///
/// Copyright © 2016-2022 The Thingsboard Authors
///
/// 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.
///

import config from 'config';
import { _logger } from '../config/logger';
import { JsInvokeMessageProcessor } from '../api/jsInvokeMessageProcessor'
import { PubSub } from '@google-cloud/pubsub';
import { IQueue } from './queue.models';
import { Message } from '@google-cloud/pubsub/build/src/subscriber';

export class PubSubTemplate implements IQueue {

    private logger = _logger(`pubSubTemplate`);
    private projectId: string = config.get('pubsub.project_id');
    private credentials = JSON.parse(config.get('pubsub.service_account'));
    private requestTopic: string = config.get('request_topic');
    private queueProperties: string = config.get('pubsub.queue_properties');

    private pubSubClient: PubSub;
    private queueProps: { [n: string]: string } = {};
    private topics: string[] = [];
    private subscriptions: string[] = [];

    constructor() {
    }

    async init() {
        try {
            this.pubSubClient = new PubSub({
                projectId: this.projectId,
                credentials: this.credentials
            });

            this.parseQueueProperties();

            const topicList = await this.pubSubClient.getTopics();

            if (topicList) {
                topicList[0].forEach(topic => {
                    this.topics.push(PubSubTemplate.getName(topic.name));
                });
            }

            const subscriptionList = await this.pubSubClient.getSubscriptions();

            if (subscriptionList) {
                topicList[0].forEach(sub => {
                    this.subscriptions.push(PubSubTemplate.getName(sub.name));
                });
            }

            if (!(this.subscriptions.includes(this.requestTopic) && this.topics.includes(this.requestTopic))) {
                await this.createTopic(this.requestTopic);
                await this.createSubscription(this.requestTopic);
            }

            const subscription = this.pubSubClient.subscription(this.requestTopic);

            const messageProcessor = new JsInvokeMessageProcessor(this);

            const messageHandler = (message: Message) => {
                messageProcessor.onJsInvokeMessage(JSON.parse(message.data.toString('utf8')));
                message.ack();
            };

            subscription.on('message', messageHandler);

        } catch (e: any) {
            this.logger.error('Failed to start ThingsBoard JavaScript Executor Microservice: %s', e.message);
            this.logger.error(e.stack);
            await this.destroy(-1);
        }
    }

    async send(responseTopic: string, scriptId: string, rawResponse: Buffer, headers: any): Promise<any> {
        if (!(this.subscriptions.includes(responseTopic) && this.topics.includes(this.requestTopic))) {
            await this.createTopic(this.requestTopic);
            await this.createSubscription(this.requestTopic);
        }

        let data = JSON.stringify(
            {
                key: scriptId,
                data: [...rawResponse],
                headers: headers
            });
        let dataBuffer = Buffer.from(data);
        return this.pubSubClient.topic(responseTopic).publishMessage({data: dataBuffer});
    }

    private parseQueueProperties() {
        const props = this.queueProperties.split(';');
        props.forEach(p => {
            const delimiterPosition = p.indexOf(':');
            this.queueProps[p.substring(0, delimiterPosition)] = p.substring(delimiterPosition + 1);
        });
    }

    private static getName(fullName: string): string {
        const delimiterPosition = fullName.lastIndexOf('/');
        return fullName.substring(delimiterPosition + 1);
    }

    private async createTopic(topic: string) {
        if (!this.topics.includes(topic)) {
            try {
                await this.pubSubClient.createTopic(topic);
                this.logger.info('Created new Pub/Sub topic: %s', topic);
            } catch (e) {
                this.logger.info('Pub/Sub topic already exists');
            }
            this.topics.push(topic);
        }
    }

    private async createSubscription(topic: string) {
        if (!this.subscriptions.includes(topic)) {
            try {
                await this.pubSubClient.createSubscription(topic, topic, {
                    topic: topic,
                    name: topic,
                    ackDeadlineSeconds: Number(this.queueProps['ackDeadlineInSec']),
                    messageRetentionDuration: {
                        seconds: this.queueProps['messageRetentionInSec']
                    }
                });
                this.logger.info('Created new Pub/Sub subscription: %s', topic);
            } catch (e) {
                this.logger.info('Pub/Sub subscription already exists.');
            }

            this.subscriptions.push(topic);
        }
    }

    static async build(): Promise<PubSubTemplate> {
        const queue = new PubSubTemplate();
        await queue.init();
        return queue;
    }

    async destroy(status: number): Promise<void> {
        this.logger.info('Exiting with status: %d ...', status);
        this.logger.info('Stopping Pub/Sub resources...');
        if (this.pubSubClient) {
            this.logger.info('Stopping Pub/Sub client...');
            try {
                const _pubSubClient = this.pubSubClient;
                // @ts-ignore
                delete this.pubSubClient;
                await _pubSubClient.close();
                this.logger.info('Pub/Sub client stopped.');
            } catch (e) {
                this.logger.info('Pub/Sub client stop error.');
            }
        }
        this.logger.info('Pub/Sub resources stopped.');
        process.exit(status);
    }
}