package uploader

import (
	"context"
	"github.com/iikira/BaiduPCS-Go/pcsutil"
	"github.com/iikira/BaiduPCS-Go/pcsutil/converter"
	"github.com/iikira/BaiduPCS-Go/requester"
	"github.com/iikira/BaiduPCS-Go/requester/rio"
	"time"
)

type (
	// MultiUpload 支持多线程的上传, 可用于断点续传
	MultiUpload interface {
		Precreate() (perr error)
		TmpFile(ctx context.Context, partseq int, partOffset int64, readerlen64 rio.ReaderLen64) (checksum string, terr error)
		CreateSuperFile(checksumList ...string) (cerr error)
	}

	// MultiUploader 多线程上传
	MultiUploader struct {
		onExecuteEvent requester.Event        //开始上传事件
		onSuccessEvent requester.Event        //成功上传事件
		onFinishEvent  requester.Event        //结束上传事件
		onCancelEvent  requester.Event        //取消上传事件
		onErrorEvent   requester.EventOnError //上传出错事件

		instanceState *InstanceState

		multiUpload MultiUpload       // 上传体接口
		file        rio.ReaderAtLen64 // 上传
		blockSize   int64
		parallel    int
		workers     workerList

		executeTime             time.Time
		executed                bool
		finished                chan struct{}
		canceled                chan struct{}
		updateInstanceStateChan chan struct{}
	}
)

// NewMultiUploader 初始化上传
func NewMultiUploader(multiUpload MultiUpload, file rio.ReaderAtLen64) *MultiUploader {
	return &MultiUploader{
		multiUpload: multiUpload,
		file:        file,
	}
}

// SetBlockSize 设置block size
func (muer *MultiUploader) SetBlockSize(blockSize int64) {
	muer.blockSize = blockSize
}

// SetParallel 设置parallel, 上传并发量
func (muer *MultiUploader) SetParallel(parallel int) {
	muer.parallel = parallel
}

// SetInstanceState 设置InstanceState, 断点续传信息
func (muer *MultiUploader) SetInstanceState(is *InstanceState) {
	muer.instanceState = is
}

func (muer *MultiUploader) lazyInit() {
	if muer.finished == nil {
		muer.finished = make(chan struct{}, 1)
	}
	if muer.canceled == nil {
		muer.canceled = make(chan struct{})
	}
	if muer.updateInstanceStateChan == nil {
		muer.updateInstanceStateChan = make(chan struct{}, 1)
	}
	if muer.parallel <= 0 {
		muer.parallel = 10
	}
	if muer.blockSize <= 0 {
		muer.blockSize = 1 * converter.GB
	}
}

func (muer *MultiUploader) check() {
	if muer.file == nil {
		panic("file is nil")
	}
	if muer.multiUpload == nil {
		panic("multiUpload is nil")
	}
}

// Execute 执行上传
func (muer *MultiUploader) Execute() {
	muer.check()
	muer.lazyInit()
	// 分配任务
	if muer.instanceState != nil {
		muer.workers = instanceStateToWorkerList(muer.instanceState, muer.file)
		uploaderVerbose.Infof("upload task CREATED from instance state\n")
	} else {
		muer.workers = instanceStateToWorkerList(&InstanceState{
			BlockList: SplitBlock(muer.file.Len(), muer.blockSize),
		}, muer.file)

		uploaderVerbose.Infof("upload task CREATED: block size: %d, num: %d\n", muer.blockSize, len(muer.workers))
	}

	// 开始上传
	muer.executed = true
	muer.executeTime = time.Now()
	pcsutil.Trigger(muer.onExecuteEvent)

	err := muer.upload()

	// 完成
	muer.finished <- struct{}{}
	if err != nil {
		if err == context.Canceled {
			if muer.onCancelEvent != nil {
				muer.onCancelEvent()
			}
		} else if muer.onErrorEvent != nil {
			muer.onErrorEvent(err)
		}
	} else {
		pcsutil.TriggerOnSync(muer.onSuccessEvent)
	}
	pcsutil.TriggerOnSync(muer.onFinishEvent)
}

// InstanceState 返回断点续传信息
func (muer *MultiUploader) InstanceState() *InstanceState {
	return workerListToInstanceState(muer.workers)
}

// Cancel 取消上传
func (muer *MultiUploader) Cancel() {
	close(muer.canceled)
}

//OnExecute 设置开始上传事件
func (muer *MultiUploader) OnExecute(onExecuteEvent requester.Event) {
	muer.onExecuteEvent = onExecuteEvent
}

//OnSuccess 设置成功上传事件
func (muer *MultiUploader) OnSuccess(onSuccessEvent requester.Event) {
	muer.onSuccessEvent = onSuccessEvent
}

//OnFinish 设置结束上传事件
func (muer *MultiUploader) OnFinish(onFinishEvent requester.Event) {
	muer.onFinishEvent = onFinishEvent
}

//OnCancel 设置取消上传事件
func (muer *MultiUploader) OnCancel(onCancelEvent requester.Event) {
	muer.onCancelEvent = onCancelEvent
}

//OnCancel 设置取消上传事件
func (muer *MultiUploader) OnError(onErrorEvent requester.EventOnError) {
	muer.onErrorEvent = onErrorEvent
}