class MetaTag < ActiveRecord::Base

  if Radiant::Config['tags.complex_strings'] == 'true'
    delim = ";"
    re_format = /^[a-zA-Z0-9,\_\-\s\/()'.&]+$/
  else
    delim = " "
    re_format = /^[a-zA-Z0-9\_\-]+$/
  end
  DELIMITER = delim
    # how to separate tags in strings (you may
    # also need to change the validates_format_of parameters 
    # if you update this)

  # if speed becomes an issue, you could remove these validations 
  # and rescue the AR index errors instead
  validates_presence_of :name
  validates_uniqueness_of :name, :case_sensitive => false
  validates_format_of :name, :with => re_format, 
    :message => "can not contain special characters"
    
  has_many_polymorphs :taggables, 
    :from => [:pages], 
    :through => :taggings, 
    :dependent => :destroy,
    :skip_duplicates => false
  
  def after_save
    # if you allow editable tag names, you might want before_save instead 
    self.name = name.downcase.strip.squeeze(" ")
  end
 
  class << self
    def find_or_create_by_name!(name)
      find_by_name(name) || create!(:name => name)
    end

    def cloud(options = {})
      options = {:by => 'popularity', :order => 'asc', :limit => 5}.merge(options)
      validate_by options[:by]
      validate_order options[:order]
      all(
        :select => 'meta_tags.*, count(*) as popularity',
        :limit => options[:limit],
        :joins => "JOIN taggings ON taggings.meta_tag_id = meta_tags.id",
        :conditions => options[:conditions],
        :group => "meta_tags.id, meta_tags.name",
        :order => "#{options[:by]} #{options[:order].upcase}"
      )
    end
    
    def validate_by(by)
      valid_field_names = column_names + ['popularity']
      valid_field_names.include?(by) or raise %Q{"by" must be one of #{valid_field_names.to_sentence}, was #{by}}
    end
    
    def validate_order(order)
      order =~ /^(asc|desc)$/i or raise %Q{"order" must be set to either "asc" or "desc"}
    end
  end
  
  def <=>(other)
    # To be able to sort an array of tags
    name <=> other.name
  end

end