// 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.s3;

import java.sql.SQLException;

import javax.inject.Inject;
import javax.servlet.http.HttpServletRequest;

import org.apache.axiom.soap.SOAPBody;
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.log4j.Logger;

import com.cloud.bridge.model.UserCredentialsVO;
import com.cloud.bridge.persist.dao.UserCredentialsDaoImpl;
import com.cloud.bridge.service.UserContext;
import com.cloud.bridge.util.S3SoapAuth;

/*
 *  For SOAP compatibility.
 */

public class AuthenticationHandler implements Handler {
    protected final static Logger logger = Logger.getLogger(AuthenticationHandler.class);
    @Inject
    UserCredentialsDaoImpl ucDao;
    protected HandlerDescription handlerDesc = new HandlerDescription("default handler");
    private String name = "S3AuthenticationHandler";

    @Override
    public void init(HandlerDescription handlerdesc) {
        this.handlerDesc = handlerdesc;
    }

    @Override
    public String getName() {
        //logger.debug( "getName entry S3AuthenticationHandler" + name );
        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);
    }

    /**
     * Verify the request's authentication signature by extracting all the
     * necessary parts of the request, obtaining the requestor's secret key, and
     * recalculating the signature.
     *
     * On Signature mismatch raise an AxisFault (i.e., a SoapFault) with what Amazon S3
     * defines as a "Client.SignatureMismatch" error.
     *
     * Special case: need to deal with anonymous requests where no AWSAccessKeyId is
     * given.   In this case just pass the request on.
     */
    @Override
    public InvocationResponse invoke(MessageContext msgContext) throws AxisFault {
        String accessKey = null;
        String operation = null;
        String msgSig = null;
        String timestamp = null;
        String secretKey = null;
        String temp = null;

        // [A] Obtain the HttpServletRequest object
        HttpServletRequest httpObj = (HttpServletRequest)msgContext.getProperty("transport.http.servletRequest");
        if (null != httpObj)
            System.out.println("S3 SOAP auth test header access - acceptable Encoding type: " + httpObj.getHeader("Accept-Encoding"));

        // [A] Try to recalculate the signature for non-anonymous requests
        try {
            SOAPEnvelope soapEnvelope = msgContext.getEnvelope();
            SOAPBody soapBody = soapEnvelope.getBody();
            String xmlBody = soapBody.toString();
            //logger.debug( "xmlrequest: " + xmlBody );

            // -> did we get here yet its an EC2 request?
            int offset = xmlBody.indexOf("http://ec2.amazonaws.com");
            if (-1 != offset)
                return InvocationResponse.CONTINUE;

            // -> if it is anonymous request, then no access key should exist
            int start = xmlBody.indexOf("AWSAccessKeyId>");
            if (-1 == start) {
                UserContext.current().initContext();
                return InvocationResponse.CONTINUE;
            }
            temp = xmlBody.substring(start + 15);
            int end = temp.indexOf("</");
            accessKey = temp.substring(0, end);
            //logger.debug( "accesskey " + accessKey );

            // -> what if we cannot find the user's key?
            if (null != (secretKey = lookupSecretKey(accessKey))) {
                // -> if any other field is missing, then the signature will not match
                if (null != (operation = soapBody.getFirstElementLocalName()))
                    operation = operation.trim();
                else
                    operation = "";
                //logger.debug( "operation " + operation );

                start = xmlBody.indexOf("Timestamp>");
                if (-1 < start) {
                    temp = xmlBody.substring(start + 10);
                    end = temp.indexOf("</");
                    timestamp = temp.substring(0, end);
                    //logger.debug( "timestamp " + timestamp );
                } else
                    timestamp = "";

                start = xmlBody.indexOf("Signature>");
                if (-1 < start) {
                    temp = xmlBody.substring(start + 10);
                    end = temp.indexOf("</");
                    msgSig = temp.substring(0, end);
                    //logger.debug( "signature " + msgSig );
                } else
                    msgSig = "";
            }
        } catch (Exception e) {
            logger.error("Signature calculation failed due to: ", e);
            throw new AxisFault(e.toString(), "Server.InternalError");
        }

        // [B] Verify that the given signature matches what we calculated here
        if (null == secretKey) {
            logger.error("Unknown AWSAccessKeyId: [" + accessKey + "]");
            throw new AxisFault("Unknown AWSAccessKeyId: [" + accessKey + "]", "Client.InvalidAccessKeyId");
        }

        // -> for SOAP requests the Cloud API keys are sent here and only here
        S3SoapAuth.verifySignature(msgSig, operation, timestamp, accessKey, secretKey);
        UserContext.current().initContext(accessKey, secretKey, accessKey, "S3 SOAP request", httpObj);
        return InvocationResponse.CONTINUE;
    }

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

    public void setName(String name) {
        //logger.debug( "setName entry S3AuthenticationHandler " + name );
        this.name = name;
    }

    /**
     * Given the user's access key, then obtain his secret key in the user database.
     *
     * @param accessKey - a unique string allocated for each registered user
     * @return the secret key or null of no matching user found
     */
    private String lookupSecretKey(String accessKey) throws InstantiationException, IllegalAccessException, ClassNotFoundException, SQLException {
        UserCredentialsVO cloudKeys = ucDao.getByAccessKey(accessKey);
        if (null == cloudKeys) {
            logger.debug(accessKey + " is not defined in the S3 service - call SetUserKeys");
            return null;
        } else
            return cloudKeys.getSecretKey();
    }

    @Override
    public void cleanup() {
        //logger.debug( "cleanup entry S3AuthenticationHandler " );
    }

    @Override
    public void flowComplete(MessageContext arg0) {
        //logger.debug( "flowComplete entry S3AuthenticationHandler " );
    }
}