group.rb

class Group < ActiveRecord::Base
	
	set_primary_key :id
	
	belongs_to :type, class_name: "GroupType"
	belongs_to :parent, class_name: "Group", foreign_key: "parent_id"
	has_many :children, class_name: "Group", foreign_key: "parent_id"

	# Haven't played around with this part too much yet.
	accepts_nested_attributes_for :children

	# NOTE:
	# 1. Shouldn't really need to include :user and check their activity
	# (I think that might be able to be done in the Membership class, but
	# it should also be handled via the membership. Maybe even strictly.
	# 2. Should a user ever really be "deactivated"?
	# 3. An expiration date of 0000-00-00 will never expire 
	has_many :memberships, :include => :user, :conditions => [ '(memberships.expiration = 0000-00-00 OR memberships.expiration > ?) AND users.active = 1', Date.today]

	has_many :roles, :through => :memberships, :order => 'roles.rank'
	has_many :members, :through => :memberships, :source => :user
	has_many :ordered_members, :through => :members, :source => :user, :order => 'roles.rank'
	
	# Provides a list of groups that are subordinate to none. (Mwahahaha)
	scope :roots, :conditions => { :parent_id => "" }

	# Checks to see whether or not this group has a parent.
	# In other words, whether it is subordinate to another
	# group or not.
	#
	# * *Returns* :
	# 	- +bool+ -> if this group has a parent
	#
	def has_parent?
		!(parent.nil? || parent == self)
	end
	
	def ordered_members
		members.joins(:memberships => :roles).order("roles.rank")
	end
	
	# Returns list of ancestors, starting from parent until root.
	#
	# subchild1.ancestors # => [child1, root]
	def ancestors
		node, nodes = self, []
		nodes << node = node.parent while node.has_parent?
		nodes
	end
	
	# Returns list of ancestors, including self until root.
	#
	# child.lineage # => [self, root]
	def lineage
		[] << self << ancestors
	end
	
	# Returns the root node of the tree.
	def root
		node = self
		node = node.parent while node.parent
		node
	end
	
	# Useful for permissions
	def child_of(adult)
		return parent.id == adult.id || (parent.child_of(adult) if has_parent?) || false
	end
	
	# Returns the short name of the group
	def short
		read_attribute(:short).empty? ? id : read_attribute(:short)
	end

	def as_json(options={})
		super(:include => [:children])
	end
end