/**
 * 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.activemq.jaas;

import java.io.File;
import java.io.IOException;
import java.security.Principal;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import javax.security.auth.Subject;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.UnsupportedCallbackException;
import javax.security.auth.login.FailedLoginException;
import javax.security.auth.login.LoginException;
import javax.security.auth.spi.LoginModule;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class PropertiesLoginModule implements LoginModule {

    private static final String USER_FILE = "org.apache.activemq.jaas.properties.user";
    private static final String GROUP_FILE = "org.apache.activemq.jaas.properties.group";

    private static final Logger LOG = LoggerFactory.getLogger(PropertiesLoginModule.class);

    private Subject subject;
    private CallbackHandler callbackHandler;

    private boolean debug;
    private boolean reload = false;
    private static volatile PrincipalProperties users;
    private static volatile PrincipalProperties groups;
    private String user;
    private final Set<Principal> principals = new HashSet<Principal>();
    private File baseDir;
    private boolean loginSucceeded;
    private boolean decrypt = true;

    @Override
    public void initialize(Subject subject, CallbackHandler callbackHandler, Map sharedState, Map options) {
        this.subject = subject;
        this.callbackHandler = callbackHandler;
        loginSucceeded = false;

        debug = "true".equalsIgnoreCase((String) options.get("debug"));
        if (options.get("reload") != null) {
            reload = "true".equalsIgnoreCase((String) options.get("reload"));
        }

        if (options.get("baseDir") != null) {
            baseDir = new File((String) options.get("baseDir"));
        }

        setBaseDir();
        String usersFile = (String) options.get(USER_FILE) + "";
        File uf = baseDir != null ? new File(baseDir, usersFile) : new File(usersFile);

        if (reload || users == null || uf.lastModified() > users.getReloadTime()) {
            if (debug) {
                LOG.debug("Reloading users from " + uf.getAbsolutePath());
            }
            users = new PrincipalProperties("user", uf, LOG);
            if( decrypt ) {
                try {
                    EncryptionSupport.decrypt(users.getPrincipals());
                } catch(NoClassDefFoundError e) {
                    // this Happens whe jasypt is not on the classpath..
                    decrypt = false;
                    LOG.info("jasypt is not on the classpath: password decryption disabled.");
                }
            }
        }

        String groupsFile = (String) options.get(GROUP_FILE) + "";
        File gf = baseDir != null ? new File(baseDir, groupsFile) : new File(groupsFile);
        if (reload || groups == null || gf.lastModified() > groups.getReloadTime()) {
            if (debug) {
                LOG.debug("Reloading groups from " + gf.getAbsolutePath());
            }
            groups = new PrincipalProperties("group", gf, LOG);
        }
    }

    private void setBaseDir() {
        if (baseDir == null) {
            if (System.getProperty("java.security.auth.login.config") != null) {
                baseDir = new File(System.getProperty("java.security.auth.login.config")).getParentFile();
                if (debug) {
                    LOG.debug("Using basedir=" + baseDir.getAbsolutePath());
                }
            }
        }
    }

    @Override
    public boolean login() throws LoginException {
        Callback[] callbacks = new Callback[2];

        callbacks[0] = new NameCallback("Username: ");
        callbacks[1] = new PasswordCallback("Password: ", false);
        try {
            callbackHandler.handle(callbacks);
        } catch (IOException ioe) {
            throw new LoginException(ioe.getMessage());
        } catch (UnsupportedCallbackException uce) {
            throw new LoginException(uce.getMessage() + " not available to obtain information from user");
        }
        user = ((NameCallback) callbacks[0]).getName();
        char[] tmpPassword = ((PasswordCallback) callbacks[1]).getPassword();
        if (tmpPassword == null) {
            tmpPassword = new char[0];
        }
        if (user == null) {
            throw new FailedLoginException("user name is null");
        }
        String password = users.getProperty(user);

        if (password == null) {
            throw new FailedLoginException("User does exist");
        }
        if (!password.equals(new String(tmpPassword))) {
            throw new FailedLoginException("Password does not match");
        }
        loginSucceeded = true;

        if (debug) {
            LOG.debug("login " + user);
        }
        return loginSucceeded;
    }

    @Override
    public boolean commit() throws LoginException {
        boolean result = loginSucceeded;
        if (result) {
            principals.add(new UserPrincipal(user));

            for (Map.Entry<String, String> entry : groups.entries()) {
                String name = entry.getKey();
                String[] userList = entry.getValue().split(",");
                for (int i = 0; i < userList.length; i++) {
                    if (user.equals(userList[i])) {
                        principals.add(new GroupPrincipal(name));
                        break;
                    }
                }
            }

            subject.getPrincipals().addAll(principals);
        }

        // will whack loginSucceeded
        clear();

        if (debug) {
            LOG.debug("commit, result: " + result);
        }
        return result;
    }

    @Override
    public boolean abort() throws LoginException {
        clear();

        if (debug) {
            LOG.debug("abort");
        }
        return true;
    }

    @Override
    public boolean logout() throws LoginException {
        subject.getPrincipals().removeAll(principals);
        principals.clear();
        clear();
        if (debug) {
            LOG.debug("logout");
        }
        return true;
    }

    private void clear() {
        user = null;
        loginSucceeded = false;
    }

    /**
     * For test-usage only.
     */
    static void resetUsersAndGroupsCache() {
        users = null;
        groups = null;
    }
}