class ViewModel::Registry

def all
  @lock.synchronize do
    resolve_deferred_classes
    @viewmodel_classes_by_name.values
  end
end

def clear_removed_classes!
  @lock.synchronize do
    resolve_deferred_classes
    @viewmodel_classes_by_name.delete_if do |_name, klass|
      !Kernel.const_defined?(klass.name)
    end
  end
end

def default_view_name(model_class_name)
  model_class_name.gsub('::', '.')
end

def for_view_name(name)
  raise ViewModel::DeserializationError::InvalidSyntax.new('ViewModel name cannot be nil') if name.nil?
  @lock.synchronize do
    # Resolve names for any deferred viewmodel classes
    resolve_deferred_classes
    viewmodel_class = @viewmodel_classes_by_name[name]
    if viewmodel_class.nil? || !(viewmodel_class < ViewModel)
      raise ViewModel::DeserializationError::UnknownView.new(name)
    end
    viewmodel_class
  end
end

def infer_model_class_name(view_name)
  view_name.gsub('.', '::')
end

def initialize
  @lock = Monitor.new
  @viewmodel_classes_by_name = {}
  @deferred_viewmodel_classes = []
end

def register(viewmodel, as: DEFERRED_NAME)
  @lock.synchronize do
    @deferred_viewmodel_classes << [viewmodel, as]
  end
end

def resolve_deferred_classes
  until @deferred_viewmodel_classes.empty?
    vm, view_name = @deferred_viewmodel_classes.pop
    if vm.should_register?
      view_name = vm.view_name if view_name == DEFERRED_NAME
      @viewmodel_classes_by_name[view_name] = vm
    end
  end
end

def roots
  all.select { |c| c.root? }
end