var hypercat = require('node-hypercat');

// Create a HyperCat
var cat = new hypercat.Hypercat();

// Load from JSON
var jsonCat = hypercat.Hypercat.fromJSON(json);

// Open a remote HyperCat
hypercat.Hypercat.get('http://data.openiot.org/cat', function (err, remoteCat) {
    var items = cat.items();
    console.log(items);
});

// View available metadata relations
var items = cat.relations();

// Get meta-data values (as array)
console.log(cat.values('urn:X-hypercat:rels:isContentType'));

// View metadata as object
console.log(cat.metadata);

// Items are resources
var items = cat.items();

// Resources have URLs
var res = items[0];
console.log(res.href());

// Resources have metadata, like HyperCats
console.log(res.relations());

// You can filter for particular items
var filteredItems = cat.items(function (item) {
    // only return plain JSON resources
    return item.values('some-link-rel').indexOf('application/json') !== -1;
});

var subCats = cat.subcatalogs();

function walkCat(url, callback) {
    hypercat.Hypercat.get(url, function (err, remoteCat) {
        console.log('Fetched ' + url);
        if (err) return callback(err);
        async.map(remoteCat.items(), function (item, callback) {
            if (item.contentType()[0] === "application/vnd.hypercat.catalogue+json") {
                // It's a HyperCat - walk it
                console.log("Walking HyperCat: " + item.href());
                walkCat(item.href(), callback);
            } else {
                // It's a resource - collect it into a list
                process.nextTick(function () {
                    callback(null, [item]);
                });
            }
        }, function (err, results) {
            console.log(results);
            if (err) return callback(err);
            var items = [];
            results.forEach(function (list) {
                items = items.concat(list);
            });
            callback(null, items);
        });
    });
}