# Copyright (C) 2009-2014 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.

require "yaml"

# Since we have a custom bsondoc type for yaml serialization, we need
# to ensure that it's properly deserialized when parsed.
#
# @since 2.0.0
YAML.add_builtin_type("bsondoc") do |type, value|
  BSON::Document[value.map{ |val| val.to_a.first }]
end

module BSON

  # This module provides behaviour for serializing and deserializing entire
  # BSON documents, according to the BSON specification.
  #
  # @note The specification is: document ::= int32 e_list "\x00"
  #
  # @see http://bsonspec.org/#/specification
  #
  # @since 2.0.0
  class Document < ::Hash

    # Get a value from the document for the provided key. Can use string or
    # symbol access, but the fastest will be to always provide a key that is of
    # the same type as the stored keys.
    #
    # @example Get an element for the key.
    #   document["field"]
    #
    # @example Get an element for the key by symbol.
    #   document[:field]
    #
    # @param [ String, Symbol ] key The key to lookup.
    #
    # @return [ Object ] The found value, or nil if none found.
    #
    # @since 2.0.0
    def [](key)
      super(key.to_bson_normalized_key)
    end

    # Set a value on the document. Will normalize symbol keys into strings.
    #
    # @example Set a value on the document.
    #   document[:test] = "value"
    #
    # @param [ String, Symbol ] key The key to update.
    # @param [ Object ] value The value to update.
    #
    # @return [ Object ] The updated value.
    #
    # @since 3.0.0
    def []=(key, value)
      super(key.to_bson_normalized_key, value.to_bson_normalized_value)
    end

    # Instantiate a new Document. Valid parameters for instantiation is a hash
    # only or nothing.
    #
    # @example Create the new Document.
    #   BSON::Document.new(name: "Joe", age: 33)
    #
    # @param [ Hash ] elements The elements of the document.
    #
    # @since 3.0.0
    def initialize(elements = nil)
      super()
      (elements || {}).each_pair{ |key, value| self[key] = value }
    end

    # Merge this document with another document, returning a new document in
    # the process.
    #
    # @example Merge with another document.
    #   document.merge(name: "Bob")
    #
    # @param [ BSON::Document, Hash ] other The document/hash to merge with.
    #
    # @eturn [ BSON::Document ] The result of the merge.
    #
    # @since 3.0.0
    def merge(other, &block)
      dup.merge!(other, &block)
    end

    # Merge this document with another document, returning the same document in
    # the process.
    #
    # @example Merge with another document.
    #   document.merge(name: "Bob")
    #
    # @param [ BSON::Document, Hash ] other The document/hash to merge with.
    #
    # @eturn [ BSON::Document ] The result of the merge.
    #
    # @since 3.0.0
    def merge!(other)
      other.each_pair do |key, value|
        value = yield(key.to_bson_normalized_key, self[key], value.to_bson_normalized_value) if block_given?
        self[key] = value
      end
      self
    end

    alias :update :merge!
  end
end