const Bluebird = require('bluebird');
const fs = require('fs');

// Run multiple promises at once and get their values
Bluebird
    .join(
        runPromise1(),
        runPromise2(),
        runPromise3()
    )
    .spread((promise1result, promise2result, promise3result) => {}) // Know .spread() is used when .then()ing multiple values with .join

// Convert a callback to a promise
function readFilePromise(path) {
    return new Bluebird((resolve, reject) => {
        fs.readFile(path, 'utf-8', (err, data) => {
            if (err) return reject(err);
            return resolve(data);
        })
    })
}

// Iterate over a collection of items asynchronously, but not necessarily in order
const collection = [
    {id: 1, name: 'Wes'},
    {id: 2, name: 'Jacob'},
    {id: 3, name: 'Nicky'}
];
Bluebird.map(collection, person => {
    return savePromise(person);
})

// Iterate over a collection of items asynchronously, and in order
Bluebird.reduce(collection, (accumulator, person) => {
    return savePromise(person)
        .then(result => {
            accumulator.push(result);
            return accumulator;
        })
}, [])

// Know that you can continue chaining values with .then, even if you're not returning a promise
callAsyncPromise()
    .then(result => {
        if (!result) {
            throw new Error('wtf something happennnnned');
        }
        return 'success';
    })
    .then(status => {
        console.log(status) // This will console.log as 'success';
        return 'continued';
    })
    .then(status => {
        console.log(status); // This will console.log as 'continued'
    })

// Know to use throw to reject execution of the current promise chain

callAsyncPromise()
    .then(result => {
        throw new Error('We want to end the promise chain.');
    })
    .catch(error => {
        console.log(error.message) // console.log reads as "We want to end the promise chain"
    })