/*
 * This software is released under a licence similar to the Apache Software Licence.
 * See org.logicalcobwebs.proxool.package.html for details.
 * The latest version is available at http://proxool.sourceforge.net
 */
package org.logicalcobwebs.proxool;

import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.Factory;
import net.sf.cglib.proxy.Callback;
import net.sf.cglib.core.NamingPolicy;
import net.sf.cglib.core.Predicate;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.Statement;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.util.HashSet;
import java.util.Set;
import java.util.Map;
import java.util.HashMap;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;

/**
 * A central place to build proxy objects. It will also provide the original
 * object given a proxy.
 * @author Bill Horsman (bill@logicalcobwebs.co.uk)
 * @author $Author: billhorsman $ (current maintainer)
 * @version $Revision: 1.33 $, $Date: 2006/04/09 21:08:43 $
 * @since Proxool 0.5
 */
class ProxyFactory {

    private static final Log LOG = LogFactory.getLog(ProxyFactory.class);

    private static Map interfaceMap = new HashMap();

    /**
     * This naming policy stops conflicts with other Cglib instances that are running
     * (Even ones in different packages). Without using our own naming policy we end
     * up with exceptions like:
     * <pre>
     * java.lang.LinkageError: duplicate class definition:
     *   $java/lang/Object$$FastClassByCGLIB$$3f697993
     * </pre>
     */
    private static NamingPolicy NAMING_POLICY = new NamingPolicy() {
        public String getClassName(String prefix, String source, Object key, Predicate names) {
            StringBuffer sb = new StringBuffer();
            sb.append(
                    (prefix != null) ?
                            (
                                    prefix.startsWith("java") ?
                                            "$" + prefix : prefix
                            )
                            : "net.sf.cglib.empty.Object"
            );
            sb.append("$$");
            sb.append(source.substring(source.lastIndexOf('.') + 1));
            sb.append("ByProxool$$");
            sb.append(Integer.toHexString(key.hashCode()));
            String base = sb.toString();
            String attempt = base;
            int index = 2;
            while (names.evaluate(attempt)) {
                attempt = base + "_" + index++;
            }

            return attempt;
        }
    };

    /**
     * Wraps up a proxyConnection inside a {@link WrappedConnection} and then proxies it as a
     * simple {@link Connection}. You should call this immediately before the connection is served
     * to the user. The WrappedConnection is disposable (it is thrown away when the connection
     * is returned to the pool).
     * @param proxyConnection the pooled connection we are wrapping up
     * @return the Connection for use
     */
    protected static Connection getWrappedConnection(ProxyConnection proxyConnection) {
        return (Connection) getProxy(proxyConnection.getConnection(), new WrappedConnection(proxyConnection), proxyConnection.getDefinition());
    }

    /**
     * Proxies a statement inside a {@link ProxyStatement}.
     * @param delegate the real statement
     * @param connectionPool the pool it belongs to
     * @param proxyConnection the connection it was built from
     * @param sqlStatement Can be null?
     * @return the proxied statement
     */
    protected static Statement getStatement(Statement delegate, ConnectionPool connectionPool, ProxyConnectionIF proxyConnection, String sqlStatement) {
        return (Statement) getProxy(delegate, new ProxyStatement(delegate, connectionPool, proxyConnection, sqlStatement), proxyConnection.getDefinition());
    }

    /**
     * Create a new DatabaseMetaData from a connection
     * @param databaseMetaData the meta data we use to delegate all calls to (except getConnection())
     * @param wrappedConnection the connection we return if asked for the connection
     * @return databaseMetaData
     */
    protected static DatabaseMetaData getDatabaseMetaData(DatabaseMetaData databaseMetaData, Connection wrappedConnection) {
        return (DatabaseMetaData) getProxy(databaseMetaData, new ProxyDatabaseMetaData(databaseMetaData, wrappedConnection), null);
    }

    private static Object getProxy(Object delegate, Object callback, ConnectionPoolDefinitionIF def) {
      try {
        Class.forName( "org.objectweb.asm.CodeVisitor" );
        Enhancer e = new Enhancer( );
        e.setNamingPolicy( NAMING_POLICY );
        e.setInterfaces( getInterfaces( delegate.getClass( ), def ) );
        e.setCallback( ( Callback ) callback );
        e.setClassLoader( ProxyFactory.class.getClassLoader( ) );
        return e.create( );
      } catch(Throwable t) {
        return Proxy.newProxyInstance( ProxyFactory.class.getClassLoader( ), getInterfaces( delegate.getClass(), def ), ( InvocationHandler ) callback);
      }
    }

    /**
     * Gets the real Statement that we got from the delegate driver. This is no longer
     * necessary and only provided for backwards compatability.
     * @param statement proxy statement
     * @return delegate statement
     * @see ProxoolFacade#getDelegateStatement(java.sql.Statement)
     */
    protected static Statement getDelegateStatement(Statement statement) {
        Statement ds = statement;
        ProxyStatement ps = (ProxyStatement) ((Factory)statement).getCallback(0);
        ds = ps.getDelegateStatement();
        return ds;
    }

    /**
     * Gets the real Connection that we got from the delegate driver. This is no longer
     * necessary and only provided for backwards compatability.
     * @param connection proxy connection
     * @return deletgate connection
     * @see ProxoolFacade#getDelegateConnection(java.sql.Connection)
     */
    protected static Connection getDelegateConnection(Connection connection) {
        WrappedConnection wc = (WrappedConnection) ((Factory)connection).getCallback(0);
        return wc.getProxyConnection().getConnection();
    }

    /**
     * Get all the interfaces that a class implements. Drills down into super interfaces too
     * and super classes too.
     * The results are cached so it's very fast second time round.
     * @param clazz the class to examine.
     * @return an array of classes (all interfaces) that this class implements.
     */
    private static Class[] getInterfaces(Class clazz, ConnectionPoolDefinitionIF cpd) {
        Class[] interfaceArray = (Class[]) interfaceMap.get(clazz);
        if (interfaceArray == null) {
            Set interfaces = new HashSet();
            traverseInterfacesRecursively(interfaces, clazz);
            if (cpd != null) {
                // Work out which interface we should be injecting (if it has been configured). Make sure
                // we check CallableStatement then PreparedStatement then Statement or all three will get
                // caught by Statement
                if (Connection.class.isAssignableFrom(clazz)) {
                    Class injectableClass = cpd.getInjectableConnectionInterface();
                    // Inject it if it was configured.
                    if (injectableClass != null) {
                        interfaces.add(injectableClass);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Injecting " + injectableClass + " into " + clazz);
                        }
                    }
                }
                if (CallableStatement.class.isAssignableFrom(clazz)) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Getting injectableCallableStatementInterface");
                    }
                    Class injectableClass = cpd.getInjectableCallableStatementInterface();
                    // Inject it if it was configured.
                    if (injectableClass != null) {
                        interfaces.add(injectableClass);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Injecting " + injectableClass + " into " + clazz);
                        }
                    }
                }
                if (PreparedStatement.class.isAssignableFrom(clazz)) {
                    Class injectableClass = cpd.getInjectablePreparedStatementInterface();
                    // Inject it if it was configured.
                    if (injectableClass != null) {
                        interfaces.add(injectableClass);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Injecting " + injectableClass + " into " + clazz);
                        }
                    }
                }
                if (Statement.class.isAssignableFrom(clazz)) {
                    Class injectableClass = cpd.getInjectableStatementInterface();
                    // Inject it if it was configured.
                    if (injectableClass != null) {
                        interfaces.add(injectableClass);
                        if (LOG.isDebugEnabled()) {
                            LOG.debug("Injecting " + injectableClass + " into " + clazz);
                        }
                    }
                }
            }
            interfaceArray = (Class[]) interfaces.toArray(new Class[interfaces.size()]);
            if (LOG.isDebugEnabled()) {
                for (int i = 0; i < interfaceArray.length; i++) {
                    Class aClass = interfaceArray[i];
                    LOG.debug("Implementing " + aClass);
                }
            }
            interfaceMap.put(clazz, interfaceArray);
/*
        } else {
            if (LOG.isDebugEnabled()) {
                LOG.debug("Reusing " + interfaceArray.length + " interfaces already looked up for " + clazz);
            }
*/
        }
        return interfaceArray;
    }

    /**
     * Recursively looks at all interfaces for a class. Also looks at interfaces implemented
     * by the super class (and its super class, etc.) Quite a lot of processing involved
     * so you shouldn't call it too often.
     * @param interfaces this set is populated with all interfaceMap it finds
     * @param clazz the base class to analyze
     */
    private static void traverseInterfacesRecursively(Set interfaces, Class clazz) {
        // Check for circular reference (avoid endless recursion)
        if (interfaces.contains(clazz)) {
            // Skip it, we've already been here.
/*
            if (LOG.isDebugEnabled()) {
                LOG.debug("Skipping " + clazz + " because we've already traversed it");
            }
*/
        } else {
/*
            if (LOG.isDebugEnabled()) {
                LOG.debug("Analyzing " + clazz);
            }
*/
            Class[] interfaceArray = clazz.getInterfaces();
            for (int i = 0; i < interfaceArray.length; i++) {
/*
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Adding " + interfaceArray[i]);
                }
*/
                traverseInterfacesRecursively(interfaces, interfaceArray[i]);
                // We're only interested in public interfaces. In fact, including
                // non-public interfaces will give IllegalAccessExceptions.
                if (Modifier.isPublic(interfaceArray[i].getModifiers())) {
                    interfaces.add(interfaceArray[i]);
                }
            }
            Class superClazz = clazz.getSuperclass();
            if (superClazz != null) {
                traverseInterfacesRecursively(interfaces, superClazz);
            }
/*
            if (LOG.isDebugEnabled()) {
                LOG.debug("Found " + interfaceArray.length + " interfaceMap for " + clazz);
            }
*/
        }
    }

    /**
     * Get the WrappedConnection behind this proxy connection.
     * @param connection the connection that was served
     * @return the wrapped connection or null if it couldn't be found
     */
    public static WrappedConnection getWrappedConnection(Connection connection) {
        return (WrappedConnection) ((Factory)connection).getCallback(0);
    }

}

/*
 Revision history:
 $Log: ProxyFactory.java,v $
 Revision 1.33  2006/04/09 21:08:43  billhorsman
 Use our own naming policy for Cglib to avoid duplicate class definition exceptions.

 Revision 1.32  2006/01/18 14:40:02  billhorsman
 Unbundled Jakarta's Commons Logging.

 Revision 1.31  2005/09/26 09:59:22  billhorsman
 Explicitly use the ProxyFactory class loader when using Cglib's Enhancer to avoid class loading issues.

 Revision 1.30  2005/05/04 16:31:41  billhorsman
 Use the definition referenced by the proxy connection rather than the pool instead.

 Revision 1.29  2004/07/27 21:44:15  billhorsman
 Remove insane amount of debug logging.

 Revision 1.28  2004/06/17 21:58:36  billhorsman
 Injectable interface fixes.

 Revision 1.27  2004/06/02 20:50:47  billhorsman
 Dropped obsolete InvocationHandler reference and injectable interface stuff.

 Revision 1.26  2004/03/23 21:19:45  billhorsman
 Added disposable wrapper to proxied connection. And made proxied objects implement delegate interfaces too.

 Revision 1.25  2003/12/12 19:29:47  billhorsman
 Now uses Cglib 2.0

 Revision 1.24  2003/09/30 18:39:08  billhorsman
 New test-before-use, test-after-use and fatal-sql-exception-wrapper-class properties.

 Revision 1.23  2003/09/10 22:21:04  chr32
 Removing > jdk 1.2 dependencies.

 Revision 1.22  2003/09/07 22:11:31  billhorsman
 Remove very persistent debug message

 Revision 1.21  2003/08/27 18:03:20  billhorsman
 added new getDelegateConnection() method

 Revision 1.20  2003/03/11 14:51:54  billhorsman
 more concurrency fixes relating to snapshots

 Revision 1.19  2003/03/10 23:43:13  billhorsman
 reapplied checkstyle that i'd inadvertently let
 IntelliJ change...

 Revision 1.18  2003/03/10 15:26:49  billhorsman
 refactoringn of concurrency stuff (and some import
 optimisation)

 Revision 1.17  2003/03/05 18:42:33  billhorsman
 big refactor of prototyping and house keeping to
 drastically reduce the number of threads when using
 many pools

 Revision 1.16  2003/03/03 11:11:58  billhorsman
 fixed licence

 Revision 1.15  2003/02/19 15:14:32  billhorsman
 fixed copyright (copy and paste error,
 not copyright change)

 Revision 1.14  2003/02/12 12:28:27  billhorsman
 added url, proxyHashcode and delegateHashcode to
 ConnectionInfoIF

 Revision 1.13  2003/02/06 17:41:04  billhorsman
 now uses imported logging

 Revision 1.12  2003/01/31 14:33:18  billhorsman
 fix for DatabaseMetaData

 Revision 1.11  2003/01/27 18:26:39  billhorsman
 refactoring of ProxyConnection and ProxyStatement to
 make it easier to write JDK 1.2 patch

 Revision 1.10  2002/12/16 11:15:19  billhorsman
 fixed getDelegateStatement

 Revision 1.9  2002/12/16 10:57:47  billhorsman
 add getDelegateStatement to allow access to the
 delegate JDBC driver's Statement

 Revision 1.8  2002/12/12 10:48:25  billhorsman
 checkstyle

 Revision 1.7  2002/12/08 22:17:35  billhorsman
 debug for proxying statement interfaces

 Revision 1.6  2002/12/06 15:57:08  billhorsman
 fix for proxied statement where Statement interface is not directly
 implemented.

 Revision 1.5  2002/12/03 12:24:00  billhorsman
 fixed fatal sql exception

 Revision 1.4  2002/11/09 15:56:52  billhorsman
 fix doc

 Revision 1.3  2002/11/02 14:22:15  billhorsman
 Documentation

 Revision 1.2  2002/10/30 21:25:08  billhorsman
 move createStatement into ProxyFactory

 Revision 1.1  2002/10/30 21:19:16  billhorsman
 make use of ProxyFactory

*/