/*
    * This file is part of Waarp Project (named also Waarp or GG).
    *
    *  Copyright (c) 2019, Waarp SAS, and individual contributors by the @author
    *  tags. See the COPYRIGHT.txt in the distribution for a full listing of
    * individual contributors.
    *
    *  All Waarp Project is free software: you can redistribute it and/or
    * modify it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or (at your
   * option) any later version.
   *
   * Waarp is distributed in the hope that it will be useful, but WITHOUT ANY
   * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   * A PARTICULAR PURPOSE. See the GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License along with
   * Waarp . If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.waarp.common.database.properties;
  
  import java.sql.Connection;
  import java.sql.ResultSet;
  import java.sql.SQLException;
  import java.sql.Statement;
  
  /**
   * PostgreSQL Database Model
   */
  public class PostgreSQLProperties implements DbProperties {
    public static final String PROTOCOL = "postgres";
  
    private static final String DRIVER_NAME = "org.postgresql.Driver";
    private static final String VALIDATION_QUERY = "select 1";
    private static final String MAX_CONNECTION_QUERY =
        "select (select setting as mc from pg_settings where name='max_connections')::int" +
        " - (select setting from pg_settings where name='superuser_reserved_connections')::int";
  
  
    public PostgreSQLProperties() {
      // nothing
    }
  
    public static String getProtocolID() {
      return PROTOCOL;
    }
  
    @Override
    public final String getDriverName() {
      return DRIVER_NAME;
    }
  
    @Override
    public final String getValidationQuery() {
      return VALIDATION_QUERY;
    }
  
    @Override
    public final int getMaximumConnections(final Connection connection)
        throws SQLException {
      Statement stm = null;
      ResultSet rs = null;
      try {
        stm = connection.createStatement();
        rs = stm.executeQuery(MAX_CONNECTION_QUERY);
        if (!rs.next()) {
          throw new SQLException("Cannot find max connection");
        }
        return rs.getInt(1);
      } finally {
        if (rs != null) {
          try {
            rs.close();
          } catch (final SQLException ignored) {
            // nothing
          }
        }
        if (stm != null) {
          try {
            stm.close();
          } catch (final SQLException ignored) {
            // nothing
          }
        }
      }
    }
  }