// 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 com.cloud.bridge.auth.ec2;

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;

import javax.inject.Inject;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.apache.axiom.soap.SOAPEnvelope;
import org.apache.axis2.AxisFault;
import org.apache.axis2.context.MessageContext;
import org.apache.axis2.description.HandlerDescription;
import org.apache.axis2.description.Parameter;
import org.apache.axis2.engine.Handler;
import org.apache.commons.codec.binary.Base64;
import org.apache.log4j.Logger;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import com.cloud.bridge.model.UserCredentialsVO;
import com.cloud.bridge.persist.dao.UserCredentialsDao;
import com.cloud.bridge.persist.dao.UserCredentialsDaoImpl;
import com.cloud.bridge.service.UserContext;
import com.cloud.bridge.util.AuthenticationUtils;


public class AuthenticationHandler implements Handler {
    protected final static Logger logger = Logger.getLogger(AuthenticationHandler.class);
    private DocumentBuilderFactory dbf = null;

    protected HandlerDescription handlerDesc = new HandlerDescription( "EC2AuthenticationHandler" );
    private String name = "EC2AuthenticationHandler";

    @Override
    public void init( HandlerDescription handlerdesc ) 
    {
        dbf = DocumentBuilderFactory.newInstance();
        dbf.setNamespaceAware( true );

        this.handlerDesc = handlerdesc;
    }

    @Override
    public String getName() 
    {
        return name;
    }

    @Override
    public String toString() 
    {
        return (name != null) ? name.toString() : null;
    }

    @Override
    public HandlerDescription getHandlerDesc() 
    {
        return handlerDesc;
    }

    @Override
    public Parameter getParameter( String name ) 
    {
        return handlerDesc.getParameter( name );
    } 


    /**
     * For EC2 SOAP calls this function's goal is to extract the X509 certificate that is
     * part of the WS-Security wrapped SOAP request.   We need the cert in order to 
     * map it to the user's Cloud API key and Cloud Secret Key.
     */
    @Override
    public InvocationResponse invoke(MessageContext msgContext) throws AxisFault 
    {
        // -> the certificate we want is embedded into the soap header
        try
        {  SOAPEnvelope soapEnvelope = msgContext.getEnvelope();
        String       xmlHeader    = soapEnvelope.toString();
        //System.out.println( "entire request: " + xmlHeader );

        InputStream is = new ByteArrayInputStream( xmlHeader.getBytes("UTF-8"));
        DocumentBuilder db = dbf.newDocumentBuilder();
        Document request = db.parse( is );   		
        NodeList certs   = request.getElementsByTagNameNS( "http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd", "BinarySecurityToken" ); 
        if (0 < certs.getLength()) {
            Node item = certs.item(0);
            String result = new String( item.getFirstChild().getNodeValue());
            byte[] certBytes = Base64.decodeBase64( result.getBytes()); 

            Certificate userCert  = null;
            CertificateFactory cf = CertificateFactory.getInstance( "X.509" );
            ByteArrayInputStream bs = new ByteArrayInputStream( certBytes );
            while (bs.available() > 0) userCert = cf.generateCertificate(bs);
            //System.out.println( "cert: " + userCert.toString());              
            String uniqueId = AuthenticationUtils.X509CertUniqueId( userCert );
            logger.debug( "X509 cert's uniqueId: " + uniqueId );

            // -> find the Cloud API key and the secret key from the cert's uniqueId 
            UserCredentialsDao ucDao = new UserCredentialsDaoImpl();
            UserCredentialsVO cloudKeys = ucDao.getByCertUniqueId(uniqueId);
            if ( null == cloudKeys ) {
                logger.error( "Cert does not map to Cloud API keys: " + uniqueId );
                throw new AxisFault( "User not properly registered: Certificate does not map to Cloud API Keys", "Client.Blocked" );
            }
            else UserContext.current().initContext( cloudKeys.getAccessKey(), cloudKeys.getSecretKey(), cloudKeys.getAccessKey(), "SOAP Request", null );
            //System.out.println( "end of cert match: " + UserContext.current().getSecretKey());
        }
        } 
        catch (AxisFault e) {
            throw e;
        } 
        catch( Exception e ) {
            logger.error("EC2 Authentication Handler: ", e);
            throw new AxisFault( "An unknown error occurred.", "Server.InternalError" );
        }    	
        return InvocationResponse.CONTINUE;
    }


    public void revoke(MessageContext msgContext) 
    {
        logger.info(msgContext.getEnvelope().toString());
    }

    public void setName(String name) 
    {
        this.name = name;
    }

    @Override
    public void cleanup() 
    {
    }

    @Override
    public void flowComplete( MessageContext arg0 ) 
    {
    }
}