From 794bdddf49b5a19a4347b81910d4db71dad6b5ac Mon Sep 17 00:00:00 2001
From: Les Hill <leshill@gmail.com>
Date: Sat, 2 Nov 2013 12:15:25 -0700
Subject: [PATCH] Load subcommand plug-ins at runtime

We use rubygems to load a subcommand plug-in gem with a file that can be
loaded at

    <command-path>/plugin.rb

The `command-path` is the namespace of the command converted to a path. For
example `Pod::Command` becomes `pod/command`.

The `plugin.rb` file should either define the subcommand(s) directly or
require the files for the subcommand(s). For example
[open_pod_bay](https://github.com/leshill/open_pod_bay) has the following
`plugin.rb`

    require 'pod/command/open'
---
 lib/claide/command.rb                  | 34 ++++++++++++++++++++++++++
 spec/command_spec.rb                   | 33 +++++++++++++++++++++++++
 spec/fixture/command/demo_plugin.rb    | 18 ++++++++++++++
 spec/fixture/command/plugin_fixture.rb |  3 +++
 4 files changed, 88 insertions(+)
 create mode 100644 spec/fixture/command/demo_plugin.rb
 create mode 100644 spec/fixture/command/plugin_fixture.rb

diff --git a/lib/claide/command.rb b/lib/claide/command.rb
index 9b0df95..cb2b0f8 100644
--- a/lib/claide/command.rb
+++ b/lib/claide/command.rb
@@ -201,6 +201,7 @@ def parse(argv)
       # @return [void]
       #
       def run(argv)
+        load_plugins
         command = parse(argv)
         command.validate!
         command.run
@@ -261,6 +262,39 @@ def banner(colorize = false)
         Banner.new(self, colorize).formatted_banner
       end
 
+      # Load additional plugins via rubygems looking for:
+      #
+      # <command-path>/plugin.rb
+      #
+      # where <command-path> is the namespace of the Command converted to a
+      # path, for example:
+      #
+      # Pod::Command
+      #
+      # maps to
+      #
+      # pod/command
+      #
+      def load_plugins
+        if Gem.respond_to? :find_latest_files
+          Gem.find_latest_files("#{underscore(name)}/plugin").each {|path| require path }
+        else
+          Gem.find_files("#{underscore(name)}/plugin").each {|path| require path }
+        end
+      end
+
+      private
+
+      # Cribbed from ActiveSupport
+      # https://github.com/rails/rails/blob/master/activesupport/MIT-LICENSE
+      def underscore(str)
+        underscored = str.to_s.dup
+        underscored.gsub!(/::/, '/')
+        underscored.gsub!(/([A-Z]+)([A-Z][a-z])/,'\1_\2')
+        underscored.gsub!(/([a-z\d])([A-Z])/,'\1_\2')
+        underscored.tr!("-", "_")
+        underscored.downcase!
+      end
     end
 
     #-------------------------------------------------------------------------#
diff --git a/spec/command_spec.rb b/spec/command_spec.rb
index d797389..6d327b9 100644
--- a/spec/command_spec.rb
+++ b/spec/command_spec.rb
@@ -16,6 +16,39 @@ module CLAide
         Fixture::Command.parse(%w{ spec-file --verbose lint }).should.be.instance_of Fixture::Command::SpecFile::Lint
         #Fixture::Command.parse(%w{ spec-file lint --help repo }).should.be.instance_of Fixture::Command::SpecFile::Lint::Repo
       end
+
+      describe "plugins" do
+        describe "when the plugin is at <command-path>/plugin.rb" do
+          PLUGIN_FIXTURE = Pathname.new(ROOT) + 'spec/fixture/command/plugin_fixture.rb'
+          PLUGIN = Pathname.new(ROOT) + 'spec/fixture/command/plugin.rb'
+
+          before do
+            FileUtils.copy PLUGIN_FIXTURE, PLUGIN
+          end
+
+          after do
+            FileUtils.remove_file PLUGIN
+          end
+
+          it "loads the plugin" do
+            Fixture::Command.subcommands.find {|subcmd| subcmd.command == 'demo-plugin'}.should.be.nil
+            Fixture::Command.load_plugins
+            plugin_class = Fixture::Command.subcommands.find {|subcmd| subcmd.command == 'demo-plugin'}
+            plugin_class.ancestors.should.include Fixture::Command
+            plugin_class.description.should =~ /plugins/
+          end
+
+          it "is available for help" do
+            Fixture::Command.load_plugins
+            CLAide::Command::Banner.new(Fixture::Command, false).formatted_banner.should =~ /demo-plugin/
+          end
+        end
+
+        it "fails normally if there is no plugin" do
+          Fixture::Command.load_plugins
+          Fixture::Command.subcommands.find {|subcmd| subcmd.name == 'demo-plugin' }.should.be.nil
+        end
+      end
     end
 
     #-------------------------------------------------------------------------#
diff --git a/spec/fixture/command/demo_plugin.rb b/spec/fixture/command/demo_plugin.rb
new file mode 100644
index 0000000..f9d3a9a
--- /dev/null
+++ b/spec/fixture/command/demo_plugin.rb
@@ -0,0 +1,18 @@
+# encoding: utf-8
+module Fixture
+  class Command
+    class DemoPlugin < Command
+      self.summary = 'Plugins!'
+      self.description = <<-DESC
+        Let’s add plugins to CLAide and CocoaPods.
+      DESC
+      self.arguments = '[NAME]'
+
+      attr_reader :name
+      def initialize(argv)
+        @name = argv.shift_argument
+        super
+      end
+    end
+  end
+end
diff --git a/spec/fixture/command/plugin_fixture.rb b/spec/fixture/command/plugin_fixture.rb
new file mode 100644
index 0000000..48f3bfe
--- /dev/null
+++ b/spec/fixture/command/plugin_fixture.rb
@@ -0,0 +1,3 @@
+# Load a CLAide plugin by requiring it in your `plugin.rb` or by
+# defining it directly in the file.
+require 'fixture/command/demo_plugin'