class MkmfRakeBuilder
  attr_writer :project_dir,
              :rake_application,
              :rake_tasks,
              :rake_file_tasks,
              :dir_class,
              :file_extension,
              :extensions_to_build,
              :file_class

  def initialize
    @extconf_file = "extconf.mkmf.rb"
  end

  def build_default_task
    task(:extension => [ :compile, :install ]) do
    end
    task(:default => [ :extension ]) do
    end
  end

  def build_compile_task
    task :compile => @extensions_to_build.collect {|ext| ext.first} do
    end    
  end

  def build_spec_task
    task :spec => [:compile, :install] do
      dir = @project_dir
      require expand_path("#{dir}/spec/spec_suite")
    end
  end

  def build_lib_task
    task :lib do
      directory "lib"
    end
  end

  def build_extension_compile_tasks
    @extensions_to_build.each do |data|
      build_extension_compile_task(data[1])
    end
  end

  def build_install_task
    extension_paths = self.extension_paths
    task :install do
      extension_paths.each do |extension_path|
        library_path = library_path(extension_path)
        raise "Extension binary for #{extension_path} does not exist. Did you run rake compile?" unless library_path
        build_path = build_path(extension_path)
        raise "File #{build_path} does not exist" unless file_exists?(build_path)
        cp build_path, library_path(extension_path)
      end
    end
    extension_paths
  end

  def build_cleanup_task
    extension_paths = self.extension_paths
    task :cleanup do
      extension_paths.each do |extension_path|
        library_path = library_path(extension_path)
        rm library_path if library_path && file_exists?(library_path)

        build_file_path = build_path(extension_path)
        rm build_file_path if build_file_path && file_exists?(build_file_path)

        make_file_path = "#{build_dir(extension_path)}/Makefile"
        rm make_file_path if make_file_path && file_exists?(make_file_path)
      end
    end
    extension_paths
  end

  protected
  def extension_paths
    @extensions_to_build.collect {|data| data[1]}
  end

  def build_extension_compile_task(extension_path)
    extension_dir = "ext/#{extension_path}"
    extension = file_name(extension_path)
    extension_path = "#{extension_dir}/#{extension}.#{@file_extension}"

    desc "Builds the #{extension} extension"
    task extension.to_sym => ["#{extension_dir}/Makefile", extension_path ]

    file "#{extension_dir}/Makefile" => ["#{extension_dir}/#{@extconf_file}"] do
      extconf extension_dir
    end

    ext_files = FileList[
      "#{extension_dir}/*.c",
      "#{extension_dir}/*.h",
      "#{extension_dir}/#{@extconf_file}",
      "#{extension_dir}/Makefile",
      "lib"
    ]
    file extension_path => ext_files do
      make extension_dir
    end
  end

  def extconf(dir)
    chdir(dir) do
      ruby @extconf_file
    end
  end

  def ruby(file)
    sh("ruby #{file}")
  end

  def make(makedir)
    chdir(makedir) do
      sh("make")
    end
  end

  def chdir(dir, &block)
    @dir_class.chdir(dir) do
      yield
    end
  end

  def desc(comment)
    @rake_application.last_comment = comment
  end

  def task(*args, &block)
    @rake_tasks.define_task(*args, &block)
  end

  def file(*args, &block)
    @rake_file_tasks.define_task(*args, &block)
  end

  def build_dir(relative_extension_path)
    "#{@project_dir}/ext/#{relative_extension_path}"
  end

  def build_path(relative_extension_path)
    basename = "#{build_dir(relative_extension_path)}/#{file_name(relative_extension_path)}"
    "#{basename}.#{@file_extension}"
  end

  def library_path(relative_extension_path)
    library_directory_path = "#{@project_dir}/lib/#{file_directory(relative_extension_path)}"
    binary_name = "#{file_name(relative_extension_path)}.#{@file_extension}"
    "#{library_directory_path}/#{binary_name}"
  end

  def expand_path(path)
    @file_class.expand_path path
  end

  def file_exists?(path)
    @file_class.exists? path
  end

  def file_name(path)
    @file_class.basename path
  end

  def file_directory(path)
    @file_class.dirname path
  end
end