import type { MatmulResult } from './types'
import type { WorkerRequest, WorkerResponse } from './benchWorker'

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(new URL('./benchWorker.ts', import.meta.url), { type: 'module' })
    worker.onmessage = (e: MessageEvent<WorkerResponse>) => {
      const p = pending.get(e.data.id)
      if (!p) return
      pending.delete(e.data.id)
      if ('error' in e.data) p.reject(new Error(e.data.error))
      else p.resolve({ ms: e.data.ms, sample: e.data.sample })
    }
  }
  return worker
}

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