Improve error messaging for no active alias. (#79)

Author: mbleigh

commands/use.js

@@ -109,7 +109,10 @@ module.exports = new Command('use [alias_or_project_id]')
           {
             type: 'input',
             name: 'alias',
-            message: 'What alias do you want to use for this project? (e.g. staging)'
+            message: 'What alias do you want to use for this project? (e.g. staging)',
+            validate: function(input) {
+              return input && input.length > 0;
+            }
           }
         ]).then(function() {
           writeAlias(options.projectRoot, options.rc, results.alias, results.project);

lib/getProjectId.js

@@ -1,5 +1,8 @@
 'use strict';
 
+var _ = require('lodash');
+var chalk = require('chalk');
+
 var FirebaseError = require('./error');
 
 /**
@@ -13,9 +16,23 @@ var FirebaseError = require('./error');
  */
 module.exports = function(options, allowNull) {
   if (!options.project && !allowNull) {
-    throw new FirebaseError('No project specified. Run with --project or inside project directory', {
-      exit: 1
-    });
+    var aliases = _.get(options, 'rc.projects', {});
+    var aliasCount = _.size(aliases);
+
+    if (aliasCount === 0) {
+      throw new FirebaseError('No project active. Run with ' + chalk.bold('--project <projectId>') + ' or define an alias by\nrunning ' + chalk.bold('firebase use --add'), {
+        exit: 1
+      });
+    } else if (aliasCount === 1) {
+      var name = _.head(_.keys(aliases));
+      throw new FirebaseError('No project active, but a project alias is available.\n\nRun ' + chalk.bold('firebase use ' + name) + ' to activate project ' + chalk.bold(aliases[name]));
+    } else {
+      var aliasList = _.map(aliases, function(projectId, aname) {
+        return '  ' + aname + ' (' + projectId + ')';
+      }).join('\n');
+
+      throw new FirebaseError('No project active, but project aliases are available.\n\nRun ' + chalk.bold('firebase use <alias>') + ' with one of these options:\n\n' + aliasList);
+    }
   }
   return options.project;
 };