Repository.Pull, PoC

3 files changed, 119 insertions, 5 deletions

diff --git a/options.go b/options.go
index 2aebbc7..0c1fefb 100644
--- a/options.go
+++ b/options.go
@@ -1,6 +1,8 @@
 package git
 
 import (
+	"errors"
+
 	"gopkg.in/src-d/go-git.v3/clients/common"
 	"gopkg.in/src-d/go-git.v4/core"
 )
@@ -10,6 +12,11 @@ const (
 	DefaultRemoteName = "origin"
 )
 
+var (
+	ErrMissingURL        = errors.New("URL field is required")
+	ErrMissingReferences = errors.New("references cannot be empty")
+)
+
 // RepositoryCloneOptions describe how a clone should be perform
 type RepositoryCloneOptions struct {
 	// The (possibly remote) repository URL to clone from
@@ -26,7 +33,12 @@ type RepositoryCloneOptions struct {
 	Depth int
 }
 
-func (o *RepositoryCloneOptions) Default() {
+// Validate validate the fields and set the default values
+func (o *RepositoryCloneOptions) Validate() error {
+	if o.URL == "" {
+		return ErrMissingURL
+	}
+
 	if o.RemoteName == "" {
 		o.RemoteName = DefaultRemoteName
 	}
@@ -34,12 +46,50 @@ func (o *RepositoryCloneOptions) Default() {
 	if o.ReferenceName == "" {
 		o.ReferenceName = core.HEAD
 	}
+
+	return nil
+}
+
+// RepositoryPullOptions describe how a pull should be perform
+type RepositoryPullOptions struct {
+	// Name of the remote to be pulled
+	RemoteName string
+	// Remote branch to clone
+	ReferenceName core.ReferenceName
+	// Fetch only ReferenceName if true
+	SingleBranch bool
+	// Limit fetching to the specified number of commits
+	Depth int
+}
+
+// Validate validate the fields and set the default values
+func (o *RepositoryPullOptions) Validate() error {
+	if o.RemoteName == "" {
+		o.RemoteName = DefaultRemoteName
+	}
+
+	if o.ReferenceName == "" {
+		o.ReferenceName = core.HEAD
+	}
+
+	return nil
 }
 
 // RemoteFetchOptions describe how a fetch should be perform
 type RemoteFetchOptions struct {
 	// Remote branchs to fetch
 	References []*core.Reference
+	// Local references present on the local storage
+	LocalReferences []*core.Reference
 	// Limit fetching to the specified number of commits
 	Depth int
 }
+
+// Validate validate the fields and set the default values
+func (o *RemoteFetchOptions) Validate() error {
+	if len(o.References) == 0 {
+		return ErrMissingReferences
+	}
+
+	return nil
+}
diff --git a/remote.go b/remote.go
index ce74af4..7e25ef7 100644
--- a/remote.go
+++ b/remote.go
@@ -80,6 +80,10 @@ func (r *Remote) Capabilities() *common.Capabilities {
 
 // Fetch returns a reader using the request
 func (r *Remote) Fetch(s core.ObjectStorage, o *RemoteFetchOptions) (err error) {
+	if err := o.Validate(); err != nil {
+		return err
+	}
+
 	req := &common.GitUploadPackRequest{}
 	req.Depth = o.Depth
 
diff --git a/repository.go b/repository.go
index b17bbea..e9aa55a 100644
--- a/repository.go
+++ b/repository.go
@@ -12,15 +12,14 @@ import (
 )
 
 var (
-	// ErrObjectNotFound object not found
 	ErrObjectNotFound = errors.New("object not found")
+	ErrUnknownRemote  = errors.New("unknown remote")
 )
 
 // Repository giturl string, auth common.AuthMethod repository struct
 type Repository struct {
 	Remotes map[string]*Remote
-
-	s core.Storage
+	s       core.Storage
 }
 
 // NewMemoryRepository creates a new repository, backed by a memory.Storage
@@ -45,7 +44,9 @@ func NewRepository(s core.Storage) (*Repository, error) {
 
 // Clone clones a remote repository
 func (r *Repository) Clone(o *RepositoryCloneOptions) error {
-	o.Default()
+	if err := o.Validate(); err != nil {
+		return err
+	}
 
 	remote, err := r.createRemote(o.RemoteName, o.URL, o.Auth)
 	if err != nil {
@@ -194,6 +195,65 @@ func (r *Repository) createRemoteReference(remote *Remote, ref *core.Reference)
 	return r.s.ReferenceStorage().Set(n)
 }
 
+// Pull incorporates changes from a remote repository into the current branch
+func (r *Repository) Pull(o *RepositoryPullOptions) error {
+	if err := o.Validate(); err != nil {
+		return err
+	}
+
+	remote, ok := r.Remotes[o.RemoteName]
+	if !ok {
+		return ErrUnknownRemote
+	}
+
+	head, err := remote.Ref(o.ReferenceName, true)
+	if err != nil {
+		return err
+	}
+
+	refs, err := r.getLocalReferences()
+	if err != nil {
+		return err
+	}
+
+	err = remote.Fetch(r.s.ObjectStorage(), &RemoteFetchOptions{
+		References:      []*core.Reference{head},
+		LocalReferences: refs,
+		Depth:           o.Depth,
+	})
+
+	if err != nil {
+		return err
+	}
+
+	return r.createLocalReferences(head)
+}
+
+func (r *Repository) getLocalReferences() ([]*core.Reference, error) {
+	var refs []*core.Reference
+	i := r.Refs()
+	defer i.Close()
+
+	for {
+		ref, err := i.Next()
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+
+			return nil, err
+		}
+
+		if ref.Type() == core.SymbolicReference {
+			continue
+		}
+
+		refs = append(refs, ref)
+	}
+
+	return refs, nil
+}
+
 // Commit return the commit with the given hash
 func (r *Repository) Commit(h core.Hash) (*Commit, error) {
 	obj, err := r.s.ObjectStorage().Get(h)