# This is the data structure it accepts, this is the output of get_vm_disks
#
# {"disks"=>
#   [{"address"=>0,
#     "description"=>"SCSI Controller",
#     "element_name"=>"SCSI Controller 0",
#     "instance_id"=>2,
#     "resource_sub_type"=>"VirtualSCSI",
#     "resource_type"=>6},
#    {"address_on_parent"=>0,
#     "description"=>"Hard disk",
#     "element_name"=>"Hard disk 1",
#     "instance_id"=>2000,
#     "parent"=>2,
#     "resource_type"=>17,
#     "capacity"=>16384,
#     "bus_sub_type"=>"VirtualSCSI",
#     "bus_type"=>6},
#    {"address"=>0,
#     "description"=>"IDE Controller",
#     "element_name"=>"IDE Controller 0",
#     "instance_id"=>3,
#     "resource_type"=>5}]}
# This is what it generates
#
# <vcloud:RasdItemsList xmlns:vcloud="http://www.vmware.com/vcloud/v1.5" 
#    xmlns:rasd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_ResourceAllocationSettingData" 
#    type="application/vnd.vmware.vcloud.rasdItemsList+xml" 
#    >
#  <vcloud:Item>
#    <rasd:Address>0</rasd:Address>
#    <rasd:Description>SCSI Controller</rasd:Description>
#    <rasd:ElementName>SCSI Controller 0</rasd:ElementName>
#    <rasd:InstanceID>2</rasd:InstanceID>
#    <rasd:ResourceSubType>VirtualSCSI</rasd:ResourceSubType>
#    <rasd:ResourceType>6</rasd:ResourceType>
#  </vcloud:Item><vcloud:Item>
#    <rasd:AddressOnParent>0</rasd:AddressOnParent>
#    <rasd:Description>Hard disk</rasd:Description> 
#    <rasd:ElementName>Hard disk 1</rasd:ElementName>
#    <rasd:HostResource vcloud:capacity="16384" vcloud:busSubType="VirtualSCSI" vcloud:busType="6"></rasd:HostResource>
#    <rasd:InstanceID>2000</rasd:InstanceID>
#    <rasd:Parent>2</rasd:Parent>
#    <rasd:ResourceType>17</rasd:ResourceType>
#  </vcloud:Item><vcloud:Item>
#     <rasd:Address>0</rasd:Address>
#     <rasd:Description>IDE Controller</rasd:Description>
#     <rasd:ElementName>IDE Controller 0</rasd:ElementName>
#     <rasd:InstanceID>3</rasd:InstanceID>
#     <rasd:ResourceType>5</rasd:ResourceType>
#  </vcloud:Item></vcloud:RasdItemsList>
# 
module Fog
  module Generators
    module Compute
      module Vcloudng

        class Disks
          
          def initialize(items=[])
            @items = items['disks']
          end
          
          def modify_hard_disk_size(disk_number, new_size)
            found = false
            @items.each do |item|
              if item['resource_type'] == 17
                if item['element_name'] == "Hard disk #{disk_number}"
                  found = true
                  raise "Hard disk size can't be reduced" if item['capacity'].to_i > new_size.to_i 
                  item['capacity'] = new_size
                end
              end
            end
            raise "Hard disk #{disk_number} not found" unless found
            true
          end
          
          def add_hard_disk(size)
            new_hard_disk = last_hard_disk.dup
            new_hard_disk['capacity'] = size
            new_hard_disk['element_name'] = increase_hard_disk_name(new_hard_disk['element_name'])
            new_hard_disk['address_on_parent'] += 1 
            new_hard_disk['instance_id'] += 1 
            @items << new_hard_disk
          end
          
          def delete_hard_disk(disk_number)
            @items.delete_if {|item| item['resource_type'] == 17 && item['element_name'] =~ /#{disk_number}$/ }
          end
          
          def disks
            { 'disks' => @items }
          end
          
          def generate_xml
            output = ""
            output << header
            @items.each do |item|
              output << case item['resource_type']
                        when 6
                          scsi_controller(item)
                        when 17
                          hard_disk_item(item)
                        when 5
                          ide_controller_item(item)
                        end
            end
            output << tail
            output
          end
          
          def header
            '<vcloud:RasdItemsList xmlns:vcloud="http://www.vmware.com/vcloud/v1.5" 
              xmlns:rasd="http://schemas.dmtf.org/wbem/wscim/1/cim-schema/2/CIM_ResourceAllocationSettingData" 
              type="application/vnd.vmware.vcloud.rasdItemsList+xml">'
          end
          
          def tail
            '</vcloud:RasdItemsList>'
          end
          
          def hard_disk_item(opts={})
            "<vcloud:Item>
              <rasd:AddressOnParent>#{opts['address_on_parent']}</rasd:AddressOnParent>
              <rasd:Description>#{opts['description']}</rasd:Description> 
              <rasd:ElementName>#{opts['element_name']}</rasd:ElementName>
              <rasd:HostResource vcloud:capacity=\"#{opts['capacity']}\" vcloud:busSubType=\"#{opts['bus_sub_type']}\" vcloud:busType=\"#{opts['bus_type']}\"></rasd:HostResource>
              <rasd:InstanceID>#{opts['instance_id']}</rasd:InstanceID>
              <rasd:Parent>#{opts['parent']}</rasd:Parent>
              <rasd:ResourceType>17</rasd:ResourceType>
            </vcloud:Item>"
          end
          
          def ide_controller_item(opts={})
            "<vcloud:Item>
               <rasd:Address>#{opts['address']}</rasd:Address>
               <rasd:Description>#{opts['description']}</rasd:Description>
               <rasd:ElementName>#{opts['element_name']}</rasd:ElementName>
               <rasd:InstanceID>#{opts['instance_id']}</rasd:InstanceID>
               <rasd:ResourceType>5</rasd:ResourceType>
            </vcloud:Item>"
          end
          
          def scsi_controller(opts={})
            "<vcloud:Item>
              <rasd:Address>#{opts['address']}</rasd:Address>
              <rasd:Description>#{opts['description']}</rasd:Description>
              <rasd:ElementName>#{opts['element_name']}</rasd:ElementName>
              <rasd:InstanceID>#{opts['instance_id']}</rasd:InstanceID>
              <rasd:ResourceSubType>#{opts['resource_sub_type']}</rasd:ResourceSubType>
              <rasd:ResourceType>6</rasd:ResourceType>
            </vcloud:Item>"
          end
          
          # helpers
          
          def last_hard_disk
             hard_disks = @items.select{|item| item['resource_type'] == 17}
             element_names = hard_disks.map{|item| item['element_name'] }
             only_numbers = element_names.map{|b| b.scan(/\d+/).first.to_i} # extract numbers
             last_number = only_numbers.sort.last # get the last number
             hard_disks.detect{|hard_disk| hard_disk["element_name"] =~ /#{last_number}$/  }
          end
          
          def increase_hard_disk_name(hard_disk_name)
            hard_disk_name.gsub(/(\d+)$/) { $1.to_i + 1 }
          end
          
        end
      end
    end
  end
end