/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
 * Copyright © 2017-2018 Amdocs
 * ================================================================================
 * 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.
 * ============LICENSE_END=========================================================
 */
package org.onap.aai.sa.auth;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Timer;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import org.onap.aai.cl.api.Logger;
import org.onap.aai.cl.eelf.LoggerFactory;
import org.onap.aai.sa.searchdbabstraction.util.SearchDbConstants;

public class SearchDbServiceAuthCore {

    private static Logger logger = LoggerFactory.getInstance().getLogger(SearchDbServiceAuthCore.class.getName());

    private static String authFileName = SearchDbConstants.SDB_AUTH_CONFIG_FILENAME;

    private enum HTTP_METHODS {
        POST,
        GET,
        PUT,
        DELETE
    }

    private static boolean usersInitialized = false;
    private static HashMap<String, SearchDbAuthUser> users;
    private static Timer timer = null;

    // Don't instantiate
    private SearchDbServiceAuthCore() {}

    public static synchronized void init() {
        if (SearchDbServiceAuthCore.authFileName == null) {
            SearchDbServiceAuthCore.authFileName = "/home/aaiadmin/etc/aaipolicy.json";
        }
        SearchDbServiceAuthCore.reloadUsers();
    }

    public static void cleanup() {
        timer.cancel();
    }

    public static synchronized void reloadUsers() {
        users = new HashMap<>();
        ObjectMapper mapper = new ObjectMapper(); // can reuse, share globally
        JSONParser parser = new JSONParser();
        try {
            parser.parse(new FileReader(authFileName));
            JsonNode rootNode = mapper.readTree(new File(authFileName));
            JsonNode rolesNode = rootNode.path("roles");

            for (JsonNode roleNode : rolesNode) {
                String roleName = roleNode.path("name").asText();

                TabularAuthRole authRole = new TabularAuthRole();
                JsonNode usersNode = roleNode.path("users");
                JsonNode functionsNode = roleNode.path("functions");
                for (JsonNode functionNode : functionsNode) {
                    String function = functionNode.path("name").asText();
                    JsonNode methodsNode = functionNode.path("methods");
                    boolean hasMethods = false;
                    for (JsonNode methodNode : methodsNode) {
                        String methodName = methodNode.path("name").asText();
                        hasMethods = true;
                        String thisFunction = methodName + ":" + function;

                        authRole.addAllowedFunction(thisFunction);
                    }

                    if (!hasMethods) {
                        // iterate the list from HTTP_METHODS
                        for (HTTP_METHODS meth : HTTP_METHODS.values()) {
                            String thisFunction = meth.toString() + ":" + function;
                            authRole.addAllowedFunction(thisFunction);
                        }
                    }

                }
                for (JsonNode userNode : usersNode) {
                    String username = userNode.path("username").asText().toLowerCase();
                    SearchDbAuthUser authUser = null;
                    if (users.containsKey(username)) {
                        authUser = users.get(username);
                    } else {
                        authUser = new SearchDbAuthUser();
                    }

                    authUser.setUser(username);
                    authUser.addRole(roleName, authRole);
                    users.put(username, authUser);
                }
            }
        } catch (FileNotFoundException fnfe) {
            logger.debug("Failed to load the policy file ");

        } catch (ParseException e) {
            logger.debug("Failed to Parse the policy file ");

        } catch (JsonProcessingException e) {
            logger.debug("JSON processing error while parsing policy file: " + e.getMessage());

        } catch (IOException e) {
            logger.debug("IO Exception while parsing policy file: " + e.getMessage());
        }

        usersInitialized = true;
    }

    public static class SearchDbAuthUser {
        public SearchDbAuthUser() {
            this.roles = new HashMap<>();
        }

        private String username;
        private HashMap<String, TabularAuthRole> roles;

        public String getUser() {
            return this.username;
        }

        public Map<String, TabularAuthRole> getRoles() {
            return this.roles;
        }

        public void addRole(String roleName, TabularAuthRole authRole) {
            this.roles.put(roleName, authRole);
        }

        public boolean checkAllowed(String checkFunc) {
            for (Map.Entry<String, TabularAuthRole> roleEntry : this.roles.entrySet()) {
                TabularAuthRole role = roleEntry.getValue();
                if (role.hasAllowedFunction(checkFunc)) {
                    return true;
                }
            }
            return false;
        }

        public void setUser(String myuser) {
            this.username = myuser;
        }
    }

    public static class TabularAuthRole {
        public TabularAuthRole() {
            this.allowedFunctions = new ArrayList<>();
        }

        private List<String> allowedFunctions;

        public void addAllowedFunction(String func) {
            this.allowedFunctions.add(func);
        }

        public void delAllowedFunction(String delFunc) {
            if (this.allowedFunctions.contains(delFunc)) {
                this.allowedFunctions.remove(delFunc);
            }
        }

        public boolean hasAllowedFunction(String afunc) {
            return this.allowedFunctions.contains(afunc);
        }
    }

    public static Map<String, SearchDbAuthUser> getUsers() {
        if (!usersInitialized || (users == null)) {
            reloadUsers();
        }
        return users;
    }

    public static boolean authorize(String username, String authFunction) {
        if (!usersInitialized || (users == null)) {
            init();
        }
        if (users.containsKey(username)) {
            return users.get(username).checkAllowed(authFunction);
        } else {
            return false;
        }
    }
}