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import {  decodeStream,  Deferred,  deferred,  Disposable,  encode,  io,} from "./deps.ts";import * as message from "./message.ts";import { Indexer } from "./indexer.ts";import { ResponseWaiter } from "./response_waiter.ts";
const MSGID_THRESHOLD = 2 ** 32;
/** * Method dispatcher */export interface Dispatcher {  [key: string]: (this: Session, ...args: unknown[]) => Promise<unknown>;}
/** * Create Dispatcher from type annotated object T */export type DispatcherFrom<T> = {  [K in keyof T]: T[K] extends (...args: infer Args) => unknown    ? (...args: { [K in keyof Args]: unknown }) => Promise<unknown>    : never;};
/** * Session options */export type SessionOptions = {  /**   * Response timeout in milliseconds   */  responseTimeout?: number;
  /**   * A callback called when session raised internal error   */  errorCallback?: (e: Error) => void;};
/** * MessagePack-RPC Session */export class Session implements Disposable {  #indexer: Indexer;  #waiter: ResponseWaiter;  #reader: Deno.Reader & Deno.Closer;  #writer: Deno.Writer;  #listener: Promise<void>;  #closed: boolean;  #closedSignal: Deferred<never>;
  /**   * API name and method map which is used to dispatch API request   */  dispatcher: Dispatcher;
  constructor(    reader: Deno.Reader & Deno.Closer,    writer: Deno.Writer,    dispatcher: Dispatcher = {},    options: SessionOptions = {},  ) {    this.dispatcher = dispatcher;    this.#indexer = new Indexer(MSGID_THRESHOLD);    this.#waiter = new ResponseWaiter(options.responseTimeout);    this.#reader = reader;    this.#writer = writer;    this.#closed = false;    this.#closedSignal = deferred();    this.#listener = this.listen().catch((e) => {      if (options.errorCallback) {        options.errorCallback(e);      } else {        console.error(`Unexpected error occured in session: ${e}`);      }    });  }
  private async send(data: Uint8Array): Promise<void> {    await io.writeAll(this.#writer, data);  }
  private async dispatch(    method: string,    ...params: unknown[]  ): Promise<unknown> {    if (!Object.prototype.hasOwnProperty.call(this.dispatcher, method)) {      const propertyNames = Object.getOwnPropertyNames(this.dispatcher);      throw new Error(        `No method '${method}' exists in ${JSON.stringify(propertyNames)}`,      );    }    return await this.dispatcher[method].apply(this, params);  }
  private async handleRequest(request: message.RequestMessage): Promise<void> {    const [_, msgid, method, params] = request;    const [result, error] = await (async () => {      let result: message.MessageResult = null;      let error: message.MessageError = null;      try {        result = await this.dispatch(method, ...params);      } catch (e) {        // Use string representation to send the error through msgpack        error = e.stack ?? e.toString();      }      return [result, error];    })();    const response: message.ResponseMessage = [1, msgid, error, result];    await this.send(encode(response));  }
  private handleResponse(response: message.ResponseMessage): void {    if (!this.#waiter.provide(response)) {      console.warn("Unexpected response message received", response);    }  }
  private async handleNotification(    notification: message.NotificationMessage,  ): Promise<void> {    const [_, method, params] = notification;    try {      await this.dispatch(method, ...params);    } catch (e) {      console.error(e);    }  }
  private async listen(): Promise<void> {    const iter = decodeStream(io.iter(this.#reader));    try {      while (!this.#closed) {        const { done, value } = await Promise.race([          this.#closedSignal,          iter.next(),        ]);        if (done) {          return;        }        if (message.isRequestMessage(value)) {          this.handleRequest(value);        } else if (message.isResponseMessage(value)) {          this.handleResponse(value);        } else if (message.isNotificationMessage(value)) {          this.handleNotification(value);        } else {          console.warn(`Unexpected data received: ${value}`);          continue;        }      }    } catch (e) {      if (e instanceof SessionClosedError) {        return;      }      // https://github.com/denoland/deno/issues/5194#issuecomment-631987928      if (e instanceof Deno.errors.BadResource) {        return;      }      throw e;    }  }
  dispose() {    this.close();  }
  /**   * Close this session   */  close(): void {    this.#closed = true;    this.#closedSignal.reject(new SessionClosedError());  }
  /**   * Wait until the session is closed   */  waitClosed(): Promise<void> {    return this.#listener;  }
  /**   * Call a method with params and return a Promise which resolves when a response message   * has received and to the result value of the method.   */  async call(method: string, ...params: unknown[]): Promise<unknown> {    if (this.#closed) {      throw new SessionClosedError();    }    const msgid = this.#indexer.next();    const data: message.RequestMessage = [0, msgid, method, params];    const [_, response] = await Promise.race([      this.#closedSignal,      Promise.all([this.send(encode(data)), this.#waiter.wait(msgid)]),    ]);    const [err, result] = response.slice(2);    if (err) {      const paramsStr = JSON.stringify(params);      const errStr = typeof err === "string" ? err : JSON.stringify(err);      throw new Error(        `Failed to call '${method}' with ${paramsStr}: ${errStr}`,      );    }    return result;  }
  /**   * Notify a method with params and return a Promise which resolves when the message has sent.   */  async notify(method: string, ...params: unknown[]): Promise<void> {    if (this.#closed) {      throw new SessionClosedError();    }    const data: message.NotificationMessage = [2, method, params];    await Promise.race([this.#closedSignal, this.send(encode(data))]);  }
  /**   * Clear an internal dispatcher   *   * @Deprecated Use `dispatcher` directly   */  clearDispatcher(): void {    this.dispatcher = {};  }
  /**   * Extend an internal dispatcher   *   * @Deprecated Use `dispatcher` directly   */  extendDispatcher(dispatcher: Dispatcher): void {    this.dispatcher = {      ...this.dispatcher,      ...dispatcher,    };  }}
/** * An error indicates that the session is closed */export class SessionClosedError extends Error {  constructor() {    super("The session is closed");    this.name = "SessionClosedError";  }}