package shard

import (
	"context"
	"errors"
	"sync"

	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"go.uber.org/zap"
)

type rebuilder struct {
	mtx    *sync.Mutex
	wg     *sync.WaitGroup
	cancel func()
}

func newRebuilder() *rebuilder {
	return &rebuilder{
		mtx:    &sync.Mutex{},
		wg:     &sync.WaitGroup{},
		cancel: nil,
	}
}

func (r *rebuilder) Start(ctx context.Context, bs *blobstor.BlobStor, mb *meta.DB, log *logger.Logger) {
	r.mtx.Lock()
	defer r.mtx.Unlock()

	r.start(ctx, bs, mb, log)
}

func (r *rebuilder) start(ctx context.Context, bs *blobstor.BlobStor, mb *meta.DB, log *logger.Logger) {
	if r.cancel != nil {
		r.stop(log)
	}
	ctx, cancel := context.WithCancel(ctx)
	r.cancel = cancel
	r.wg.Add(1)
	go func() {
		defer r.wg.Done()

		log.Info(logs.BlobstoreRebuildStarted)
		if err := bs.Rebuild(ctx, &mbStorageIDUpdate{mb: mb}); err != nil {
			log.Warn(logs.FailedToRebuildBlobstore, zap.Error(err))
		} else {
			log.Info(logs.BlobstoreRebuildCompletedSuccessfully)
		}
	}()
}

func (r *rebuilder) Stop(log *logger.Logger) {
	r.mtx.Lock()
	defer r.mtx.Unlock()

	r.stop(log)
}

func (r *rebuilder) stop(log *logger.Logger) {
	if r.cancel == nil {
		return
	}

	r.cancel()
	r.wg.Wait()
	r.cancel = nil
	log.Info(logs.BlobstoreRebuildStopped)
}

var errMBIsNotAvailable = errors.New("metabase is not available")

type mbStorageIDUpdate struct {
	mb *meta.DB
}

func (u *mbStorageIDUpdate) UpdateStorageID(ctx context.Context, addr oid.Address, storageID []byte) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	default:
	}

	if u.mb == nil {
		return errMBIsNotAvailable
	}

	var prm meta.UpdateStorageIDPrm
	prm.SetAddress(addr)
	prm.SetStorageID(storageID)
	_, err := u.mb.UpdateStorageID(prm)
	return err
}