1 files changed, 146 insertions, 0 deletions
diff --git a/plumbing/reference.go b/plumbing/reference.go
new file mode 100644
index 0000000..98516c7
--- /dev/null
+++ b/plumbing/reference.go
@@ -0,0 +1,146 @@
+package plumbing
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+const (
+	refPrefix       = "refs/"
+	refHeadPrefix   = refPrefix + "heads/"
+	refTagPrefix    = refPrefix + "tags/"
+	refRemotePrefix = refPrefix + "remotes/"
+	refNotePrefix   = refPrefix + "notes/"
+	symrefPrefix    = "ref: "
+)
+
+var (
+	ErrReferenceNotFound = errors.New("reference not found")
+)
+
+// ReferenceType reference type's
+type ReferenceType int8
+
+const (
+	InvalidReference  ReferenceType = 0
+	HashReference     ReferenceType = 1
+	SymbolicReference ReferenceType = 2
+)
+
+// ReferenceName reference name's
+type ReferenceName string
+
+func (r ReferenceName) String() string {
+	return string(r)
+}
+
+// Short returns the short name of a ReferenceName
+func (r ReferenceName) Short() string {
+	parts := strings.Split(string(r), "/")
+	return parts[len(parts)-1]
+}
+
+const (
+	HEAD ReferenceName = "HEAD"
+)
+
+// Reference is a representation of git reference
+type Reference struct {
+	t      ReferenceType
+	n      ReferenceName
+	h      Hash
+	target ReferenceName
+}
+
+// NewReferenceFromStrings creates a reference from name and target as string,
+// the resulting reference can be a SymbolicReference or a HashReference base
+// on the target provided
+func NewReferenceFromStrings(name, target string) *Reference {
+	n := ReferenceName(name)
+
+	if strings.HasPrefix(target, symrefPrefix) {
+		target := ReferenceName(target[len(symrefPrefix):])
+		return NewSymbolicReference(n, target)
+	}
+
+	return NewHashReference(n, NewHash(target))
+}
+
+// NewSymbolicReference creates a new SymbolicReference reference
+func NewSymbolicReference(n, target ReferenceName) *Reference {
+	return &Reference{
+		t:      SymbolicReference,
+		n:      n,
+		target: target,
+	}
+}
+
+// NewHashReference creates a new HashReference reference
+func NewHashReference(n ReferenceName, h Hash) *Reference {
+	return &Reference{
+		t: HashReference,
+		n: n,
+		h: h,
+	}
+}
+
+// Type return the type of a reference
+func (r *Reference) Type() ReferenceType {
+	return r.t
+}
+
+// Name return the name of a reference
+func (r *Reference) Name() ReferenceName {
+	return r.n
+}
+
+// Hash return the hash of a hash reference
+func (r *Reference) Hash() Hash {
+	return r.h
+}
+
+// Target return the target of a symbolic reference
+func (r *Reference) Target() ReferenceName {
+	return r.target
+}
+
+// IsBranch check if a reference is a branch
+func (r *Reference) IsBranch() bool {
+	return strings.HasPrefix(string(r.n), refHeadPrefix)
+}
+
+// IsNote check if a reference is a note
+func (r *Reference) IsNote() bool {
+	return strings.HasPrefix(string(r.n), refNotePrefix)
+}
+
+// IsRemote check if a reference is a remote
+func (r *Reference) IsRemote() bool {
+	return strings.HasPrefix(string(r.n), refRemotePrefix)
+}
+
+// IsTag check if a reference is a tag
+func (r *Reference) IsTag() bool {
+	return strings.HasPrefix(string(r.n), refTagPrefix)
+}
+
+// Strings dump a reference as a [2]string
+func (r *Reference) Strings() [2]string {
+	var o [2]string
+	o[0] = r.Name().String()
+
+	switch r.Type() {
+	case HashReference:
+		o[1] = r.Hash().String()
+	case SymbolicReference:
+		o[1] = symrefPrefix + r.Target().String()
+	}
+
+	return o
+}
+
+func (r *Reference) String() string {
+	s := r.Strings()
+	return fmt.Sprintf("%s %s", s[1], s[0])
+}