# encoding: utf-8
module Mongoid #:nodoc

  # The collections module is used for providing functionality around setting
  # up and updating collections.
  module Collections
    extend ActiveSupport::Concern

    included do
      cattr_accessor :_collection, :collection_name
      self.collection_name = self.name.collectionize
    end

    # Get the collection for the class.
    #
    # @note Defining methods instead of delegate to avoid calls to
    #   Kernel.caller for class load performance reasons.
    #
    # @example Get the collection.
    #   person.collection
    #
    # @return [ Collection ] The class collection.
    #
    # @since 1.0.0
    def collection
      self.class.collection
    end

    # Get the database for the class.
    #
    # @note Defining methods instead of delegate to avoid calls to
    #   Kernel.caller for class load performance reasons.
    #
    # @example Get the database.
    #   person.db
    #
    # @return [ DB ] The class db.
    #
    # @since 1.0.0
    def db
      self.class.db
    end

    module ClassMethods #:nodoc:

      # Returns the collection associated with this +Document+. If the
      # document is embedded, there will be no collection associated
      # with it unless it's in a cyclic relation.
      #
      # @example Get the collection.
      #   Model.collection
      #
      # @return [ Collection ] The Mongoid collection wrapper.
      def collection
        raise Errors::InvalidCollection.new(self) if embedded? && !cyclic
        self._collection || set_collection
        add_indexes; self._collection
      end

      # Return the database associated with this collection.
      #
      # @example Get the database object.
      #   Model.db
      #
      # @return [ Mongo::DB ] The Mongo daatabase object.
      def db
        collection.db
      end

      # Convenience method for getting index information from the collection.
      #
      # @example Get the index information from the collection.
      #   Model.index_information
      #
      # @return [ Array ] The collection index information.
      def index_information
        collection.index_information
      end

      # Macro for setting the collection name to store in.
      #
      # @example Store in a separate collection than the default.
      #   Model.store_in :population
      #
      # @example Store in a capped collection.
      #   Model.store_in :population, :capped => true, :max => 10000
      #
      # @param [ Symbol ] name The name of the collection.
      # @param [ Hash ] options The collection options.
      #
      # @option options [ true, false ] :capped If the collection is capped.
      # @option options [ Integer ] :size The capped collection size.
      # @option options [ Integer ] :max The maximum number of docs in the
      #   capped collection.
      def store_in(name, options = {})
        self.collection_name = name.to_s
        set_collection(options)
      end

      protected

      # Set the collection on the class.
      #
      # @example Set the collection.
      #   Model.set_collection
      #
      # @param [ Hash ] options The collection options.
      #
      # @option options [ true, false ] :capped If the collection is capped.
      # @option options [ Integer ] :size The capped collection size.
      # @option options [ Integer ] :max The maximum number of docs in the
      #   capped collection.

      # @return [ Collection ] The Mongoid collection wrapper.
      def set_collection(options = {})
        self._collection = Collection.new(self, self.collection_name, options)
      end
    end
  end
end