package pl.kyku;

import java.sql.Array;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.NClob;
import java.sql.PreparedStatement;
import java.sql.SQLClientInfoException;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.SQLXML;
import java.sql.Savepoint;
import java.sql.Statement;
import java.sql.Struct;
import java.util.Enumeration;
import java.util.Map;
import java.util.Properties;
import java.util.Vector;

public class ConnectionPool
{
  private final Vector<JDCConnection> connections;
  private final String url;
  private final String user;
  private final String password;
  private final long timeout = 60000L;
  private final ConnectionReaper reaper;
  private final int poolsize = 10;

  public ConnectionPool(String url, String user, String password)
    throws ClassNotFoundException
  {
    Class.forName("com.mysql.jdbc.Driver");
    this.url = url;
    this.user = user;
    this.password = password;
    this.connections = new Vector(10);
    this.reaper = new ConnectionReaper(null);
    this.reaper.start();
  }

  public synchronized Connection getConnection()
    throws SQLException
  {
    for (int i = 0; i < this.connections.size(); i++)
    {
      JDCConnection conn = (JDCConnection)this.connections.get(i);
      if (conn.lease())
      {
        if (conn.isValid()) {
          return conn;
        }
        this.connections.remove(conn);
        conn.terminate();
      }
    }
    JDCConnection conn = new JDCConnection(DriverManager.getConnection(this.url, this.user, this.password));
    conn.lease();
    if (!conn.isValid())
    {
      conn.terminate();
      throw new SQLException("Failed to validate a brand new connection");
    }
    this.connections.add(conn);
    return conn;
  }

  private synchronized void reapConnections()
  {
    long stale = System.currentTimeMillis() - 60000L;
    for (JDCConnection conn : this.connections) {
      if ((conn.inUse()) && (stale > conn.getLastUse()) && (!conn.isValid())) {
        this.connections.remove(conn);
      }
    }
  }

  public synchronized void closeConnections()
  {
    Enumeration<JDCConnection> conns = this.connections.elements();
    while (conns.hasMoreElements())
    {
      JDCConnection conn = (JDCConnection)conns.nextElement();
      this.connections.remove(conn);
      conn.terminate();
    }
  }

  private class ConnectionReaper
    extends Thread
  {
    private ConnectionReaper() {}

    public void run()
    {
      for (;;)
      {
        try
        {
          Thread.sleep(300000L);
        }
        catch (InterruptedException e) {}
        ConnectionPool.this.reapConnections();
      }
    }
  }

  private class JDCConnection
    implements Connection
  {
    private final Connection conn;
    private boolean inuse;
    private long timestamp;

    public JDCConnection(Connection conn)
    {
      this.conn = conn;
      this.inuse = false;
      this.timestamp = 0L;
    }

    public void terminate()
    {
      try
      {
        this.conn.close();
      }
      catch (SQLException ex) {}
    }

    public synchronized boolean lease()
    {
      if (this.inuse) {
        return false;
      }
      this.inuse = true;
      this.timestamp = System.currentTimeMillis();
      return true;
    }

    public boolean inUse()
    {
      return this.inuse;
    }

    public long getLastUse()
    {
      return this.timestamp;
    }

    public void close()
    {
      this.inuse = false;
      try
      {
        if (!this.conn.getAutoCommit()) {
          this.conn.setAutoCommit(true);
        }
      }
      catch (SQLException ex)
      {
        ConnectionPool.this.connections.remove(this.conn);
        terminate();
      }
    }

    public PreparedStatement prepareStatement(String sql)
      throws SQLException
    {
      return this.conn.prepareStatement(sql);
    }

    public CallableStatement prepareCall(String sql)
      throws SQLException
    {
      return this.conn.prepareCall(sql);
    }

    public Statement createStatement()
      throws SQLException
    {
      return this.conn.createStatement();
    }

    public String nativeSQL(String sql)
      throws SQLException
    {
      return this.conn.nativeSQL(sql);
    }

    public void setAutoCommit(boolean autoCommit)
      throws SQLException
    {
      this.conn.setAutoCommit(autoCommit);
    }

    public boolean getAutoCommit()
      throws SQLException
    {
      return this.conn.getAutoCommit();
    }

    public void commit()
      throws SQLException
    {
      this.conn.commit();
    }

    public void rollback()
      throws SQLException
    {
      this.conn.rollback();
    }

    public boolean isClosed()
      throws SQLException
    {
      return this.conn.isClosed();
    }

    public DatabaseMetaData getMetaData()
      throws SQLException
    {
      return this.conn.getMetaData();
    }

    public void setReadOnly(boolean readOnly)
      throws SQLException
    {
      this.conn.setReadOnly(readOnly);
    }

    public boolean isReadOnly()
      throws SQLException
    {
      return this.conn.isReadOnly();
    }

    public void setCatalog(String catalog)
      throws SQLException
    {
      this.conn.setCatalog(catalog);
    }

    public String getCatalog()
      throws SQLException
    {
      return this.conn.getCatalog();
    }

    public void setTransactionIsolation(int level)
      throws SQLException
    {
      this.conn.setTransactionIsolation(level);
    }

    public int getTransactionIsolation()
      throws SQLException
    {
      return this.conn.getTransactionIsolation();
    }

    public SQLWarning getWarnings()
      throws SQLException
    {
      return this.conn.getWarnings();
    }

    public void clearWarnings()
      throws SQLException
    {
      this.conn.clearWarnings();
    }

    public Array createArrayOf(String typeName, Object[] elements)
      throws SQLException
    {
      return this.conn.createArrayOf(typeName, elements);
    }

    public Blob createBlob()
      throws SQLException
    {
      return this.conn.createBlob();
    }

    public Clob createClob()
      throws SQLException
    {
      return this.conn.createClob();
    }

    public NClob createNClob()
      throws SQLException
    {
      return this.conn.createNClob();
    }

    public SQLXML createSQLXML()
      throws SQLException
    {
      return this.conn.createSQLXML();
    }

    public Statement createStatement(int resultSetType, int resultSetConcurrency)
      throws SQLException
    {
      return this.conn.createStatement(resultSetType, resultSetConcurrency);
    }

    public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability)
      throws SQLException
    {
      return this.conn.createStatement(resultSetType, resultSetConcurrency, resultSetHoldability);
    }

    public Struct createStruct(String typeName, Object[] attributes)
      throws SQLException
    {
      return this.conn.createStruct(typeName, attributes);
    }

    public Properties getClientInfo()
      throws SQLException
    {
      return this.conn.getClientInfo();
    }

    public String getClientInfo(String name)
      throws SQLException
    {
      return this.conn.getClientInfo(name);
    }

    public int getHoldability()
      throws SQLException
    {
      return this.conn.getHoldability();
    }

    public Map<String, Class<?>> getTypeMap()
      throws SQLException
    {
      return this.conn.getTypeMap();
    }

    public boolean isValid()
    {
      try
      {
        return this.conn.isValid(1);
      }
      catch (SQLException ex) {}
      return false;
    }

    public boolean isValid(int timeout)
      throws SQLException
    {
      return this.conn.isValid(timeout);
    }

    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency)
      throws SQLException
    {
      return this.conn.prepareCall(sql, resultSetType, resultSetConcurrency);
    }

    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
      throws SQLException
    {
      return this.conn.prepareCall(sql, resultSetType, resultSetConcurrency, resultSetHoldability);
    }

    public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys)
      throws SQLException
    {
      return this.conn.prepareStatement(sql, autoGeneratedKeys);
    }

    public PreparedStatement prepareStatement(String sql, int[] columnIndexes)
      throws SQLException
    {
      return this.conn.prepareStatement(sql, columnIndexes);
    }

    public PreparedStatement prepareStatement(String sql, String[] columnNames)
      throws SQLException
    {
      return this.conn.prepareStatement(sql, columnNames);
    }

    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency)
      throws SQLException
    {
      return this.conn.prepareStatement(sql, resultSetType, resultSetConcurrency);
    }

    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability)
      throws SQLException
    {
      return this.conn.prepareStatement(sql, resultSetType, resultSetConcurrency, resultSetHoldability);
    }

    public void releaseSavepoint(Savepoint savepoint)
      throws SQLException
    {
      this.conn.releaseSavepoint(savepoint);
    }

    public void rollback(Savepoint savepoint)
      throws SQLException
    {
      this.conn.rollback(savepoint);
    }

    public void setClientInfo(Properties properties)
      throws SQLClientInfoException
    {
      this.conn.setClientInfo(properties);
    }

    public void setClientInfo(String name, String value)
      throws SQLClientInfoException
    {
      this.conn.setClientInfo(name, value);
    }

    public void setHoldability(int holdability)
      throws SQLException
    {
      this.conn.setHoldability(holdability);
    }

    public Savepoint setSavepoint()
      throws SQLException
    {
      return this.conn.setSavepoint();
    }

    public Savepoint setSavepoint(String name)
      throws SQLException
    {
      return this.conn.setSavepoint(name);
    }

    public void setTypeMap(Map<String, Class<?>> map)
      throws SQLException
    {
      this.conn.setTypeMap(map);
    }

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

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