menuFetcher.js

var request = require('request');
var cache = require('./cache');
var config = require('./config');
var charset = require('charset');
var iconv = require('iconv-lite');

module.exports.fetchMenu = function(url, date, postParams, parseCallback, doneCallback) {
    var cached = cache.get(date + ":" + url);
    if (cached && !process.env.AT11_NO_CACHE)
    {
        doneCallback(null, cached);
    }
    else
    {
        load(url, date, postParams, parseCallback, function(error, menu) {
            if (!error)
            {
                if (menu.length > 0)
                {
                    cache.set(date + ":" + url, menu);
                }
                //we need to go through cache to get cache timestamp
                doneCallback(null, cache.get(date + ":" + url));
            }
            else
            {
                console.error("Error for %s: %s", url, error);
                doneCallback(error);
            }
        });
    }

    function load(url, date, postParams, parse, done) {
        var options = {
            url: url,
            method: postParams ? "POST" : "GET",
            form: postParams,
            encoding: 'binary',
            timeout: 10 * 1000 // 10s timeout for request
        };
        request(options, function(error, response, body) {
            if (!error && response.statusCode === 200)
            {
                var enc = charset(response.headers, body);
                if (enc !== 'utf-8')
                {
                    body = iconv.decode(new Buffer(body, 'binary'), enc).toString('utf-8');
                }

                var timer = setTimeout(function() {
                    timer = null;//clear needed as value is kept even after timeout fired
                    done(new Error("Parser timeout"));
                }, config.parserTimeout);

                try
                {
                    parse(body, date, function(menu) {
                        if (!timer)
                        {
                            //multiple calls in parser or parser called after timeout
                            return;
                        }
                        clearTimeout(timer);
                        timer = null; //clearTimeout does not null the value

                        try
                        {
                            if (!Array.isArray(menu))
                            {
                                throw "Invalid menu returned (expected array, got " + typeof menu + ")";
                            }
                            menu.forEach(function(item) {
                                if (typeof item !== "object")
                                {
                                    throw "Menu item should be object, but got " + typeof item;
                                }
                                if (typeof item.isSoup !== "boolean")
                                {
                                    throw "Menu item has wrong 'isSoup' flag (" + typeof item.isSoup + ")";
                                }
                                if (typeof item.text !== "string")
                                {
                                    throw "Menu item has wrong 'text' property (" + typeof item.text + ")";
                                }
                                if (typeof item.price !== "number")
                                {
                                    throw "Menu item has wrong 'price' property (" + typeof item.price + ")";
                                }
                                item.price = isNaN(item.price) ? "" : item.price.toFixed(2).replace(".", ",") + " €"; //convert to presentable form
                            });
                            done(null, menu);
                        }
                        catch (err)
                        {
                            done(err);
                        }
                    });
                }
                catch (err) //catches only synchronous errors in parser code
                {
                    clearTimeout(timer);
                    doneCallback(err);
                }
            }
            else
            {
                doneCallback(error || new Error("Response code " + response.statusCode));
            }
        });
    }
};