require 'rubygems'
require 'rake'
require 'rake/tasklib'
require 'date'
require 'git'

module GithubGem

  # Detects the gemspc file of this project using heuristics.
  def self.detect_gemspec_file
    FileList['*.gemspec'].first
  end

  # Detects the main include file of this project using heuristics
  def self.detect_main_include
    if detect_gemspec_file =~ /^(\.*)\.gemspec$/ && File.exist?("lib/#{$1}.rb")
      "lib/#{$1}.rb"
    elsif FileList['lib/*.rb'].length == 1
      FileList['lib/*.rb'].first
    else
      nil
    end
  end

  class RakeTasks

    attr_reader   :gemspec, :modified_files, :git
    attr_accessor :gemspec_file, :task_namespace, :main_include, :root_dir, :spec_pattern, :test_pattern, :remote, :remote_branch, :local_branch

    # Initializes the settings, yields itself for configuration
    # and defines the rake tasks based on the gemspec file.
    def initialize(task_namespace = :gem)
      @gemspec_file   = GithubGem.detect_gemspec_file
      @task_namespace = task_namespace
      @main_include   = GithubGem.detect_main_include
      @modified_files = []
      @root_dir       = Dir.pwd
      @test_pattern   = 'test/**/*_test.rb'
      @spec_pattern   = 'spec/**/*_spec.rb'
      @local_branch   = 'master'
      @remote         = 'origin'
      @remote_branch  = 'master'

      yield(self) if block_given?

      @git = Git.open(@root_dir)
      load_gemspec!
      define_tasks!
    end

    protected

    # Define Unit test tasks
    def define_test_tasks!
      require 'rake/testtask'

      namespace(:test) do
        Rake::TestTask.new(:basic) do |t|
          t.pattern = test_pattern
          t.verbose = true
          t.libs << 'test'
        end
      end

      desc "Run all unit tests for #{gemspec.name}"
      task(:test => ['test:basic'])
    end

    # Defines RSpec tasks
    def define_rspec_tasks!
      require 'spec/rake/spectask'

      namespace(:spec) do
        desc "Verify all RSpec examples for #{gemspec.name}"
        Spec::Rake::SpecTask.new(:basic) do |t|
          t.spec_files = FileList[spec_pattern]
        end

        desc "Verify all RSpec examples for #{gemspec.name} and output specdoc"
        Spec::Rake::SpecTask.new(:specdoc) do |t|
          t.spec_files = FileList[spec_pattern]
          t.spec_opts << '--format' << 'specdoc' << '--color'
        end

        desc "Run RCov on specs for #{gemspec.name}"
        Spec::Rake::SpecTask.new(:rcov) do |t|
          t.spec_files = FileList[spec_pattern]
          t.rcov = true
          t.rcov_opts = ['--exclude', '"spec/*,gems/*"', '--rails']
        end
      end

      desc "Verify all RSpec examples for #{gemspec.name} and output specdoc"
      task(:spec => ['spec:specdoc'])
    end

    # Defines the rake tasks
    def define_tasks!

      define_test_tasks!  if has_tests?
      define_rspec_tasks! if has_specs?

      namespace(@task_namespace) do
        desc "Updates the filelist in the gemspec file"
        task(:manifest) { manifest_task }

        desc "Builds the .gem package"
        task(:build => :manifest) { build_task }

        desc "Sets the version of the gem in the gemspec"
        task(:set_version => [:check_version, :check_current_branch]) { version_task }
        task(:check_version => :fetch_origin) { check_version_task }

        task(:fetch_origin) { fetch_origin_task }
        task(:check_current_branch) { check_current_branch_task }
        task(:check_clean_status) { check_clean_status_task }
        task(:check_not_diverged => :fetch_origin) { check_not_diverged_task }

        checks = [:check_current_branch, :check_clean_status, :check_not_diverged, :check_version]
        checks.unshift('spec:basic') if has_specs?
        checks.unshift('test:basic') if has_tests?
        # checks.push << [:check_rubyforge] if gemspec.rubyforge_project

        desc "Perform all checks that would occur before a release"
        task(:release_checks => checks)

        release_tasks = [:release_checks, :set_version, :build, :github_release, :gemcutter_release]
        # release_tasks << [:rubyforge_release] if gemspec.rubyforge_project

        desc "Release a new version of the gem using the VERSION environment variable"
        task(:release => release_tasks) { release_task }
        
        namespace(:release) do
          desc "Release the next version of the gem, by incrementing the last version segment by 1"
          task(:next => [:next_version] + release_tasks) { release_task }

          desc "Release the next version of the gem, using a bump increment (0.0.1)"
          task(:bump => [:next_bump_version] + release_tasks) { release_task }

          desc "Release the next version of the gem, using a minor increment (0.1.0)"
          task(:minor => [:next_minor_version] + release_tasks) { release_task }

          desc "Release the next version of the gem, using a major increment (1.0.0)"
          task(:major => [:next_major_version] + release_tasks) { release_task }
        end

        # task(:check_rubyforge)   { check_rubyforge_task }
        # task(:rubyforge_release) { rubyforge_release_task }
        task(:gemcutter_release) { gemcutter_release_task }
        task(:github_release => [:commit_modified_files, :tag_version]) { github_release_task }
        task(:tag_version) { tag_version_task }
        task(:commit_modified_files) { commit_modified_files_task }

        task(:next_version)       { next_version_task }
        task(:next_bump_version)  { next_version_task(:bump) }
        task(:next_minor_version) { next_version_task(:minor) }
        task(:next_major_version) { next_version_task(:major) }
        
        desc "Updates the gem release tasks with the latest version on Github"
        task(:update_tasks) { update_tasks_task }
      end
    end

    # Updates the files list and test_files list in the gemspec file using the list of files
    # in the repository and the spec/test file pattern.
    def manifest_task
      # Load all the gem's files using "git ls-files"
      repository_files = git.ls_files.keys
      test_files       = Dir[test_pattern] + Dir[spec_pattern]

      update_gemspec(:files, repository_files)
      update_gemspec(:test_files, repository_files & test_files)
    end

    # Builds the gem
    def build_task
      sh "gem build -q #{gemspec_file}"
      Dir.mkdir('pkg') unless File.exist?('pkg')
      sh "mv #{gemspec.name}-#{gemspec.version}.gem pkg/#{gemspec.name}-#{gemspec.version}.gem"
    end

    def newest_version
      git.tags.map { |tag| tag.name.split('-').last }.compact.map { |v| Gem::Version.new(v) }.max || Gem::Version.new('0.0.0')
    end

    def next_version(increment = nil)
      next_version = newest_version.segments
      increment_index = case increment
        when :micro then 3
        when :bump  then 2
        when :minor then 1
        when :major then 0
        else next_version.length - 1
      end
      
      next_version[increment_index] ||= 0
      next_version[increment_index] = next_version[increment_index].succ
      ((increment_index + 1)...next_version.length).each { |i| next_version[i] = 0 }
      
      Gem::Version.new(next_version.join('.'))
    end

    def next_version_task(increment = nil)
      ENV['VERSION'] = next_version(increment).version
      puts "Releasing version #{ENV['VERSION']}..."
    end

    # Updates the version number in the gemspec file, the VERSION constant in the main
    # include file and the contents of the VERSION file.
    def version_task
      update_gemspec(:version, ENV['VERSION']) if ENV['VERSION']
      update_gemspec(:date, Date.today)

      update_version_file(gemspec.version)
      update_version_constant(gemspec.version)
    end

    def check_version_task
      raise "#{ENV['VERSION']} is not a valid version number!" if ENV['VERSION'] && !Gem::Version.correct?(ENV['VERSION'])
      proposed_version = Gem::Version.new(ENV['VERSION'] || gemspec.version)
      raise "This version (#{proposed_version}) is not higher than the highest tagged version (#{newest_version})" if newest_version >= proposed_version
    end

    # Checks whether the current branch is not diverged from the remote branch
    def check_not_diverged_task
      raise "The current branch is diverged from the remote branch!" if git.log.between('HEAD', git.remote(remote).branch(remote_branch).gcommit).any?
    end

    # Checks whether the repository status ic clean
    def check_clean_status_task
      raise "The current working copy contains modifications" if git.status.changed.any?
    end

    # Checks whether the current branch is correct
    def check_current_branch_task
      raise "Currently not on #{local_branch} branch!" unless git.branch.name == local_branch.to_s
    end

    # Fetches the latest updates from Github
    def fetch_origin_task
      git.fetch('origin')
    end

    # Commits every file that has been changed by the release task.
    def commit_modified_files_task
      if modified_files.any?
        modified_files.each { |file| git.add(file) }
        git.commit("Released #{gemspec.name} gem version #{gemspec.version}")
      end
    end

    # Adds a tag for the released version
    def tag_version_task
      git.add_tag("#{gemspec.name}-#{gemspec.version}")
    end

    # Pushes the changes and tag to github
    def github_release_task
      git.push(remote, remote_branch, true)
    end

    # # Checks whether Rubyforge is configured properly
    # def check_rubyforge_task
    #   # Login no longer necessary when using rubyforge 2.0.0 gem
    #   # raise "Could not login on rubyforge!" unless `rubyforge login 2>&1`.strip.empty?
    #   output = `rubyforge names`.split("\n")
    #   raise "Rubyforge group not found!"   unless output.any? { |line| %r[^groups\s*\:.*\b#{Regexp.quote(gemspec.rubyforge_project)}\b.*] =~ line }
    #   raise "Rubyforge package not found!" unless output.any? { |line| %r[^packages\s*\:.*\b#{Regexp.quote(gemspec.name)}\b.*] =~ line }
    # end

    # # Task to release the .gem file toRubyforge.
    # def rubyforge_release_task
    #   sh 'rubyforge', 'add_release', gemspec.rubyforge_project, gemspec.name, gemspec.version.to_s, "pkg/#{gemspec.name}-#{gemspec.version}.gem"
    # end
    
    def gemcutter_release_task
      sh "gem push pkg/#{gemspec.name}-#{gemspec.version}.gem"
    end

    # Gem release task.
    # All work is done by the task's dependencies, so just display a release completed message.
    def release_task
      puts
      puts '------------------------------------------------------------'
      puts "Released #{gemspec.name} version #{gemspec.version}"
    end

    private

    # Checks whether this project has any RSpec files
    def has_specs?
      FileList[spec_pattern].any?
    end

    # Checks whether this project has any unit test files
    def has_tests?
      FileList[test_pattern].any?
    end

    # Loads the gemspec file
    def load_gemspec!
      @gemspec = eval(File.read(@gemspec_file))
    end

    # Updates the VERSION file with the new version
    def update_version_file(version)
      if File.exists?('VERSION')
        File.open('VERSION', 'w') { |f| f << version.to_s }
        modified_files << 'VERSION'
      end
    end

    # Updates the VERSION constant in the main include file if it exists
    def update_version_constant(version)
      if main_include && File.exist?(main_include)
        file_contents = File.read(main_include)
        if file_contents.sub!(/^(\s+VERSION\s*=\s*)[^\s].*$/) { $1 + version.to_s.inspect }
          File.open(main_include, 'w') { |f| f << file_contents }
          modified_files << main_include
        end
      end
    end

    # Updates an attribute of the gemspec file.
    # This function will open the file, and search/replace the attribute using a regular expression.
    def update_gemspec(attribute, new_value, literal = false)

      unless literal
        new_value = case new_value
          when Array        then "%w(#{new_value.join(' ')})"
          when Hash, String then new_value.inspect
          when Date         then new_value.strftime('%Y-%m-%d').inspect
          else              raise "Cannot write value #{new_value.inspect} to gemspec file!"
        end
      end

      spec   = File.read(gemspec_file)
      regexp = Regexp.new('^(\s+\w+\.' + Regexp.quote(attribute.to_s) + '\s*=\s*)[^\s].*$')
      if spec.sub!(regexp) { $1 + new_value }
        File.open(gemspec_file, 'w') { |f| f << spec }
        modified_files << gemspec_file

        # Reload the gemspec so the changes are incorporated
        load_gemspec!
      end
    end

    # Updates the tasks file using the latest file found on Github
    def update_tasks_task
      require 'net/http'

      server = 'github.com'
      path   = '/wvanbergen/github-gem/raw/master/tasks/github-gem.rake'

      Net::HTTP.start(server) do |http|
        response = http.get(path)
        open(__FILE__, "w") { |file| file.write(response.body) }
      end

      relative_file = File.expand_path(__FILE__).sub(%r[^#{git.dir.path}/], '')
      if git.status[relative_file] && git.status[relative_file].type == 'M'
        git.add(relative_file)
        git.commit("Updated to latest gem release management tasks.")
        puts "Updated to latest version of gem release management tasks."
      else
        puts "Release managament tasks already are at the latest version."
      end
    end

  end
end
