class Shoulda::Matchers::ActiveModel::ValidateAbsenceOfMatcher

def collection?
  if reflection
    [:has_many, :has_and_belongs_to_many].include?(reflection.macro)
  else
    false
  end
end

def column_type
  @subject.class.respond_to?(:columns_hash) &&
    @subject.class.columns_hash[@attribute.to_s].respond_to?(:type) &&
    @subject.class.columns_hash[@attribute.to_s].type
end

def does_not_match?(subject)
  super(subject)
  allows_value_of(value, @expected_message)
end

def enum_column?
  @subject.class.respond_to?(:defined_enums) &&
    @subject.class.defined_enums.key?(@attribute.to_s)
end

def enum_values
  @subject.class.defined_enums[@attribute.to_s].values
end

def initialize(attribute)
  super
  @expected_message = :present
end

def matches?(subject)
  super(subject)
  disallows_value_of(value, @expected_message)
end

def reflection
  @subject.class.respond_to?(:reflect_on_association) &&
    @subject.class.reflect_on_association(@attribute)
end

def simple_description
  "validate that :#{@attribute} is empty/falsy"
end

def value
  if reflection
    obj = reflection.klass.new
    if collection?
      [obj]
    else
      obj
    end
  elsif array_column?
    ['an arbitrary value']
  elsif enum_column?
    enum_values.first
  else
    case column_type
    when :integer, :float then 1
    when :decimal then BigDecimal(1, 0)
    when :datetime, :time, :timestamp then Time.current
    when :date then Date.new
    when :binary then '0'
    when :uuid then SecureRandom.uuid
    else 'an arbitrary value'
    end
  end
end