module MetricFu

  # A list of metrics which are available in the MetricFu system.
  #
  # These are metrics which have been developed for the system.  Of
  # course, in order to use these metrics, their respective gems must
  # be installed on the system.
  AVAILABLE_METRICS = [:churn, :flog, :flay, :reek, 
                       :roodi, :saikuro, :rcov]

  AVAILABLE_GRAPHS = [:flog, :flay, :reek, :roodi, :rcov]

  # The @@configuration class variable holds a global type configuration
  # object for any parts of the system to use.
  def self.configuration
    @@configuration ||= Configuration.new
  end

  # = Configuration
  #
  # The Configuration class, as it sounds, provides methods for
  # configuring the behaviour of MetricFu.
  #
  # == Customization for Rails
  #
  # The Configuration class checks for the presence of a
  # 'config/environment.rb' file.  If the file is present, it assumes
  # it is running in a Rails project.  If it is, it will:
  #
  # * Add 'app' to the @code_dirs directory to include the
  #   code in the app directory in the processing
  # * Add :stats to the list of metrics to run to get the Rails stats
  #   task
  #
  # == Customization for CruiseControl.rb
  #
  # The Configuration class checks for the presence of a 
  # 'CC_BUILD_ARTIFACTS' environment variable.  If it's found
  # it will change the default output directory from the default
  # "tmp/metric_fu to the directory represented by 'CC_BUILD_ARTIFACTS'
  #
  # == Deprications
  #
  # The Configuration class checks for several deprecated constants
  # that were previously used to configure MetricFu.  These include
  # CHURN_OPTIONS, DIRECTORIES_TO_FLOG, SAIKURO_OPTIONS, 
  # and MetricFu::SAIKURO_OPTIONS.
  #
  # These have been replaced by config.churn, config.flog and
  # config.saikuro respectively.
  class Configuration

    def initialize #:nodoc:#
      warn_about_deprecated_config_options
      reset
      add_attr_accessors_to_self
      add_class_methods_to_metric_fu
    end
  
    # Searches through the instance variables of the class and
    # creates a class method on the MetricFu module to read the value
    # of the instance variable from the Configuration class.
    def add_class_methods_to_metric_fu
      instance_variables.each do |name|
        method_name = name[1..-1].to_sym
        method = <<-EOF
                  def self.#{method_name}
                    configuration.send(:#{method_name})
                  end
        EOF
        MetricFu.module_eval(method)
      end
    end
   
    # Searches through the instance variables of the class and creates
    # an attribute accessor on this instance of the Configuration 
    # class for each instance variable.
    def add_attr_accessors_to_self
      instance_variables.each do |name|
        method_name = name[1..-1].to_sym
        MetricFu::Configuration.send(:attr_accessor, method_name)
      end
    end

    # Check if certain constants that are deprecated have been
    # assigned.  If so, warn the user about them, and the 
    # fact that they will have no effect.
    def warn_about_deprecated_config_options
      if defined?(::MetricFu::CHURN_OPTIONS)
        raise("Use config.churn instead of MetricFu::CHURN_OPTIONS")
      end
      if defined?(::MetricFu::DIRECTORIES_TO_FLOG)
        raise("Use config.flog[:dirs_to_flog] "+
              "instead of MetricFu::DIRECTORIES_TO_FLOG") 
      end
      if defined?(::MetricFu::SAIKURO_OPTIONS)
        raise("Use config.saikuro instead of MetricFu::SAIKURO_OPTIONS")
      end
      if defined?(SAIKURO_OPTIONS)
        raise("Use config.saikuro instead of SAIKURO_OPTIONS")
      end
    end

    # This allows us to have a nice syntax like:
    #
    #   MetricFu.run do |config|
    #     config.base_directory = 'tmp/metric_fu'
    #   end
    #
    # See the README for more information on configuration options.
    def self.run
      yield MetricFu.configuration
    end
   
    # This does the real work of the Configuration class, by setting
    # up a bunch of instance variables to represent the configuration
    # of the MetricFu app.
    def reset
      @base_directory = ENV['CC_BUILD_ARTIFACTS'] || 'tmp/metric_fu'
      @scratch_directory = File.join(@base_directory, 'scratch')
      @output_directory = File.join(@base_directory, 'output')
      @data_directory = File.join(@base_directory, '_data')
      @metric_fu_root_directory = File.join(File.dirname(__FILE__), 
                                                        '..', '..')
      @template_directory =  File.join(@metric_fu_root_directory, 
                                       'lib', 'templates') 
      @template_class = AwesomeTemplate
      set_metrics
      set_graphs
      set_code_dirs
      @flay     = { :dirs_to_flay => @code_dirs  } 
      @flog     = { :dirs_to_flog => @code_dirs  }
      @reek     = { :dirs_to_reek => @code_dirs  }
      @roodi    = { :dirs_to_roodi => @code_dirs }
      @saikuro  = { :output_directory => @scratch_directory + '/saikuro', 
                    :input_directory => @code_dirs,
                    :cyclo => "",
                    :filter_cyclo => "0",
                    :warn_cyclo => "5",
                    :error_cyclo => "7",
                    :formater => "text"}
      @churn    = {}
      @stats    = {}
      @rcov     = { :test_files => ['test/**/*_test.rb', 
                                    'spec/**/*_spec.rb'],
                    :rcov_opts => ["--sort coverage", 
                                   "--no-html", 
                                   "--text-coverage",
                                   "--no-color",
                                   "--profile",
                                   "--rails",
                                   "--exclude /gems/,/Library/,/usr/,spec"]}
                                   
      @graph_theme = { :colors => %w(orange purple green white red blue pink yellow),
                       :marker_color => 'blue',
                       :background_colors => %w(white white)}
      
      relative_font_path = [File.dirname(__FILE__), '..', '..', 'vendor', '_fonts', 'monaco.ttf']
      @graph_font = File.expand_path(File.join(relative_font_path))
      
    end

    # Perform a simple check to try and guess if we're running
    # against a rails app.
    #
    # @todo  This should probably be made a bit more robust.
    def rails?
      @rails = File.exist?("config/environment.rb")
    end

    # Add the :stats task to the AVAILABLE_METRICS constant if we're
    # running within rails.
    def set_metrics
      if rails?
        @metrics = MetricFu::AVAILABLE_METRICS + [:stats]
      else
        @metrics = MetricFu::AVAILABLE_METRICS
      end 
    end
    
    def set_graphs
      @graphs = MetricFu::AVAILABLE_GRAPHS 
    end

    # Add the 'app' directory if we're running within rails.
    def set_code_dirs
      if rails?
        @code_dirs = ['app', 'lib']
      else
        @code_dirs = ['lib']
      end
    end
    
    def platform #:nodoc:
      return PLATFORM
    end
    
    def is_cruise_control_rb?
      !!ENV['CC_BUILD_ARTIFACTS']
    end
  end
end