module JsonbAccessor::TypeHelper

def fetch(type)
  case type
  when :array
    new_array(value)
  when ARRAY_MATCHER
    fetch_active_record_array_type(type)
  when :value
    value
  else
    fetch_active_record_type(type)
  end
end

def fetch_active_record_array_type(type)
  subtype = type.to_s.sub(ARRAY_MATCHER, "")
  new_array(fetch_active_record_type(subtype))
end

def fetch_active_record_type(type)
  class_name = type.to_s.camelize
  klass = value_descendants.find do |ar_type|
    ar_type.to_s.split(CONSTANT_SEPARATOR).last == class_name
  end
  if klass
    klass.new
  else
    raise JsonbAccessor::TypeHelper::UnknownType
  end
end

def new_array(subtype)
  ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Array.new(subtype)
end

def value
  ActiveRecord::Type::Value.new
end

def value_descendants
  grouped_types = ActiveRecord::Type::Value.descendants.group_by do |ar_type|
    !!ar_type.to_s.match(ActiveRecord::ConnectionAdapters::PostgreSQL::OID.to_s)
  end
  grouped_types[true] + grouped_types[false]
end