// host-services.js
// Copyright (C) 2024 DTP Technologies, LLC
// All Rights Reserved

'use strict';

import 'dotenv/config';

import path, { dirname } from 'path';
import fs from 'node:fs';
import readline from 'node:readline';

import { SiteRuntime } from '../../lib/site-lib.js';

import { CronJob } from 'cron';
const CRON_TIMEZONE = 'America/New_York';

import { Readable, pipeline } from 'node:stream';
import { promisify } from 'node:util';
const streamPipeline = promisify(pipeline);

class ChatLinksService extends SiteRuntime {

  static get name ( ) { return 'ChatLinksWorker'; }
  static get slug ( ) { return 'chatLinks'; }

  static get BLOCKLIST_URL ( ) { return 'https://raw.githubusercontent.com/StevenBlack/hosts/master/alternates/porn/hosts'; }

  constructor (rootPath) {
    super(ChatLinksService, rootPath);
  }

  async start ( ) {
    await super.start();

    const mongoose = await import('mongoose');
    this.Link = mongoose.model('Link');

    this.viewModel = { };
    await this.populateViewModel(this.viewModel);

    this.blacklist = {
      porn: path.join(this.config.root, 'data', 'blacklist', 'porn'),
    };

    /*
     * Bull Queue job processors
     */

    this.log.info('registering link-ingest job processor', { config: this.config.jobQueues.links });
    this.linksProcessingQueue = this.services.jobQueue.getJobQueue('links', this.config.jobQueues.links);
    this.linksProcessingQueue.process('link-ingest', 1, this.ingestLink.bind(this));

    /*
     * Cron jobs
     */

    const cronBlacklistUpdate = '0 0 3 * * *'; // Ever day at 3:00 a.m.
    this.log.info('created URL blacklist update cron', { cronBlacklistUpdate });
    this.updateBlacklistJob = new CronJob(
      cronBlacklistUpdate,
      this.updateUrlBlacklist.bind(this),
      null,
      true,
      CRON_TIMEZONE,
    );
  }

  async shutdown ( ) {
    this.log.alert('ChatLinksWorker shutting down');
    await super.shutdown();
  }

  async ingestLink (job) {
    const { link: linkService, user: userService } = this.services;
    this.log.info('received link ingest job', { data: job.data });
  
    try {
      if (!job.data.submitterId) {
        this.log.error('link ingest submitted without submitterId');
        return;
      }
  
      job.data.submitter = await userService.getUserAccount(job.data.submitterId);
      if (!job.data.submitter) {
        this.log.error('link submitted with invalid User', { submitterId: job.data.submitterId });
        return;
      }
  
      /*
       * Is the submitter blocked from sharing links?
       */
      if (!job.data.submitter.permissions.canShareLinks) {
        this.log.alert('Submitter is not permitted to share links', {
          submitter: {
            _id: job.data.submitter._id,
            username: job.data.submitter.username,
          },
        });
        return;
      }
  
      this.log.info('fetching link from database');
      job.data.link = await linkService.getById(job.data.linkId);
      if (!job.data.link) {
        this.log.error('link not found in database', { linkId: job.data.linkId });
        return;
      }
  
      /*
       * Is the domain or URL already known to be blocked?
       */
      if (job.data.link.flags && job.data.link.flags.isBlocked) {
        this.log.alert('aborting ingest of blocked link', {
          submitter: {
            _id: job.data.submitter._id,
            username: job.data.submitter.username,
          },
          domain: job.data.link.domain,
          url: job.data.link.url,
        });
        return;
      }
  
      /*
       * Is the domain currently blocked?
       */
      const isDomainBlocked = await linkService.isDomainBlocked(job.data.link.domain);
      if (isDomainBlocked) {
        /*
         * Make sure the flag is set on the Link
         */
        await this.Link.updateOne(
          { _id: job.data.link._id },
          {
            $set: {
              'flags.isBlocked': true,
            },
          },
        );
        /*
         * Log the rejection
         */
        this.log.alert('prohibiting link from blocked domain', {
          submitter: {
            _id: job.data.submitter._id,
            username: job.data.submitter.username,
          },
          domain: job.data.link.domain,
          url: job.data.link.url,
        });
  
        return; // bye!
      }
  
      this.log.info('fetching link preview', {
        domain: job.data.link.domain,
        url: job.data.link.url,
      });

      job.data.preview = await linkService.generatePagePreview(job.data.link.url);
      if (!job.data.preview) {
        throw new Error('failed to load link preview');
      }
  
      this.log.info('updating link record in Mongo', {
        link: job.data.link._id,
        preview: job.data.preview,
      });
      job.data.link = await this.Link.findOneAndUpdate(
        { _id: job.data.link._id },
        {
          $set: {
            lastPreviewFetched: job.data.preview.fetched,
            title: job.data.preview.title,
            siteName: job.data.preview.siteName,
            description: job.data.preview.description,
            tags: job.data.preview.tags,
            mediaType: job.data.preview.mediaType,
            contentType: job.data.preview.contentType,
            images: job.data.preview.images,
            videos: job.data.preview.videos,
            audios: job.data.preview.audios,
            favicons: job.data.preview.favicons,
            oembed: job.data.preview.oembed,
            'flags.havePreview': true,
          },
        },
        { new: true },
      );
      job.data.link = await this.Link.populate(job.data.link, linkService.populateLink);
  
      this.log.info('link ingest complete', {
        submitter: {
          _id: job.data.submitter._id,
          username: job.data.submitter.username,
        },
        link: job.data.link,
      });

      if (job.data?.options?.channelId) {
        const viewModel = Object.assign({ link: job.data.link }, this.viewModel);
        const displayList = linkService.createDisplayList('replace-preview');
        displayList.replaceElement(
          `.link-container[data-link-id="${job.data.link._id}"]`,
          await linkService.renderPreview(viewModel),
        );
        this.emitter.to(job.data.options.channelId).emit('chat-control', { displayList });
      }
    } catch (error) {
      await this.log.error('failed to ingest link', {
        domain: job.data.link.domain,
        url: job.data.link.url,
        error
      });
      throw error;
    }
  }

  async updateUrlBlacklist ( ) {
    try {
      /*
       * Fetch latest to local file
       */
      this.log.info('fetching updated domain blacklist');
      const response = await fetch(ChatLinksService.BLOCKLIST_URL);
      if (!response.ok) {
        throw new Error(`unexpected response ${response.statusText}`);
      }

      await streamPipeline(Readable.fromWeb(response.body), fs.createWriteStream(this.blacklist.porn));
  
      /*
       * Read local file line-by-line with filtering and comment removal to insert
       * to Redis set of blocked domains
       */
      const fileStream = fs.createReadStream(this.blacklist.porn);
      const rl = readline.createInterface({
        input: fileStream,
        crlfDelay: Infinity,
      });
      for await (let line of rl) {
        line = line.trim();
        if (line[0] === '#') {
          continue;
        }
        const tokens = line.split(' ');
        if (tokens[0] !== '0.0.0.0' || tokens[1] === '0.0.0.0') {
          continue;
        }
  
        const r = await this.redis.sadd(ChatLinksService.DOMAIN_BLACKLIST_KEY, tokens[1]);
        if (r > 0) {
          this.log.info('added domain to Redis blocklist', { domain: tokens[1] });
        }
      }
    } catch (error) {
      this.log.error('failed to update domain blacklist', { error });
      // fall through
    } finally {
      this.log.info('domain block list updated');
    }
  }
}

(async ( ) => {
  
  try {
    const { fileURLToPath } = await import('node:url');
    const __dirname = dirname(fileURLToPath(import.meta.url)); // jshint ignore:line

    const worker = new ChatLinksService(path.resolve(__dirname, '..', '..'));
    await worker.start();

  } catch (error) {
    console.error('failed to start Host Cache worker', { error });
    process.exit(-1);
  }

})();