module Gem
  # A Requirement is a set of one or more version restrictions. It supports a few
  # (`=, !=, >, <, >=, <=, ~>`) different restriction operators.
  #
  # See Gem::Version for a description on how versions and requirements work
  # together in RubyGems.
  #
  class Requirement
    type operator = "=" | "!=" | ">" | "<" | ">=" | "<=" | "~>"

    # Raised when a bad requirement is encountered
    #
    class BadRequirementError < ArgumentError
    end

    # The default requirement matches any version
    #
    DefaultPrereleaseRequirement: [ operator, Gem::Version ]

    # The default requirement matches any non-prerelease version
    #
    DefaultRequirement: [ operator, Gem::Version ]

    # A regular expression that matches a requirement
    #
    PATTERN: Regexp

    # Factory method to create a Gem::Requirement object.  Input may be a Version, a
    # String, or nil.  Intended to simplify client code.
    #
    # If the input is "weird", the default version requirement is returned.
    #
    def self.create: (*(String | Gem::Version | Gem::Requirement | nil) inputs) -> instance

    def self.default: () -> instance

    def self.default_prerelease: () -> instance

    # Parse `obj`, returning an `[op, version]` pair. `obj` can be a String or a
    # Gem::Version.
    #
    # If `obj` is a String, it can be either a full requirement specification, like
    # `">= 1.2"`, or a simple version number, like `"1.2"`.
    #
    #     parse("> 1.0")                 # => [">", Gem::Version.new("1.0")]
    #     parse("1.0")                   # => ["=", Gem::Version.new("1.0")]
    #     parse(Gem::Version.new("1.0")) # => ["=,  Gem::Version.new("1.0")]
    #
    def self.parse: (String | Gem::Version obj) -> [ operator, Gem::Version ]

    # Constructs a requirement from `requirements`. Requirements can be Strings,
    # Gem::Versions, or Arrays of those. `nil` and duplicate requirements are
    # ignored. An empty set of `requirements` is the same as `">= 0"`.
    #
    def initialize: (*(String | Gem::Version) requirements) -> void

    # Concatenates the `new` requirements onto this requirement.
    #
    def concat: (Array[String | Gem::Version] new) -> void

    # true if the requirement is for only an exact version
    #
    def exact?: () -> bool

    # true if this gem has no requirements.
    #
    def none?: () -> bool

    # A requirement is a prerelease if any of the versions inside of it are
    # prereleases
    #
    def prerelease?: () -> bool

    # True if `version` satisfies this Requirement.
    #
    def satisfied_by?: (Gem::Version version) -> bool

    alias === satisfied_by?
    alias =~ satisfied_by?

    # True if the requirement will not always match the latest version.
    #
    def specific?: () -> bool
  end
end