git-bug/bug/operation.go

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package bug
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import (
"crypto/sha256"
"encoding/json"
"fmt"
"time"
"github.com/MichaelMure/git-bug/util/git"
"github.com/pkg/errors"
)
// OperationType is an operation type identifier
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type OperationType int
const (
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_ OperationType = iota
CreateOp
SetTitleOp
AddCommentOp
SetStatusOp
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LabelChangeOp
EditCommentOp
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)
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// Operation define the interface to fulfill for an edit operation of a Bug
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type Operation interface {
// base return the OpBase of the Operation, for package internal use
base() *OpBase
// Hash return the hash of the operation, to be used for back references
Hash() (git.Hash, error)
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// Time return the time when the operation was added
Time() time.Time
// GetUnixTime return the unix timestamp when the operation was added
GetUnixTime() int64
// GetFiles return the files needed by this operation
GetFiles() []git.Hash
// Apply the operation to a Snapshot to create the final state
Apply(snapshot *Snapshot)
// Validate check if the operation is valid (ex: a title is a single line)
Validate() error
// SetMetadata store arbitrary metadata about the operation
SetMetadata(key string, value string)
// GetMetadata retrieve arbitrary metadata about the operation
GetMetadata(key string) (string, bool)
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}
func hashRaw(data []byte) git.Hash {
hasher := sha256.New()
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// Write can't fail
_, _ = hasher.Write(data)
return git.Hash(fmt.Sprintf("%x", hasher.Sum(nil)))
}
// hash compute the hash of the serialized operation
func hashOperation(op Operation) (git.Hash, error) {
base := op.base()
if base.hash != "" {
return base.hash, nil
}
data, err := json.Marshal(op)
if err != nil {
return "", err
}
base.hash = hashRaw(data)
return base.hash, nil
}
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// OpBase implement the common code for all operations
type OpBase struct {
OperationType OperationType `json:"type"`
Author Person `json:"author"`
UnixTime int64 `json:"timestamp"`
hash git.Hash
Metadata map[string]string `json:"metadata,omitempty"`
}
// newOpBase is the constructor for an OpBase
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func newOpBase(opType OperationType, author Person, unixTime int64) OpBase {
return OpBase{
OperationType: opType,
Author: author,
UnixTime: unixTime,
}
}
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// Time return the time when the operation was added
func (op *OpBase) Time() time.Time {
return time.Unix(op.UnixTime, 0)
}
// GetUnixTime return the unix timestamp when the operation was added
func (op *OpBase) GetUnixTime() int64 {
return op.UnixTime
}
// GetFiles return the files needed by this operation
func (op *OpBase) GetFiles() []git.Hash {
return nil
}
// Validate check the OpBase for errors
func opBaseValidate(op Operation, opType OperationType) error {
if op.base().OperationType != opType {
return fmt.Errorf("incorrect operation type (expected: %v, actual: %v)", opType, op.base().OperationType)
}
if _, err := op.Hash(); err != nil {
return errors.Wrap(err, "op is not serializable")
}
if op.GetUnixTime() == 0 {
return fmt.Errorf("time not set")
}
if err := op.base().Author.Validate(); err != nil {
return errors.Wrap(err, "author")
}
for _, hash := range op.GetFiles() {
if !hash.IsValid() {
return fmt.Errorf("file with invalid hash %v", hash)
}
}
return nil
}
// SetMetadata store arbitrary metadata about the operation
func (op *OpBase) SetMetadata(key string, value string) {
if op.Metadata == nil {
op.Metadata = make(map[string]string)
}
op.Metadata[key] = value
}
// GetMetadata retrieve arbitrary metadata about the operation
func (op *OpBase) GetMetadata(key string) (string, bool) {
val, ok := op.Metadata[key]
return val, ok
}