'use strict';

const express = require('express');
const app = express();

app.get('/api/p1', p1);
app.get('/api/p2', p2);

app.use(errorHandler); // after request handlers

app.listen(3000, () => console.log('Server is running...'));

function p1(request, response, next) {
    getData()
        .then(data => response.end('ok: ' + data))
        .catch(error => next(error));
}

function p2(request, response, next) {
    getDataFails()
        .then(data => response.end(data))
        .catch(next);
}

function errorHandler(error, request, response, next) { // there must be 4 arguments
    response.status(500).send('error: ' + error.toString());
}

function getData() {
    return Promise.resolve('some data');
}

function getDataFails() {
    return Promise.reject('some error');
}