/*
 * 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 com.epam.datalab.backendapi.service.impl;

import com.epam.datalab.auth.UserInfo;
import com.epam.datalab.backendapi.annotation.Project;
import com.epam.datalab.backendapi.annotation.ProjectAdmin;
import com.epam.datalab.backendapi.annotation.User;
import com.epam.datalab.backendapi.dao.EnvDAO;
import com.epam.datalab.backendapi.dao.ExploratoryDAO;
import com.epam.datalab.backendapi.dao.UserSettingsDAO;
import com.epam.datalab.backendapi.domain.ProjectDTO;
import com.epam.datalab.backendapi.resources.dto.UserDTO;
import com.epam.datalab.backendapi.resources.dto.UserResourceInfo;
import com.epam.datalab.backendapi.service.ComputationalService;
import com.epam.datalab.backendapi.service.EnvironmentService;
import com.epam.datalab.backendapi.service.ExploratoryService;
import com.epam.datalab.backendapi.service.ProjectService;
import com.epam.datalab.backendapi.service.SecurityService;
import com.epam.datalab.dto.UserInstanceDTO;
import com.epam.datalab.dto.UserInstanceStatus;
import com.epam.datalab.dto.status.EnvResource;
import com.epam.datalab.dto.status.EnvResourceList;
import com.epam.datalab.exceptions.ResourceConflictException;
import com.epam.datalab.model.ResourceEnum;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import lombok.extern.slf4j.Slf4j;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Stream;

import static com.epam.datalab.backendapi.resources.dto.UserDTO.Status.ACTIVE;
import static com.epam.datalab.backendapi.resources.dto.UserDTO.Status.NOT_ACTIVE;
import static com.epam.datalab.dto.UserInstanceStatus.CREATING;
import static com.epam.datalab.dto.UserInstanceStatus.CREATING_IMAGE;
import static com.epam.datalab.dto.UserInstanceStatus.RUNNING;
import static com.epam.datalab.dto.UserInstanceStatus.STARTING;
import static com.epam.datalab.rest.contracts.ComputationalAPI.AUDIT_MESSAGE;
import static java.util.stream.Collectors.toList;

@Singleton
@Slf4j
public class EnvironmentServiceImpl implements EnvironmentService {
    private static final String ERROR_MSG_FORMAT = "Can not %s environment because on of user resource is in status CREATING or STARTING";
    private static final String AUDIT_QUOTA_MESSAGE = "Billing quota reached";
    private static final String AUDIT_UPDATE_STATUS = "Sync up with console status";
    private static final String DATALAB_SYSTEM_USER = "DataLab system user";

    private final EnvDAO envDAO;
    private final UserSettingsDAO settingsDAO;
    private final ExploratoryDAO exploratoryDAO;
    private final ExploratoryService exploratoryService;
    private final ComputationalService computationalService;
    private final SecurityService securityService;
    private final ProjectService projectService;

    @Inject
    public EnvironmentServiceImpl(EnvDAO envDAO, UserSettingsDAO settingsDAO, ExploratoryDAO exploratoryDAO,
                                  ExploratoryService exploratoryService, ComputationalService computationalService,
                                  SecurityService securityService, ProjectService projectService) {
        this.envDAO = envDAO;
        this.settingsDAO = settingsDAO;
        this.exploratoryDAO = exploratoryDAO;
        this.exploratoryService = exploratoryService;
        this.computationalService = computationalService;
        this.securityService = securityService;
        this.projectService = projectService;
    }

    @Override
    public List<UserDTO> getUsers() {
        final Set<String> activeUsers = envDAO.fetchActiveEnvUsers();
        log.trace("Active users: {}", activeUsers);
        final Set<String> notActiveUsers = envDAO.fetchUsersNotIn(activeUsers);
        log.trace("Not active users: {}", notActiveUsers);
        final Stream<UserDTO> activeUsersStream = activeUsers
                .stream()
                .map(u -> toUserDTO(u, ACTIVE));
        final Stream<UserDTO> notActiveUsersStream = notActiveUsers
                .stream()
                .map(u -> toUserDTO(u, NOT_ACTIVE));
        return Stream.concat(activeUsersStream, notActiveUsersStream)
                .collect(toList());
    }

    @Override
    public List<UserResourceInfo> getAllEnv(UserInfo user) {
        log.debug("Getting all user's environment...");
        List<UserInstanceDTO> expList = exploratoryDAO.getInstances();
        return projectService.getProjects(user)
                .stream()
                .map(projectDTO -> getProjectEnv(projectDTO, expList))
                .flatMap(Collection::stream)
                .collect(toList());
    }

    @Override
    public void stopAll() {
        log.debug("Stopping environment for all users...");
        projectService.getProjects()
                .stream()
                .map(ProjectDTO::getName)
                .forEach(this::stopProjectEnvironment);
    }

    @Override
    public void stopEnvironmentWithServiceAccount(String user) {
        log.debug("Stopping environment for user {} by scheduler", user);
        checkState(user, "stop");
        exploratoryDAO.fetchRunningExploratoryFields(user)
                .forEach(this::stopNotebookWithServiceAccount);
    }

    @Override
    public void stopProjectEnvironment(String project) {
        log.debug("Stopping environment for project {}", project);
        checkProjectResourceConditions(project, "stop");
        exploratoryDAO.fetchRunningExploratoryFieldsForProject(project)
                .forEach(this::stopNotebookWithServiceAccount);

        projectService.get(project).getEndpoints()
                .stream()
                .filter(e -> RUNNING == e.getStatus())
                .forEach(endpoint -> projectService.stop(securityService.getServiceAccountInfo(DATALAB_SYSTEM_USER),
                        endpoint.getName(), project, AUDIT_QUOTA_MESSAGE));
    }

    @ProjectAdmin
    @Override
    public void stopExploratory(@User UserInfo userInfo, String user, @Project String project, String exploratoryName) {
        exploratoryService.stop(userInfo, user, project, exploratoryName, null);
    }

    @ProjectAdmin
    @Override
    public void stopComputational(@User UserInfo userInfo, String user, @Project String project, String exploratoryName, String computationalName) {
        computationalService.stopSparkCluster(userInfo, user, project, exploratoryName, computationalName,
                String.format(AUDIT_MESSAGE, exploratoryName));
    }

    @ProjectAdmin
    @Override
    public void terminateExploratory(@User UserInfo userInfo, String user, @Project String project, String exploratoryName) {
        exploratoryService.terminate(userInfo, user, project, exploratoryName, null);
    }

    @ProjectAdmin
    @Override
    public void terminateComputational(@User UserInfo userInfo, String user, @Project String project, String exploratoryName, String computationalName) {
        computationalService.terminateComputational(userInfo, user, project, exploratoryName, computationalName, String.format(AUDIT_MESSAGE, exploratoryName));
    }

    @Override
    public void updateEnvironmentStatuses(EnvResourceList resourceList) {
        resourceList.getHostList()
                .forEach(this::updateHostStatuses);
    }

    private void updateHostStatuses(EnvResource envResource) {
        final UserInstanceStatus status = UserInstanceStatus.of(envResource.getStatus());
        if (Objects.nonNull(status)) {
            UserInfo systemUser = new UserInfo(DATALAB_SYSTEM_USER, null);
            final String endpoint = envResource.getEndpoint();
            final String instanceID = envResource.getId();
            final String name = envResource.getName();
            final String project = envResource.getProject();

            switch (envResource.getResourceType()) {
                case EDGE:
                    projectService.updateAfterStatusCheck(systemUser, project, endpoint, instanceID, status, AUDIT_UPDATE_STATUS);
                    break;
                case EXPLORATORY:
                    exploratoryService.updateAfterStatusCheck(systemUser, project, endpoint, name, instanceID, status, AUDIT_UPDATE_STATUS);
                    break;
                case COMPUTATIONAL:
                    computationalService.updateAfterStatusCheck(systemUser, project, endpoint, name, instanceID, status, AUDIT_UPDATE_STATUS);
                    break;
                default:
                    log.warn("Resource {} has unknown resource type {}", envResource, envResource.getResourceType());
            }
        } else {
            log.warn("Resource {} has unknown status {}", envResource, envResource.getStatus());
        }
    }

    private UserDTO toUserDTO(String u, UserDTO.Status status) {
        return new UserDTO(u, settingsDAO.getAllowedBudget(u).orElse(null), status);
    }

    private void checkState(String user, String action) {
        final List<UserInstanceDTO> userInstances = exploratoryDAO.fetchUserExploratoriesWhereStatusIn(user, Arrays.asList(CREATING, STARTING, CREATING_IMAGE),
                CREATING, STARTING, CREATING_IMAGE);
        if (!userInstances.isEmpty()) {
            log.error(String.format(ERROR_MSG_FORMAT, action));
            throw new ResourceConflictException(String.format(ERROR_MSG_FORMAT, action));
        }
    }

    private void stopNotebookWithServiceAccount(UserInstanceDTO instance) {
        final UserInfo userInfo = securityService.getServiceAccountInfo(DATALAB_SYSTEM_USER);
        exploratoryService.stop(userInfo, instance.getUser(), instance.getProject(), instance.getExploratoryName(), AUDIT_QUOTA_MESSAGE);
    }

    private List<UserResourceInfo> getProjectEnv(ProjectDTO projectDTO, List<UserInstanceDTO> allInstances) {
        final Stream<UserResourceInfo> userResources = allInstances
                .stream()
                .filter(instance -> instance.getProject().equals(projectDTO.getName()))
                .map(this::toUserResourceInfo);
        if (projectDTO.getEndpoints() != null) {
            final Stream<UserResourceInfo> edges = projectDTO.getEndpoints()
                    .stream()
                    .map(e -> UserResourceInfo.builder()
                            .resourceType(ResourceEnum.EDGE_NODE)
                            .resourceStatus(e.getStatus().toString())
                            .project(projectDTO.getName())
                            .endpoint(e.getName())
                            .ip(e.getEdgeInfo() != null ? e.getEdgeInfo().getPublicIp() : null)
                            .build());
            return Stream.concat(edges, userResources).collect(toList());
        } else {
            return userResources.collect(toList());
        }
    }

    private UserResourceInfo toUserResourceInfo(UserInstanceDTO userInstance) {
        return UserResourceInfo.builder()
                .resourceType(ResourceEnum.NOTEBOOK)
                .resourceName(userInstance.getExploratoryName())
                .resourceShape(userInstance.getShape())
                .resourceStatus(userInstance.getStatus())
                .computationalResources(userInstance.getResources())
                .user(userInstance.getUser())
                .project(userInstance.getProject())
                .endpoint(userInstance.getEndpoint())
                .cloudProvider(userInstance.getCloudProvider())
                .exploratoryUrls(userInstance.getResourceUrl())
                .build();
    }

    private void checkProjectResourceConditions(String project, String action) {
        final List<UserInstanceDTO> userInstances = exploratoryDAO.fetchProjectExploratoriesWhereStatusIn(project,
                Arrays.asList(CREATING, STARTING, CREATING_IMAGE), CREATING, STARTING, CREATING_IMAGE);

        if (!userInstances.isEmpty()) {
            log.error(String.format(ERROR_MSG_FORMAT, action));
            throw new ResourceConflictException(String.format(ERROR_MSG_FORMAT, action));
        }
    }
}