// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"context"
	"encoding/hex"
	"fmt"
	"sort"
	"strings"
	"time"

	"github.com/minio/minio/internal/amztime"
	"github.com/minio/minio/internal/bucket/replication"
	"github.com/minio/minio/internal/hash/sha256"
	xhttp "github.com/minio/minio/internal/http"
	"github.com/minio/minio/internal/logger"
	"github.com/minio/pkg/v2/sync/errgroup"
)

// Object was stored with additional erasure codes due to degraded system at upload time
const minIOErasureUpgraded = "x-minio-internal-erasure-upgraded"

const erasureAlgorithm = "rs-vandermonde"

// GetChecksumInfo - get checksum of a part.
func (e ErasureInfo) GetChecksumInfo(partNumber int) (ckSum ChecksumInfo) {
	for _, sum := range e.Checksums {
		if sum.PartNumber == partNumber {
			// Return the checksum
			return sum
		}
	}
	return ChecksumInfo{Algorithm: DefaultBitrotAlgorithm}
}

// ShardFileSize - returns final erasure size from original size.
func (e ErasureInfo) ShardFileSize(totalLength int64) int64 {
	if totalLength == 0 {
		return 0
	}
	if totalLength == -1 {
		return -1
	}
	numShards := totalLength / e.BlockSize
	lastBlockSize := totalLength % e.BlockSize
	lastShardSize := ceilFrac(lastBlockSize, int64(e.DataBlocks))
	return numShards*e.ShardSize() + lastShardSize
}

// ShardSize - returns actual shared size from erasure blockSize.
func (e ErasureInfo) ShardSize() int64 {
	return ceilFrac(e.BlockSize, int64(e.DataBlocks))
}

// IsValid - tells if erasure info fields are valid.
func (fi FileInfo) IsValid() bool {
	if fi.Deleted {
		// Delete marker has no data, no need to check
		// for erasure coding information
		return true
	}
	dataBlocks := fi.Erasure.DataBlocks
	parityBlocks := fi.Erasure.ParityBlocks
	correctIndexes := (fi.Erasure.Index > 0 &&
		fi.Erasure.Index <= dataBlocks+parityBlocks &&
		len(fi.Erasure.Distribution) == (dataBlocks+parityBlocks))
	return ((dataBlocks >= parityBlocks) &&
		(dataBlocks > 0) && (parityBlocks >= 0) &&
		correctIndexes)
}

// ToObjectInfo - Converts metadata to object info.
func (fi FileInfo) ToObjectInfo(bucket, object string, versioned bool) ObjectInfo {
	object = decodeDirObject(object)
	versionID := fi.VersionID
	if versioned && versionID == "" {
		versionID = nullVersionID
	}

	objInfo := ObjectInfo{
		IsDir:            HasSuffix(object, SlashSeparator),
		Bucket:           bucket,
		Name:             object,
		ParityBlocks:     fi.Erasure.ParityBlocks,
		DataBlocks:       fi.Erasure.DataBlocks,
		VersionID:        versionID,
		IsLatest:         fi.IsLatest,
		DeleteMarker:     fi.Deleted,
		Size:             fi.Size,
		ModTime:          fi.ModTime,
		Legacy:           fi.XLV1,
		ContentType:      fi.Metadata["content-type"],
		ContentEncoding:  fi.Metadata["content-encoding"],
		NumVersions:      fi.NumVersions,
		SuccessorModTime: fi.SuccessorModTime,
		CacheControl:     fi.Metadata["cache-control"],
	}

	if exp, ok := fi.Metadata["expires"]; ok {
		if t, err := amztime.ParseHeader(exp); err == nil {
			objInfo.Expires = t.UTC()
		}
	}

	// Extract etag from metadata.
	objInfo.ETag = extractETag(fi.Metadata)

	// Add user tags to the object info
	tags := fi.Metadata[xhttp.AmzObjectTagging]
	if len(tags) != 0 {
		objInfo.UserTags = tags
	}

	// Add replication status to the object info
	objInfo.ReplicationStatusInternal = fi.ReplicationState.ReplicationStatusInternal
	objInfo.VersionPurgeStatusInternal = fi.ReplicationState.VersionPurgeStatusInternal
	objInfo.ReplicationStatus = fi.ReplicationStatus()
	if objInfo.ReplicationStatus.Empty() { // overlay x-amx-replication-status if present for replicas
		if st, ok := fi.Metadata[xhttp.AmzBucketReplicationStatus]; ok && st == string(replication.Replica) {
			objInfo.ReplicationStatus = replication.StatusType(st)
		}
	}
	objInfo.VersionPurgeStatus = fi.VersionPurgeStatus()

	objInfo.TransitionedObject = TransitionedObject{
		Name:        fi.TransitionedObjName,
		VersionID:   fi.TransitionVersionID,
		Status:      fi.TransitionStatus,
		FreeVersion: fi.TierFreeVersion(),
		Tier:        fi.TransitionTier,
	}

	// etag/md5Sum has already been extracted. We need to
	// remove to avoid it from appearing as part of
	// response headers. e.g, X-Minio-* or X-Amz-*.
	// Tags have also been extracted, we remove that as well.
	objInfo.UserDefined = cleanMetadata(fi.Metadata)

	// All the parts per object.
	objInfo.Parts = fi.Parts

	// Update storage class
	if fi.TransitionTier != "" {
		objInfo.StorageClass = fi.TransitionTier
	} else if sc, ok := fi.Metadata[xhttp.AmzStorageClass]; ok {
		objInfo.StorageClass = sc
	} else {
		objInfo.StorageClass = globalMinioDefaultStorageClass
	}

	// set restore status for transitioned object
	restoreHdr, ok := fi.Metadata[xhttp.AmzRestore]
	if ok {
		if restoreStatus, err := parseRestoreObjStatus(restoreHdr); err == nil {
			objInfo.RestoreOngoing = restoreStatus.Ongoing()
			objInfo.RestoreExpires, _ = restoreStatus.Expiry()
		}
	}
	objInfo.Checksum = fi.Checksum
	objInfo.Inlined = fi.InlineData()
	// Success.
	return objInfo
}

// TransitionInfoEquals returns true if transition related information are equal, false otherwise.
func (fi FileInfo) TransitionInfoEquals(ofi FileInfo) bool {
	switch {
	case fi.TransitionStatus != ofi.TransitionStatus,
		fi.TransitionTier != ofi.TransitionTier,
		fi.TransitionedObjName != ofi.TransitionedObjName,
		fi.TransitionVersionID != ofi.TransitionVersionID:
		return false
	}
	return true
}

// MetadataEquals returns true if FileInfos Metadata maps are equal, false otherwise.
func (fi FileInfo) MetadataEquals(ofi FileInfo) bool {
	if len(fi.Metadata) != len(ofi.Metadata) {
		return false
	}
	for k, v := range fi.Metadata {
		if ov, ok := ofi.Metadata[k]; !ok || ov != v {
			return false
		}
	}
	return true
}

// ReplicationInfoEquals returns true if server-side replication related fields are equal, false otherwise.
func (fi FileInfo) ReplicationInfoEquals(ofi FileInfo) bool {
	switch {
	case fi.MarkDeleted != ofi.MarkDeleted,
		!fi.ReplicationState.Equal(ofi.ReplicationState):
		return false
	}
	return true
}

// objectPartIndex - returns the index of matching object part number.
func objectPartIndex(parts []ObjectPartInfo, partNumber int) int {
	for i, part := range parts {
		if partNumber == part.Number {
			return i
		}
	}
	return -1
}

// AddObjectPart - add a new object part in order.
func (fi *FileInfo) AddObjectPart(partNumber int, partETag string, partSize, actualSize int64, modTime time.Time, idx []byte, checksums map[string]string) {
	partInfo := ObjectPartInfo{
		Number:     partNumber,
		ETag:       partETag,
		Size:       partSize,
		ActualSize: actualSize,
		ModTime:    modTime,
		Index:      idx,
		Checksums:  checksums,
	}

	// Update part info if it already exists.
	for i, part := range fi.Parts {
		if partNumber == part.Number {
			fi.Parts[i] = partInfo
			return
		}
	}

	// Proceed to include new part info.
	fi.Parts = append(fi.Parts, partInfo)

	// Parts in FileInfo should be in sorted order by part number.
	sort.Slice(fi.Parts, func(i, j int) bool { return fi.Parts[i].Number < fi.Parts[j].Number })
}

// ObjectToPartOffset - translate offset of an object to offset of its individual part.
func (fi FileInfo) ObjectToPartOffset(ctx context.Context, offset int64) (partIndex int, partOffset int64, err error) {
	if offset == 0 {
		// Special case - if offset is 0, then partIndex and partOffset are always 0.
		return 0, 0, nil
	}
	partOffset = offset
	// Seek until object offset maps to a particular part offset.
	for i, part := range fi.Parts {
		partIndex = i
		// Offset is smaller than size we have reached the proper part offset.
		if partOffset < part.Size {
			return partIndex, partOffset, nil
		}
		// Continue to towards the next part.
		partOffset -= part.Size
	}
	logger.LogIf(ctx, InvalidRange{})
	// Offset beyond the size of the object return InvalidRange.
	return 0, 0, InvalidRange{}
}

func findFileInfoInQuorum(ctx context.Context, metaArr []FileInfo, modTime time.Time, etag string, quorum int) (FileInfo, error) {
	// with less quorum return error.
	if quorum < 1 {
		return FileInfo{}, errErasureReadQuorum
	}
	metaHashes := make([]string, len(metaArr))
	h := sha256.New()
	for i, meta := range metaArr {
		if !meta.IsValid() {
			continue
		}
		etagOnly := modTime.Equal(timeSentinel) && (etag != "" && etag == meta.Metadata["etag"])
		mtimeValid := meta.ModTime.Equal(modTime)
		if mtimeValid || etagOnly {
			fmt.Fprintf(h, "%v", meta.XLV1)
			if !etagOnly {
				// Verify dataDir is same only when mtime is valid and etag is not considered.
				fmt.Fprintf(h, "%v", meta.GetDataDir())
			}
			for _, part := range meta.Parts {
				fmt.Fprintf(h, "part.%d", part.Number)
			}

			if !meta.Deleted && meta.Size != 0 {
				fmt.Fprintf(h, "%v+%v", meta.Erasure.DataBlocks, meta.Erasure.ParityBlocks)
				fmt.Fprintf(h, "%v", meta.Erasure.Distribution)
			}

			// ILM transition fields
			fmt.Fprint(h, meta.TransitionStatus)
			fmt.Fprint(h, meta.TransitionTier)
			fmt.Fprint(h, meta.TransitionedObjName)
			fmt.Fprint(h, meta.TransitionVersionID)

			// Server-side replication fields
			fmt.Fprintf(h, "%v", meta.MarkDeleted)
			fmt.Fprint(h, meta.Metadata[string(meta.ReplicationState.ReplicaStatus)])
			fmt.Fprint(h, meta.Metadata[meta.ReplicationState.ReplicationStatusInternal])
			fmt.Fprint(h, meta.Metadata[meta.ReplicationState.VersionPurgeStatusInternal])

			metaHashes[i] = hex.EncodeToString(h.Sum(nil))
			h.Reset()
		}
	}

	metaHashCountMap := make(map[string]int)
	for _, hash := range metaHashes {
		if hash == "" {
			continue
		}
		metaHashCountMap[hash]++
	}

	maxHash := ""
	maxCount := 0
	for hash, count := range metaHashCountMap {
		if count > maxCount {
			maxCount = count
			maxHash = hash
		}
	}

	if maxCount < quorum {
		return FileInfo{}, errErasureReadQuorum
	}

	// Find the successor mod time in quorum, otherwise leave the
	// candidate's successor modTime as found
	succModTimeMap := make(map[time.Time]int)
	var candidate FileInfo
	var found bool
	for i, hash := range metaHashes {
		if hash == maxHash {
			if metaArr[i].IsValid() {
				if !found {
					candidate = metaArr[i]
					found = true
				}
				succModTimeMap[metaArr[i].SuccessorModTime]++
			}
		}
	}
	var succModTime time.Time
	var smodTimeQuorum bool
	for smodTime, count := range succModTimeMap {
		if count >= quorum {
			smodTimeQuorum = true
			succModTime = smodTime
			break
		}
	}

	if found {
		if smodTimeQuorum {
			candidate.SuccessorModTime = succModTime
			candidate.IsLatest = succModTime.IsZero()
		}
		return candidate, nil
	}
	return FileInfo{}, errErasureReadQuorum
}

// pickValidFileInfo - picks one valid FileInfo content and returns from a
// slice of FileInfo.
func pickValidFileInfo(ctx context.Context, metaArr []FileInfo, modTime time.Time, etag string, quorum int) (FileInfo, error) {
	return findFileInfoInQuorum(ctx, metaArr, modTime, etag, quorum)
}

// writeUniqueFileInfo - writes unique `xl.meta` content for each disk concurrently.
func writeUniqueFileInfo(ctx context.Context, disks []StorageAPI, bucket, prefix string, files []FileInfo, quorum int) ([]StorageAPI, error) {
	g := errgroup.WithNErrs(len(disks))

	// Start writing `xl.meta` to all disks in parallel.
	for index := range disks {
		index := index
		g.Go(func() error {
			if disks[index] == nil {
				return errDiskNotFound
			}
			// Pick one FileInfo for a disk at index.
			fi := files[index]
			fi.Erasure.Index = index + 1
			if fi.IsValid() {
				return disks[index].WriteMetadata(ctx, bucket, prefix, fi)
			}
			return errCorruptedFormat
		}, index)
	}

	// Wait for all the routines.
	mErrs := g.Wait()

	err := reduceWriteQuorumErrs(ctx, mErrs, objectOpIgnoredErrs, quorum)
	return evalDisks(disks, mErrs), err
}

func commonParity(parities []int, defaultParityCount int) int {
	N := len(parities)

	occMap := make(map[int]int)
	for _, p := range parities {
		occMap[p]++
	}

	var maxOcc, cparity int
	for parity, occ := range occMap {
		if parity == -1 {
			// Ignore non defined parity
			continue
		}

		readQuorum := N - parity
		if defaultParityCount > 0 && parity == 0 {
			// In this case, parity == 0 implies that this object version is a
			// delete marker
			readQuorum = N/2 + 1
		}
		if occ < readQuorum {
			// Ignore this parity since we don't have enough shards for read quorum
			continue
		}

		if occ > maxOcc {
			maxOcc = occ
			cparity = parity
		}
	}

	if maxOcc == 0 {
		// Did not found anything useful
		return -1
	}
	return cparity
}

func listObjectParities(partsMetadata []FileInfo, errs []error) (parities []int) {
	parities = make([]int, len(partsMetadata))
	for index, metadata := range partsMetadata {
		if errs[index] != nil {
			parities[index] = -1
			continue
		}
		if !metadata.IsValid() {
			parities[index] = -1
			continue
		}
		// Delete marker or zero byte objects take highest parity.
		if metadata.Deleted || metadata.Size == 0 {
			parities[index] = len(partsMetadata) / 2
		} else {
			parities[index] = metadata.Erasure.ParityBlocks
		}
	}
	return
}

// Returns per object readQuorum and writeQuorum
// readQuorum is the min required disks to read data.
// writeQuorum is the min required disks to write data.
func objectQuorumFromMeta(ctx context.Context, partsMetaData []FileInfo, errs []error, defaultParityCount int) (objectReadQuorum, objectWriteQuorum int, err error) {
	// There should be at least half correct entries, if not return failure
	expectedRQuorum := len(partsMetaData) / 2
	if defaultParityCount == 0 {
		// if parity count is '0', we expected all entries to be present.
		expectedRQuorum = len(partsMetaData)
	}

	reducedErr := reduceReadQuorumErrs(ctx, errs, objectOpIgnoredErrs, expectedRQuorum)
	if reducedErr != nil {
		return -1, -1, reducedErr
	}

	// special case when parity is '0'
	if defaultParityCount == 0 {
		return len(partsMetaData), len(partsMetaData), nil
	}

	parities := listObjectParities(partsMetaData, errs)
	parityBlocks := commonParity(parities, defaultParityCount)
	if parityBlocks < 0 {
		return -1, -1, errErasureReadQuorum
	}

	if parityBlocks == 0 {
		// For delete markers do not use 'defaultParityCount' as it is not expected to be the case.
		// Use maximum allowed read quorum instead, writeQuorum+1 is returned for compatibility sake
		// but there are no callers that shall be using this.
		readQuorum := len(partsMetaData) / 2
		return readQuorum, readQuorum + 1, nil
	}

	dataBlocks := len(partsMetaData) - parityBlocks

	writeQuorum := dataBlocks
	if dataBlocks == parityBlocks {
		writeQuorum++
	}

	// Since all the valid erasure code meta updated at the same time are equivalent, pass dataBlocks
	// from latestFileInfo to get the quorum
	return dataBlocks, writeQuorum, nil
}

const (
	tierFVID     = "tier-free-versionID"
	tierFVMarker = "tier-free-marker"
)

// SetTierFreeVersionID sets free-version's versionID. This method is used by
// object layer to pass down a versionID to set for a free-version that may be
// created.
func (fi *FileInfo) SetTierFreeVersionID(versionID string) {
	if fi.Metadata == nil {
		fi.Metadata = make(map[string]string)
	}
	fi.Metadata[ReservedMetadataPrefixLower+tierFVID] = versionID
}

// TierFreeVersionID returns the free-version's version id.
func (fi *FileInfo) TierFreeVersionID() string {
	return fi.Metadata[ReservedMetadataPrefixLower+tierFVID]
}

// SetTierFreeVersion sets fi as a free-version. This method is used by
// lower layers to indicate a free-version.
func (fi *FileInfo) SetTierFreeVersion() {
	if fi.Metadata == nil {
		fi.Metadata = make(map[string]string)
	}
	fi.Metadata[ReservedMetadataPrefixLower+tierFVMarker] = ""
}

// TierFreeVersion returns true if version is a free-version.
func (fi *FileInfo) TierFreeVersion() bool {
	_, ok := fi.Metadata[ReservedMetadataPrefixLower+tierFVMarker]
	return ok
}

// IsRestoreObjReq returns true if fi corresponds to a RestoreObject request.
func (fi *FileInfo) IsRestoreObjReq() bool {
	if restoreHdr, ok := fi.Metadata[xhttp.AmzRestore]; ok {
		if restoreStatus, err := parseRestoreObjStatus(restoreHdr); err == nil {
			if !restoreStatus.Ongoing() {
				return true
			}
		}
	}
	return false
}

// VersionPurgeStatus returns overall version purge status for this object version across targets
func (fi *FileInfo) VersionPurgeStatus() VersionPurgeStatusType {
	return fi.ReplicationState.CompositeVersionPurgeStatus()
}

// ReplicationStatus returns overall version replication status for this object version across targets
func (fi *FileInfo) ReplicationStatus() replication.StatusType {
	return fi.ReplicationState.CompositeReplicationStatus()
}

// DeleteMarkerReplicationStatus returns overall replication status for this delete marker version across targets
func (fi *FileInfo) DeleteMarkerReplicationStatus() replication.StatusType {
	if fi.Deleted {
		return fi.ReplicationState.CompositeReplicationStatus()
	}
	return replication.StatusType("")
}

// GetInternalReplicationState is a wrapper method to fetch internal replication state from the map m
func GetInternalReplicationState(m map[string][]byte) ReplicationState {
	m1 := make(map[string]string, len(m))
	for k, v := range m {
		m1[k] = string(v)
	}
	return getInternalReplicationState(m1)
}

// getInternalReplicationState fetches internal replication state from the map m
func getInternalReplicationState(m map[string]string) ReplicationState {
	d := ReplicationState{}
	for k, v := range m {
		switch {
		case equals(k, ReservedMetadataPrefixLower+ReplicationTimestamp):
			d.ReplicaTimeStamp, _ = amztime.ParseReplicationTS(v)
		case equals(k, ReservedMetadataPrefixLower+ReplicaTimestamp):
			d.ReplicaTimeStamp, _ = amztime.ParseReplicationTS(v)
		case equals(k, ReservedMetadataPrefixLower+ReplicaStatus):
			d.ReplicaStatus = replication.StatusType(v)
		case equals(k, ReservedMetadataPrefixLower+ReplicationStatus):
			d.ReplicationStatusInternal = v
			d.Targets = replicationStatusesMap(v)
		case equals(k, VersionPurgeStatusKey):
			d.VersionPurgeStatusInternal = v
			d.PurgeTargets = versionPurgeStatusesMap(v)
		case strings.HasPrefix(k, ReservedMetadataPrefixLower+ReplicationReset):
			arn := strings.TrimPrefix(k, fmt.Sprintf("%s-", ReservedMetadataPrefixLower+ReplicationReset))
			if d.ResetStatusesMap == nil {
				d.ResetStatusesMap = make(map[string]string, 1)
			}
			d.ResetStatusesMap[arn] = v
		}
	}
	return d
}