import { Client } from 'pg';
const copyTo = require('pg-copy-streams').to;
const copyFrom = require('pg-copy-streams').from;

const fromDb = new Client({
    host: 'oldDb.rds.amazonaws.com',
    user: 'username',
    password: 'password',
    database: 'api_logs'
});

const toDb = new Client({
    host: 'newDb.rds.amazonaws.com',
    user: 'username',
    password: 'password',
    database: 'api_logs'
});
// query to select the api logs for the month of september
let query1 = "COPY (SELECT id, api_key, statuscode, latency, method, time FROM logs WHERE time >= '2017-09-01T00:00:00' AND time < '2017-10-01T00:00:00') TO STDOUT";

// query to map the data retrieved above to specific columns
let query2 = "COPY logs_201709 (id, api_key, statuscode, latency, method, time) FROM STDIN";

fromDb.connect().then(() => toDb.connect()).then(() => {
    let fromStream = fromDb.query(copyTo(query1));
    let toStream = toDb.query(copyFrom(query2));
    // pipe data from source to destination DB
    fromStream.pipe(toStream);
    fromStream.on('end', done);
    fromStream.on('error',done);
});

let done = (err) => {
    if (err) console.log('err', err);
    console.log('Completed');
}