1// Package bug contains the bug data model and low-level related functions
2package bug
3
4import (
5 "encoding/json"
6 "fmt"
7 "strings"
8
9 "github.com/pkg/errors"
10
11 "github.com/MichaelMure/git-bug/entity"
12 "github.com/MichaelMure/git-bug/identity"
13 "github.com/MichaelMure/git-bug/repository"
14 "github.com/MichaelMure/git-bug/util/lamport"
15)
16
17const bugsRefPattern = "refs/bugs/"
18const bugsRemoteRefPattern = "refs/remotes/%s/bugs/"
19
20const opsEntryName = "ops"
21const rootEntryName = "root"
22const mediaEntryName = "media"
23
24const createClockEntryPrefix = "create-clock-"
25const createClockEntryPattern = "create-clock-%d"
26const editClockEntryPrefix = "edit-clock-"
27const editClockEntryPattern = "edit-clock-%d"
28
29const creationClockName = "bug-create"
30const editClockName = "bug-edit"
31
32var ErrBugNotExist = errors.New("bug doesn't exist")
33
34func NewErrMultipleMatchBug(matching []entity.Id) *entity.ErrMultipleMatch {
35 return entity.NewErrMultipleMatch("bug", matching)
36}
37
38func NewErrMultipleMatchOp(matching []entity.Id) *entity.ErrMultipleMatch {
39 return entity.NewErrMultipleMatch("operation", matching)
40}
41
42var _ Interface = &Bug{}
43var _ entity.Interface = &Bug{}
44
45// Bug hold the data of a bug thread, organized in a way close to
46// how it will be persisted inside Git. This is the data structure
47// used to merge two different version of the same Bug.
48type Bug struct {
49
50 // A Lamport clock is a logical clock that allow to order event
51 // inside a distributed system.
52 // It must be the first field in this struct due to https://github.com/golang/go/issues/599
53 createTime lamport.Time
54 editTime lamport.Time
55
56 // Id used as unique identifier
57 id entity.Id
58
59 lastCommit repository.Hash
60 rootPack repository.Hash
61
62 // all the committed operations
63 packs []OperationPack
64
65 // a temporary pack of operations used for convenience to pile up new operations
66 // before a commit
67 staging OperationPack
68}
69
70// NewBug create a new Bug
71func NewBug() *Bug {
72 // No id yet
73 // No logical clock yet
74 return &Bug{}
75}
76
77// FindLocalBug find an existing Bug matching a prefix
78func FindLocalBug(repo repository.ClockedRepo, prefix string) (*Bug, error) {
79 ids, err := ListLocalIds(repo)
80
81 if err != nil {
82 return nil, err
83 }
84
85 // preallocate but empty
86 matching := make([]entity.Id, 0, 5)
87
88 for _, id := range ids {
89 if id.HasPrefix(prefix) {
90 matching = append(matching, id)
91 }
92 }
93
94 if len(matching) == 0 {
95 return nil, errors.New("no matching bug found.")
96 }
97
98 if len(matching) > 1 {
99 return nil, NewErrMultipleMatchBug(matching)
100 }
101
102 return ReadLocalBug(repo, matching[0])
103}
104
105// ReadLocalBug will read a local bug from its hash
106func ReadLocalBug(repo repository.ClockedRepo, id entity.Id) (*Bug, error) {
107 ref := bugsRefPattern + id.String()
108 return readBug(repo, ref)
109}
110
111// ReadRemoteBug will read a remote bug from its hash
112func ReadRemoteBug(repo repository.ClockedRepo, remote string, id string) (*Bug, error) {
113 ref := fmt.Sprintf(bugsRemoteRefPattern, remote) + id
114 return readBug(repo, ref)
115}
116
117// readBug will read and parse a Bug from git
118func readBug(repo repository.ClockedRepo, ref string) (*Bug, error) {
119 refSplit := strings.Split(ref, "/")
120 id := entity.Id(refSplit[len(refSplit)-1])
121
122 if err := id.Validate(); err != nil {
123 return nil, errors.Wrap(err, "invalid ref ")
124 }
125
126 hashes, err := repo.ListCommits(ref)
127
128 // TODO: this is not perfect, it might be a command invoke error
129 if err != nil {
130 return nil, ErrBugNotExist
131 }
132
133 bug := Bug{
134 id: id,
135 editTime: 0,
136 }
137
138 // Load each OperationPack
139 for _, hash := range hashes {
140 entries, err := repo.ReadTree(hash)
141 if err != nil {
142 return nil, errors.Wrap(err, "can't list git tree entries")
143 }
144
145 bug.lastCommit = hash
146
147 var opsEntry repository.TreeEntry
148 opsFound := false
149 var rootEntry repository.TreeEntry
150 rootFound := false
151 var createTime uint64
152 var editTime uint64
153
154 for _, entry := range entries {
155 if entry.Name == opsEntryName {
156 opsEntry = entry
157 opsFound = true
158 continue
159 }
160 if entry.Name == rootEntryName {
161 rootEntry = entry
162 rootFound = true
163 }
164 if strings.HasPrefix(entry.Name, createClockEntryPrefix) {
165 n, err := fmt.Sscanf(entry.Name, createClockEntryPattern, &createTime)
166 if err != nil {
167 return nil, errors.Wrap(err, "can't read create lamport time")
168 }
169 if n != 1 {
170 return nil, fmt.Errorf("could not parse create time lamport value")
171 }
172 }
173 if strings.HasPrefix(entry.Name, editClockEntryPrefix) {
174 n, err := fmt.Sscanf(entry.Name, editClockEntryPattern, &editTime)
175 if err != nil {
176 return nil, errors.Wrap(err, "can't read edit lamport time")
177 }
178 if n != 1 {
179 return nil, fmt.Errorf("could not parse edit time lamport value")
180 }
181 }
182 }
183
184 if !opsFound {
185 return nil, errors.New("invalid tree, missing the ops entry")
186 }
187 if !rootFound {
188 return nil, errors.New("invalid tree, missing the root entry")
189 }
190
191 if bug.rootPack == "" {
192 bug.rootPack = rootEntry.Hash
193 bug.createTime = lamport.Time(createTime)
194 }
195
196 // Due to rebase, edit Lamport time are not necessarily ordered
197 if editTime > uint64(bug.editTime) {
198 bug.editTime = lamport.Time(editTime)
199 }
200
201 // Update the clocks
202 createClock, err := repo.GetOrCreateClock(creationClockName)
203 if err != nil {
204 return nil, err
205 }
206 if err := createClock.Witness(bug.createTime); err != nil {
207 return nil, errors.Wrap(err, "failed to update create lamport clock")
208 }
209 editClock, err := repo.GetOrCreateClock(editClockName)
210 if err != nil {
211 return nil, err
212 }
213 if err := editClock.Witness(bug.editTime); err != nil {
214 return nil, errors.Wrap(err, "failed to update edit lamport clock")
215 }
216
217 data, err := repo.ReadData(opsEntry.Hash)
218 if err != nil {
219 return nil, errors.Wrap(err, "failed to read git blob data")
220 }
221
222 opp := &OperationPack{}
223 err = json.Unmarshal(data, &opp)
224
225 if err != nil {
226 return nil, errors.Wrap(err, "failed to decode OperationPack json")
227 }
228
229 // tag the pack with the commit hash
230 opp.commitHash = hash
231
232 bug.packs = append(bug.packs, *opp)
233 }
234
235 // Make sure that the identities are properly loaded
236 resolver := identity.NewSimpleResolver(repo)
237 err = bug.EnsureIdentities(resolver)
238 if err != nil {
239 return nil, err
240 }
241
242 return &bug, nil
243}
244
245func RemoveLocalBug(repo repository.ClockedRepo, id entity.Id) error {
246 ref := bugsRefPattern + id.String()
247 return repo.RemoveRef(ref)
248}
249
250type StreamedBug struct {
251 Bug *Bug
252 Err error
253}
254
255// ReadAllLocalBugs read and parse all local bugs
256func ReadAllLocalBugs(repo repository.ClockedRepo) <-chan StreamedBug {
257 return readAllBugs(repo, bugsRefPattern)
258}
259
260// ReadAllRemoteBugs read and parse all remote bugs for a given remote
261func ReadAllRemoteBugs(repo repository.ClockedRepo, remote string) <-chan StreamedBug {
262 refPrefix := fmt.Sprintf(bugsRemoteRefPattern, remote)
263 return readAllBugs(repo, refPrefix)
264}
265
266// Read and parse all available bug with a given ref prefix
267func readAllBugs(repo repository.ClockedRepo, refPrefix string) <-chan StreamedBug {
268 out := make(chan StreamedBug)
269
270 go func() {
271 defer close(out)
272
273 refs, err := repo.ListRefs(refPrefix)
274 if err != nil {
275 out <- StreamedBug{Err: err}
276 return
277 }
278
279 for _, ref := range refs {
280 b, err := readBug(repo, ref)
281
282 if err != nil {
283 out <- StreamedBug{Err: err}
284 return
285 }
286
287 out <- StreamedBug{Bug: b}
288 }
289 }()
290
291 return out
292}
293
294// ListLocalIds list all the available local bug ids
295func ListLocalIds(repo repository.Repo) ([]entity.Id, error) {
296 refs, err := repo.ListRefs(bugsRefPattern)
297 if err != nil {
298 return nil, err
299 }
300
301 return refsToIds(refs), nil
302}
303
304func refsToIds(refs []string) []entity.Id {
305 ids := make([]entity.Id, len(refs))
306
307 for i, ref := range refs {
308 split := strings.Split(ref, "/")
309 ids[i] = entity.Id(split[len(split)-1])
310 }
311
312 return ids
313}
314
315// Validate check if the Bug data is valid
316func (bug *Bug) Validate() error {
317 // non-empty
318 if len(bug.packs) == 0 && bug.staging.IsEmpty() {
319 return fmt.Errorf("bug has no operations")
320 }
321
322 // check if each pack and operations are valid
323 for _, pack := range bug.packs {
324 if err := pack.Validate(); err != nil {
325 return err
326 }
327 }
328
329 // check if staging is valid if needed
330 if !bug.staging.IsEmpty() {
331 if err := bug.staging.Validate(); err != nil {
332 return errors.Wrap(err, "staging")
333 }
334 }
335
336 // The very first Op should be a CreateOp
337 firstOp := bug.FirstOp()
338 if firstOp == nil || firstOp.base().OperationType != CreateOp {
339 return fmt.Errorf("first operation should be a Create op")
340 }
341
342 // The bug Id should be the hash of the first commit
343 if len(bug.packs) > 0 && string(bug.packs[0].commitHash) != bug.id.String() {
344 return fmt.Errorf("bug id should be the first commit hash")
345 }
346
347 // Check that there is no more CreateOp op
348 // Check that there is no colliding operation's ID
349 it := NewOperationIterator(bug)
350 createCount := 0
351 ids := make(map[entity.Id]struct{})
352 for it.Next() {
353 if it.Value().base().OperationType == CreateOp {
354 createCount++
355 }
356 if _, ok := ids[it.Value().Id()]; ok {
357 return fmt.Errorf("id collision: %s", it.Value().Id())
358 }
359 ids[it.Value().Id()] = struct{}{}
360 }
361
362 if createCount != 1 {
363 return fmt.Errorf("only one Create op allowed")
364 }
365
366 return nil
367}
368
369// Append an operation into the staging area, to be committed later
370func (bug *Bug) Append(op Operation) {
371 bug.staging.Append(op)
372}
373
374// Commit write the staging area in Git and move the operations to the packs
375func (bug *Bug) Commit(repo repository.ClockedRepo) error {
376
377 if !bug.NeedCommit() {
378 return fmt.Errorf("can't commit a bug with no pending operation")
379 }
380
381 if err := bug.Validate(); err != nil {
382 return errors.Wrap(err, "can't commit a bug with invalid data")
383 }
384
385 // Write the Ops as a Git blob containing the serialized array
386 hash, err := bug.staging.Write(repo)
387 if err != nil {
388 return err
389 }
390
391 if bug.rootPack == "" {
392 bug.rootPack = hash
393 }
394
395 // Make a Git tree referencing this blob
396 tree := []repository.TreeEntry{
397 // the last pack of ops
398 {ObjectType: repository.Blob, Hash: hash, Name: opsEntryName},
399 // always the first pack of ops (might be the same)
400 {ObjectType: repository.Blob, Hash: bug.rootPack, Name: rootEntryName},
401 }
402
403 // Reference, if any, all the files required by the ops
404 // Git will check that they actually exist in the storage and will make sure
405 // to push/pull them as needed.
406 mediaTree := makeMediaTree(bug.staging)
407 if len(mediaTree) > 0 {
408 mediaTreeHash, err := repo.StoreTree(mediaTree)
409 if err != nil {
410 return err
411 }
412 tree = append(tree, repository.TreeEntry{
413 ObjectType: repository.Tree,
414 Hash: mediaTreeHash,
415 Name: mediaEntryName,
416 })
417 }
418
419 // Store the logical clocks as well
420 // --> edit clock for each OperationPack/commits
421 // --> create clock only for the first OperationPack/commits
422 //
423 // To avoid having one blob for each clock value, clocks are serialized
424 // directly into the entry name
425 emptyBlobHash, err := repo.StoreData([]byte{})
426 if err != nil {
427 return err
428 }
429
430 editClock, err := repo.GetOrCreateClock(editClockName)
431 if err != nil {
432 return err
433 }
434 bug.editTime, err = editClock.Increment()
435 if err != nil {
436 return err
437 }
438
439 tree = append(tree, repository.TreeEntry{
440 ObjectType: repository.Blob,
441 Hash: emptyBlobHash,
442 Name: fmt.Sprintf(editClockEntryPattern, bug.editTime),
443 })
444 if bug.lastCommit == "" {
445 createClock, err := repo.GetOrCreateClock(creationClockName)
446 if err != nil {
447 return err
448 }
449 bug.createTime, err = createClock.Increment()
450 if err != nil {
451 return err
452 }
453
454 tree = append(tree, repository.TreeEntry{
455 ObjectType: repository.Blob,
456 Hash: emptyBlobHash,
457 Name: fmt.Sprintf(createClockEntryPattern, bug.createTime),
458 })
459 }
460
461 // Store the tree
462 hash, err = repo.StoreTree(tree)
463 if err != nil {
464 return err
465 }
466
467 // Write a Git commit referencing the tree, with the previous commit as parent
468 if bug.lastCommit != "" {
469 hash, err = repo.StoreCommitWithParent(hash, bug.lastCommit)
470 } else {
471 hash, err = repo.StoreCommit(hash)
472 }
473
474 if err != nil {
475 return err
476 }
477
478 bug.lastCommit = hash
479
480 // if it was the first commit, use the commit hash as bug id
481 if bug.id == "" {
482 bug.id = entity.Id(hash)
483 }
484
485 // Create or update the Git reference for this bug
486 // When pushing later, the remote will ensure that this ref update
487 // is fast-forward, that is no data has been overwritten
488 ref := fmt.Sprintf("%s%s", bugsRefPattern, bug.id)
489 err = repo.UpdateRef(ref, hash)
490
491 if err != nil {
492 return err
493 }
494
495 bug.staging.commitHash = hash
496 bug.packs = append(bug.packs, bug.staging)
497 bug.staging = OperationPack{}
498
499 return nil
500}
501
502func (bug *Bug) CommitAsNeeded(repo repository.ClockedRepo) error {
503 if !bug.NeedCommit() {
504 return nil
505 }
506 return bug.Commit(repo)
507}
508
509func (bug *Bug) NeedCommit() bool {
510 return !bug.staging.IsEmpty()
511}
512
513func makeMediaTree(pack OperationPack) []repository.TreeEntry {
514 var tree []repository.TreeEntry
515 counter := 0
516 added := make(map[repository.Hash]interface{})
517
518 for _, ops := range pack.Operations {
519 for _, file := range ops.GetFiles() {
520 if _, has := added[file]; !has {
521 tree = append(tree, repository.TreeEntry{
522 ObjectType: repository.Blob,
523 Hash: file,
524 // The name is not important here, we only need to
525 // reference the blob.
526 Name: fmt.Sprintf("file%d", counter),
527 })
528 counter++
529 added[file] = struct{}{}
530 }
531 }
532 }
533
534 return tree
535}
536
537// Merge a different version of the same bug by rebasing operations of this bug
538// that are not present in the other on top of the chain of operations of the
539// other version.
540func (bug *Bug) Merge(repo repository.Repo, other Interface) (bool, error) {
541 var otherBug = bugFromInterface(other)
542
543 // Note: a faster merge should be possible without actually reading and parsing
544 // all operations pack of our side.
545 // Reading the other side is still necessary to validate remote data, at least
546 // for new operations
547
548 if bug.id != otherBug.id {
549 return false, errors.New("merging unrelated bugs is not supported")
550 }
551
552 if len(otherBug.staging.Operations) > 0 {
553 return false, errors.New("merging a bug with a non-empty staging is not supported")
554 }
555
556 if bug.lastCommit == "" || otherBug.lastCommit == "" {
557 return false, errors.New("can't merge a bug that has never been stored")
558 }
559
560 ancestor, err := repo.FindCommonAncestor(bug.lastCommit, otherBug.lastCommit)
561 if err != nil {
562 return false, errors.Wrap(err, "can't find common ancestor")
563 }
564
565 ancestorIndex := 0
566 newPacks := make([]OperationPack, 0, len(bug.packs))
567
568 // Find the root of the rebase
569 for i, pack := range bug.packs {
570 newPacks = append(newPacks, pack)
571
572 if pack.commitHash == ancestor {
573 ancestorIndex = i
574 break
575 }
576 }
577
578 if len(otherBug.packs) == ancestorIndex+1 {
579 // Nothing to rebase, return early
580 return false, nil
581 }
582
583 // get other bug's extra packs
584 for i := ancestorIndex + 1; i < len(otherBug.packs); i++ {
585 // clone is probably not necessary
586 newPack := otherBug.packs[i].Clone()
587
588 newPacks = append(newPacks, newPack)
589 bug.lastCommit = newPack.commitHash
590 }
591
592 // rebase our extra packs
593 for i := ancestorIndex + 1; i < len(bug.packs); i++ {
594 pack := bug.packs[i]
595
596 // get the referenced git tree
597 treeHash, err := repo.GetTreeHash(pack.commitHash)
598
599 if err != nil {
600 return false, err
601 }
602
603 // create a new commit with the correct ancestor
604 hash, err := repo.StoreCommitWithParent(treeHash, bug.lastCommit)
605
606 if err != nil {
607 return false, err
608 }
609
610 // replace the pack
611 newPack := pack.Clone()
612 newPack.commitHash = hash
613 newPacks = append(newPacks, newPack)
614
615 // update the bug
616 bug.lastCommit = hash
617 }
618
619 bug.packs = newPacks
620
621 // Update the git ref
622 err = repo.UpdateRef(bugsRefPattern+bug.id.String(), bug.lastCommit)
623 if err != nil {
624 return false, err
625 }
626
627 return true, nil
628}
629
630// Id return the Bug identifier
631func (bug *Bug) Id() entity.Id {
632 if bug.id == "" {
633 // simply panic as it would be a coding error
634 // (using an id of a bug not stored yet)
635 panic("no id yet")
636 }
637 return bug.id
638}
639
640// CreateLamportTime return the Lamport time of creation
641func (bug *Bug) CreateLamportTime() lamport.Time {
642 return bug.createTime
643}
644
645// EditLamportTime return the Lamport time of the last edit
646func (bug *Bug) EditLamportTime() lamport.Time {
647 return bug.editTime
648}
649
650// Lookup for the very first operation of the bug.
651// For a valid Bug, this operation should be a CreateOp
652func (bug *Bug) FirstOp() Operation {
653 for _, pack := range bug.packs {
654 for _, op := range pack.Operations {
655 return op
656 }
657 }
658
659 if !bug.staging.IsEmpty() {
660 return bug.staging.Operations[0]
661 }
662
663 return nil
664}
665
666// Lookup for the very last operation of the bug.
667// For a valid Bug, should never be nil
668func (bug *Bug) LastOp() Operation {
669 if !bug.staging.IsEmpty() {
670 return bug.staging.Operations[len(bug.staging.Operations)-1]
671 }
672
673 if len(bug.packs) == 0 {
674 return nil
675 }
676
677 lastPack := bug.packs[len(bug.packs)-1]
678
679 if len(lastPack.Operations) == 0 {
680 return nil
681 }
682
683 return lastPack.Operations[len(lastPack.Operations)-1]
684}
685
686// Compile a bug in a easily usable snapshot
687func (bug *Bug) Compile() Snapshot {
688 snap := Snapshot{
689 id: bug.id,
690 Status: OpenStatus,
691 }
692
693 it := NewOperationIterator(bug)
694
695 for it.Next() {
696 op := it.Value()
697 op.Apply(&snap)
698 snap.Operations = append(snap.Operations, op)
699 }
700
701 return snap
702}