# Groups organize the User. 
# 
# Group have the following attributes
# * name
# * description
# * type (to specify, if it is a OrderGroup)
# * role_admin, role_suppliers, role_article_eta, role_finance, role_orders
# * weekly_task (if the group should do a job ervery week)
# * weekday (on which weekday should the job be done? 1 means monday and so on)
#
# A Member gets the roles from the Group
class Group < ActiveRecord::Base
  has_many :memberships, :dependent => :destroy
  has_many :users, :through => :memberships
  has_many :tasks
  # returns all non-finished tasks
  has_many :open_tasks, :class_name => 'Task', :conditions => ['done = ?', false], :order => 'due_date ASC'
  
  attr_accessible :name, :description, :role_admin, :role_suppliers, :role_article_meta, :role_finance, :role_orders, 
                  :weekly_task, :weekday, :task_name, :task_description, :task_required_users
  
  validates_length_of :name, :in => 1..25
  validates_uniqueness_of :name
  
  # messages
  ERR_LAST_ADMIN_GROUP_UPDATE = "Der letzten Gruppe mit Admin-Rechten darf die Admin-Rolle nicht entzogen werden"
  ERR_LAST_ADMIN_GROUP_DELETE = "Die letzte Gruppe mit Admin-Rechten darf nicht gelöscht werden"
  
  # Returns true if the given user if is an member of this group.
  def member?(user)
    memberships.find_by_user_id(user.id)
  end
  
  # Returns all NONmembers and a checks for possible multiple OrderGroup-Memberships
  def non_members
    nonMembers = Array.new
    for user in User.find(:all, :order => "nick")
      unless self.users.include?(user) || ( self.is_a?(OrderGroup) && user.find_ordergroup )
        nonMembers << user      
      end  
    end
    return nonMembers
  end
  
  # Check before destroy a group, if this is the last group with admin role
  def before_destroy
    raise ERR_LAST_ADMIN_GROUP_DELETE if self.role_admin == true && Group.find_all_by_role_admin(true).size == 1
  end
  
  # Returns an Array with date-objects to represent the next weekly-tasks
  def next_weekly_tasks(number = 8)
    # our system starts from 0 (sunday) to 6 (saturday)
    # get difference between groups weekday and now
    diff = self.weekday - Time.now.wday 
    if diff >= 0  
      # weektask is in current week
      nextTask = diff.day.from_now
    else
      # weektask is in the next week
      nextTask = (diff + 7).day.from_now
    end
    # now generate the Array
    nextTasks = Array.new
    number.times do
      nextTasks << nextTask
      nextTask = 1.week.from_now(nextTask)
    end
    return nextTasks
  end
 
  # get all groups, which are NOT OrderGroups
  #TODO: better implement a new model, which inherits from Group, e.g. WorkGroup
  def self.workgroups
    Group.find :all, :conditions => "type IS NULL"
  end
  
  protected
  
  # validates uniqueness of the Group.name. Checks groups and order_groups
  def validate
    errors.add(:name, "ist schon vergeben") if (group = Group.find_by_name(name) || group = OrderGroup.find_by_name(name)) && self != group
  end

  # add validation check on update
  def validate_on_update
    # error if this is the last group with admin role and role_admin should set to false
    errors.add(:role_admin, ERR_LAST_ADMIN_GROUP_UPDATE) if self.role_admin == false && Group.find_all_by_role_admin(true).size == 1 && self == Group.find(:first, :conditions => "role_admin = 1")
  end
  
end