import { Injectable } from '@nestjs/common';
import { QueryResult } from 'src/modules/data_sources/query_result.type';
import { QueryService } from 'src/modules/data_sources/query_service.interface';
import { ConnectionTestResult } from 'src/modules/data_sources/connection_test_result.type';
const { MongoClient } = require("mongodb");

@Injectable()
export default class MongodbService implements QueryService {

  async run(sourceOptions: any, queryOptions: any, dataSourceId: string): Promise<QueryResult> {

    const db = await this.getConnection(sourceOptions);
    let result = { };
    const operation = queryOptions.operation;

    try {
      switch (operation) {
        case 'list_collections':
          result = await db.listCollections().toArray();
          break;  
        case 'insert_one':
          result = await db.collection(queryOptions.collection).insertOne(JSON.parse(queryOptions.document));
          break;
        case 'insert_many':
          result = await db.collection(queryOptions.collection).insertMany(JSON.parse(queryOptions.documents));
          break; 
      }
    } catch (err) {
      console.log(err);
    }

    return {
      status: 'ok',
      data: result
    }
  }

  async testConnection(sourceOptions: object): Promise<ConnectionTestResult> {
    const db = await this.getConnection(sourceOptions);
    await db.listCollections().toArray();

    return {
      status: 'ok'
    }
  }

  async getConnection(sourceOptions: any): Promise<any> { 
    let db = null;
    const connectionType = sourceOptions['connection_type'];

    if(connectionType === 'manual') {
      const database = sourceOptions.database;
      const host = sourceOptions.host;
      const port = sourceOptions.port;
      const username = sourceOptions.username;
      const password = sourceOptions.password;

      const needsAuthentication = username !== '' && password !== '';
      const uri = needsAuthentication ? `mongodb://${username}:${password}@${host}:${port}` : `mongodb://${host}:${port}`;

      const client = new MongoClient(uri, {
        directConnection: true
      });
      await client.connect();

      db = client.db(database);

    } else { 
      const connectionString = sourceOptions['connection_string'];
      const client = new MongoClient(connectionString, { useNewUrlParser: true, useUnifiedTopology: true });
      await client.connect();
      db = client.db();
    }

    return db;
  }
}