package storage

import (
	"fmt"
	"time"

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

func (v *Volume) GetVolumeInfo() *volume_server_pb.VolumeInfo {
	return v.volumeInfo
}

func (v *Volume) maybeLoadVolumeInfo() (found bool) {

	var err error
	var hasRemoteFile bool
	v.volumeInfo, hasRemoteFile, found, err = volume_info.MaybeLoadVolumeInfo(v.FileName(".vif"))
	v.hasRemoteFile.Store(hasRemoteFile)
	internVolumeInfoStrings(v.volumeInfo)

	if v.volumeInfo.Version == 0 {
		v.volumeInfo.Version = uint32(needle.GetCurrentVersion())
	}

	if hasRemoteFile {
		glog.V(0).Infof("volume %d is tiered to %s as %s and read only", v.Id,
			v.volumeInfo.Files[0].BackendName(), v.volumeInfo.Files[0].Key)
	} else {
		if v.volumeInfo.BytesOffset == 0 {
			v.volumeInfo.BytesOffset = uint32(types.OffsetSize)
		}
	}

	if v.volumeInfo.BytesOffset != 0 && v.volumeInfo.BytesOffset != uint32(types.OffsetSize) {
		var m string
		if types.OffsetSize == 5 {
			m = "without"
		} else {
			m = "with"
		}
		glog.Exitf("BytesOffset mismatch in volume info file %s, try use binary version %s large_disk", v.FileName(".vif"), m)
		return
	}

	if err != nil {
		glog.Warningf("load volume %d.vif file: %v", v.Id, err)
		return
	}

	return

}

// internVolumeInfoStrings shares the values every volume's .vif repeats. A
// tiered volume names its replication and its backend on every load, and the
// decode allocates a fresh copy of each, so a server holding millions of them
// otherwise holds millions of copies of the same handful of names. The remote
// key is left alone: it names one volume.
func internVolumeInfoStrings(volumeInfo *volume_server_pb.VolumeInfo) {
	volumeInfo.Replication = internVolumeString(volumeInfo.Replication)
	for _, remoteFile := range volumeInfo.GetFiles() {
		remoteFile.BackendType = internVolumeString(remoteFile.BackendType)
		remoteFile.BackendId = internVolumeString(remoteFile.BackendId)
		remoteFile.Extension = internVolumeString(remoteFile.Extension)
	}
}

func (v *Volume) HasRemoteFile() bool {
	return v.hasRemoteFile.Load()
}

// LoadRemoteFile swaps the data backend to the remote tier object under
// dataFileAccessLock. Call this from a context that does NOT already hold the
// lock — the live tier-upload handler, where the heartbeat may be reading the
// backend concurrently. load() must instead use loadRemoteFileLocked, since it
// can be reached with the lock already held (CommitCompact).
func (v *Volume) LoadRemoteFile() error {
	v.dataFileAccessLock.Lock()
	defer v.dataFileAccessLock.Unlock()
	return v.loadRemoteFileLocked()
}

// loadRemoteFileLocked swaps the data backend to the remote tier object. The
// caller must hold dataFileAccessLock or be single-threaded (load() during
// construction or a compaction-commit reload). It marks the volume tiered in the
// same locked step so a later heartbeat does not treat a removed local .dat as a
// phantom volume and stop reporting it to the master.
func (v *Volume) loadRemoteFileLocked() error {
	// Callers only reach here for a tiered volume (HasRemoteFile / a just-appended
	// remote file), but guard the index so a stray call is a clean error, not a panic.
	if len(v.volumeInfo.GetFiles()) == 0 {
		return fmt.Errorf("volume %d has no remote file to load", v.Id)
	}
	tierFile := v.volumeInfo.GetFiles()[0]
	backendStorage, found := backend.BackendStorages[tierFile.BackendName()]
	if !found {
		return fmt.Errorf("backend storage %s not found", tierFile.BackendName())
	}
	v.swapDataBackendLocked(backendStorage.NewStorageFile(tierFile.Key, v.volumeInfo), true)
	return nil
}

func (v *Volume) SaveVolumeInfo() error {

	tierFileName := v.FileName(".vif")
	if v.Ttl != nil {
		ttlSeconds := v.Ttl.ToSeconds()
		if ttlSeconds > 0 {
			v.volumeInfo.ExpireAtSec = uint64(time.Now().Unix()) + ttlSeconds //calculated destroy time from the ec volume was created
		}
	}

	return volume_info.SaveVolumeInfo(tierFileName, v.volumeInfo)

}
