class Disk < ApplicationRecord
  belongs_to :hardware
  belongs_to :storage
  belongs_to :storage_profile
  belongs_to :backing, :polymorphic => true
  has_many :partitions
  virtual_column :allocated_space,             :type => :integer, :uses => :partitions
  virtual_column :allocated_space_percent,     :type => :float,   :uses => :allocated_space
  virtual_column :unallocated_space,           :type => :integer, :uses => :allocated_space
  virtual_column :unallocated_space_percent,   :type => :float,   :uses => :unallocated_space
  # TODO: add arel
  virtual_column :used_percent_of_provisioned, :type => :float
  virtual_column :partitions_aligned,          :type => :string,  :uses => {:partitions => :aligned}
  virtual_attribute :used_disk_storage, :integer, :arel => (lambda do |t|
    t.grouping(t.coalesce([t[:size_on_disk], t[:size], 0]))
  end)

  # A performance improvement was introduced in Rails 6:
  #
  #   https://github.com/rails/rails/commit/cc2d614e
  #
  # Causes the `present` column in this class to raise the following error:
  #
  #   ActiveRecord::DangerousAttributeError:
  #     present? is defined by Active Record. Check to make sure that you don't
  #     have an attribute or method with the same name.
  #
  # Since there is no whitelist for this method, this attempts to circumvent
  # that autogenerated error to allow our previously named column to still work
  # properly.
  #
  def self.dangerous_attribute_method?(name)
    return if name == "present?"

    super
  end

  def self.find_hard_disks
    where("device_type != 'floppy' AND device_type NOT LIKE '%cdrom%'").to_a
  end

  def self.find_floppies
    where("device_type = 'floppy'").to_a
  end

  def self.find_cdroms
    where("device_type LIKE '%cdrom%'").to_a
  end

  def allocated_space
    return nil if size.nil?

    partitions.inject(0) { |t, p| t + p.size }
  end

  def allocated_space_percent
    return nil if size.nil? || size == 0

    Float(allocated_space) / size * 100
  end

  def unallocated_space
    return nil if size.nil?

    size - allocated_space
  end

  def unallocated_space_percent
    return nil if size.nil? || size == 0

    Float(unallocated_space) / size * 100
  end

  def volumes
    partitions.collect(&:volumes).flatten.uniq
  end

  def used_percent_of_provisioned
    size.to_i == 0 ? 0.0 : (size_on_disk.to_f / size.to_f * 1000.0).round / 10.0
  end

  def rdm_disk?
    disk_type && disk_type.starts_with?("rdm")
  end

  def partitions_aligned
    return "Not Applicable" if rdm_disk?

    plist = partitions
    return "Unknown" if plist.empty?
    return "True"    if plist.all?(&:aligned?)
    return "False"   if plist.any? { |p| p.aligned? == false }

    "Unknown"
  end

  def used_disk_storage
    return self["used_disk_storage"] if has_attribute?("used_disk_storage")

    size_on_disk || size || 0
  end
end
