module Entrails::ActiveRecord::BetterConditions
  
  protected
  
  # Allows arrays to represent logical symbolic expressions by use of the
  # symbols :and, :or, and :not and the embedding of nested array and hash
  # conditions.
  def sanitize_sql_array_with_better_conditions(array)
    conditions = []
    joiner = 'OR'
    negate = false
    index = 0
    array.each_with_index do |element, index|
      case element
      when :and, 'and' : joiner = 'AND'
      when :or,  'or'  : joiner = 'OR'
      when :not, 'not' : negate = !negate
      else
        # following matches pattern for ActiveRecord's built-in array support
        return sanitize_sql_array_without_better_conditions(array) if index == 0 and element.is_a?(String)
        conditions << sanitize_sql(element)
      end
    end
    return if conditions.empty?
    sql = (conditions.size==1) ? conditions.first : "(#{conditions.join(") #{joiner} (")})"
    sql = "NOT (#{sql})" if negate
    sql
  end
 
  # Allows true or false to be used as a convenience to short-circuit conditional
  # branches.  
  def sanitize_sql_with_better_conditions(object)
    case object
    when true  : '1=1'
    when false : '1=0'
    else sanitize_sql_without_better_conditions(object)
    end
  end
 
  def self.extended(host)
    super
    class << host
      alias_method_chain :sanitize_sql, :better_conditions
      alias_method_chain :sanitize_sql_array, :better_conditions
    end
  end
  
end