protocol/packp: add reference update request encoder. (#147)

* add ReferenceUpdateRequest struct.
* add ReferenceUpdateRequest decoder.
* add ReferenceUpdateRequest encoder.

1 files changed, 84 insertions, 0 deletions

diff --git a/plumbing/protocol/packp/updreq.go b/plumbing/protocol/packp/updreq.go
new file mode 100644
index 0000000..90d6e09
--- /dev/null
+++ b/plumbing/protocol/packp/updreq.go
@@ -0,0 +1,84 @@
+package packp
+
+import (
+	"errors"
+
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/protocol/packp/capability"
+)
+
+var (
+	ErrEmptyCommands    = errors.New("commands cannot be empty")
+	ErrMalformedCommand = errors.New("malformed command")
+)
+
+// ReferenceUpdateRequest values represent reference upload requests.
+// Values from this type are not zero-value safe, use the New function instead.
+//
+// TODO: Add support for push-cert
+type ReferenceUpdateRequest struct {
+	Capabilities *capability.List
+	Commands     []*Command
+	Shallow      *plumbing.Hash
+}
+
+// New returns a pointer to a new ReferenceUpdateRequest value.
+func NewReferenceUpdateRequest() *ReferenceUpdateRequest {
+	return &ReferenceUpdateRequest{
+		Capabilities: capability.NewList(),
+		Commands:     nil,
+	}
+}
+
+func (r *ReferenceUpdateRequest) validate() error {
+	if len(r.Commands) == 0 {
+		return ErrEmptyCommands
+	}
+
+	for _, c := range r.Commands {
+		if err := c.validate(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+type Action string
+
+const (
+	Create  Action = "create"
+	Update         = "update"
+	Delete         = "delete"
+	Invalid        = "invalid"
+)
+
+type Command struct {
+	Name string
+	Old  plumbing.Hash
+	New  plumbing.Hash
+}
+
+func (c *Command) Action() Action {
+	if c.Old == plumbing.ZeroHash && c.New == plumbing.ZeroHash {
+		return Invalid
+	}
+
+	if c.Old == plumbing.ZeroHash {
+		return Create
+	}
+
+	if c.New == plumbing.ZeroHash {
+		return Delete
+	}
+
+	return Update
+}
+
+func (c *Command) validate() error {
+	if c.Action() == Invalid {
+		return ErrMalformedCommand
+	}
+
+	return nil
+}