module RubyQA
  class Resource
    # This is responsible for data gathering & parsing to provide the test-writers direct access to 
    # resource information without needing to manually specify them in their code. 
    attr_reader :name, :data

    # REQUIREMENTS
    #  This is a Hash that is meant to serve as a way of determining if a resource needs to be
    #  added to a host. If a key is defined here it will be checked against the information
    #  configured on the host. If it does not find matching keys it will not be added
    #
    #  If empty it will just be assumed that this resource can be added to the host.
    #
    #  This MUST be defined in each Resourced subclass, as otherwise manager will error when 
    #  adding this resource to host.
    REQUIREMENTS = {}


    def initialize (host)
      @host = host
      @data = Hash.new
      @gather_command = ""
    end

    # TODO: Create validate_host method to replace REQUIREMENTS for a bit more flexiblity on 
    #       determining if a host is valid for this resource to be added to it.

    # TODO: Add a discovery method for the resource to find out if the necessary utilities or
    #      otherwise are on the host
    
    def gather
      # Handles gathering the information from the host. Provided the developer has provided a 
      # @gather_command it will run that command on the remote host & provide the output to the
      # user/dev implemented parse command. This can be overwritten by the sublcass to make it all in one in cases
      # where something needs to be done differently
      if not @gather_command.empty?
        output = @host.exec(@gather_command)
        parse(output)
      else
        raise "@gather_command was not defined on Resource[#{@name}]"
      end
    end

    def parse(output)
      # Subclass Implemented method that is supposed to handle parsing the gathered data on the remote node.
      raise "parse not yet implemented on Resource[#{@name}]"
    end

    def self.all_resources
      ## This will allow me to iterate through all subclasses without
      ## having to manually define them elsewhere
      ObjectSpace.each_object(Class).select{|klass| klass < self}
    end
  end


  ## Gathers the facts from the remote machine via the facter utility
  class Facts < Resource
    require 'json'

    REQUIREMENTS = {}
    def initialize (host)
      super host
      @name = 'facts'
      @gather_command = "facter -j"
    end

    def parse (output)
      @data = JSON.load(output)
    end
  end

  class DRDB < Resource
    # Handles gathering DRBD related information from the drbdadm utility. 
    
    REQUIREMENTS = {
      :cluster => true
    }

    def initialize (host)
      super host
      @name = 'facts'
      @gather_command = "sudo drbdadm"
    end

    # TODO: Add a XML parser to requires & have the parse method load the config from the `sudo drbdadm dump-xml`
    #       command 

    def parse (output)
      @data = output
    end
  end


end