/* Copyright 2004, 2005, 2006 Acegi Technology Pty Limited
 *
 * Licensed 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.springframework.security.openid;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.openid4java.association.AssociationException;
import org.openid4java.consumer.ConsumerException;
import org.openid4java.consumer.ConsumerManager;
import org.openid4java.consumer.VerificationResult;
import org.openid4java.discovery.DiscoveryException;
import org.openid4java.discovery.DiscoveryInformation;
import org.openid4java.discovery.Identifier;
import org.openid4java.message.AuthRequest;
import org.openid4java.message.Message;
import org.openid4java.message.MessageException;
import org.openid4java.message.MessageExtension;
import org.openid4java.message.ParameterList;
import org.openid4java.message.ax.AxMessage;
import org.openid4java.message.ax.FetchRequest;
import org.openid4java.message.ax.FetchResponse;
import org.springframework.util.StringUtils;


/**
 * @author Ray Krueger
 * @author Luke Taylor
 */
@SuppressWarnings("unchecked")
public class OpenID4JavaConsumer implements OpenIDConsumer {
    private static final String DISCOVERY_INFO_KEY = DiscoveryInformation.class.getName();
    private static final String ATTRIBUTE_LIST_KEY = "SPRING_SECURITY_OPEN_ID_ATTRIBUTES_FETCH_LIST";

    //~ Instance fields ================================================================================================

    protected final Log logger = LogFactory.getLog(getClass());

    private final ConsumerManager consumerManager;
    private final AxFetchListFactory attributesToFetchFactory;

    //~ Constructors ===================================================================================================

    public OpenID4JavaConsumer() throws ConsumerException {
        this(new ConsumerManager(), new NullAxFetchListFactory());
    }

    /**
     * @deprecated use the {@link AxFetchListFactory} version instead.
     */
    @Deprecated
    public OpenID4JavaConsumer(List<OpenIDAttribute> attributes) throws ConsumerException {
        this(new ConsumerManager(), attributes);
    }

    @Deprecated
    public OpenID4JavaConsumer(ConsumerManager consumerManager, final List<OpenIDAttribute> attributes)
            throws ConsumerException {
        this.consumerManager = consumerManager;
        this.attributesToFetchFactory = new AxFetchListFactory() {
            private final List<OpenIDAttribute> fetchAttrs = Collections.unmodifiableList(attributes);

            public List<OpenIDAttribute> createAttributeList(String identifier) {
                return fetchAttrs;
            }
        };
    }

    public OpenID4JavaConsumer(AxFetchListFactory attributesToFetchFactory) throws ConsumerException {
        this(new ConsumerManager(), attributesToFetchFactory);
    }

    public OpenID4JavaConsumer(ConsumerManager consumerManager, AxFetchListFactory attributesToFetchFactory)
            throws ConsumerException {
        this.consumerManager = consumerManager;
        this.attributesToFetchFactory = attributesToFetchFactory;
    }

    //~ Methods ========================================================================================================

    public String beginConsumption(HttpServletRequest req, String identityUrl, String returnToUrl, String realm)
            throws OpenIDConsumerException {
        List<DiscoveryInformation> discoveries;

        try {
            discoveries = consumerManager.discover(identityUrl);
        } catch (DiscoveryException e) {
            throw new OpenIDConsumerException("Error during discovery", e);
        }

        DiscoveryInformation information = consumerManager.associate(discoveries);
        req.getSession().setAttribute(DISCOVERY_INFO_KEY, information);

        AuthRequest authReq;

        try {
            authReq = consumerManager.authenticate(information, returnToUrl, realm);

            logger.debug("Looking up attribute fetch list for identifier: " + identityUrl);

            List<OpenIDAttribute> attributesToFetch = attributesToFetchFactory.createAttributeList(identityUrl);

            if (!attributesToFetch.isEmpty()) {
                req.getSession().setAttribute(ATTRIBUTE_LIST_KEY, attributesToFetch);
                FetchRequest fetchRequest = FetchRequest.createFetchRequest();
                for (OpenIDAttribute attr : attributesToFetch) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Adding attribute " + attr.getType() + " to fetch request");
                    }
                    fetchRequest.addAttribute(attr.getName(), attr.getType(), attr.isRequired(), attr.getCount());
                }
                authReq.addExtension(fetchRequest);
            }
        } catch (MessageException e) {
            throw new OpenIDConsumerException("Error processing ConsumerManager authentication", e);
        } catch (ConsumerException e) {
            throw new OpenIDConsumerException("Error processing ConsumerManager authentication", e);
        }

        return authReq.getDestinationUrl(true);
    }

    public OpenIDAuthenticationToken endConsumption(HttpServletRequest request) throws OpenIDConsumerException {
        // extract the parameters from the authentication response
        // (which comes in as a HTTP request from the OpenID provider)
        ParameterList openidResp = new ParameterList(request.getParameterMap());

        // retrieve the previously stored discovery information
        DiscoveryInformation discovered = (DiscoveryInformation) request.getSession().getAttribute(DISCOVERY_INFO_KEY);

        if (discovered == null) {
            throw new OpenIDConsumerException("DiscoveryInformation is not available. Possible causes are lost session or replay attack");
        }

        List<OpenIDAttribute> attributesToFetch = (List<OpenIDAttribute>) request.getSession().getAttribute(ATTRIBUTE_LIST_KEY);

        request.getSession().removeAttribute(DISCOVERY_INFO_KEY);
        request.getSession().removeAttribute(ATTRIBUTE_LIST_KEY);

        // extract the receiving URL from the HTTP request
        StringBuffer receivingURL = request.getRequestURL();
        String queryString = request.getQueryString();

        if (StringUtils.hasLength(queryString)) {
            receivingURL.append("?").append(request.getQueryString());
        }

        // verify the response
        VerificationResult verification;

        try {
            verification = consumerManager.verify(receivingURL.toString(), openidResp, discovered);
        } catch (MessageException e) {
            throw new OpenIDConsumerException("Error verifying openid response", e);
        } catch (DiscoveryException e) {
            throw new OpenIDConsumerException("Error verifying openid response", e);
        } catch (AssociationException e) {
            throw new OpenIDConsumerException("Error verifying openid response", e);
        }

        // examine the verification result and extract the verified identifier
        Identifier verified = verification.getVerifiedId();

        if (verified == null) {
            Identifier id = discovered.getClaimedIdentifier();
            return new OpenIDAuthenticationToken(OpenIDAuthenticationStatus.FAILURE,
                    id == null ? "Unknown" : id.getIdentifier(),
                    "Verification status message: [" + verification.getStatusMsg() + "]",
                    Collections.<OpenIDAttribute>emptyList());
        }

        List<OpenIDAttribute> attributes = fetchAxAttributes(verification.getAuthResponse(), attributesToFetch);

        return new OpenIDAuthenticationToken(OpenIDAuthenticationStatus.SUCCESS, verified.getIdentifier(),
                        "some message", attributes);
    }

    List<OpenIDAttribute> fetchAxAttributes(Message authSuccess, List<OpenIDAttribute> attributesToFetch)
            throws OpenIDConsumerException {

        if (attributesToFetch == null || !authSuccess.hasExtension(AxMessage.OPENID_NS_AX)) {
            return Collections.emptyList();
        }

        logger.debug("Extracting attributes retrieved by attribute exchange");

        List<OpenIDAttribute> attributes = Collections.emptyList();

        try {
            MessageExtension ext = authSuccess.getExtension(AxMessage.OPENID_NS_AX);
            if (ext instanceof FetchResponse) {
                FetchResponse fetchResp = (FetchResponse) ext;
                attributes = new ArrayList<OpenIDAttribute>(attributesToFetch.size());

                for (OpenIDAttribute attr : attributesToFetch) {
                    List<String> values = fetchResp.getAttributeValues(attr.getName());
                    if (!values.isEmpty()) {
                        OpenIDAttribute fetched = new OpenIDAttribute(attr.getName(), attr.getType(), values);
                        fetched.setRequired(attr.isRequired());
                        attributes.add(fetched);
                    }
                }
            }
        } catch (MessageException e) {
            throw new OpenIDConsumerException("Attribute retrieval failed", e);
        }

        if (logger.isDebugEnabled()) {
            logger.debug("Retrieved attributes" + attributes);
        }

        return attributes;
    }
}
