import { randomUUID } from 'crypto'
import { Worker } from 'worker_threads'
import initLog from './log.js'

const log = initLog("Worker Setup")

let workerFarm = []
let workerReady = []

function waitForThread() {
    return new Promise(
        (resolve, reject) => {
            let interval = setInterval(
                () => {
                    const readyIndex = workerReady.indexOf(true)
                    if (readyIndex !== -1) {
                        clearInterval(interval)
                        resolve(readyIndex)
                    }
                },
                50
            )
        }
    )
}

export function initWorkers(threads) {
    for (let i = 0;  i < threads; ++i) {
        workerFarm.push(new Worker('./libs/utils/multithread/genericWorker.js'))
    }

    for (const i in workerFarm) {
        const worker = workerFarm[i]
        worker.postMessage({
            type: 'initWorker',
            name: `Worker ${parseInt(i) + 1}`
        })
        workerReady[i] = true
    }

    log(`Initialised ${threads} workers!`)
}

export function spread(script, data) {
    return new Promise(
        async (resolve, reject) => {
            const readyIndex = await waitForThread()
            workerReady[readyIndex] = false

            const worker = workerFarm[readyIndex]
            const jobID = randomUUID()
            worker.postMessage({
                type: 'runScript',
                script,
                data,
                id: jobID
            })

            const messageHandler = message => {
                if (message.id === jobID) {
                    workerReady[readyIndex] = true
                    worker.removeListener(
                        'message',
                        messageHandler
                    )
                    resolve(message.result)
                }
            }

            worker.on(
                'message',
                messageHandler
            )
        }
    )
}