package uploader

import (
	"context"
	"github.com/iikira/BaiduPCS-Go/pcsutil/waitgroup"
	"github.com/oleiade/lane"
	"os"
	"time"
)

type (
	worker struct {
		id         int
		partOffset int64
		splitUnit  SplitUnit
		checksum   string
	}

	workerList []*worker
)

// CheckSumList 返回所以worker的checksum
// TODO: 实现sort
func (werl *workerList) CheckSumList() []string {
	checksumList := make([]string, 0, len(*werl))
	for _, wer := range *werl {
		checksumList = append(checksumList, wer.checksum)
	}
	return checksumList
}

func (werl *workerList) Readed() int64 {
	var readed int64
	for _, wer := range *werl {
		readed += wer.splitUnit.Readed()
	}
	return readed
}

func (muer *MultiUploader) upload() (uperr error) {
	err := muer.multiUpload.Precreate()
	if err != nil {
		return err
	}

	var (
		deque = lane.NewDeque()

		// 控制并发量
		wg = waitgroup.NewWaitGroup(muer.parallel)
	)

	// 加入队列
	for _, wer := range muer.workers {
		if wer.checksum == "" {
			deque.Append(wer)
		}
	}

	for {
		e := deque.Shift()
		if e == nil { // 任务为空
			if wg.Parallel() == 0 { // 结束
				break
			} else {
				time.Sleep(1e9)
				continue
			}
		}

		wer := e.(*worker)
		wg.AddDelta()
		go func() {
			defer wg.Done()

			var (
				ctx, cancel = context.WithCancel(context.Background())
				doneChan    = make(chan struct{})
				checksum    string
				terr        error
			)
			go func() {
				checksum, terr = muer.multiUpload.TmpFile(ctx, int(wer.id), wer.partOffset, wer.splitUnit)
				close(doneChan)
			}()
			select {
			case <-muer.canceled:
				cancel()
				return
			case <-doneChan:
				// continue
			}
			cancel()
			if terr != nil {
				if me, ok := terr.(*MultiError); ok {
					if me.Terminated { // 终止
						close(muer.canceled)
						uperr = me.Err
						return
					}
				}

				uploaderVerbose.Warnf("upload err: %s, id: %d\n", terr, wer.id)
				wer.splitUnit.Seek(0, os.SEEK_SET)
				deque.Append(wer)
				return
			}
			wer.checksum = checksum

			// 通知更新
			if muer.updateInstanceStateChan != nil && len(muer.updateInstanceStateChan) < cap(muer.updateInstanceStateChan) {
				muer.updateInstanceStateChan <- struct{}{}
			}
		}()
	}
	wg.Wait()

	select {
	case <-muer.canceled:
		if uperr != nil {
			return uperr
		}
		return context.Canceled
	default:
	}

	cerr := muer.multiUpload.CreateSuperFile(muer.workers.CheckSumList()...)
	if cerr != nil {
		return cerr
	}

	return
}