import * as chokidar from "chokidar";

import { Bus } from "./bus";

export interface Watcher {
  watchSourceFileChanged(): void;
}

export let createWatcher = (dependencies: { bus: Bus }): Watcher => {
  let { bus } = dependencies;
  return {
    watchSourceFileChanged: () => {
      let timeout: any;
      let watch = chokidar.watch("./**/*.ts", {
        ignored: [".d.ts", "node_modules", "build/**/*", "dist/**/*"],
        ignoreInitial: true,
      });
      watch.on("all", () => {
        // batch events for a short amount of time to catch an IDE doing a save-all
        if (timeout === undefined) {
          timeout = setTimeout(() => {
            timeout = undefined;
            bus.signal("source-files-changed");
          }, 200);
        }
      });
    },
  };
};