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import util from "../../lib/util.ts";import events from "./events.ts";
// ESM Hot Module Replacement (ESM-HMR) Specification// https://github.com/withastro/esm-hmr
class Module {  private _specifier: string;  private _isAccepted = false;  private _isDeclined = false;  private _isLocked = false;  private _acceptCallbacks: CallableFunction[] = [];  private _declineDelay = 0;
  constructor(specifier: string) {    this._specifier = specifier;  }
  accept(callback?: CallableFunction): void {    if (this._isLocked) {      return;    }    if (!this._isAccepted) {      sendMessage({ specifier: this._specifier, type: "hotAccept" });      this._isAccepted = true;    }    if (callback) {      this._acceptCallbacks.push(callback);    }  }
  decline(delay?: number): void {    this._isDeclined = true;    if (!Number.isNaN(Number(delay))) {      this._declineDelay = Math.max(Number(delay), 0);    }    this.accept();  }
  watchFile(filename: string, callback: () => void) {    const specifier = "." + util.cleanPath(filename);    const handler = (data: Record<string, unknown>) => {      if (data.specifier === specifier) {        callback();      }    };    events.on("hmr:modify", handler);    sendMessage({ specifier, type: "hotAccept" });    return () => events.off("hmr:modify", handler);  }
  // don't accept updates if the module is locked  lock(): void {    this._isLocked = true;  }
  async applyUpdate() {    if (this._isDeclined) {      if (this._declineDelay > 0) {        await new Promise((resolve) => setTimeout(resolve, this._declineDelay));      }      location.reload();      return;    }    try {      const url = this._specifier.slice(1) + (this._specifier.endsWith(".css") ? "?module&" : "?") + "t=" + Date.now();      const module = await import(url);      this._acceptCallbacks.forEach((cb) => cb(module));    } catch (err) {      console.error(err);      // todo: ui feedback    }  }}
export default function createHotContext(specifier: string) {  if (modules.has(specifier)) {    const mod = modules.get(specifier)!;    mod.lock();    return mod;  }  const mod = new Module(specifier);  modules.set(specifier, mod);  return mod;}
const modules: Map<string, Module> = new Map();const messageQueue: string[] = [];
let conn: WebSocket | null = null;function sendMessage(msg: Record<string, unknown>) {  const json = JSON.stringify(msg);  if (!conn || conn.readyState !== WebSocket.OPEN) {    messageQueue.push(json);  } else {    conn.send(json);  }}
function connect() {  const { location, __hmrWebSocketUrl } = window as { location: Location; __hmrWebSocketUrl?: string };  const { protocol, host } = location;  const wsUrl = __hmrWebSocketUrl || `${protocol === "https:" ? "wss" : "ws"}://${host}/-/hmr`;  const ws = new WebSocket(wsUrl);  const ping = (callback: () => void) => {    setTimeout(() => {      const ws = new WebSocket(wsUrl);      ws.addEventListener("open", callback);      ws.addEventListener("close", () => {        ping(callback); // retry      });    }, 500);  };
  ws.addEventListener("open", () => {    conn = ws;    messageQueue.splice(0, messageQueue.length).forEach((msg) => ws.send(msg));    console.log("%c[HMR]", "color:#999", "listening for file changes...");  });
  ws.addEventListener("close", () => {    if (conn !== null) {      conn = null;      console.log("[HMR] closed.");      // re-connect after 0.5s      setTimeout(() => {        connect();      }, 500);    } else {      // reload the page when re-connected      ping(() => location.reload());    }  });
  ws.addEventListener("message", ({ data }: { data?: string }) => {    if (data) {      try {        const { type, specifier, routePattern } = JSON.parse(data);        switch (type) {          case "create": {            events.emit("hmr:create", { specifier, routePattern });            break;          }          case "modify": {            const mod = modules.get(specifier);            if (mod) {              mod.applyUpdate();            }            events.emit("hmr:modify", { specifier });            break;          }          case "remove": {            if (modules.has(specifier)) {              modules.delete(specifier);            }            events.emit("hmr:remove", { specifier });            break;          }          case "reload": {            location.reload();          }        }        console.log("%c[HMR]", "color:#999", `${type} ${JSON.stringify(specifier)}`);      } catch (err) {        console.warn(err);      }    }  });}
addEventListener("load", connect);