module MultiJson

def adapter
  return @adapter if defined?(@adapter) && @adapter
  use nil # load default adapter
  @adapter
end

def current_adapter(options = {})
  if (new_adapter = options[:adapter])
    load_adapter(new_adapter)
  else
    adapter
  end
end

def default_adapter
  return :oj if defined?(::Oj)
  return :yajl if defined?(::Yajl)
  return :jr_jackson if defined?(::JrJackson)
  return :json_gem if defined?(::JSON::Ext::Parser)
  return :gson if defined?(::Gson)
  REQUIREMENT_MAP.each do |adapter, library|
    begin
      require library
      return adapter
    rescue ::LoadError
      next
    end
  end
  Kernel.warn '[WARNING] MultiJson is using the default adapter (ok_json). ' \
    'We recommend loading a different JSON library to improve performance.'
  :ok_json
end

def default_options
  Kernel.warn "MultiJson.default_options is deprecated\n" \
    'Use MultiJson.load_options or MultiJson.dump_options instead'
  load_options
end

def default_options=(value)
  Kernel.warn "MultiJson.default_options setter is deprecated\n" \
    'Use MultiJson.load_options and MultiJson.dump_options instead'
  self.load_options = self.dump_options = value
end

def dump(object, options = {})
  current_adapter(options).dump(object, options)
end

def load(string, options = {})
  adapter = current_adapter(options)
  begin
    adapter.load(string, options)
  rescue adapter::ParseError => exception
    raise ParseError.build(exception, string)
  end
end

def load_adapter(new_adapter)
  case new_adapter
  when String, Symbol
    load_adapter_from_string_name new_adapter.to_s
  when NilClass, FalseClass
    load_adapter default_adapter
  when Class, Module
    new_adapter
  else
    fail ::LoadError, new_adapter
  end
rescue ::LoadError => exception
  raise AdapterError.build(exception)
end

def load_adapter_from_string_name(name)
  name = ALIASES.fetch(name, name)
  require "multi_json/adapters/#{name.downcase}"
  klass_name = name.to_s.split('_').map(&:capitalize) * ''
  MultiJson::Adapters.const_get(klass_name)
end

def use(new_adapter)
  @adapter = load_adapter(new_adapter)
ensure
  OptionsCache.reset
end

def with_adapter(new_adapter)
  old_adapter = adapter
  self.adapter = new_adapter
  yield
ensure
  self.adapter = old_adapter
end