# Rack ships no signatures. This names the vocabulary the middleware in
# lib/pro_tacts speaks — the environment, the response triple, and an
# app to delegate to — plus the two constants used directly: the status
# phrases the debug logger prints, and the middleware config.ru's
# comment explains (web.rb mounts it so a body can be read twice).
module Rack
  # The CGI-ish hash a middleware is called with. Values stay untyped:
  # anything upstream may put anything in it, which is why the code
  # reads it through fetch and to_s.
  type env = Hash[String, untyped]

  type headers = Hash[String, String]

  # What every middleware returns and what every middleware in this app
  # passes along, rebuilt from parts once the body has been consumed.
  type response = [Integer, headers, _Body]

  # A response body: enumerable once, and closeable if it holds a
  # resource — which only respond_to? can tell you, so it is here and
  # close is not.
  interface _Body
    def each: () { (String) -> void } -> void
    def respond_to?: (Symbol name) -> bool
  end

  # The request body, as env["rack.input"] carries it.
  interface _Input
    def read: () -> String
    def rewind: () -> void
  end

  # The app a middleware wraps.
  interface _App
    def call: (env) -> response
  end

  module Utils
    HTTP_STATUS_CODES: Hash[Integer, String]
  end

  class RewindableInput
    class Middleware
    end
  end
end