package job

import (
	"github.com/vmware/harbor/dao"
	"github.com/vmware/harbor/job/config"
	"github.com/vmware/harbor/models"
	"github.com/vmware/harbor/utils/log"
)

type workerPool struct {
	workerChan chan *Worker
	workerList []*Worker
}

// WorkerPool is a set of workers each worker is associate to a statemachine for handling jobs.
// it consists of a channel for free workers and a list to all workers
var WorkerPool *workerPool

// StopJobs accepts a list of jobs and will try to stop them if any of them is being executed by the worker.
func (wp *workerPool) StopJobs(jobs []int64) {
	log.Debugf("Works working on jobs: %v will be stopped", jobs)
	for _, id := range jobs {
		for _, w := range wp.workerList {
			if w.SM.JobID == id {
				log.Debugf("found a worker whose job ID is %d, will try to stop it", id)
				w.SM.Stop(id)
			}
		}
	}
}

// Worker consists of a channel for job from which worker gets the next job to handle, and a pointer to a statemachine,
// the actual work to handle the job is done via state machine.
type Worker struct {
	ID      int
	RepJobs chan int64
	SM      *SM
	quit    chan bool
}

// Start is a loop worker gets id from its channel and handle it.
func (w *Worker) Start() {
	go func() {
		for {
			WorkerPool.workerChan <- w
			select {
			case jobID := <-w.RepJobs:
				log.Debugf("worker: %d, will handle job: %d", w.ID, jobID)
				w.handleRepJob(jobID)
			case q := <-w.quit:
				if q {
					log.Debugf("worker: %d, will stop.", w.ID)
					return
				}
			}
		}
	}()
}

// Stop ...
func (w *Worker) Stop() {
	go func() {
		w.quit <- true
	}()
}

func (w *Worker) handleRepJob(id int64) {
	err := w.SM.Reset(id)
	if err != nil {
		log.Errorf("Worker %d, failed to re-initialize statemachine for job: %d, error: %v", w.ID, id, err)
		err2 := dao.UpdateRepJobStatus(id, models.JobError)
		if err2 != nil {
			log.Errorf("Failed to update job status to ERROR, job: %d, error:%v", id, err2)
		}
		return
	}
	if w.SM.Parms.Enabled == 0 {
		log.Debugf("The policy of job:%d is disabled, will cancel the job")
		_ = dao.UpdateRepJobStatus(id, models.JobCanceled)
	} else {
		w.SM.Start(models.JobRunning)
	}
}

// NewWorker returns a pointer to new instance of worker
func NewWorker(id int) *Worker {
	w := &Worker{
		ID:      id,
		RepJobs: make(chan int64),
		quit:    make(chan bool),
		SM:      &SM{},
	}
	w.SM.Init()
	return w
}

// InitWorkerPool create workers according to configuration.
func InitWorkerPool() {
	WorkerPool = &workerPool{
		workerChan: make(chan *Worker, config.MaxJobWorkers()),
		workerList: make([]*Worker, 0, config.MaxJobWorkers()),
	}
	for i := 0; i < config.MaxJobWorkers(); i++ {
		worker := NewWorker(i)
		WorkerPool.workerList = append(WorkerPool.workerList, worker)
		worker.Start()
		log.Debugf("worker %d started", worker.ID)
	}
}

// Dispatch will listen to the jobQueue of job service and try to pick a free worker from the worker pool and assign the job to it.
func Dispatch() {
	for {
		select {
		case job := <-jobQueue:
			go func(jobID int64) {
				log.Debugf("Trying to dispatch job: %d", jobID)
				worker := <-WorkerPool.workerChan
				worker.RepJobs <- jobID
			}(job)
		}
	}
}