module RBS
  module Types
    # _TypeBase interface represents the operations common to all of the types.
    #
    interface _TypeBase
      # Location for types in the RBS source code.
      # `nil` means there is no RBS source code for the type.
      #
      def location: () -> Location?

      # Returns names of free variables of a type.
      # You can pass a Set instance to add the free variables to the set to avoid Set object allocation.
      #
      def free_variables: (?Set[Symbol]) -> Set[Symbol]

      # Receives a substitution and returns a new type applied the substitution.
      #
      def sub: (Substitution) -> t

      # Maps type names included in the type and returns new instance of type.
      def map_type_name: () { (TypeName, Location?, t) -> TypeName } -> t

      # Yields all direct sub types included in the type.
      # It doesn't yield the type itself.
      #
      #   parse("Hash[String, Array[Symbol]]").each_type do |ty|
      #     ...       # Yields String and Array[Symbol]
      #   end
      #
      def each_type: () { (t) -> void } -> void
                   | () -> Enumerator[t, void]

      # Returns a JSON representation.
      #
      def to_json: (*untyped) -> String

      # Returns a String representation.
      # `level` is used internally.
      #
      #   parse("String").to_s               # => "String"
      #   parse("String | Integer").to_s()   # => "String | Integer"
      #   parse("String | Integer").to_s(1)  # => "(String | Integer)"
      #
      def to_s: (?Integer level) -> String
    end

    # t represents union of all possible types.
    #
    type t = Bases::Bool | Bases::Void | Bases::Any | Bases::Nil | Bases::Top | Bases::Bottom | Bases::Self | Bases::Instance | Bases::Class
           | Variable | ClassSingleton | Interface | ClassInstance | Alias | Tuple | Record | Optional | Union | Intersection | Proc | Literal

    module NoFreeVariables
      def free_variables: (?Set[Symbol]) -> Set[Symbol]
    end

    module NoSubst
      def sub: (Substitution) -> self
    end

    module EmptyEachType
      def each_type: () { (t) -> void } -> void
                   | () -> Enumerator[t, void]
    end

    module NoTypeName
      def map_type_name: () { (TypeName, Location?, t) -> TypeName } -> self
    end

    module Bases
      class Base
        include _TypeBase

        def initialize: (location: Location?) -> void

        def ==: (untyped other) -> bool

        def hash: () -> Integer

        alias eql? ==

        include NoFreeVariables
        include NoSubst
        include EmptyEachType
        include NoTypeName
      end

      class Bool < Base
      end

      class Void < Base
      end

      class Any < Base
      end

      class Nil < Base
      end

      class Top < Base
      end

      class Bottom < Base
      end

      class Self < Base
      end

      class Instance < Base
        def sub: (Substitution sub) -> t
      end

      class Class < Base
      end
    end

    class Variable
      attr_reader name: Symbol
      attr_reader location: Location?

      @@count: Integer

      include _TypeBase

      include NoTypeName
      include EmptyEachType

      def initialize: (name: Symbol, location: Location?) -> void

      def ==: (untyped other) -> bool

      alias eql? ==

      def hash: () -> Integer

      def self.build: (Symbol) -> Variable
                    | (Array[Symbol]) -> Array[Variable]

      def self.fresh: (?Symbol) -> Variable
    end

    class ClassSingleton
      attr_reader name: TypeName
      attr_reader location: Location?

      include _TypeBase

      def initialize: (name: TypeName, location: Location?) -> void

      def ==: (untyped other) -> bool

      alias eql? ==

      def hash: () -> Integer

      include NoFreeVariables
      include NoSubst
      include EmptyEachType      
    end

    module Application
      attr_reader name: TypeName
      attr_reader args: Array[t]

      def ==: (untyped) -> bool

      alias eql? ==

      def hash: () -> Integer

      def free_variables: (?Set[Symbol]) -> Set[Symbol]

      def to_s: (?Integer level) -> String

      def each_type: () { (t) -> void } -> void
                   | () -> Enumerator[t, void]
    end

    class Interface
      include Application

      attr_reader location: Location?

      def initialize: (name: TypeName, args: Array[t], location: Location?) -> void

      include _TypeBase
    end

    # ClassInstance represents a type of an instance of a class.
    #
    #    String           # Type of an instance of String class.
    #    Array[String]    # Type of an instance of Array class with instances of String.
    #    Kernel           # Type of an instance of a class which includes Kernel.
    #
    class ClassInstance
      include Application

      attr_reader location: Location?

      def initialize: (name: TypeName, args: Array[t], location: Location?) -> void

      include _TypeBase
    end

    class Alias
      attr_reader location: Location?
      attr_reader name: TypeName

      def initialize: (name: TypeName, location: Location?) -> void

      include _TypeBase
      include NoFreeVariables
      include NoSubst
      include EmptyEachType
    end

    class Tuple
      attr_reader types: Array[t]
      attr_reader location: Location?

      def initialize: (types: Array[t], location: Location?) -> void

      include _TypeBase
    end

    class Record
      attr_reader fields: Hash[Symbol, t]
      attr_reader location: Location?

      def initialize: (fields: Hash[Symbol, t], location: Location?) -> void

      include _TypeBase
    end

    class Optional
      attr_reader type: t
      attr_reader location: Location?

      def initialize: (type: t, location: Location?) -> void

      include _TypeBase
    end

    class Union
      attr_reader types: Array[t]
      attr_reader location: Location?

      def initialize: (types: Array[t], location: Location?) -> void

      include _TypeBase

      def map_type: () { (t) -> t } -> Union
                  | () -> Enumerator[t, Union]
    end

    class Intersection
      attr_reader types: Array[t]
      attr_reader location: Location?

      def initialize: (types: Array[t], location: Location?) -> void

      include _TypeBase

      def map_type: () { (t) -> t } -> Intersection
                  | () -> Enumerator[t, Intersection]
    end

    class Function
      class Param
        attr_reader type: t
        attr_reader name: Symbol?

        def initialize: (type: t, name: Symbol?) -> void

        def map_type: { (t) -> t } -> Param
                    | -> Enumerator[t, Param]
      end

      attr_reader required_positionals: Array[Param]
      attr_reader optional_positionals: Array[Param]
      attr_reader rest_positionals: Param?
      attr_reader trailing_positionals: Array[Param]
      attr_reader required_keywords: Hash[Symbol, Param]
      attr_reader optional_keywords: Hash[Symbol, Param]
      attr_reader rest_keywords: Param?
      attr_reader return_type: t

      def initialize: (required_positionals: Array[Param],
                       optional_positionals: Array[Param],
                       rest_positionals: Param?,
                       trailing_positionals: Array[Param],
                       required_keywords: Hash[Symbol, Param],
                       optional_keywords: Hash[Symbol, Param],
                       rest_keywords: Param?,
                       return_type: t) -> void

      def free_variables: (?Set[Symbol]) -> Set[Symbol]

      def map_type: { (t) -> t } -> Function
                  | -> Enumerator[t, Function]

      def map_type_name: () { (TypeName, Location?, t) -> TypeName } -> Function

      def each_type: () { (t) -> void } -> void
                   | -> Enumerator[t, void]

      def each_param: () { (Param) -> void } -> void
                    | -> Enumerator[Param, void]

      def to_json: (*untyped) -> String

      def sub: (Substitution) -> Function

      def self.empty: (t) -> instance

      def with_return_type: (t) -> Function

      def update: (?required_positionals: Array[Param],
                   ?optional_positionals: Array[Param],
                   ?rest_positionals: Param?,
                   ?trailing_positionals: Array[Param],
                   ?required_keywords: Hash[Symbol, Param],
                   ?optional_keywords: Hash[Symbol, Param],
                   ?rest_keywords: Param?,
                   ?return_type: t) -> Function

      def empty?: () -> bool

      def param_to_s: () -> String
      def return_to_s: () -> String

      def drop_head: () -> [Param, Function]
      def drop_tail: () -> [Param, Function]

      def has_keyword?: () -> bool
    end

    class Proc
      attr_reader type: Function
      attr_reader location: Location?

      def initialize: (location: Location?, type: Function) -> void

      include _TypeBase
    end

    class Literal
      type literal = String | Integer | Symbol | TrueClass | FalseClass

      attr_reader literal: literal
      attr_reader location: Location?

      def initialize: (literal: literal, location: Location?) -> void

      include _TypeBase
      include NoFreeVariables
      include NoSubst
      include EmptyEachType
      include NoTypeName
    end
  end
end