class Pipette
  module Commands

    # cmd_opts:
    #
    #   size: Size of each volume, in GB
    #   name: Name of the volume group to create
    #   ebs_per_mirror: Number of EBS volumes to put in each mirrored disk. Default 2.
    #   num_mirrors: Number of mirrors to create, to be spanned by the volume group. Default 2.
    def init(cmd_opts)
      raise "No volume group name specified" unless cmd_opts[:name]
      raise "No EBS volume size specified" unless cmd_opts[:size]

      md_devs = create_mirrors(cmd_opts[:size],
                               cmd_opts[:num_mirrors],
                               cmd_opts[:ebs_per_mirror])


      vg_create cmd_opts[:name], md_devs
    end

    def append(cmd_opts)
      raise "No volume group name specified" unless cmd_opts[:name]
      raise "No EBS volume size specified" unless cmd_opts[:size]

      md_devs = create_mirrors(cmd_opts[:size],
                               cmd_opts[:num_mirrors],
                               cmd_opts[:ebs_per_mirror])

      vg_extend cmd_opts[:name], md_devs
    end

    def add(cmd_opts)
      raise "No logical volume name specified" unless cmd_opts[:name]
      raise "No logical volume size specified" unless cmd_opts[:size]
      raise "No volume group name specified" unless cmd_opts[:volume]

      dev = lv_create(cmd_opts[:name], cmd_opts[:volume], cmd_opts[:size])
      format(dev)
      mount(dev, "/data/#{cmd_opts[:name]}")
    end

    def grow(cmd_opts)
      raise "No logical volume name specified" unless cmd_opts[:name]
      raise "No logical volume size specified" unless cmd_opts[:size]
      raise "No volume group name specified" unless cmd_opts[:volume]

      dev = lv_dev(cmd_opts[:volume], cmd_opts[:name])
      lv_extend(dev, cmd_opts[:size])
      growfs(dev)
    end

		def remove(cmd_opts)
      raise "No logical volume name specified" unless cmd_opts[:name]
      raise "No volume group name specified" unless cmd_opts[:volume]

			dev = lv_dev(cmd_opts[:volume], cmd_opts[:name])
			umount(dev)
			lv_remove(dev)
		end

    protected

    def create_mirrors(size, num_mirrors = 2, num_disks = 2)
      md_devs = []
      num_mirrors.times do
        volumes = []
        num_disks.times do
          volumes << create_volume(size)
        end

        devices = []
        volumes.each do |v_id|
          mp = next_avail_disk
          mount_volume v_id, mp
          devices << mp
        end

        wait_for devices

        md_dev = next_md
        create_md_mirror md_dev, *devices

        pv_create md_dev
        md_devs << md_dev
      end

      md_devs
    end

  end
end