feat(dir2config): defaults

pkg/clustersconfig/defaults.go

@@ -0,0 +1,143 @@
+package clustersconfig
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"path"
+	"strings"
+
+	billy "gopkg.in/src-d/go-billy.v4"
+	git "gopkg.in/src-d/go-git.v4"
+	"gopkg.in/src-d/go-git.v4/plumbing"
+	"gopkg.in/src-d/go-git.v4/plumbing/object"
+	yaml "gopkg.in/yaml.v2"
+)
+
+type Defaults struct {
+	repo *git.Repository
+	fs   billy.Filesystem
+}
+
+type defaultRef struct {
+	From string
+}
+
+func NewDefaults(path string) (d *Defaults, err error) {
+	repo, err := git.PlainOpen(path)
+	if err != nil {
+		return
+	}
+
+	d = &Defaults{
+		repo: repo,
+	}
+
+	return
+}
+
+func (d *Defaults) Load(dir, suffix string, value Rev, data []byte) (err error) {
+	ref := defaultRef{}
+
+	if err = yaml.Unmarshal(data, &ref); err != nil {
+		return
+	}
+
+	if len(ref.From) != 0 {
+		if Debug {
+			log.Printf("loading defaults %q", ref.From)
+		}
+
+		parts := strings.SplitN(ref.From, ":", 2)
+		if len(parts) != 2 {
+			err = fmt.Errorf("bad default reference: %q", ref.From)
+			return
+		}
+		rev, fileName := parts[0], parts[1]
+
+		if err = d.decodeDefault(rev, path.Join(dir, fileName+suffix), value); err != nil {
+			return
+		}
+
+		value.SetRev(rev)
+	}
+
+	err = yaml.Unmarshal(data, value)
+
+	return
+}
+
+func (d *Defaults) Open(rev, filePath string) (rd io.Reader, err error) {
+	tree, err := d.treeAt(rev)
+	if err != nil {
+		return
+	}
+
+	file, err := tree.File(filePath)
+	if err != nil {
+		return
+	}
+
+	return file.Reader()
+}
+
+func (d *Defaults) ReadAll(rev, filePath string) (ba []byte, err error) {
+	rd, err := d.Open(rev, filePath)
+	return ioutil.ReadAll(rd)
+}
+
+func (d *Defaults) List(rev, dir string) (names []string, err error) {
+	tree, err := d.treeAt(rev)
+	if err != nil {
+		return
+	}
+
+	err = tree.Files().ForEach(func(f *object.File) (err error) {
+		if !strings.HasSuffix(f.Name, ".yaml") {
+			return
+		}
+		names = append(names, strings.TrimSuffix(f.Name, ".yaml"))
+		return
+	})
+	return
+}
+
+func (d *Defaults) treeAt(rev string) (tree *object.Tree, err error) {
+	h, err := d.repo.ResolveRevision(plumbing.Revision(rev))
+	if err != nil {
+		return
+	}
+
+	obj, err := d.repo.Object(plumbing.AnyObject, *h)
+	if err != nil {
+		return
+	}
+
+	for {
+		switch o := obj.(type) {
+		case *object.Tag: // tag -> commit
+			obj, err = o.Object()
+
+		case *object.Commit: // commit -> tree
+			return o.Tree()
+
+		default:
+			err = object.ErrUnsupportedObject
+		}
+
+		if err != nil {
+			return
+		}
+	}
+}
+
+func (d *Defaults) decodeDefault(rev, filePath string, value Rev) (err error) {
+	ba, err := d.ReadAll(rev, filePath)
+
+	if err != nil {
+		return
+	}
+
+	return yaml.Unmarshal(ba, value)
+}