carbsbot.js

var sys = require("sys"),
    http = require("http"),
    querystring = require("querystring"),
    htmlparser = require("htmlparser"),
    soupselect = require("soupselect"),
    irc = require("irc");

/**
 * Wrapper for making an HTTP request, reading the data, instantiating a htmlparser.Parser
 * and parsing the page. htmlparserHandlerFunction will be passed to htmlparser.DefualtHandler.
 */
var fetchAndParsePage = function(host, path, htmlparserHandlerFunction) {
    var request = http.createClient(80, host).request("GET", path, {"host": host});

    request.on("response", function(response) {
        response.setEncoding("utf8");
        var body = "";

        response.on("data", function(chunk) {
            body += chunk;
        });

        response.on("end", function() {
            var handler = new htmlparser.DefaultHandler(htmlparserHandlerFunction);

            var parser = new htmlparser.Parser(handler);
            parser.parseComplete(body);
        });
    });
    request.end();
};

/**
 * Search CalorieKing's database and call a function with the path to the food that
 * is the result of the search. Path is in the format '/foo/bar' relative to www.calorieking.com
 *
 * arg:searchString = The name of the food to search for
 * arg:pathCallback = pathCallback(error, path) will be called when the URL is parsed from the page
 */
var getNutritionFactsPath = function(searchString, pathCallback) {
    fetchAndParsePage("www.calorieking.com",
                      "http://www.calorieking.com/foods/search.php?" + querystring.stringify({"keywords": searchString, "go": "Search", "showresults": "yes"}),
        function(error, dom) {
            if (error) {
                console.log("Error! " + error);
            } else {
                var foodLinks = soupselect.select(dom, ".food-search-result-name");
                if (foodLinks[0])
                {
                    pathCallback(null, foodLinks[0].attribs.href);
                } else {
                    pathCallback("No results for food search '" + searchString + "'", null);
                }
            }
    });
};

/**
 * Parses a CalorieKing nutrition facts page and returns relevant information.
 *
 * arg:nutritionFactsPath = the result of getNutritionFactsPath
 * arg:factsCallback = factsCallback(object) will be called with the parsed nutrition facts
 */
var parseFacts = function(nutritionFactsPath, factsCallback) {
    fetchAndParsePage("www.calorieking.com",
                      nutritionFactsPath,
        function(error, dom) {
            if (error) {
                console.log("Error!:" + error);
            } else {
                var foodNameSpan = soupselect.select(dom, "#heading-food-cat-desc")[0];
                factsCallback({"carbs": soupselect.select(dom, "#total_carbohydrate")[0].children[0].raw.replace(""", "'").replace("&", "&"),
                               "servingSize": soupselect.select(dom, "#units option")[0].children[0].raw.replace(""", "'").replace("&", "&"),
                               "foodName": foodNameSpan.children[foodNameSpan.children.length-1].raw.replace(""", "'").replace("&", "&").trim()});
            }
    });
};

/**
 * Now we just join an IRC channel and wait for !carbs messages
 */
var main = function() {
    var client = new irc.Client("localhost", "carbs-bot", {
        "userName": "carbs",
        "realName": "carbs-bot",
        "channels": ["#carbs-bot"],
        "autoRejoin": false});
    client.addListener("message", function(from, to, msg) {
        if (msg.indexOf("!carbs") == 0)
        {
            var searchString = msg.substr("!carbs ".length);
            getNutritionFactsPath(searchString, function(error, path) {
                if (error)
                {
                    client.say(to, "Error: " + error);
                } else {
                    parseFacts(path, function(facts) {
                        client.say(to, "Nutrition facts for " + facts.foodName);
                        client.say(to, facts.carbs + " carbs in one serving of " + facts.servingSize);
                        client.say(to, "Details: " + path);
                    });
                }
            });
        }
    });
};

main();