module BigBench
  
  # The configuration is configured in the test reciepts and looks like this:
  #
  #    BigBench.configure = {
  #      :duration    => 10.seconds,
  #      :output      => "test.ljson",
  #      :users       => 20,
  #      :basic_auth  => ['username', 'secret']
  #    }
  # 
  # Single values can be set and retrieved like this:
  # 
  #    BigBench.config.duration = 20.minutes
  #    BigBench.config.duration # => 1200 (seconds)
  # 
  # The following configuration values are possible - stared configurations need to be present:
  #
  # [duration*]   How long will the benchmark take by default. This value can be overridden by every benchmark.
  # [output*]     The file where the results should be written to. Usually one takes the <tt>*.ljson</tt> format which is simply a file
  #               that contains a fully valid JSON object on every line. This makes it easy to process the results later on, because there's
  #               no need to parse the whole results JSON, which can get huge, at once.
  # [users]       How many users execute the benchmarks concurrently. This can be overridden by every benchmark and defaults to <tt>1</tt>.
  # [basic_auth]  A basic authentication that is used by ALL requests. This can be overridden per fragment in every benchmark.
  #
  #                 BigBench.config.basic_auth = ['username', 'password']
  #
  module Configuration
    
    # The main config object for BigBench. It allows config options to
    # be added and forces some default values before it is <tt>valid?</tt>
    class Config
      attr_accessor :duration
      attr_accessor :output
      attr_accessor :users
      attr_accessor :mode
      attr_accessor :bot_checks_every
      attr_accessor :basic_auth
      
      VALIDATE_OPTIONS = [:duration, :output, :users]
      
      def initialize
        @users, @duration, @mode, @bot_checks_every = 1, 1.second, :local, 1.minute
      end
      
      def self.add_option(name)
        attr_accessor name unless self.respond_to?(name)
      end
      
      def valid?
        VALIDATE_OPTIONS.each{ |option| return false if send(option).nil? }
        true
      end
    end
    
    # Is returned if the configuration is not filled sufficiently
    class InvalidOptions < StandardError
      def message
        "At least: #{Config::VALIDATE_OPTIONS.join(', ')} are required"
      end
    end
    
    @config = Config.new
    
    # Configures the benchmarks with a hash. If the config methods are not present yet,
    # they are added to the config object
    def self.configure=(config)
      raise "Config must be a Hash" unless config.is_a?(Hash)
      config.each { |option, value|
        @config.class.add_option(option)
        @config.send "#{option}=", value
      }
    end
    
    # Returns the current config object
    def self.config
      @config
    end
    
    # Resets the config object
    def self.reset!
      @config = Config.new
    end
    
  end
  
  # Configure the benchmark by supplying a hash of options like this:
  # 
  #    BigBench.configure = {
  #      :duration    => 10.seconds,
  #      :output      => "test.ljson",
  #      :users       => 20,
  #      :basic_auth  => ['username', 'secret']
  #    }
  #
  # Those values can then be set and retreived with <tt>BigBench.config.duration</tt>, ...
  def self.configure=(config)
    Configuration.configure=(config)
  end
  
  # Set and retreive the config values like this:
  #
  #    BigBench.config.duration # => 10.seconds
  #    BigBench.config.duration = 20.minutes
  #
  def self.config
    Configuration.config
  end
  
  # Checks if all necessary config options are set and raises an <tt>InvalidOptions</tt> exception if not
  def self.check_config!
    raise Configuration::InvalidOptions.new unless config.valid?
    true
  end
  
end