module TimeLogger
  class TimeLogger

    def initialize(timer, ui)
      @timer, @ui = timer, ui
    end
    
    def start(name)
      unless @current_task.nil?
        if @current_task.name != name
          stop(@current_task.name)
        end
      end      
      @current_task = tasks[name]
      if @current_task.nil?
        @current_task = Task.new(name)
        tasks[name] = @current_task
      end
      @current_task.start(@timer)
      
      @ui.start(@current_task)
    end

    def stop(name)
      task = tasks[name]
      task.stop(@timer)
      @current_task = nil
      
      @ui.stop(task)
    end

    def list
      @ui.list(tasks.values)
    end

    private

    def tasks
      @tasks ||= {}
    end
  end

  class Task
    
    def initialize(name)
      @name = name
    end

    def name
      @name
    end

    def start(timer)
      @activity = TaskActivity.new(timer)
      @activity.start
    end

    def stop(timer)
      @activity.stop
      past_activities << @activity
      @activity = nil
    end

    def time
      past_activities.inject(0) { |t, a| t + a.time }
    end

    private

    def past_activities
      @past_activities ||= []
    end
  end

  class TaskActivity

    def initialize(timer)
      @timer = timer
    end

    def start
      @started_at = @timer.now()
    end

    def stop
      @stopped_at = @timer.now()
    end

    def time
      diff = @stopped_at.to_i - @started_at.to_i
      mins = diff / 60
    end
  end

  class Timer

    def now
      @now ||= Time.now
    end

    def add_minutes(val)
      @now = Time.at(@now.to_i + val * 60)
    end
  end

  class UI

    def start(task)
      message("Started task: #{task.name}")
    end

    def stop(task)
      message("Stopped task: #{task.name} (#{task.time} minutes)")
    end

    def list(tasks)
      tasks.each do |task|
        message("#{task.name} (#{task.time} minutes)")
      end
    end

    def message(msg)
      msgs << msg
    end

    def msgs
      @msgs ||= []
    end
  end
end