module Buildr

  class ReleaseTask < Rake::Task

    VERSION_NUMBER_PATTERN  = /VERSION_NUMBER\s*=\s*(["'])(.*)\1/
    NEXT_VERSION_PATTERN    = /NEXT_VERSION\s*=\s*(["'])(.*)\1/

    def initialize(*args)
      super
      enhance do |task|
        # Make sure we don't have anything uncommitted in SVN.
        fail "Uncommitted SVN files violate the First Principle Of Release!" unless
          svn("status").empty?
        # Load the Rakefile and find the version numbers.
        next_ver = update_version
        # Run the deployment externally using the new version number.
        sh "rake deploy"
        update_next_version next_ver
        tag_repository
      end
    end

    # Change the Rakefile and update the current version number to the
    # next version number (VERSION_NUMBER = NEXT_VERSION). We need this
    # before making a release with the next version. Return the next version.
    def update_version()
      rakefile = File.read(Rake.application.rakefile)
      version = rakefile.scan(VERSION_NUMBER_PATTERN)[0][1] or
        fail "Looking for VERSION_NUMBER = \"...\" in your Rakefile, none found"
      next_ver = rakefile.scan(NEXT_VERSION_PATTERN)[0][1] or
        fail "Looking for NEXT_VERSION = \"...\" in your Rakefile, none found"
      if verbose
        puts "Current version:  #{version}"
        puts "Next version:     #{next_ver}"
      end

      # Switch version numbers.
      rakefile.gsub!(VERSION_NUMBER_PATTERN) { |ver| ver.sub(/(["']).*\1/, %Q{"#{next_ver}"}) }
      File.open(Rake.application.rakefile, "w") { |file| file.write rakefile }

      next_ver
    end

    # Change the Rakefile and update the next version number to one after
    # (NEXT_VERSION = NEXT_VERSION + 1). We do this to automatically increment
    # future version number after each successful release.
    def update_next_version(version)
      # Update to new version number.
      nums = version.split(".")
      nums[-1] = nums[-1].to_i + 1
      next_ver = nums.join(".")
      rakefile = File.read(Rake.application.rakefile)
      rakefile.gsub!(NEXT_VERSION_PATTERN) { |ver| ver.sub(/(["']).*\1/, %Q{"#{next_ver}"}) }
      File.open(Rake.application.rakefile, "w") { |file| file.write rakefile }

      # Commit new version number.
      svn "commit", "-m", "Changed release number to #{version}"
    end

    # Create a tag in the SVN repository.
    def tag_repository()
      # Copy to tag.
      cur_url = svn("info").scan(/URL: (.*)/)[0][0]
      new_url = cur_url.sub(/trunk$/, "tags/#{cur_ver}")
      svn "copy", cur_url, new_url
    end

    def svn(*args)
      stdin, stdout, stderr = Open3.popen3("svn", *args)
      stdin.close
      error = stderr.read
      fail error unless error.empty?
      stdout.read
    end
  end

  # Handles the build and clean tasks.
  desc "Clean all projects"
  LocalDirectoryTask.define_task("clean")
  desc "Build all projects"
  LocalDirectoryTask.define_task("build")
  desc "Make a release"
  ReleaseTask.define_task "release"

  class Project
    def build(*args, &block)
      returning(@build_task ||= recursive_task("build")) do |task|
        task.enhance args, &block
      end
    end

    def clean(*args, &block)
      returning(@clean_task ||= recursive_task("clean")) do |task|
        task.enhance args, &block
      end
    end
  end

  Project.on_create do |project|
    desc "Clean all files generated during the build process"
    project.clean

    desc "Build this project"
    project.build
  end

end