/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.naming.factory;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.SQLException;
import java.util.Hashtable;

import javax.naming.Context;
import javax.naming.Name;
import javax.naming.NamingException;
import javax.naming.RefAddr;
import javax.naming.Reference;
import javax.sql.DataSource;



/**
 * <p>Object factory for resource links for shared data sources.</p>
 * 
 * @author Filip Hanik
 */
public class DataSourceLinkFactory extends ResourceLinkFactory {

    public static void setGlobalContext(Context newGlobalContext) {
        ResourceLinkFactory.setGlobalContext(newGlobalContext);
    }
    // ------------------------------------------------- ObjectFactory Methods


    /**
     * Create a new DataSource instance.
     * 
     * @param obj The reference object describing the DataSource
     */
    @Override
    public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable environment)
        throws NamingException {
        Object result = super.getObjectInstance(obj, name, nameCtx, environment);
        // Can we process this request?
        if (result!=null) {
            Reference ref = (Reference) obj;
            RefAddr userAttr = ref.get("username");
            RefAddr passAttr = ref.get("password");
            if (userAttr.getContent()!=null && passAttr.getContent()!=null) {
                result = wrapDataSource(result,userAttr.getContent().toString(), passAttr.getContent().toString());
            }
        }
        return result;
    }
    
    protected Object wrapDataSource(Object datasource, String username, String password) throws NamingException {
        try {
            Class<?> proxyClass = Proxy.getProxyClass(datasource.getClass().getClassLoader(), datasource.getClass().getInterfaces());
            Constructor<?> proxyConstructor = proxyClass.getConstructor(new Class[] { InvocationHandler.class });
            DataSourceHandler handler = new DataSourceHandler((DataSource)datasource, username, password);
            return proxyConstructor.newInstance(handler);    
        }catch (Exception x) {
            if (x instanceof NamingException) throw (NamingException)x;
            else {
                NamingException nx = new NamingException(x.getMessage());
                nx.initCause(x);
                throw nx;
            }
        }
    }
    
    /**
     * Simple wrapper class that will allow a user to configure a ResourceLink for a data source
     * so that when {@link javax.sql.DataSource#getConnection()} is called, it will invoke 
     * {@link javax.sql.DataSource#getConnection(String, String)} with the preconfigured username and password.
     */
    public static class DataSourceHandler implements InvocationHandler {
        private final DataSource ds; 
        private final String username; 
        private final String password;
        private final Method getConnection;
        public DataSourceHandler(DataSource ds, String username, String password) throws Exception {
            this.ds = ds;
            this.username = username;
            this.password = password;
            getConnection = ds.getClass().getMethod("getConnection", String.class, String.class);
        }
        

        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            
            if ("getConnection".equals(method.getName()) && (args==null || args.length==0)) {
                args = new String[] {username,password};
                method = getConnection;
            } else if ("unwrap".equals(method.getName())) {
                return unwrap((Class<?>)args[0]);
            }
            try {
                return method.invoke(ds,args);
            }catch (Throwable t) {
                if (t instanceof InvocationTargetException) {
                    InvocationTargetException it = (InvocationTargetException)t;
                    throw it.getCause()!=null?it.getCause():it;
                } else {
                    throw t;
                }
            }
        }
        
        public Object unwrap(Class<?> iface) throws SQLException {
            if (iface == DataSource.class) {
                return ds;
            } else {
                throw new SQLException("Not a wrapper of "+iface.getName());
            }
        }
        
    }
    
    


}