/* eslint-disable @typescript-eslint/no-unsafe-argument */
/* eslint-disable @typescript-eslint/no-unsafe-member-access */
/* eslint-disable @typescript-eslint/no-unsafe-assignment */
/* eslint-disable @typescript-eslint/no-implied-eval */

import { CancelableFn, Fn } from "./Fn";

export class Debounce {
  protected _handle: NodeJS.Timeout;
  protected _last: any;

  constructor(readonly fn: Fn, readonly wait_ms: number = 100) {
    this._handle;
    this._last;
  }

  public add(...args: any[]) {
    this._last = args;
    this._unschedule();
    this._schedule();
  }

  public cancel() {
    this._unschedule();
    this._last = undefined;
  }

  protected _unschedule() {
    clearTimeout(this._handle);
  }

  protected _schedule() {
    this._handle = setTimeout(this._process.bind(this), this.wait_ms);
    if (this._handle.unref) {
      this._handle.unref();
    }
  }

  protected _process() {
    if (!this._last) return;
    this.fn(...this._last);
  }
}

/**
 * Debounce allows repeated calls to a function but will delay execution of the
 * function until a a timeout period expires. Upon expiration, the function is
 * called with the last value that was provided
 *
 * @example
 * const debounce_ms = 100;
 * const fn = n => console.log(n, new Date());
 * const debouncedFn = debounce(fn, debounce_ms);
 * debouncedFn('h');
 * debouncedFn('he');
 * debouncedFn('hel');
 * debouncedFn('hell');
 * debouncedFn('hello');
 */
export function debounce(fn: Fn, debounce_ms: number = 100): CancelableFn {
  const i = new Debounce(fn, debounce_ms);
  const add = i.add.bind(i);
  add.cancel = i.cancel.bind(i);
  return add as CancelableFn;
}