/*
 * This file defines the routes for the prometheus monitoring running on the api server
 * It uses express router so it can be placed under any path, and will then
 * assume everything else is under the root of that path.
 * e.g. to place under /metrics you would do:
 *
 * var appHttps = [main app setup]
 * var promRouterFactory = require(<this file>);
 * var promRouter = prometheusRouterFactory();
 * appHttps.use('/metrics', promRouter);
 */
'use strict';

var path = require('path');
var express = require('express');
var morgan = require('morgan');
var promClient = require('prom-client');

const AUTHORIZATION_TOKEN = 'f7632bff-7ef4-4ecb-aba1-0ab678712556';

module.exports = (function() {
    return function prometheusRouterFactory() {
        var router = express.Router();

        //
        // Logging middleware
        //
        router.use(morgan('combined'));

        /*
         * If the request looks like a request for metrics then return them.
         */
        router.use('/', function(req, res, next) {
            /**
             * Check the authorization header value is correct
             */
            if (req.headers.authorization !== 'Bearer ' + AUTHORIZATION_TOKEN) {
                res.status(401).end();
            } else {
                /**
                 * All ok, so return the metrics
                 */
                res.end(promClient.register.metrics());
            }
        });

        /*
         * Return the configured router
         */
        return router;
    };
})();