# Copyright (C) 2013 MongoDB Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

module BSON

  # Injects behaviour for encoding and decoding symbol values to and from
  # raw bytes as specified by the BSON spec.
  #
  # @note Symbols are deprecated in the BSON spec, but they are still
  #   currently supported here for backwards compatibility.
  #
  # @see http://bsonspec.org/#/specification
  #
  # @since 2.0.0
  module Symbol

    # A symbol is type 0x0E in the BSON spec.
    #
    # @since 2.0.0
    BSON_TYPE = 14.chr.force_encoding(BINARY).freeze

    # Get the symbol as encoded BSON.
    #
    # @example Get the symbol as encoded BSON.
    #   :test.to_bson
    #
    # @return [ Symbol ] The encoded symbol.
    #
    # @see http://bsonspec.org/#/specification
    #
    # @since 2.0.0
    def to_bson(encoded = ''.force_encoding(BINARY))
      to_s.to_bson(encoded)
    end

    # Get the symbol as a BSON key name encoded C symbol.
    #
    # @example Get the symbol as a key name.
    #   :test.to_bson_key
    #
    # @return [ String ] The encoded symbol as a BSON key.
    #
    # @see http://bsonspec.org/#/specification
    #
    # @since 2.0.0
    def to_bson_key(encoded = ''.force_encoding(BINARY))
      to_s.to_bson_key(encoded)
    end

    module ClassMethods
      # Deserialize a symbol from BSON.
      #
      # @param [ BSON ] bson The bson representing a symbol.
      #
      # @return [ Regexp ] The decoded symbol.
      #
      # @see http://bsonspec.org/#/specification
      #
      # @since 2.0.0
      def from_bson(bson)
        bson.read(Int32.from_bson(bson)).from_bson_string.chop!.intern
      end
    end

    # Register this type when the module is loaded.
    #
    # @since 2.0.0
    Registry.register(BSON_TYPE, ::Symbol)
  end

  # Enrich the core Symbol class with this module.
  #
  # @since 2.0.0
  ::Symbol.send(:include, Symbol)
  ::Symbol.send(:extend, Symbol::ClassMethods)
end