import type { MatmulResult } from './types'

// Dedicated classic worker for the pthread-capable WASM modules (threaded
// custom C, libFLAME/BLIS st + mt). It's a classic worker served verbatim
// from public/matmul/ (see worker.js for why it can't be a Vite module
// worker). Resolve it relative to the deployed base.
const WORKER_URL = new URL(
  `${import.meta.env.BASE_URL}matmul/worker.js`,
  window.location.href,
)

let worker: Worker | null = null
let nextId = 0
const pending = new Map<number, { resolve: (r: MatmulResult) => void; reject: (e: Error) => void }>()

function getWorker(): Worker {
  if (!worker) {
    worker = new Worker(WORKER_URL) // classic worker (no { type: 'module' })
    worker.onmessage = (e: MessageEvent<{ id: number; ms?: number; sample?: number; error?: string }>) => {
      const p = pending.get(e.data.id)
      if (!p) return
      pending.delete(e.data.id)
      if (e.data.error) p.reject(new Error(e.data.error))
      else p.resolve({ ms: e.data.ms!, sample: e.data.sample! })
    }
  }
  return worker
}

export function runInThreadedWorker(
  kind: string,
  n: number,
  seedA: number,
  seedB: number,
  threads: number,
): Promise<MatmulResult> {
  const w = getWorker()
  const id = nextId++
  return new Promise((resolve, reject) => {
    pending.set(id, { resolve, reject })
    w.postMessage({ id, kind, n, seedA, seedB, threads })
  })
}