begin
  require 'activerecord'
rescue LoadError
  require 'active_record'
end

class ActiveRecord::Base
  extend OrmAdapter::ToAdapter
  
  class OrmAdapter < ::OrmAdapter::Base

    # Do not consider these to be part of the class list
    def self.except_classes
      @@except_classes ||= [
        "CGI::Session::ActiveRecordStore::Session",
        "ActiveRecord::SessionStore::Session"
      ]
    end

    # Gets a list of the available models for this adapter
    def self.model_classes
      begin
        klasses = ::ActiveRecord::Base.__send__(:descendants) # Rails 3
      rescue
        klasses = ::ActiveRecord::Base.__send__(:subclasses) # Rails 2
      end

      klasses.select do |klass|
        !klass.abstract_class? && !except_classes.include?(klass.name)
      end
    end

    # Return list of column/property names
    def column_names
      klass.column_names
    end

    # @see OrmAdapter::Base#get!
    def get!(id)
      klass.find(wrap_key(id))
    end

    # @see OrmAdapter::Base#get
    def get(id)
      klass.first :conditions => { klass.primary_key => wrap_key(id) }
    end

    # @see OrmAdapter::Base#find_first
    def find_first(options)
      conditions, order = extract_conditions_and_order!(options)
      klass.first :conditions => conditions_to_fields(conditions), :order => order_clause(order)
    end

    # @see OrmAdapter::Base#find_all
    def find_all(options)
      conditions, order = extract_conditions_and_order!(options)
      klass.all :conditions => conditions_to_fields(conditions), :order => order_clause(order)
    end
    
    # @see OrmAdapter::Base#create!
    def create!(attributes)
      klass.create!(attributes)
    end
    
  protected

    # Introspects the klass to convert and objects in conditions into foreign key and type fields
    def conditions_to_fields(conditions)
      fields = {}
      conditions.each do |key, value|
        if value.is_a?(ActiveRecord::Base) && (assoc = klass.reflect_on_association(key.to_sym)) && assoc.belongs_to?
          fields[assoc.primary_key_name] = value.send(value.class.primary_key)          
          fields[assoc.options[:foreign_type]] = value.class.base_class.name.to_s if assoc.options[:polymorphic]
        else
          fields[key] = value
        end
      end
      fields
    end
    
    def order_clause(order)
      order.map {|pair| "#{pair[0]} #{pair[1]}"}.join(",")
    end
  end
end