import { parentPort, workerData } from 'worker_threads'

import { getBlockAtDifficulty } from './utilities'

const block = workerData.args[0]
const difficulty = workerData.args[1]
const index = workerData.args[2]
const step = workerData.args[3]

parentPort!.postMessage(getBlockAtDifficulty(block, difficulty, index, step))

export function detect(hash: string, difficulty: number) {
  let i, b
  for (i = 0, b = hash.length; i < b; i++) {
    if (hash[i] !== '0') {
      break;
    }
  }
  return i === difficulty;
}

export function getBlockAtDifficulty(block: Partial<Block>, difficulty: number, index = 0, step = 1) {
  let result: Block
  let nonce = index
  do {
    result = new Block({ ...block, nonce: String(nonce) })
    nonce += step
  } while (!detect(Hash.encode(String(result)), difficulty))
  return result
}

export interface MultiServiceThreadpoolResolution { [threadpool: string]: any }

export class MultiService {
  private static resolver = new Subject<MultiServiceThreadpoolResolution>()
  static resolver$: Observable<MultiServiceThreadpoolResolution>
  static initialize() {
    MultiService.resolver$ = MultiService.resolver.asObservable()
  }
  static resolve(pr: Promise<any>, threadpool: string) {
    pr
      .then(v => MultiService.resolver.next({ [threadpool]: v }))
      .catch(e => console.error(e))
  }
}
MultiService.initialize()

/**
 * spawns threads to resolve hash at difficulty, publishing result in 
 * MultiService
 * @param block Block to resolve hash of
 * @param difficulty Difficulty of hash to resolve
 * @returns uuid of multiservice to subscribe to
 * usage:
 * const multiService = new MultiService()
 * const task = getBlockAtDifficultyMultiThreaded(myBlock, someDifficulty)
 * multiService.resolve$
 *   .pipe(first(resolution => resolution.hasOwnProperty(task)))
 *   .subscribe(resolution => onSuccess(resolution[task]))
 */
export function getBlockAtDifficultyMultiThreaded(block: Partial<Block>, difficulty: number): UUID {
  const uuid = uuidV4() // our task identifier
  const workers: Array<Worker> = []
  const threads = os.cpus()
  threads.forEach((_, i) => {
    const args = [block, difficulty, i, threads]
    const worker: Worker = TSWorker('get-block-at-difficulty.worker.ts', {
      workerData: { args }
    });

    workers.push(worker)
    worker.on('message', (result: Block) => {
      MultiService.resolve(new Promise(res => res(result)), uuid)
      workers.forEach(w => w.terminate())
    })
  })
  return uuid
}

describe('getBlockAtDifficultyMultithreaded', () => {
  it('should produce a hash multithreaded', done => {
    const chain: Array<Block> = []
    const data = ['Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.']

    chain.push(Block.factoryGenesisBlock())

    const task = getBlockAtDifficultyMultiThreaded(factoryNextBlock({ data }, chain), 8)
    MultiService.resolver$.pipe(first(resolution => resolution.hasOwnProperty(task))).subscribe(resolution => {
      chain.push(resolution[task])

      console.log(Hash.encode(String(chain[1])))

      expect(difficulty(Hash.encode(String(chain[1])))).toEqual(8)
      done()
    })
  })
})

    const worker: Worker = TSWorker([__dirname, 'get-block-at-difficulty.worker.ts'].join('/'), {
      workerData: { args }
    });