module GraphQL::Schema::Validation::Rules

def self.assert_named_items_are_valid(item_name, get_items_proc)
  -> (type) {
    items = get_items_proc.call(type)
    error_message = nil
    items.each do |item|
      item_message = GraphQL::Schema::Validation.validate(item)
      if item_message
        error_message = "#{item_name} #{item.name.inspect} #{item_message}"
        break
      end
    end
    error_message
  }
end

def self.assert_property(property_name, *allowed_classes)
  allowed_classes_message = allowed_classes.map(&:name).join(" or ")
  -> (obj) {
    property_value = obj.public_send(property_name)
    is_valid_value = allowed_classes.any? { |allowed_class| property_value.is_a?(allowed_class) }
    is_valid_value ? nil : "#{property_name} must return #{allowed_classes_message}, not #{property_value.class.name} (#{property_value.inspect})"
  }
end

def self.assert_property_list_of(property_name, list_member_class)
  -> (obj) {
    property_value = obj.public_send(property_name)
    if !property_value.is_a?(Array)
      "#{property_name} must be an Array of #{list_member_class.name}, not a #{property_value.class.name} (#{property_value.inspect})"
    else
      invalid_member = property_value.find { |value| !value.is_a?(list_member_class) }
      if invalid_member
        "#{property_name} must contain #{list_member_class.name}, not #{invalid_member.class.name} (#{invalid_member.inspect})"
      else
        nil # OK
      end
    end
  }
end

def self.assert_property_mapping(property_name, from_class, to_class)
  -> (obj) {
    property_value = obj.public_send(property_name)
    error_message = nil
    if !property_value.is_a?(Hash)
      "#{property_name} must be a hash of {#{from_class.name} => #{to_class.name}}, not a #{property_value.class.name} (#{property_value.inspect})"
    else
      invalid_key, invalid_value = property_value.find { |key, value| !key.is_a?(from_class) || !value.is_a?(to_class) }
      if invalid_key
        "#{property_name} must map #{from_class} => #{to_class}, not #{invalid_key.class.name} => #{invalid_value.class.name} (#{invalid_key.inspect} => #{invalid_value.inspect})"
      else
        nil # OK
      end
    end
  }
end