Fix #13: Add option -r to select a random cow

cli.js

@@ -32,9 +32,10 @@ var argv = require("optimist")
 	"n" : "If it is specified, the given message will not be word-wrapped.",
 	"W" : "Specifies roughly where the message should be wrapped. The default is equivalent to -W 40 i.e. wrap words at or before the 40th column.",
 	"f" : "Specifies a cow picture file (''cowfile'') to use. It can be either a path to a cow file or the name of one of cows included in the package.",
+	"r" : "Select a random cow",
 	"l" : "List all cowfiles included in this package."
 })
-.boolean(["b", "d", "g", "p", "s", "t", "w", "y", "n", "h", "l"])
+.boolean(["b", "d", "g", "p", "s", "t", "w", "y", "n", "h", "r", "l"])
 .argv;
 
 if (argv.l) {

index.js

@@ -13,7 +13,16 @@ exports.think = function (options) {
 exports.list = cows.list;
 
 function doIt (options, sayAloud) {
-	var cow = cows.get(options.f || "default");
+  var cowFile;
+
+	if (options.r) {
+		var cowsList = cows.listSync();
+		cowFile = cowsList[Math.floor(Math.random() * cowsList.length)];
+  } else {
+    cowFile = options.f || "default";
+  }
+
+  var cow = cows.get(cowFile);
 	var face = faces(options);
 	face.thoughts = sayAloud ? "\\" : "o";
 

lib/cows.js

@@ -3,6 +3,13 @@ var fs = require("fs");
 var replacer = require("./replacer");
 
 var textCache = {};
+var cowsPath = path.join(__dirname, "../cows");
+
+function cowNamesFromFiles (files) {
+  return files.map(function (cow) {
+    return path.basename(cow, ".cow");
+  });
+}
 
 exports.get = function (cow) {
 	var text = textCache[cow];
@@ -25,13 +32,13 @@ exports.get = function (cow) {
 }
 
 exports.list = function (callback) {
-	fs.readdir(path.join(__dirname, "../cows"), function (err, files) {
+	fs.readdir(cowsPath, function (err, files) {
 		if (err) return callback(err);
 
-		var cows = files.map(function (cow) {
-			return path.basename(cow, ".cow");
-		});
-
-		return callback(null, cows);
+		return callback(null, cowNamesFromFiles(files));
 	});
 }
+
+exports.listSync = function () {
+  return cowNamesFromFiles(fs.readdirSync(cowsPath))
+}