/*
 * 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.karaf.jaas.modules.properties;

import java.security.Principal;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.felix.utils.properties.Properties;
import org.apache.karaf.jaas.boot.principal.GroupPrincipal;
import org.apache.karaf.jaas.boot.principal.RolePrincipal;
import org.apache.karaf.jaas.boot.principal.UserPrincipal;
import org.apache.karaf.jaas.modules.BackingEngine;
import org.apache.karaf.jaas.modules.encryption.EncryptionSupport;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class PropertiesBackingEngine implements BackingEngine {

    private static final transient Logger LOGGER = LoggerFactory.getLogger(PropertiesBackingEngine.class);

    private Properties users;
    private EncryptionSupport encryptionSupport;

    public PropertiesBackingEngine(Properties users) {
        this.users = users;
        this.encryptionSupport = EncryptionSupport.noEncryptionSupport();
    }

    public PropertiesBackingEngine(Properties users, EncryptionSupport encryptionSupport) {
        this.users = users;
        this.encryptionSupport = encryptionSupport;
    }

    @Override
    public void addUser(String username, String password) {
        if (username.startsWith(GROUP_PREFIX))
            throw new IllegalArgumentException("Prefix not permitted: " + GROUP_PREFIX);

        addUserInternal(username, password);
    }

    private void addUserInternal(String username, String password) {
        String[] infos = null;
        StringBuilder userInfoBuffer = new StringBuilder();

        String encPassword = encryptionSupport.encrypt(password);
        String userInfos = users.get(username);

        //If user already exists, update password
        if (userInfos != null && userInfos.length() > 0) {
            infos = userInfos.split(",");
            userInfoBuffer.append(encPassword);

            for (int i = 1; i < infos.length; i++) {
                userInfoBuffer.append(",");
                userInfoBuffer.append(infos[i]);
            }
            String newUserInfo = userInfoBuffer.toString();
            users.put(username, newUserInfo);
        } else {
            users.put(username, encPassword);
        }

        try {
            users.save();
        } catch (Exception ex) {
            LOGGER.error("Cannot update users file,", ex);
        }
    }

    @Override
    public void deleteUser(String username) {
        // delete all its groups first, for garbage collection of the groups
        for (GroupPrincipal gp : listGroups(username)) {
            deleteGroup(username, gp.getName());
        }

        users.remove(username);

        try {
            users.save();
        } catch (Exception ex) {
            LOGGER.error("Cannot remove users file,", ex);
        }
    }

    @Override
    public List<UserPrincipal> listUsers() {
        List<UserPrincipal> result = new ArrayList<>();

        for (Object user : users.keySet()) {
            String userName = (String) user;
            if (userName.startsWith(GROUP_PREFIX))
                continue;

            UserPrincipal userPrincipal = new UserPrincipal(userName);
            result.add(userPrincipal);
        }
        return result;
    }

    @Override
    public UserPrincipal lookupUser(String username) {
        for (UserPrincipal userPrincipal : listUsers()) {
            if (userPrincipal.getName().equals(username)) {
                return userPrincipal;
            }
        }
        return null;
    }

    @Override
    public List<RolePrincipal> listRoles(Principal principal) {
        String userName = principal.getName();
        if (principal instanceof  GroupPrincipal) {
            userName = GROUP_PREFIX + userName;
        }
        return listRoles(userName);
    }

    private List<RolePrincipal> listRoles(String name) {

        List<RolePrincipal> result = new ArrayList<>();
        String userInfo = users.get(name);
        String[] infos = userInfo.split(",");
        for (int i = 1; i < infos.length; i++) {
            String roleName = infos[i];
            if (roleName.startsWith(GROUP_PREFIX)) {
                for (RolePrincipal rp : listRoles(roleName)) {
                    if (!result.contains(rp)) {
                        result.add(rp);
                    }
                }
            } else {
                RolePrincipal rp = new RolePrincipal(roleName);
                if (!result.contains(rp)) {
                    result.add(rp);
                }
            }
        }
        return result;
    }

    @Override
    public void addRole(String username, String role) {
        String userInfos = users.get(username);
        if (userInfos != null) {
            for (RolePrincipal rp : listRoles(username)) {
                if (role.equals(rp.getName())) {
                    return; 
                }
            }
            for (GroupPrincipal gp : listGroups(username)) {
                if (role.equals(GROUP_PREFIX + gp.getName())) {
                    return; 
                }
            }
            String newUserInfos = userInfos + "," + role;
            users.put(username, newUserInfos);
        }
        try {
            users.save();
        } catch (Exception ex) {
            LOGGER.error("Cannot update users file,", ex);
        }
    }

    @Override
    public void deleteRole(String username, String role) {
        String[] infos = null;
        StringBuilder userInfoBuffer = new StringBuilder();

        String userInfos = users.get(username);

        //If user already exists, remove the role
        if (userInfos != null && userInfos.length() > 0) {
            infos = userInfos.split(",");
            String password = infos[0];
            userInfoBuffer.append(password);

            for (int i = 1; i < infos.length; i++) {
                if (infos[i] != null && !infos[i].equals(role)) {
                    userInfoBuffer.append(",");
                    userInfoBuffer.append(infos[i]);
                }
            }
            String newUserInfo = userInfoBuffer.toString();
            users.put(username, newUserInfo);
        }

        try {
            users.save();
        } catch (Exception ex) {
            LOGGER.error("Cannot update users file,", ex);
        }
    }

    @Override
    public List<GroupPrincipal> listGroups(UserPrincipal user) {
        String userName = user.getName();
        return listGroups(userName);
    }

    private List<GroupPrincipal> listGroups(String userName) {
        List<GroupPrincipal> result = new ArrayList<>();
        String userInfo = users.get(userName);
        if (userInfo != null) {
            String[] infos = userInfo.split(",");
            for (int i = 1; i < infos.length; i++) {
                String name = infos[i];
                if (name.startsWith(GROUP_PREFIX)) {
                    result.add(new GroupPrincipal(name.substring(GROUP_PREFIX.length())));
                }
            }
        }
        return result;
    }

    @Override
    public void addGroup(String username, String group) {
        String groupName = GROUP_PREFIX + group;
        if (users.get(groupName) == null) {
            addUserInternal(groupName, "group");
        }
        addRole(username, groupName);
    }

    @Override
    public void deleteGroup(String username, String group) {
        deleteRole(username, GROUP_PREFIX + group);

        // garbage collection, clean up the groups if needed
        for (UserPrincipal user : listUsers()) {
            for (GroupPrincipal g : listGroups(user)) {
                if (group.equals(g.getName())) {
                    // there is another user of this group, nothing to clean up
                    return;
                }
            }
        }

        // nobody is using this group any more, remove it
        deleteUser(GROUP_PREFIX + group);
    }

    @Override
    public void addGroupRole(String group, String role) {
        addRole(GROUP_PREFIX + group, role);
    }

    @Override
    public void deleteGroupRole(String group, String role) {
        deleteRole(GROUP_PREFIX + group, role);
    }

    public Map<GroupPrincipal, String> listGroups() {
        Map<GroupPrincipal, String> result = new HashMap<>();
        for (String name : users.keySet()) {
            if (name.startsWith(GROUP_PREFIX)) {
                result.put(new GroupPrincipal(name.substring(GROUP_PREFIX.length())), users.get(name));
            }
        }
        return result;
    }

    public void createGroup(String group) {
        String groupName = GROUP_PREFIX + group;
        if (users.get(groupName) == null) {
            addUserInternal(groupName, "group");
        } else {
            throw new IllegalArgumentException("Group: " + group + " already exist");
        }
    }

}
