import { simulate } from './solver';
import { simulateGPU } from './gpu';
import type { BeadSystem, Excitation, SimOptions, SimResult } from './types';

export interface WorkerRequest {
  sys: BeadSystem;
  exc: Excitation;
  opt: SimOptions;
  gpu: boolean;
}

const buffers = (r: SimResult) =>
  [r.audio, r.frames, r.frameTimes, r.energy, r.balance, r.contactForce, r.malletPos].filter((a) => a).map((a) => a!.buffer) as ArrayBuffer[];

self.onmessage = async (ev: MessageEvent<WorkerRequest>) => {
  const { sys, exc, opt, gpu } = ev.data;
  const progress = (f: number) => self.postMessage({ type: 'progress', fraction: f });
  const partial = (result: SimResult) => self.postMessage({ type: 'partial', result }, { transfer: buffers(result) });
  try {
    let result: SimResult | undefined;
    let fallback: string | undefined;
    if (gpu) {
      try {
        const r = await simulateGPU(sys, exc, opt, progress, (p) => partial({ ...p, backend: `WebGPU (${(p as SimResult & { device: string }).device})` }));
        result = { ...r, backend: `WebGPU (${r.device})` };
      } catch (e) {
        fallback = (e as Error).message ?? String(e);
      }
    }
    result ??= { ...simulate(sys, exc, opt, progress, (p) => partial({ ...p, backend: 'CPU', fallback })), backend: 'CPU', fallback };
    self.postMessage({ type: 'done', result }, { transfer: buffers(result) });
  } catch (e) {
    self.postMessage({ type: 'error', message: String(e) });
  }
};