Add a rake task

README.md

@@ -104,6 +104,20 @@ So, if you got error like this:
 
 It's time to create this token or wait for 1 hour before GitHub reset the counter for your IP.
 
+
+### Rake task
+
+You love Rake? So do we! And so we've made it easier for you by providing a Rake task library for your Change log generation. In your Rakefile, use:
+
+```ruby
+GitHubChangelogGenerator::RakeTask.new :changelog do |config|
+  config.since_tag = '0.1.14'
+  config.future_release = '0.2.0'
+end
+```
+
+All command line options can be passed to the Rake task as `config` parameters. Since you're naming the Rake task yourself, you can create as many as you want, too.
+
 ##Features and advantages of this project
 - Generate canonical, neat change log file, followed by [basic change log guidelines](http://keepachangelog.com/) :gem:
 - Possible to generate **Unreleased** changes (closed issues that have not released yet) :dizzy:

lib/github_changelog_generator/parser.rb

@@ -14,7 +14,7 @@ module GitHubChangelogGenerator
       parser.parse!
 
       if options[:user].nil? || options[:project].nil?
-        detect_user_and_project(options)
+        detect_user_and_project(options, ARGV[0], ARGV[1])
       end
 
       if !options[:user] || !options[:project]
@@ -180,8 +180,8 @@ module GitHubChangelogGenerator
     end
 
     # Detects user and project from git
-    def self.detect_user_and_project(options)
-      options[:user], options[:project] = user_project_from_option(ARGV[0], ARGV[1], options[:github_site])
+    def self.detect_user_and_project(options, arg0 = nil, arg1 = nil)
+      options[:user], options[:project] = user_project_from_option(arg0, arg1, options[:github_site])
       if !options[:user] || !options[:project]
         if ENV["RUBYLIB"] =~ /ruby-debug-ide/
           options[:user] = "skywinder"

lib/github_changelog_generator/task.rb

@@ -0,0 +1,68 @@
+require "rake"
+require "rake/tasklib"
+require "github_changelog_generator"
+
+module GitHubChangelogGenerator
+  class RakeTask < ::Rake::TaskLib
+    include ::Rake::DSL if defined?(::Rake::DSL)
+
+    OPTIONS = %w( user project token date_format output
+                  bug_prefix enhancement_prefix issue_prefix
+                  header merge_prefix issues
+                  add_issues_wo_labels add_pr_wo_labels
+                  pulls filter_issues_by_milestone author
+                  unreleased_only unreleased unreleased_label
+                  compare_link include_labels exclude_labels
+                  bug_labels enhancement_labels
+                  between_tags exclude_tags since_tag max_issues
+                  github_site github_endpoint simple_list
+                  future_release verbose )
+
+    OPTIONS.each do |o|
+      attr_accessor o.to_sym
+    end
+
+    # Public: Initialise a new GitHubChangelogGenerator::RakeTask.
+    #
+    # Example
+    #
+    #   GitHubChangelogGenerator::RakeTask.new
+    def initialize(*args, &task_block)
+      @name = args.shift || :changelog
+
+      define(args, &task_block)
+    end
+
+    def define(args, &task_block)
+      desc "Generate a Change log from GitHub"
+
+      task_block.call(*[self, args].slice(0, task_block.arity)) if task_block
+
+      # clear any (auto-)pre-existing task
+      Rake::Task[@name].clear if Rake::Task.task_defined?(@name)
+
+      task @name do
+        # mimick parse_options
+        options = Parser.get_default_options
+
+        if options[:user].nil? || options[:project].nil?
+          Parser.detect_user_and_project(options)
+        end
+
+        OPTIONS.each do |o|
+          v = instance_variable_get("@#{o}")
+          options[o.to_sym] = v if v
+        end
+
+        generator = Generator.new options
+
+        log = generator.compound_changelog
+
+        output_filename = "#{options[:output]}"
+        File.open(output_filename, "w") { |file| file.write(log) }
+        puts "Done!"
+        puts "Generated log placed in #{Dir.pwd}/#{output_filename}"
+      end
+    end
+  end
+end