class T::Enum

def self._load(args)
  deserialize(Marshal.load(args))
end

def self._register_instance(instance)
  @values ||= []
  @values << T.cast(instance, T.attached_class)
end

def self.deserialize(mongo_value)
  if self == T::Enum
    raise "Cannot call T::Enum.deserialize directly. You must call on a specific child class."
  end
  self.from_serialized(mongo_value)
end

def self.each_value(&blk)
  if blk
    values.each(&blk)
  else
    values.each
  end
end

def self.enums(&blk)
  raise "enums cannot be defined for T::Enum" if self == T::Enum
  raise "Enum #{self} was already initialized" if @fully_initialized
  raise "Enum #{self} is still initializing" if @started_initializing
  @started_initializing = true
  @values = T.let(nil, T.nilable(T::Array[T.attached_class]))
  yield
  @mapping = T.let(nil, T.nilable(T::Hash[SerializedVal, T.attached_class]))
  @mapping = {}
  # Freeze the Enum class and bind the constant names into each of the instances.
  self.constants(false).each do |const_name|
    instance = self.const_get(const_name, false)
    if !instance.is_a?(self)
      raise "Invalid constant #{self}::#{const_name} on enum. " \
        "All constants defined for an enum must be instances itself (e.g. `Foo = new`)."
    end
    instance._bind_name(const_name)
    serialized = instance.serialize
    if @mapping.include?(serialized)
      raise "Enum values must have unique serializations. Value '#{serialized}' is repeated on #{self}."
    end
    @mapping[serialized] = instance
  end
  @values.freeze
  @mapping.freeze
  orphaned_instances = T.must(@values) - @mapping.values
  if !orphaned_instances.empty?
    raise "Enum values must be assigned to constants: #{orphaned_instances.map {|v| v.instance_variable_get('@serialized_val')}}"
  end
  @fully_initialized = true
end

def self.from_serialized(serialized_val)
  res = try_deserialize(serialized_val)
  if res.nil?
    raise KeyError.new("Enum #{self} key not found: #{serialized_val.inspect}")
  end
  res
end

def self.fully_initialized?
  @fully_initialized = T.let(@fully_initialized, T.nilable(T::Boolean))
  @fully_initialized ||= false
end

def self.has_serialized?(serialized_val)
  if @mapping.nil?
    raise "Attempting to access serialization map of #{self.class} before it has been initialized." \
      " Enums are not initialized until the 'enums do' block they are defined in has finished running."
  end
  @mapping.include?(serialized_val)
end

def self.inherited(child_class)
  super
  raise "Inheriting from children of T::Enum is prohibited" if self != T::Enum
end

def self.serialize(instance)
  # This is needed otherwise if a Chalk::ODM::Document with a property of the shape
  # T::Hash[T.nilable(MyEnum), Integer] and a value that looks like {nil => 0} is
  # serialized, we throw the error on L102.
  return nil if instance.nil?
  if self == T::Enum
    raise "Cannot call T::Enum.serialize directly. You must call on a specific child class."
  end
  if instance.class != self
    raise "Cannot call #serialize on a value that is not an instance of #{self}."
  end
  instance.serialize
end

def self.started_initializing?
  @started_initializing = T.let(@started_initializing, T.nilable(T::Boolean))
  @started_initializing ||= false
end

def self.try_deserialize(serialized_val)
  if @mapping.nil?
    raise "Attempting to access serialization map of #{self.class} before it has been initialized." \
      " Enums are not initialized until the 'enums do' block they are defined in has finished running."
  end
  @mapping[serialized_val]
end

def self.values
  if @values.nil?
    raise "Attempting to access values of #{self.class} before it has been initialized." \
      " Enums are not initialized until the 'enums do' block they are defined in has finished running."
  end
  @values
end

def <=>(other)
  case other
  when self.class
    self.serialize <=> other.serialize
  else
    nil
  end
end

def ==(other)
  case other
  when String
    if T::Configuration.legacy_t_enum_migration_mode?
      comparison_assertion_failed(:==, other)
      self.serialize == other
    else
      false
    end
  else
    super(other)
  end
end

def ===(other)
  case other
  when String
    if T::Configuration.legacy_t_enum_migration_mode?
      comparison_assertion_failed(:===, other)
      self.serialize == other
    else
      false
    end
  else
    super(other)
  end
end

def _bind_name(const_name)
  @const_name = const_name
  @serialized_val = const_to_serialized_val(const_name) if @serialized_val.nil?
  freeze
end

def _dump(_level)
  Marshal.dump(serialize)
end

def assert_bound!
nst_name.nil?
e "Attempting to access Enum value on #{self.class} before it has been initialized." \
Enums are not initialized until the 'enums do' block they are defined in has finished running."

def clone
  self
end

def comparison_assertion_failed(method, other)
figuration.soft_assert_handler(
m to string comparison not allowed. Compare to the Enum instance directly instead. See go/enum-migration',
ytime: {
ass: self.class.name,
lf: self.inspect,
her: other,
her_class: other.class.name,
thod: method,

def const_to_serialized_val(const_name)
orical note: We convert to lowercase names because the majority of existing calls to
e_accessible` were arrays of lowercase strings. Doing this conversion allowed for the
t amount of repetition in migrated declarations.
name.to_s.downcase.freeze

def dup
  self
end

def initialize(serialized_val=nil)
  raise 'T::Enum is abstract' if self.class == T::Enum
  if !self.class.started_initializing?
    raise "Must instantiate all enum values of #{self.class} inside 'enums do'."
  end
  if self.class.fully_initialized?
    raise "Cannot instantiate a new enum value of #{self.class} after it has been initialized."
  end
  serialized_val = serialized_val.frozen? ? serialized_val : serialized_val.dup.freeze
  @serialized_val = T.let(serialized_val, T.nilable(SerializedVal))
  @const_name = T.let(nil, T.nilable(Symbol))
  self.class._register_instance(self)
end

def inspect
  "#<#{self.class.name}::#{@const_name || '__UNINITIALIZED__'}>"
end

def serialize
  assert_bound!
  @serialized_val
end

def to_json(*args)
  serialize.to_json(*args)
end

def to_s
  inspect
end

def to_str
  msg = 'Implicit conversion of Enum instances to strings is not allowed. Call #serialize instead.'
  if T::Configuration.legacy_t_enum_migration_mode?
    T::Configuration.soft_assert_handler(
      msg,
      storytime: {class: self.class.name},
    )
    serialize.to_s
  else
    raise NoMethodError.new(msg)
  end
end