import { Injectable, Logger } from '@nestjs/common';
import { DatabaseListen } from '../../constants';
import { EventBus } from '@nestjs/cqrs';
import { ChangeDocEvent } from '../../domain/events/change-doc.event';
import { ConfigService } from '@nestjs/config';

import * as Nano from 'nano';

@Injectable()
export class CouchService {
  constructor(
    private eventBus: EventBus,
    private configService: ConfigService,
  ) {}

  get nanoInstance() {
    const couchConfiguration = this.configService.get<string>('COUCHDB_CONFIG');
    return Nano(couchConfiguration);
  }

  async onModuleInit() {
    const nano = this.nanoInstance;
    for (const database of DatabaseListen) {
      const db = nano.db.use(database);
      db.changesReader.start({ includeDocs: true }).on('change', (change) => {
        Logger.log(
          `Receive Data from ${database}: ${change?.id}`,
          'CouchService',
        );
        this.changeDoc(change, database);
      });

      Logger.log(`start listen database ${database}`, 'CouchService');
    }
  }

  private changeDoc(data, database) {
    this.eventBus.publish(
      new ChangeDocEvent({
        id: data.id,
        database: database,
        data: data.doc,
      }),
    );
  }

  public async createDoc(data, database) {
    try {
      const nano = this.nanoInstance;
      const db = nano.use(database);
      return await db.insert(data);
    } catch (error) {}
  }

  public async deleteDoc(data, database) {
    try {
      const nano = this.nanoInstance;
      const db = nano.use(database);
      const result = await db.get(data.id);
      await db.destroy(data.id, result._rev);
    } catch (error) {}
  }

  public async updateDoc(data, database) {
    try {
      const nano = this.nanoInstance;
      const db = nano.use(database);
      const result = await db.get(data.id);
      await db.insert({
        ...data,
        _rev: result._rev,
      });
    } catch (error) {}
  }
}