import type { BeadSystem, Excitation, SimOptions, SimResult } from './types';

export interface Running {
  promise: Promise<SimResult>;
  cancel: () => void;
}

// Starts a solver worker (src/sim/worker.ts). The page loads it from its own file; the
// embedded widget, which runs on other sites, has it inlined (a worker must be same-origin).
export type MakeWorker = () => Worker;

// onPartial gets the result so far every few seconds while the run is in progress
export function runInWorker(
  makeWorker: MakeWorker,
  sys: BeadSystem,
  exc: Excitation,
  opt: SimOptions,
  gpu: boolean,
  onProgress: (f: number) => void,
  onPartial?: (r: SimResult) => void,
): Running {
  const worker = makeWorker();
  let reject!: (e: Error) => void;
  const promise = new Promise<SimResult>((res, rej) => {
    reject = rej;
    worker.onmessage = (ev) => {
      const m = ev.data;
      if (m.type === 'progress') onProgress(m.fraction);
      else if (m.type === 'partial') onPartial?.(m.result);
      else if (m.type === 'done') {
        worker.terminate();
        res(m.result);
      } else {
        worker.terminate();
        rej(new Error(m.message));
      }
    };
    worker.onerror = (e) => {
      worker.terminate();
      rej(new Error(e.message));
    };
  });
  worker.postMessage({ sys, exc, opt, gpu });
  return {
    promise,
    cancel: () => {
      worker.terminate();
      reject(new Error('cancelled'));
    },
  };
}