worktree: reset and checkout support for submodules

1 files changed, 154 insertions, 7 deletions

diff --git a/submodule.go b/submodule.go
index c711a2b..fd23b9d 100644
--- a/submodule.go
+++ b/submodule.go
@@ -1,10 +1,13 @@
 package git
 
 import (
+	"bytes"
 	"errors"
+	"fmt"
 
 	"gopkg.in/src-d/go-git.v4/config"
 	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/format/index"
 )
 
 var (
@@ -15,6 +18,7 @@ var (
 // Submodule a submodule allows you to keep another Git repository in a
 // subdirectory of your repository.
 type Submodule struct {
+	// initialized defines if a submodule was already initialized.
 	initialized bool
 
 	c *config.Submodule
@@ -26,7 +30,7 @@ func (s *Submodule) Config() *config.Submodule {
 	return s.c
 }
 
-// Init initialize the submodule reading the recoreded Entry in the index for
+// Init initialize the submodule reading the recorded Entry in the index for
 // the given submodule
 func (s *Submodule) Init() error {
 	cfg, err := s.w.r.Storer.Config()
@@ -45,8 +49,54 @@ func (s *Submodule) Init() error {
 	return s.w.r.Storer.SetConfig(cfg)
 }
 
+// Status returns the status of the submodule.
+func (s *Submodule) Status() (*SubmoduleStatus, error) {
+	idx, err := s.w.r.Storer.Index()
+	if err != nil {
+		return nil, err
+	}
+
+	return s.status(idx)
+}
+
+func (s *Submodule) status(idx *index.Index) (*SubmoduleStatus, error) {
+	e, err := idx.Entry(s.c.Path)
+	if err != nil {
+		return nil, err
+	}
+
+	status := &SubmoduleStatus{
+		Path:     s.c.Path,
+		Expected: e.Hash,
+	}
+
+	if !s.initialized {
+		return status, nil
+	}
+
+	r, err := s.Repository()
+	if err != nil {
+		return nil, err
+	}
+
+	head, err := r.Head()
+	if err == nil {
+		status.Current = head.Hash()
+	}
+
+	if err != nil && err == plumbing.ErrReferenceNotFound {
+		err = nil
+	}
+
+	return status, err
+}
+
 // Repository returns the Repository represented by this submodule
 func (s *Submodule) Repository() (*Repository, error) {
+	if !s.initialized {
+		return nil, ErrSubmoduleNotInitialized
+	}
+
 	storer, err := s.w.r.Storer.Module(s.c.Name)
 	if err != nil {
 		return nil, err
@@ -76,9 +126,13 @@ func (s *Submodule) Repository() (*Repository, error) {
 }
 
 // Update the registered submodule to match what the superproject expects, the
-// submodule should be initilized first calling the Init method or setting in
+// submodule should be initialized first calling the Init method or setting in
 // the options SubmoduleUpdateOptions.Init equals true
 func (s *Submodule) Update(o *SubmoduleUpdateOptions) error {
+	return s.update(o, plumbing.ZeroHash)
+}
+
+func (s *Submodule) update(o *SubmoduleUpdateOptions, forceHash plumbing.Hash) error {
 	if !s.initialized && !o.Init {
 		return ErrSubmoduleNotInitialized
 	}
@@ -89,17 +143,27 @@ func (s *Submodule) Update(o *SubmoduleUpdateOptions) error {
 		}
 	}
 
-	e, err := s.w.readIndexEntry(s.c.Path)
+	idx, err := s.w.r.Storer.Index()
 	if err != nil {
 		return err
 	}
 
+	hash := forceHash
+	if hash.IsZero() {
+		e, err := idx.Entry(s.c.Path)
+		if err != nil {
+			return err
+		}
+
+		hash = e.Hash
+	}
+
 	r, err := s.Repository()
 	if err != nil {
 		return err
 	}
 
-	if err := s.fetchAndCheckout(r, o, e.Hash); err != nil {
+	if err := s.fetchAndCheckout(r, o, hash); err != nil {
 		return err
 	}
 
@@ -123,6 +187,7 @@ func (s *Submodule) doRecursiveUpdate(r *Repository, o *SubmoduleUpdateOptions)
 
 	new := &SubmoduleUpdateOptions{}
 	*new = *o
+
 	new.RecurseSubmodules--
 	return l.Update(new)
 }
@@ -148,10 +213,10 @@ func (s *Submodule) fetchAndCheckout(r *Repository, o *SubmoduleUpdateOptions, h
 	return r.Storer.SetReference(head)
 }
 
-// Submodules list of several submodules from the same repository
+// Submodules list of several submodules from the same repository.
 type Submodules []*Submodule
 
-// Init initializes the submodules in this list
+// Init initializes the submodules in this list.
 func (s Submodules) Init() error {
 	for _, sub := range s {
 		if err := sub.Init(); err != nil {
@@ -162,7 +227,7 @@ func (s Submodules) Init() error {
 	return nil
 }
 
-// Update updates all the submodules in this list
+// Update updates all the submodules in this list.
 func (s Submodules) Update(o *SubmoduleUpdateOptions) error {
 	for _, sub := range s {
 		if err := sub.Update(o); err != nil {
@@ -172,3 +237,85 @@ func (s Submodules) Update(o *SubmoduleUpdateOptions) error {
 
 	return nil
 }
+
+// Status returns the status of the submodules.
+func (s Submodules) Status() (SubmodulesStatus, error) {
+	var list SubmodulesStatus
+
+	var r *Repository
+	for _, sub := range s {
+		if r == nil {
+			r = sub.w.r
+		}
+
+		idx, err := r.Storer.Index()
+		if err != nil {
+			return nil, err
+		}
+
+		status, err := sub.status(idx)
+		if err != nil {
+			return nil, err
+		}
+
+		list = append(list, status)
+	}
+
+	return list, nil
+}
+
+// SubmodulesStatus contains the status for all submodiles in the worktree
+type SubmodulesStatus []*SubmoduleStatus
+
+// String is equivalent to `git submodule status`
+func (s SubmodulesStatus) String() string {
+	buf := bytes.NewBuffer(nil)
+	for _, sub := range s {
+		fmt.Fprintln(buf, sub)
+	}
+
+	return buf.String()
+}
+
+// SubmoduleStatus contains the status for a submodule in the worktree
+type SubmoduleStatus struct {
+	Path     string
+	Current  plumbing.Hash
+	Expected plumbing.Hash
+	Branch   plumbing.ReferenceName
+}
+
+// IsClean is the HEAD of the submodule is equals to the expected commit
+func (s *SubmoduleStatus) IsClean() bool {
+	return s.Current == s.Expected
+}
+
+// String is equivalent to `git submodule status <submodule>`
+//
+// This will print the SHA-1 of the currently checked out commit for a
+// submodule, along with the submodule path and the output of git describe fo
+// the SHA-1. Each SHA-1 will be prefixed with - if the submodule is not
+// initialized, + if the currently checked out submodule commit does not match
+// the SHA-1 found in the index of the containing repository.
+func (s *SubmoduleStatus) String() string {
+	var extra string
+	var status = ' '
+
+	if s.Current.IsZero() {
+		status = '-'
+	} else if !s.IsClean() {
+		status = '+'
+	}
+
+	if len(s.Branch) != 0 {
+		extra = string(s.Branch[5:])
+	} else if !s.Current.IsZero() {
+		extra = s.Current.String()[:7]
+	}
+
+	if extra != "" {
+		extra = fmt.Sprintf(" (%s)", extra)
+	}
+
+	return fmt.Sprintf("%c%s %s%s", status, s.Expected, s.Path, extra)
+}