/*
 ************************************************************************
 *******************  CANADIAN ASTRONOMY DATA CENTRE  *******************
 **************  CENTRE CANADIEN DE DONNÉES ASTRONOMIQUES  **************
 *
 *  (c) 2014.                            (c) 2014.
 *  Government of Canada                 Gouvernement du Canada
 *  National Research Council            Conseil national de recherches
 *  Ottawa, Canada, K1A 0R6              Ottawa, Canada, K1A 0R6
 *  All rights reserved                  Tous droits réservés
 *
 *  NRC disclaims any warranties,        Le CNRC dénie toute garantie
 *  expressed, implied, or               énoncée, implicite ou légale,
 *  statutory, of any kind with          de quelque nature que ce
 *  respect to the software,             soit, concernant le logiciel,
 *  including without limitation         y compris sans restriction
 *  any warranty of merchantability      toute garantie de valeur
 *  or fitness for a particular          marchande ou de pertinence
 *  purpose. NRC shall not be            pour un usage particulier.
 *  liable in any event for any          Le CNRC ne pourra en aucun cas
 *  damages, whether direct or           être tenu responsable de tout
 *  indirect, special or general,        dommage, direct ou indirect,
 *  consequential or incidental,         particulier ou général,
 *  arising from the use of the          accessoire ou fortuit, résultant
 *  software.  Neither the name          de l'utilisation du logiciel. Ni
 *  of the National Research             le nom du Conseil National de
 *  Council of Canada nor the            Recherches du Canada ni les noms
 *  names of its contributors may        de ses  participants ne peuvent
 *  be used to endorse or promote        être utilisés pour approuver ou
 *  products derived from this           promouvoir les produits dérivés
 *  software without specific prior      de ce logiciel sans autorisation
 *  written permission.                  préalable et particulière
 *                                       par écrit.
 *
 *  This file is part of the             Ce fichier fait partie du projet
 *  OpenCADC project.                    OpenCADC.
 *
 *  OpenCADC is free software:           OpenCADC est un logiciel libre ;
 *  you can redistribute it and/or       vous pouvez le redistribuer ou le
 *  modify it under the terms of         modifier suivant les termes de
 *  the GNU Affero General Public        la “GNU Affero General Public
 *  License as published by the          License” telle que publiée
 *  Free Software Foundation,            par la Free Software Foundation
 *  either version 3 of the              : soit la version 3 de cette
 *  License, or (at your option)         licence, soit (à votre gré)
 *  any later version.                   toute version ultérieure.
 *
 *  OpenCADC is distributed in the       OpenCADC est distribué
 *  hope that it will be useful,         dans l’espoir qu’il vous
 *  but WITHOUT ANY WARRANTY;            sera utile, mais SANS AUCUNE
 *  without even the implied             GARANTIE : sans même la garantie
 *  warranty of MERCHANTABILITY          implicite de COMMERCIALISABILITÉ
 *  or FITNESS FOR A PARTICULAR          ni d’ADÉQUATION À UN OBJECTIF
 *  PURPOSE.  See the GNU Affero         PARTICULIER. Consultez la Licence
 *  General Public License for           Générale Publique GNU Affero
 *  more details.                        pour plus de détails.
 *
 *  You should have received             Vous devriez avoir reçu une
 *  a copy of the GNU Affero             copie de la Licence Générale
 *  General Public License along         Publique GNU Affero avec
 *  with OpenCADC.  If not, see          OpenCADC ; si ce n’est
 *  <http://www.gnu.org/licenses/>.      pas le cas, consultez :
 *                                       <http://www.gnu.org/licenses/>.
 *
 *  $Revision: 4 $
 *
 ************************************************************************
 */
package ca.nrc.cadc.ac.client;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.security.AccessControlException;
import java.security.Principal;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;

import javax.security.auth.Subject;
import javax.security.auth.x500.X500Principal;

import ca.nrc.cadc.reg.Standards;
import ca.nrc.cadc.reg.client.LocalAuthority;
import org.apache.log4j.Logger;

import ca.nrc.cadc.ac.ReaderException;
import ca.nrc.cadc.ac.User;
import ca.nrc.cadc.ac.UserAlreadyExistsException;
import ca.nrc.cadc.ac.UserNotFoundException;
import ca.nrc.cadc.ac.WriterException;
import ca.nrc.cadc.ac.xml.UserReader;
import ca.nrc.cadc.ac.xml.UserWriter;
import ca.nrc.cadc.auth.AuthMethod;
import ca.nrc.cadc.auth.AuthenticationUtil;
import ca.nrc.cadc.auth.NumericPrincipal;
import ca.nrc.cadc.net.HttpDownload;
import ca.nrc.cadc.net.HttpUpload;
import ca.nrc.cadc.net.NetUtil;
import ca.nrc.cadc.reg.client.RegistryClient;


/**
 * Client class for performing user searching and user actions
 * with the access control web service.
 */
public class UserClient
{
    private static final Logger log = Logger.getLogger(UserClient.class);

    private URI serviceID;

    /**
     * Constructor.
     *
     * @param serviceID    The URI of the supporting access control web service
     *                      obtained from the registry.
     */
    public UserClient(URI serviceID)
            throws IllegalArgumentException
    {
        if (serviceID == null)
            throw new IllegalArgumentException("Service URI cannot be null.");
        if (serviceID.getFragment() != null)
            throw new IllegalArgumentException("invalid serviceURI (fragment not allowed): " + serviceID);
        this.serviceID = serviceID;
    }

    /**
     * This method takes a subject with at least one valid principal,
     * uses the ac user web service to get all the other
     * associated principals which are then added to the subject.
     *
     * @param subject           The Subject to pull Princials for.
     * @throws MalformedURLException
     */
    public void augmentSubject(Subject subject) throws MalformedURLException
    {
    	Principal principal = this.getPrincipal(subject);
    	if (principal != null)
    	{

	        String userID = principal.getName();
	        String path = "/" + NetUtil.encode(userID) + "?idType=" + this.getIdType(principal) + "&detail=identity";

	        // augment subject calls are always https with client certs
            URL usersURL = getRegistryClient()
                .getServiceURL(this.serviceID, Standards.UMS_USERS_01, AuthMethod.CERT);
            URL getUserURL = new URL(usersURL.toExternalForm() + path);

	        if (getUserURL == null)
	            throw new IllegalArgumentException("No service endpoint for uri " + Standards.UMS_USERS_01);

	    	log.debug("augmentSubject request to " + getUserURL.toString());
	        ByteArrayOutputStream out = new ByteArrayOutputStream();
	        HttpDownload download = new HttpDownload(getUserURL, out);
	        download.run();

	        int responseCode = download.getResponseCode();
	        if (responseCode == 404) // not found
	        {
	            return;
	        }
	        if (responseCode != 200)
	        {
	            String message = "Error calling /ac to augment subject";
	            if (download.getThrowable() != null)
	            {
	                throw new IllegalStateException(message, download.getThrowable());
	            }
	            throw new IllegalStateException(message);
	        }

	        subject.getPrincipals().clear();
	        subject.getPrincipals().addAll(this.getPrincipals(out));
    	}
    }

    /**
     * Obtain all of the users as userID - name in JSON format.
     *
     * @return List of HTTP Principal users.
     * @throws IOException Any errors in reading.
     */
    public List<User> getDisplayUsers() throws IOException
    {
        URL usersURL = getRegistryClient()
            .getServiceURL(this.serviceID, Standards.UMS_USERS_01, AuthMethod.CERT);
        final List<User> webUsers = new ArrayList<User>();
        HttpDownload httpDownload =
                new HttpDownload(usersURL,
                                 new JsonUserListInputStreamWrapper(webUsers));
        httpDownload.setRequestProperty("Accept", "application/json");
        httpDownload.run();

        final Throwable error = httpDownload.getThrowable();

        if (error != null)
        {
            final String errMessage = error.getMessage();
            final int responseCode = httpDownload.getResponseCode();
            log.debug("getDisplayUsers response " + responseCode + ": "
                      + errMessage);
            if ((responseCode == 401) || (responseCode == 403)
                || (responseCode == -1))
            {
                throw new AccessControlException(errMessage);
            }
            else if (responseCode == 400)
            {
                throw new IllegalArgumentException(errMessage);
            }
            else
            {
                throw new IOException("HttpResponse (" + responseCode + ") - "
                                      + errMessage);
            }
        }

        log.debug("Content-Length: " + httpDownload.getContentLength());
        log.debug("Content-Type: " + httpDownload.getContentType());

        return webUsers;
    }

    /**
     * Create an auto-approved user directly in the user tree (not
     * the userRequest tree) from the principal.
     *
     * @param principal Their x500 Principal
     * @throws UserAlreadyExistsException
     * @throws WriterException
     * @throws IOException
     * @throws URISyntaxException
     * @throws ReaderException
     */
    public User createUser(Principal principal)
            throws UserAlreadyExistsException, IOException, WriterException,
                   ReaderException, URISyntaxException
    {
        if (principal == null)
        {
            throw new IllegalArgumentException("principal required");
        }

        User user = new User();
        user.getIdentities().add(principal);
        UserWriter userWriter = new UserWriter();
        StringBuilder userXML = new StringBuilder();
        userWriter.write(user, userXML);

        URL createUserURL = getRegistryClient()
            .getServiceURL(this.serviceID, Standards.UMS_USERS_01, AuthMethod.CERT);

        if (createUserURL == null)
            throw new IllegalArgumentException("No service endpoint for uri " + Standards.UMS_REQS_01);
        log.debug("createUser request to " + createUserURL.toString());

        ByteArrayInputStream in = new ByteArrayInputStream(userXML.toString().getBytes());
        HttpUpload put = new HttpUpload(in, createUserURL);

        put.run();
        int responseCode = put.getResponseCode();

        if (responseCode == 200 || responseCode == 201)
        {
            try
            {
                return getUser(principal);
            }
            catch (UserNotFoundException e)
            {
                log.error("user created but not found",  e);
                // should not happen
                throw new IllegalStateException("user created but not found", e);
            }
        }

        String message = "";
        if (put.getThrowable() != null)
        {
            log.debug("error calling createX509User", put.getThrowable());
            message = put.getThrowable().getMessage();
        }

        if (responseCode == 400)
        {
            throw new IllegalArgumentException(message);
        }
        if (responseCode == 409) // conflict
        {
            throw new UserAlreadyExistsException(message);
        }
        if (responseCode == 403)
        {
            throw new AccessControlException(message);
        }
        throw new IllegalStateException(message);
    }

    /**
     * Given a pricipal return the user object.
     *
     * @param principal The principal to lookup.
     * @throws URISyntaxException
     * @throws IOException
     * @throws ReaderException
     * @throws UserNotFoundException
     */
    public User getUser(Principal principal)
            throws ReaderException, IOException, URISyntaxException, UserNotFoundException
    {
        String id = NetUtil.encode(principal.getName());
        String path = "/" + id + "?idType=" + AuthenticationUtil.getPrincipalType(principal);

        URL usersURL = getRegistryClient()
            .getServiceURL(this.serviceID, Standards.UMS_USERS_01, AuthMethod.CERT);
        URL getUserURL = new URL(usersURL.toExternalForm() + path);
        if (getUserURL == null)
            throw new IllegalArgumentException("No service endpoint for uri " + Standards.UMS_USERS_01);
        log.debug("getUser request to " + getUserURL.toString());

        ByteArrayOutputStream out = new ByteArrayOutputStream();
        HttpDownload get = new HttpDownload(getUserURL, out);

        get.run();
        int responseCode = get.getResponseCode();

        if (responseCode == 200)
        {
            UserReader userReader = new UserReader();
            return userReader.read(out.toString());
        }

        String message = "";
        if (get.getThrowable() != null)
        {
            log.debug("error calling get user", get.getThrowable());
            message = get.getThrowable().getMessage();
        }

        if (responseCode == 400)
        {
            throw new IllegalArgumentException(message);
        }
        if (responseCode == 404)
        {
            throw new UserNotFoundException(message);
        }
        if (responseCode == 403)
        {
            throw new AccessControlException(message);
        }
        throw new IllegalStateException(message);
    }

    protected Principal getPrincipal(final Subject subject)
    {
        if (subject == null || subject.getPrincipals() == null || subject.getPrincipals().isEmpty())
        {
            return null;
        }

        if (subject.getPrincipals().size() == 1)
        {
            return subject.getPrincipals().iterator().next();
        }

        // in the case that there is more than one principal in the
        // subject, favor x500 principals then numeric principals
        Set<X500Principal> x500Principals = subject.getPrincipals(X500Principal.class);
        if (x500Principals.size() > 0)
        {
            return x500Principals.iterator().next();
        }

        Set<NumericPrincipal> numericPrincipals = subject.getPrincipals(NumericPrincipal.class);
        if (numericPrincipals.size() > 0)
        {
            return numericPrincipals.iterator().next();
        }

        // just return the first one
        return subject.getPrincipals().iterator().next();
    }

    protected Set<Principal> getPrincipals(ByteArrayOutputStream out)
    {
    	try
    	{
	        String userXML = new String(out.toByteArray(), "UTF-8");
	        log.debug("userXML Input to getPrincipals(): " + userXML);

	        User user = new UserReader().read(userXML);
	        return user.getIdentities();
    	}
    	catch (Exception e)
    	{
    		throw new RuntimeException(e);
    	}
    }

    protected String getIdType(Principal principal)
    {
		String idTypeStr = AuthenticationUtil.getPrincipalType(principal);
        if (idTypeStr == null)
        {
    		final String msg = "Subject has unsupported principal " +
    				principal.getName();
	        throw new IllegalArgumentException(msg);
        }

        return idTypeStr;
    }

    protected RegistryClient getRegistryClient()
    {
        return new RegistryClient();
    }

}