1 files changed, 58 insertions, 29 deletions

diff --git a/entity/dag/entity_actions.go b/entity/dag/entity_actions.go
index 8dcf91e6..83ff7ddc 100644
--- a/entity/dag/entity_actions.go
+++ b/entity/dag/entity_actions.go
@@ -9,6 +9,7 @@ import (
 	"github.com/MichaelMure/git-bug/repository"
 )
 
+// ListLocalIds list all the available local Entity's Id
 func ListLocalIds(typename string, repo repository.RepoData) ([]entity.Id, error) {
 	refs, err := repo.ListRefs(fmt.Sprintf("refs/%s/", typename))
 	if err != nil {
@@ -56,6 +57,21 @@ func Pull(def Definition, repo repository.ClockedRepo, remote string) error {
 	return nil
 }
 
+// MergeAll will merge all the available remote Entity:
+//
+// Multiple scenario exist:
+// 1. if the remote Entity doesn't exist locally, it's created
+//    --> emit entity.MergeStatusNew
+// 2. if the remote and local Entity have the same state, nothing is changed
+//    --> emit entity.MergeStatusNothing
+// 3. if the local Entity has new commits but the remote don't, nothing is changed
+//    --> emit entity.MergeStatusNothing
+// 4. if the remote has new commit, the local bug is updated to match the same history
+//    (fast-forward update)
+//    --> emit entity.MergeStatusUpdated
+// 5. if both local and remote Entity have new commits (that is, we have a concurrent edition),
+//    a merge commit with an empty operationPack is created to join both branch and form a DAG.
+//    --> emit entity.MergeStatusUpdated
 func MergeAll(def Definition, repo repository.ClockedRepo, remote string) <-chan entity.MergeResult {
 	out := make(chan entity.MergeResult)
 
@@ -81,6 +97,8 @@ func MergeAll(def Definition, repo repository.ClockedRepo, remote string) <-chan
 	return out
 }
 
+// merge perform a merge to make sure a local Entity is up to date.
+// See MergeAll for more details.
 func merge(def Definition, repo repository.ClockedRepo, remoteRef string) entity.MergeResult {
 	id := entity.RefToId(remoteRef)
 
@@ -102,36 +120,24 @@ func merge(def Definition, repo repository.ClockedRepo, remoteRef string) entity
 
 	localRef := fmt.Sprintf("refs/%s/%s", def.namespace, id.String())
 
+	// SCENARIO 1
+	// if the remote Entity doesn't exist locally, it's created
+
 	localExist, err := repo.RefExist(localRef)
 	if err != nil {
 		return entity.NewMergeError(err, id)
 	}
 
-	// the bug is not local yet, simply create the reference
 	if !localExist {
+		// the bug is not local yet, simply create the reference
 		err := repo.CopyRef(remoteRef, localRef)
 		if err != nil {
 			return entity.NewMergeError(err, id)
 		}
 
-		return entity.NewMergeStatus(entity.MergeStatusNew, id, remoteEntity)
+		return entity.NewMergeNewStatus(id, remoteEntity)
 	}
 
-	// var updated bool
-	// err = repo.MergeRef(localRef, remoteRef, func() repository.Hash {
-	// 	updated = true
-	//
-	// })
-	// if err != nil {
-	// 	return entity.NewMergeError(err, id)
-	// }
-	//
-	// if updated {
-	// 	return entity.NewMergeStatus(entity.MergeStatusUpdated, id, )
-	// } else {
-	// 	return entity.NewMergeStatus(entity.MergeStatusNothing, id, )
-	// }
-
 	localCommit, err := repo.ResolveRef(localRef)
 	if err != nil {
 		return entity.NewMergeError(err, id)
@@ -142,18 +148,38 @@ func merge(def Definition, repo repository.ClockedRepo, remoteRef string) entity
 		return entity.NewMergeError(err, id)
 	}
 
+	// SCENARIO 2
+	// if the remote and local Entity have the same state, nothing is changed
+
 	if localCommit == remoteCommit {
 		// nothing to merge
-		return entity.NewMergeStatus(entity.MergeStatusNothing, id, remoteEntity)
+		return entity.NewMergeNothingStatus(id)
 	}
 
-	// fast-forward is possible if otherRef include ref
+	// SCENARIO 3
+	// if the local Entity has new commits but the remote don't, nothing is changed
+
+	localCommits, err := repo.ListCommits(localRef)
+	if err != nil {
+		return entity.NewMergeError(err, id)
+	}
+
+	for _, hash := range localCommits {
+		if hash == localCommit {
+			return entity.NewMergeNothingStatus(id)
+		}
+	}
+
+	// SCENARIO 4
+	// if the remote has new commit, the local bug is updated to match the same history
+	// (fast-forward update)
 
 	remoteCommits, err := repo.ListCommits(remoteRef)
 	if err != nil {
 		return entity.NewMergeError(err, id)
 	}
 
+	// fast-forward is possible if otherRef include ref
 	fastForwardPossible := false
 	for _, hash := range remoteCommits {
 		if hash == localCommit {
@@ -167,9 +193,13 @@ func merge(def Definition, repo repository.ClockedRepo, remoteRef string) entity
 		if err != nil {
 			return entity.NewMergeError(err, id)
 		}
-		return entity.NewMergeStatus(entity.MergeStatusUpdated, id, remoteEntity)
+		return entity.NewMergeUpdatedStatus(id, remoteEntity)
 	}
 
+	// SCENARIO 5
+	// if both local and remote Entity have new commits (that is, we have a concurrent edition),
+	// a merge commit with an empty operationPack is created to join both branch and form a DAG.
+
 	// fast-forward is not possible, we need to create a merge commit
 	// For simplicity when reading and to have clocks that record this change, we store
 	// an empty operationPack.
@@ -180,6 +210,7 @@ func merge(def Definition, repo repository.ClockedRepo, remoteRef string) entity
 		return entity.NewMergeError(err, id)
 	}
 
+	// TODO: pack clock
 	// err = localEntity.packClock.Witness(remoteEntity.packClock.Time())
 	// if err != nil {
 	// 	return entity.NewMergeError(err, id)
@@ -199,27 +230,25 @@ func merge(def Definition, repo repository.ClockedRepo, remoteRef string) entity
 		Operations: nil,
 		CreateTime: 0,
 		EditTime:   editTime,
+		// TODO: pack clock
 		// PackTime:   packTime,
 	}
 
-	treeHash, err := opp.Write(def, repo)
-	if err != nil {
-		return entity.NewMergeError(err, id)
-	}
-
-	// Create the merge commit with two parents
-	newHash, err := repo.StoreCommit(treeHash, localCommit, remoteCommit)
+	commitHash, err := opp.Write(def, repo, localCommit, remoteCommit)
 	if err != nil {
 		return entity.NewMergeError(err, id)
 	}
 
 	// finally update the ref
-	err = repo.UpdateRef(localRef, newHash)
+	err = repo.UpdateRef(localRef, commitHash)
 	if err != nil {
 		return entity.NewMergeError(err, id)
 	}
 
-	return entity.NewMergeStatus(entity.MergeStatusUpdated, id, localEntity)
+	// Note: we don't need to update localEntity state (lastCommit, operations...) as we
+	// discard it entirely anyway.
+
+	return entity.NewMergeUpdatedStatus(id, localEntity)
 }
 
 func Remove() error {