/**
 * Gecko XPCOM builtins.
 */
declare global {
  /**
   * Generic IDs are created by most code which passes a nsID to js.
   * https://searchfox.org/mozilla-central/source/js/xpconnect/src/XPCJSID.cpp#24
   */
  interface nsID<uuid = string> {
    readonly number: uuid;
  }

  /**
   * In addition to nsID, interface IIDs support instanceof type guards,
   * and expose constants defined on the class, including variants from enums.
   * https://searchfox.org/mozilla-central/source/js/xpconnect/src/XPCJSID.cpp#45
   */
  type nsJSIID<iface, enums = {}> = nsID & Constants<iface> & enums & {
    new (_: never): void;
    prototype: iface;
  }

  /** A union type of all known interface IIDs. */
  type nsIID = nsIXPCComponents_Interfaces[keyof nsIXPCComponents_Interfaces];

  /** A generic to resolve QueryInterface return type from a nsIID. */
  export type nsQIResult<iid> = iid extends { prototype: infer U } ? U : never;

  /** u32 */
  type nsresult = u32;

  // Numeric typedefs, useful as a quick reference in method signatures.
  type double = number;
  type float = number;
  type i16 = number;
  type i32 = number;
  type i64 = number;
  type u16 = number;
  type u32 = number;
  type u64 = number;
  type u8 = number;
}

/**
 * XPCOM utility types.
 */

/** XPCOM inout param is passed in as a js object with a value property. */
type InOutParam<T> = { value: T };

/** XPCOM out param is written to the passed in object's value property. */
type OutParam<T> = { value?: T };

/** A named type to enable interfaces to inherit from enums. */
type Enums<enums> = enums;

/** Callable accepts either form of a [function] interface. */
type Callable<iface> = iface | Extract<iface[keyof iface], Function>

/** Picks only const number properties from T. */
type Constants<T> = { [K in keyof T as IfConst<K, T[K]>]: T[K] };

/** Resolves only for keys K whose corresponding type T is a narrow number. */
type IfConst<K, T> = T extends number ? (number extends T ? never : K) : never;

export {};