConnectionProvider implements ConnectionProvider {
    private static final Map<String, Driver> registeredDrivers = registeredDrivers();
  
    private final String url;
    private final String username;
    private final String password;
  
    public JdbcConnectionProvider(String driver, String url, String username, String password) {
      this(null, driver, url, username, password);
    }
  
    public JdbcConnectionProvider(ClassLoader classLoader, String driver, String url, String username, String password) {
      this.url = url;
      this.username = username;
      this.password = password;
      registerDriver(classLoader, driver);
    }
  
    @Override
    public Connection getConnection() throws SQLException {
      return DriverManager.getConnection(url, username, password);
    }
  
    private void registerDriver(ClassLoader classLoader, String driver) {
      registeredDrivers.computeIfAbsent(driver, d -> createDriverClass(classLoader, d));
    }
  
    private Driver createDriverClass(ClassLoader classLoader, String driver) {
      try {
        final Class<?> driverClass = classLoader == null ? Class.forName(driver)
            : Class.forName(driver, true, classLoader);
        final Driver driverInstance = (Driver) driverClass.getDeclaredConstructor().newInstance();
        final DriverShim driverShim = new DriverShim(driverInstance);
        DriverManager.registerDriver(driverShim);
        return driverShim;
      } catch (final Exception e) {
        throw new IllegalStateException("Failed to register driver " + driver, e);
      }
    }
  
    private static Map<String, Driver> registeredDrivers() {
      final Map<String, Driver> registeredDrivers = new HashMap<>();
      final Enumeration<Driver> drivers = DriverManager.getDrivers();
      while (drivers.hasMoreElements()) {
        final Driver driver = drivers.nextElement();
        registeredDrivers.put(driver.getClass().getName(), driver);
      }
      return registeredDrivers;
    }
  }