package weed_server

import (
	"context"
	"errors"
	"fmt"
	"io"

	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"

	"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
	"github.com/seaweedfs/seaweedfs/weed/storage"
	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
	"github.com/seaweedfs/seaweedfs/weed/storage/types"
)

func (vs *VolumeServer) VolumeIncrementalCopy(req *volume_server_pb.VolumeIncrementalCopyRequest, stream volume_server_pb.VolumeServer_VolumeIncrementalCopyServer) error {

	v := vs.store.GetVolume(needle.VolumeId(req.VolumeId))
	if v == nil {
		return fmt.Errorf("not found volume id %d", req.VolumeId)
	}
	if err := v.UnavailableError(); err != nil {
		return err
	}

	stopOffset, _, _ := v.FileStat()

	var startOffset int64
	if req.EntryCount > 0 {
		foundOffset, upToDate, err := v.ResumeByLastEntry(
			req.EntryCount,
			types.NeedleId(req.LastNeedleKey),
			req.LastNeedleCookie,
			types.Size(req.LastNeedleSize),
			req.EntriesHash,
		)
		if err != nil {
			if errors.Is(err, storage.ErrIncrementalCopyDiverged) {
				return status.Error(codes.FailedPrecondition, err.Error())
			}
			return fmt.Errorf("fail to locate by entry %d: %s", req.EntryCount, err)
		}
		if upToDate {
			return nil
		}
		startOffset = foundOffset.ToActualOffset()
	} else {
		foundOffset, isLastOne, err := v.BinarySearchByAppendAtNs(req.SinceNs)
		if err != nil {
			return fmt.Errorf("fail to locate by appendAtNs %d: %s", req.SinceNs, err)
		}
		if isLastOne {
			return nil
		}
		startOffset = foundOffset.ToActualOffset()
	}

	buf := make([]byte, 1024*1024*2)
	return sendFileContent(v, buf, startOffset, int64(stopOffset), stream)

}

func (vs *VolumeServer) VolumeSyncStatus(ctx context.Context, req *volume_server_pb.VolumeSyncStatusRequest) (*volume_server_pb.VolumeSyncStatusResponse, error) {

	v := vs.store.GetVolume(needle.VolumeId(req.VolumeId))
	if v == nil {
		return nil, fmt.Errorf("not found volume id %d", req.VolumeId)
	}

	resp := v.GetVolumeSyncStatus()

	return resp, nil

}

func sendFileContent(v *storage.Volume, buf []byte, startOffset, stopOffset int64, stream volume_server_pb.VolumeServer_VolumeIncrementalCopyServer) error {
	var blockSizeLimit = int64(len(buf))
	for i := int64(0); i < stopOffset-startOffset; i += blockSizeLimit {
		if err := v.UnavailableError(); err != nil {
			return err
		}
		n, readErr := v.DataBackend.ReadAt(buf, startOffset+i)
		if readErr == nil || readErr == io.EOF {
			resp := &volume_server_pb.VolumeIncrementalCopyResponse{}
			resp.FileContent = buf[:int64(n)]
			sendErr := stream.Send(resp)
			if sendErr != nil {
				return sendErr
			}
		} else {
			return readErr
		}
	}
	return nil
}