conversation.rb

class Conversation < ActiveRecord::Base
  belongs_to :initiator, :class_name => '::User'
  belongs_to :recipient, :class_name => '::User'
  has_many :messages
  has_one  :last_message, -> { order("created_at DESC") }, :class_name => '::Message'
  scope :visible, -> do
    joins("LEFT OUTER JOIN blockings b ON (b.blocker_id=conversations.initiator_id AND b.blocked_id=conversations.recipient_id) OR (b.blocked_id=conversations.initiator_id AND b.blocker_id=conversations.recipient_id)").where("b.id IS NULL")
  end
  scope :between, ->(user1,user2) { with(user1).with(user2) }
  scope :with,    ->(other) { where("? IN (initiator_id,recipient_id)", other.id) }
  scope :recent,  -> { order("updated_at" => :desc) }
  scope :unread,  -> { where("messages.read" => false) } # always do includes(:last_message) for this
  delegate :read?, :to => :last_message

  def other(user)
    initiator == user ? recipient : initiator
  end

  def accessible?
    !!Conversation.visible.where(:id => self.id)
  end

end