entity/dag: proper base operation for simplified implementation

- reduce boilerplace necessary to implement an operation
- consolidate what an operation is in the core, which in turn pave the way for a generic cache layer mechanism
- avoid the previously complex unmarshalling process
- support operation metadata from the core
- simplified testing

1 files changed, 9 insertions, 68 deletions

diff --git a/bug/op_create.go b/bug/op_create.go
index 9c972195..ed2fd994 100644
--- a/bug/op_create.go
+++ b/bug/op_create.go
@@ -1,7 +1,6 @@
 package bug
 
 import (
-	"encoding/json"
 	"fmt"
 
 	"github.com/MichaelMure/git-bug/entity"
@@ -17,53 +16,38 @@ var _ dag.OperationWithFiles = &CreateOperation{}
 
 // CreateOperation define the initial creation of a bug
 type CreateOperation struct {
-	OpBase
+	dag.OpBase
 	Title   string            `json:"title"`
 	Message string            `json:"message"`
 	Files   []repository.Hash `json:"files"`
 }
 
 func (op *CreateOperation) Id() entity.Id {
-	return idOperation(op, &op.OpBase)
-}
-
-// OVERRIDE
-func (op *CreateOperation) SetMetadata(key string, value string) {
-	// sanity check: we make sure we are not in the following scenario:
-	// - the bug is created with a first operation
-	// - Id() is used
-	// - metadata are added, which will change the Id
-	// - Id() is used again
-
-	if op.id != entity.UnsetId {
-		panic("usage of Id() after changing the first operation")
-	}
-
-	op.OpBase.SetMetadata(key, value)
+	return dag.IdOperation(op, &op.OpBase)
 }
 
 func (op *CreateOperation) Apply(snapshot *Snapshot) {
 	// sanity check: will fail when adding a second Create
 	if snapshot.id != "" && snapshot.id != entity.UnsetId && snapshot.id != op.Id() {
-		panic("adding a second Create operation")
+		return
 	}
 
 	snapshot.id = op.Id()
 
-	snapshot.addActor(op.Author_)
-	snapshot.addParticipant(op.Author_)
+	snapshot.addActor(op.Author())
+	snapshot.addParticipant(op.Author())
 
 	snapshot.Title = op.Title
 
 	comment := Comment{
 		id:       entity.CombineIds(snapshot.Id(), op.Id()),
 		Message:  op.Message,
-		Author:   op.Author_,
+		Author:   op.Author(),
 		UnixTime: timestamp.Timestamp(op.UnixTime),
 	}
 
 	snapshot.Comments = []Comment{comment}
-	snapshot.Author = op.Author_
+	snapshot.Author = op.Author()
 	snapshot.CreateTime = op.Time()
 
 	snapshot.Timeline = []TimelineItem{
@@ -82,13 +66,6 @@ func (op *CreateOperation) Validate() error {
 		return err
 	}
 
-	if len(op.Nonce) > 64 {
-		return fmt.Errorf("create nonce is too big")
-	}
-	if len(op.Nonce) < 20 {
-		return fmt.Errorf("create nonce is too small")
-	}
-
 	if text.Empty(op.Title) {
 		return fmt.Errorf("title is empty")
 	}
@@ -103,45 +80,9 @@ func (op *CreateOperation) Validate() error {
 	return nil
 }
 
-// UnmarshalJSON is a two step JSON unmarshalling
-// This workaround is necessary to avoid the inner OpBase.MarshalJSON
-// overriding the outer op's MarshalJSON
-func (op *CreateOperation) UnmarshalJSON(data []byte) error {
-	// Unmarshal OpBase and the op separately
-
-	base := OpBase{}
-	err := json.Unmarshal(data, &base)
-	if err != nil {
-		return err
-	}
-
-	aux := struct {
-		Nonce   []byte            `json:"nonce"`
-		Title   string            `json:"title"`
-		Message string            `json:"message"`
-		Files   []repository.Hash `json:"files"`
-	}{}
-
-	err = json.Unmarshal(data, &aux)
-	if err != nil {
-		return err
-	}
-
-	op.OpBase = base
-	op.Nonce = aux.Nonce
-	op.Title = aux.Title
-	op.Message = aux.Message
-	op.Files = aux.Files
-
-	return nil
-}
-
-// Sign post method for gqlgen
-func (op *CreateOperation) IsAuthored() {}
-
 func NewCreateOp(author identity.Interface, unixTime int64, title, message string, files []repository.Hash) *CreateOperation {
 	return &CreateOperation{
-		OpBase:  newOpBase(CreateOp, author, unixTime),
+		OpBase:  dag.NewOpBase(CreateOp, author, unixTime),
 		Title:   title,
 		Message: message,
 		Files:   files,
@@ -153,7 +94,7 @@ type CreateTimelineItem struct {
 	CommentTimelineItem
 }
 
-// Sign post method for gqlgen
+// IsAuthored is a sign post method for gqlgen
 func (c *CreateTimelineItem) IsAuthored() {}
 
 // Convenience function to apply the operation