Initial commit.

README.md

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+Hacker News Reader App
+
+** More to come ***

app.js

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+
+/**
+ * Module dependencies.
+ */
+
+var express = require('express'),
+    hn = require('./lib/hn');
+
+var app = module.exports = express.createServer(),
+    PORT;
+
+// Configuration
+
+app.configure(function(){
+  app.set('views', __dirname + '/views');
+  app.set('view engine', 'ejs');
+  app.use(express.logger());
+  app.use(express.bodyParser());
+  app.use(express.methodOverride());
+  app.use(app.router);
+  app.use(express.static(__dirname + '/public'));
+});
+
+app.configure('development', function(){
+  PORT = 8000;
+  app.use(express.errorHandler({ dumpExceptions: true, showStack: true })); 
+});
+
+app.configure('production', function(){
+  PORT = 80;
+  app.use(express.errorHandler()); 
+});
+
+// Routes
+
+app.get('/top.json', function(req, res){
+  hn.topFeed.getJSON(function(json) {
+    res.send(json);
+  });
+});
+
+// Only listen on $ node app.js
+
+if (!module.parent) {
+  app.listen(PORT);
+  console.log("Express server listening on port %d", app.address().port);
+}

lib/hn/feeds/top.js

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+var fs = require('fs'),
+    libxmljs = require('libxmljs'),
+    request = require('request'),
+    NewsItem = require('../news_item').NewsItem;
+
+function TopFeed(config) {
+  this.config = config;
+  this.cacheFile = './cache/top.json'
+}
+
+/*
+ * Public API
+ */
+
+/*
+ * Returns top news items as an object array
+ */
+TopFeed.prototype.get = function(next) {
+  var that = this;
+
+  that._isCached({
+    yes: function() {
+      // Load news items from cache
+      that._fromCache(next);
+    },
+    no: function() {
+      that._getItems(function(items) {
+        that._respondWith(items, items, next);
+      });
+    }
+  });
+};
+
+/*
+ * Returns top news items as a JSON string
+ */
+TopFeed.prototype.getJSON = function(next) {
+  var that = this;
+
+  that._isCached({
+    yes: function() {
+      // Load news items from cache
+      that._fromCache(next, 'json');
+    },
+    no: function() {
+      that._getItems(function(items) {
+        that._respondWith(JSON.stringify(items), items, next);
+      });
+    }
+  });
+};
+
+/*
+ * Private helper methods
+ */
+
+TopFeed.prototype._getItems = function(next) {
+  var that = this;
+  that._getRSSXML(function(rss) {
+    that._itemsFromRSS(rss, function(newsItems) {
+      next(newsItems);
+    });
+  });
+};
+
+TopFeed.prototype._getRSSXML = function(next) {
+  request('http://news.ycombinator.com/rss', function(err, resp, body) {
+    next(libxmljs.parseXmlString(body));
+  });
+};
+
+TopFeed.prototype._itemsFromRSS = function(rss, next) {
+  var newsItem, 
+  newsItems = [];
+
+  rss.find("//rss/channel/item").forEach(function(item) {
+    newsItem = new NewsItem({
+      title:        item.get('title').text(),
+      link:         item.get('link').text(),
+      comments:     item.get('comments').text()
+    });
+    newsItems.push(newsItem);
+  });
+
+  next(newsItems);
+};
+
+TopFeed.prototype._respondWith = function(toReturn, toCache, next) {
+  next(toReturn);
+  this._cache(toCache);
+};
+
+TopFeed.prototype._isCached = function(callbacks) {
+  var that = this;
+  fs.stat(that.cacheFile, function(err, stat) {
+    // Cache miss or cache has expired, load it from RSS feed
+    if((err && err.code === 'ENOENT') ||
+       (stat.mtime.getTime() < ((new Date()).getTime() - (that.config.cache_expiration_time*1000*60)))) {
+      callbacks.no();
+    }
+    else {
+      callbacks.yes();
+    }
+  });
+};
+
+TopFeed.prototype._fromCache = function(next, returnAs) {
+  var newsItem, 
+  newsItems = [];
+
+  fs.readFile(this.cacheFile, 'utf8', function(err, data) {
+    if(returnAs === 'json') {
+      next(data);
+    }
+    else {
+      var items = JSON.parse(data)
+      items.forEach(function(item) {
+        newsItem = new NewsItem({
+          title:        item.title,
+          link:         item.link,
+          comments:     item.comments
+        });
+        newsItems.push(newsItem);
+      });
+      next(newsItems);
+    }
+  });
+};
+
+TopFeed.prototype._cache = function(newsItems) {
+  fs.writeFile(this.cacheFile, JSON.stringify(newsItems));
+};
+
+module.exports = function(config) {
+  return new TopFeed(config);
+}

lib/hn/index.js

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+var config = {
+  cache_expiration_time: 3 // Minutes to keep news items cached
+}
+
+exports.topFeed = require('./feeds/top')(config);

lib/hn/news_item.js

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+var url = require('url');
+
+function NewsItem(defaults) { 
+  this.title    = defaults.title    || '';
+  this.link     = defaults.link     || '';
+  this.comments = defaults.comments || '';
+  this.host     = this.link === '' ? '' : url.parse(this.link).host;
+};
+
+NewsItem.prototype.print = function() {
+  console.log(this.title);
+  console.log(this.link);
+  console.log('');
+}
+
+exports.NewsItem = NewsItem;