package storage

import (
	"fmt"
	"os"
	"time"

	"github.com/chrislusf/seaweedfs/weed/glog"
	"github.com/chrislusf/seaweedfs/weed/stats"
	"github.com/chrislusf/seaweedfs/weed/storage/backend"
	idx2 "github.com/chrislusf/seaweedfs/weed/storage/idx"
	"github.com/chrislusf/seaweedfs/weed/storage/needle"
	"github.com/chrislusf/seaweedfs/weed/storage/needle_map"
	. "github.com/chrislusf/seaweedfs/weed/storage/types"
	"github.com/chrislusf/seaweedfs/weed/util"
)

func (v *Volume) garbageLevel() float64 {
	if v.ContentSize() == 0 {
		return 0
	}
	return float64(v.DeletedSize()) / float64(v.ContentSize())
}

func (v *Volume) Compact(preallocate int64, compactionBytePerSecond int64) error {

	if v.MemoryMapMaxSizeMb == 0 { //it makes no sense to compact in memory
		glog.V(3).Infof("Compacting volume %d ...", v.Id)
		//no need to lock for copy on write
		//v.accessLock.Lock()
		//defer v.accessLock.Unlock()
		//glog.V(3).Infof("Got Compaction lock...")
		v.isCompacting = true
		defer func() {
			v.isCompacting = false
		}()

		filePath := v.FileName()
		v.lastCompactIndexOffset = v.IndexFileSize()
		v.lastCompactRevision = v.SuperBlock.CompactionRevision
		glog.V(3).Infof("creating copies for volume %d ,last offset %d...", v.Id, v.lastCompactIndexOffset)
		return v.copyDataAndGenerateIndexFile(filePath+".cpd", filePath+".cpx", preallocate, compactionBytePerSecond)
	} else {
		return nil
	}
}

func (v *Volume) Compact2() error {

	if v.MemoryMapMaxSizeMb == 0 { //it makes no sense to compact in memory
		glog.V(3).Infof("Compact2 volume %d ...", v.Id)

		v.isCompacting = true
		defer func() {
			v.isCompacting = false
		}()

		filePath := v.FileName()
		glog.V(3).Infof("creating copies for volume %d ...", v.Id)
		return v.copyDataBasedOnIndexFile(filePath+".cpd", filePath+".cpx")
	} else {
		return nil
	}
}

func (v *Volume) CommitCompact() error {
	if v.MemoryMapMaxSizeMb == 0 { //it makes no sense to compact in memory
		glog.V(0).Infof("Committing volume %d vacuuming...", v.Id)

		v.isCompacting = true
		defer func() {
			v.isCompacting = false
		}()

		v.dataFileAccessLock.Lock()
		defer v.dataFileAccessLock.Unlock()

		glog.V(3).Infof("Got volume %d committing lock...", v.Id)
		v.nm.Close()
		if err := v.DataBackend.Close(); err != nil {
			glog.V(0).Infof("fail to close volume %d", v.Id)
		}
		v.DataBackend = nil
		stats.VolumeServerVolumeCounter.WithLabelValues(v.Collection, "volume").Dec()

		var e error
		if e = v.makeupDiff(v.FileName()+".cpd", v.FileName()+".cpx", v.FileName()+".dat", v.FileName()+".idx"); e != nil {
			glog.V(0).Infof("makeupDiff in CommitCompact volume %d failed %v", v.Id, e)
			e = os.Remove(v.FileName() + ".cpd")
			if e != nil {
				return e
			}
			e = os.Remove(v.FileName() + ".cpx")
			if e != nil {
				return e
			}
		} else {
			var e error
			if e = os.Rename(v.FileName()+".cpd", v.FileName()+".dat"); e != nil {
				return fmt.Errorf("rename %s: %v", v.FileName()+".cpd", e)
			}
			if e = os.Rename(v.FileName()+".cpx", v.FileName()+".idx"); e != nil {
				return fmt.Errorf("rename %s: %v", v.FileName()+".cpx", e)
			}
		}

		//glog.V(3).Infof("Pretending to be vacuuming...")
		//time.Sleep(20 * time.Second)

		os.RemoveAll(v.FileName() + ".ldb")
		os.RemoveAll(v.FileName() + ".bdb")

		glog.V(3).Infof("Loading volume %d commit file...", v.Id)
		if e = v.load(true, false, v.needleMapKind, 0); e != nil {
			return e
		}
	}
	return nil
}

func (v *Volume) cleanupCompact() error {
	glog.V(0).Infof("Cleaning up volume %d vacuuming...", v.Id)

	e1 := os.Remove(v.FileName() + ".cpd")
	e2 := os.Remove(v.FileName() + ".cpx")
	if e1 != nil {
		return e1
	}
	if e2 != nil {
		return e2
	}
	return nil
}

func fetchCompactRevisionFromDatFile(datBackend backend.DataStorageBackend) (compactRevision uint16, err error) {
	superBlock, err := ReadSuperBlock(datBackend)
	if err != nil {
		return 0, err
	}
	return superBlock.CompactionRevision, nil
}

func (v *Volume) makeupDiff(newDatFileName, newIdxFileName, oldDatFileName, oldIdxFileName string) (err error) {
	var indexSize int64

	oldIdxFile, err := os.Open(oldIdxFileName)
	defer oldIdxFile.Close()

	oldDatFile, err := os.Open(oldDatFileName)
	oldDatBackend := backend.NewDiskFile(oldDatFile)
	defer oldDatBackend.Close()

	if indexSize, err = verifyIndexFileIntegrity(oldIdxFile); err != nil {
		return fmt.Errorf("verifyIndexFileIntegrity %s failed: %v", oldIdxFileName, err)
	}
	if indexSize == 0 || uint64(indexSize) <= v.lastCompactIndexOffset {
		return nil
	}

	oldDatCompactRevision, err := fetchCompactRevisionFromDatFile(oldDatBackend)
	if err != nil {
		return fmt.Errorf("fetchCompactRevisionFromDatFile src %s failed: %v", oldDatFile.Name(), err)
	}
	if oldDatCompactRevision != v.lastCompactRevision {
		return fmt.Errorf("current old dat file's compact revision %d is not the expected one %d", oldDatCompactRevision, v.lastCompactRevision)
	}

	type keyField struct {
		offset Offset
		size   uint32
	}
	incrementedHasUpdatedIndexEntry := make(map[NeedleId]keyField)

	for idxOffset := indexSize - NeedleMapEntrySize; uint64(idxOffset) >= v.lastCompactIndexOffset; idxOffset -= NeedleMapEntrySize {
		var IdxEntry []byte
		if IdxEntry, err = readIndexEntryAtOffset(oldIdxFile, idxOffset); err != nil {
			return fmt.Errorf("readIndexEntry %s at offset %d failed: %v", oldIdxFileName, idxOffset, err)
		}
		key, offset, size := idx2.IdxFileEntry(IdxEntry)
		glog.V(4).Infof("key %d offset %d size %d", key, offset, size)
		if _, found := incrementedHasUpdatedIndexEntry[key]; !found {
			incrementedHasUpdatedIndexEntry[key] = keyField{
				offset: offset,
				size:   size,
			}
		}
	}

	// no updates during commit step
	if len(incrementedHasUpdatedIndexEntry) == 0 {
		return nil
	}

	// deal with updates during commit step
	var (
		dst, idx *os.File
	)
	if dst, err = os.OpenFile(newDatFileName, os.O_RDWR, 0644); err != nil {
		return fmt.Errorf("open dat file %s failed: %v", newDatFileName, err)
	}
	dstDatBackend := backend.NewDiskFile(dst)
	defer dstDatBackend.Close()

	if idx, err = os.OpenFile(newIdxFileName, os.O_RDWR, 0644); err != nil {
		return fmt.Errorf("open idx file %s failed: %v", newIdxFileName, err)
	}
	defer idx.Close()

	var newDatCompactRevision uint16
	newDatCompactRevision, err = fetchCompactRevisionFromDatFile(dstDatBackend)
	if err != nil {
		return fmt.Errorf("fetchCompactRevisionFromDatFile dst %s failed: %v", dst.Name(), err)
	}
	if oldDatCompactRevision+1 != newDatCompactRevision {
		return fmt.Errorf("oldDatFile %s 's compact revision is %d while newDatFile %s 's compact revision is %d", oldDatFileName, oldDatCompactRevision, newDatFileName, newDatCompactRevision)
	}

	for key, increIdxEntry := range incrementedHasUpdatedIndexEntry {

		idxEntryBytes := needle_map.ToBytes(key, increIdxEntry.offset, increIdxEntry.size)

		var offset int64
		if offset, err = dst.Seek(0, 2); err != nil {
			glog.V(0).Infof("failed to seek the end of file: %v", err)
			return
		}
		//ensure file writing starting from aligned positions
		if offset%NeedlePaddingSize != 0 {
			offset = offset + (NeedlePaddingSize - offset%NeedlePaddingSize)
			if offset, err = dst.Seek(offset, 0); err != nil {
				glog.V(0).Infof("failed to align in datafile %s: %v", dst.Name(), err)
				return
			}
		}

		//updated needle
		if !increIdxEntry.offset.IsZero() && increIdxEntry.size != 0 && increIdxEntry.size != TombstoneFileSize {
			//even the needle cache in memory is hit, the need_bytes is correct
			glog.V(4).Infof("file %d offset %d size %d", key, increIdxEntry.offset.ToAcutalOffset(), increIdxEntry.size)
			var needleBytes []byte
			needleBytes, err = needle.ReadNeedleBlob(oldDatBackend, increIdxEntry.offset.ToAcutalOffset(), increIdxEntry.size, v.Version())
			if err != nil {
				return fmt.Errorf("ReadNeedleBlob %s key %d offset %d size %d failed: %v", oldDatFile.Name(), key, increIdxEntry.offset.ToAcutalOffset(), increIdxEntry.size, err)
			}
			dst.Write(needleBytes)
			util.Uint32toBytes(idxEntryBytes[8:12], uint32(offset/NeedlePaddingSize))
		} else { //deleted needle
			//fakeDelNeedle 's default Data field is nil
			fakeDelNeedle := new(needle.Needle)
			fakeDelNeedle.Id = key
			fakeDelNeedle.Cookie = 0x12345678
			fakeDelNeedle.AppendAtNs = uint64(time.Now().UnixNano())
			_, _, _, err = fakeDelNeedle.Append(dstDatBackend, v.Version())
			if err != nil {
				return fmt.Errorf("append deleted %d failed: %v", key, err)
			}
			util.Uint32toBytes(idxEntryBytes[8:12], uint32(0))
		}

		if _, err := idx.Seek(0, 2); err != nil {
			return fmt.Errorf("cannot seek end of indexfile %s: %v",
				newIdxFileName, err)
		}
		_, err = idx.Write(idxEntryBytes)
	}

	return nil
}

type VolumeFileScanner4Vacuum struct {
	version        needle.Version
	v              *Volume
	dstBackend     backend.DataStorageBackend
	nm             *NeedleMap
	newOffset      int64
	now            uint64
	writeThrottler *util.WriteThrottler
}

func (scanner *VolumeFileScanner4Vacuum) VisitSuperBlock(superBlock SuperBlock) error {
	scanner.version = superBlock.Version()
	superBlock.CompactionRevision++
	_, err := scanner.dstBackend.WriteAt(superBlock.Bytes(), 0)
	scanner.newOffset = int64(superBlock.BlockSize())
	return err

}
func (scanner *VolumeFileScanner4Vacuum) ReadNeedleBody() bool {
	return true
}

func (scanner *VolumeFileScanner4Vacuum) VisitNeedle(n *needle.Needle, offset int64, needleHeader, needleBody []byte) error {
	if n.HasTtl() && scanner.now >= n.LastModified+uint64(scanner.v.Ttl.Minutes()*60) {
		return nil
	}
	nv, ok := scanner.v.nm.Get(n.Id)
	glog.V(4).Infoln("needle expected offset ", offset, "ok", ok, "nv", nv)
	if ok && nv.Offset.ToAcutalOffset() == offset && nv.Size > 0 && nv.Size != TombstoneFileSize {
		if err := scanner.nm.Put(n.Id, ToOffset(scanner.newOffset), n.Size); err != nil {
			return fmt.Errorf("cannot put needle: %s", err)
		}
		if _, _, _, err := n.Append(scanner.dstBackend, scanner.v.Version()); err != nil {
			return fmt.Errorf("cannot append needle: %s", err)
		}
		delta := n.DiskSize(scanner.version)
		scanner.newOffset += delta
		scanner.writeThrottler.MaybeSlowdown(delta)
		glog.V(4).Infoln("saving key", n.Id, "volume offset", offset, "=>", scanner.newOffset, "data_size", n.Size)
	}
	return nil
}

func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string, preallocate int64, compactionBytePerSecond int64) (err error) {
	var (
		dst backend.DataStorageBackend
		idx *os.File
	)
	if dst, err = createVolumeFile(dstName, preallocate, 0); err != nil {
		return
	}
	defer dst.Close()

	if idx, err = os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
		return
	}
	defer idx.Close()

	scanner := &VolumeFileScanner4Vacuum{
		v:              v,
		now:            uint64(time.Now().Unix()),
		nm:             NewBtreeNeedleMap(idx),
		dstBackend:     dst,
		writeThrottler: util.NewWriteThrottler(compactionBytePerSecond),
	}
	err = ScanVolumeFile(v.dir, v.Collection, v.Id, v.needleMapKind, scanner)
	return
}

func (v *Volume) copyDataBasedOnIndexFile(dstName, idxName string) (err error) {
	var (
		dst, idx, oldIndexFile *os.File
	)
	if dst, err = os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
		return
	}
	dstDatBackend := backend.NewDiskFile(dst)
	defer dstDatBackend.Close()

	if idx, err = os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
		return
	}
	defer idx.Close()

	if oldIndexFile, err = os.OpenFile(v.FileName()+".idx", os.O_RDONLY, 0644); err != nil {
		return
	}
	defer oldIndexFile.Close()

	nm := NewBtreeNeedleMap(idx)
	now := uint64(time.Now().Unix())

	v.SuperBlock.CompactionRevision++
	dst.Write(v.SuperBlock.Bytes())
	newOffset := int64(v.SuperBlock.BlockSize())

	idx2.WalkIndexFile(oldIndexFile, func(key NeedleId, offset Offset, size uint32) error {
		if offset.IsZero() || size == TombstoneFileSize {
			return nil
		}

		nv, ok := v.nm.Get(key)
		if !ok {
			return nil
		}

		n := new(needle.Needle)
		err := n.ReadData(v.DataBackend, offset.ToAcutalOffset(), size, v.Version())
		if err != nil {
			return nil
		}

		if n.HasTtl() && now >= n.LastModified+uint64(v.Ttl.Minutes()*60) {
			return nil
		}

		glog.V(4).Infoln("needle expected offset ", offset, "ok", ok, "nv", nv)
		if nv.Offset == offset && nv.Size > 0 {
			if err = nm.Put(n.Id, ToOffset(newOffset), n.Size); err != nil {
				return fmt.Errorf("cannot put needle: %s", err)
			}
			if _, _, _, err = n.Append(dstDatBackend, v.Version()); err != nil {
				return fmt.Errorf("cannot append needle: %s", err)
			}
			newOffset += n.DiskSize(v.Version())
			glog.V(3).Infoln("saving key", n.Id, "volume offset", offset, "=>", newOffset, "data_size", n.Size)
		}
		return nil
	})

	return
}