Using generators internally + refactoring flow

Makefile

@@ -1,10 +1,13 @@
 
+NODE ?= node
+NODE_FLAGS ?= $(shell $(NODE) --v8-options | grep generators | cut -d ' ' -f 3)
+
 BIN := ./node_modules/.bin
-MOCHA := $(BIN)/mocha
+MOCHA := $(BIN)/_mocha
 ESLINT := $(BIN)/eslint
 
 test: node_modules
-	@$(MOCHA)
+	@$(NODE) $(NODE_FLAGS) $(MOCHA)
 
 node_modules: package.json
 	@npm install

lib/github.js

@@ -1,62 +1,110 @@
 /* eslint-disable camelcase */
 
-var base = 'https://api.github.com/';
+/**
+ * Module dependencies.
+ */
+
+var debug = require('debug')('duo:gh-resolve:github');
+var request = require('co-request');
 var path = require('path');
-var request = require('request');
 
-module.exports = function (opts) {
-  var token = opts.token || opts.password;
 
-  return {
-    tags: tags.bind(null, token),
-    branch: branch.bind(null, token)
-  };
+/**
+ * Retrieve the list of tags for a given repository.
+ *
+ * @param {String} token
+ * @param {Object} options
+ * @return {Object}
+ */
+
+exports.tags = function* (token, options) {
+  return yield get(token, [
+    'repos',
+    options.owner,
+    options.repo,
+    'tags'
+  ]);
 };
 
-function tags(token, owner, repo, callback) {
-  return request({
-    url: url('repos', owner, repo, 'tags'),
-    qs: { access_token: token },
-    json: true,
-    headers: {
-      'Accept': 'application/vnd.github.quicksilver-preview+json',
-      'User-Agent': 'duo:gh-resolve'
-    },
-    followRedirects: true
-  }, handle(callback));
-}
+/**
+ * Retrieve the information about a specific branch for a repository.
+ *
+ * @param {String} token
+ * @param {Object} options
+ * @return {Object}
+ */
+
+exports.branch = function* (token, options) {
+  return yield get(token, [
+    'repos',
+    options.owner,
+    options.repo,
+    'branches',
+    options.branch
+  ]);
+};
+
+/**
+ * Helper for performing an HTTP GET against the Github API.
+ *
+ * @param {String} token
+ * @param {Array:String} parts  Pieces of the URL
+ * @return {Response}
+ */
+
+function* get(token, parts, attempts) {
+  var url = 'https://api.github.com/' + path.join.apply(path, parts);
+  debug('--> GET %s', url);
 
-function branch(token, owner, repo, branch, callback) {
-  return request({
-    url: url('repos', owner, repo, 'branches', branch),
+  var res = yield request({
+    url: url,
     qs: { access_token: token },
-    json: true,
-    headers: {
-      'Accept': 'application/vnd.github.quicksilver-preview+json',
-      'User-Agent': 'duo:gh-resolve'
-    },
-    followRedirects: true
-  }, handle(callback));
-}
+    headers: { 'User-Agent': 'duo:gh-resolve' },
+    followRedirects: true,
+    json: true
+  });
 
-function url() {
-  var parts = [].slice.call(arguments);
-  return base + path.join.apply(path, parts);
-}
+  debug('<-- %s %s', res.statusCode, url);
+  rateLimit(res.headers);
 
-function handle(callback) {
-  return function (err, res, data) {
-    if (err) {
-      callback(err, res);
-    } else if (isError(res.statusCode)) {
-      callback(new Error(data.message));
+  if (isError(res.statusCode)) {
+    var msg = res.body.message;
+    debug('error', msg);
+
+    if (msg === 'Not Found' || attempts > 5) {
+      throw new Error(msg);
     } else {
-      callback(null, res, data);
+      // retry!
+      return yield get(token, parts, attempts + 1);
     }
-  };
+  }
+
+  return res;
 }
 
+/**
+ * Helper for determining if a status code is an error.
+ * (ie: 4xx or 5xx)
+ *
+ * @param {Number} code
+ * @return {Boolean}
+ */
+
 function isError(code) {
   var type = Math.floor(code / 100);
   return type === 4 || type === 5;
 }
+
+/**
+ * Outputs rate-limit information via debug.
+ *
+ * @param {Object} headers
+ * @api private
+ */
+
+function rateLimit(headers) {
+  var remaining = headers['x-ratelimit-remaining'];
+  var limit = headers['x-ratelimit-limit'];
+  var reset = new Date(headers['x-ratelimit-reset'] * 1000);
+  debug('rate limit status: %d / %d (resets: %s)', remaining, limit, reset);
+}