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import { deferPromise } from "./utils.ts";
/** * The `Error` class used when an invalid transition is performed. */export class InvalidTransitionError extends TypeError {  constructor(readonly state: StateNames, readonly transition: Transitions) {    super(      `Invalid transition - ${state}.${transition}()`,    );  }}
/** * The `Error` class used when the `send` transition is performed on a closed channel. */export class SendOnClosedError extends Error {  constructor() {    super("Send on closed channel");  }}
/** @internal */export type LogFn = (...args: unknown[]) => void;
/** @internal */export type State<T> =  | Idle<T>  | SendStuck<T>  | GetStuck<T>  | Closed<T>;
/** @internal */export type StateBase<T> =  & { [t in "get" | "close"]: () => State<T> }  & { send: (val: T) => State<T> };
/** @internal */export type Transitions = keyof StateBase<unknown>;
/** @internal */export type StateNames = State<unknown>["name"];
/** @internal */export interface Idle<T> extends StateBase<T> {  name: "Idle";  get: () => GetStuck<T>;  send: (val: T) => SendStuck<T>;  close: () => Closed<T>;}
/** @internal */export function Idle<T>(debug: LogFn): Idle<T> {  return {    name: "Idle",    get: () => GetStuck(debug),    send: (val: T): SendStuck<T> => SendStuck(val, debug),    close: () => Closed(debug),  };}
/** @internal */export function isIdle<T>(s: State<T>): s is Idle<T> {  return s.name === "Idle";}
/** @internal */export interface SendStuck<T> extends StateBase<T> {  name: "SendStuck";  promise: Promise<T>;  get: () => Idle<T>;  send: (val: T) => never;  close: () => Closed<T>;}
/** @internal */export function SendStuck<T>(val: T, debug: LogFn): SendStuck<T> {  const name = "SendStuck";  const [promise, resolve, reject] = deferPromise<T>();  return {    name,    promise: promise.then(      (pVal) => {        debug(`${name}.promise.resolve(pVal)`, { pVal, val });        return pVal;      },      (error) => {        debug(`${name}.promise.rejected(error)`, { error, val });        return Promise.reject(error);      },    ),    get: () => {      debug(`${name}.get()`, { val });      resolve(val);      return Idle(debug);    },    send: () => {      debug(`${name}.send()`, { val });      throw new InvalidTransitionError(name, "send");    },    close: () => {      debug(`${name}.close()`, { val });      reject(new SendOnClosedError());      return Closed(debug);    },  };}
/** @internal */export function isSendStuck<T>(s: State<T>): s is SendStuck<T> {  return s.name === "SendStuck";}
/** @internal */export interface GetStuck<T> extends StateBase<T> {  name: "GetStuck";  promise: Promise<[T, true] | [undefined, false]>;  get: () => never;  send: (val: T) => Idle<T>;  close: () => Closed<T>;}
/** @internal */export function GetStuck<T>(debug: LogFn): GetStuck<T> {  const name = "GetStuck";  const closeErr = new Error("Get on closed Channel");  const [promise, resolve, reject] = deferPromise<T>();  return {    name,    promise: promise.then(      (val) => {        debug(`${name}.promise.resolved(val)`, { val });        return [val, true];      },      (error) => {        debug(`${name}.promise.rejected(error)`, { error });        if (error === closeErr) return [undefined, false];        return Promise.reject(error);      },    ),    get: () => {      debug(`${name}.get()`);      throw new InvalidTransitionError(name, "get");    },    send: (val: T) => {      debug(`${name}.send()`);      resolve(val);      return Idle(debug);    },    close: () => {      debug(`${name}.close()`, new Error().stack);      reject(closeErr);      return Closed(debug);    },  };}
/** @internal */export function isGetStuck<T>(s: State<T>): s is GetStuck<T> {  return s.name === "GetStuck";}
/** @internal */export interface Closed<T> extends StateBase<T> {  name: "Closed";  get: () => never;  send: (val: T) => never;  close: () => Closed<T>;}
/** @internal */export function Closed<T>(debug: LogFn): Closed<T> {  const name = "Closed";  return {    name,    get: () => {      debug(`${name}.get()`);      throw new InvalidTransitionError(name, "get");    },    send: () => {      debug(`${name}.send()`);      throw new InvalidTransitionError(name, "get");    },    close: () => {      debug(`${name}.close()`);      return Closed(debug);    },  };}
/** @internal */export function isClosed<T>(s: State<T>): s is Closed<T> {  return s.name === "Closed";}