1 files changed, 136 insertions, 0 deletions
diff --git a/config/modules.go b/config/modules.go
new file mode 100644
index 0000000..8b3d2b8
--- /dev/null
+++ b/config/modules.go
@@ -0,0 +1,136 @@
+package config
+
+import (
+	"bytes"
+	"errors"
+
+	format "gopkg.in/src-d/go-git.v4/plumbing/format/config"
+)
+
+var (
+	ErrModuleEmptyURL  = errors.New("module config: empty URL")
+	ErrModuleEmptyPath = errors.New("module config: empty path")
+)
+
+// Modules defines the submodules properties, represents a .gitmodules file
+// https://www.kernel.org/pub/software/scm/git/docs/gitmodules.html
+type Modules struct {
+	// Submodules is a map of submodules being the key the name of the submodule
+	Submodules map[string]*Submodule
+
+	raw *format.Config
+}
+
+// NewModules returns a new empty Modules
+func NewModules() *Modules {
+	return &Modules{
+		Submodules: make(map[string]*Submodule, 0),
+		raw:        format.New(),
+	}
+}
+
+const (
+	submoduleSection = "submodule"
+	pathKey          = "path"
+	branchKey        = "branch"
+)
+
+// Unmarshal parses a git-config file and stores it
+func (m *Modules) Unmarshal(b []byte) error {
+	r := bytes.NewBuffer(b)
+	d := format.NewDecoder(r)
+
+	m.raw = format.New()
+	if err := d.Decode(m.raw); err != nil {
+		return err
+	}
+
+	s := m.raw.Section(submoduleSection)
+	for _, sub := range s.Subsections {
+		mod := &Submodule{}
+		mod.unmarshal(sub)
+
+		m.Submodules[mod.Path] = mod
+	}
+
+	return nil
+}
+
+// Marshal returns Modules encoded as a git-config file
+func (m *Modules) Marshal() ([]byte, error) {
+	s := m.raw.Section(submoduleSection)
+	s.Subsections = make(format.Subsections, len(m.Submodules))
+
+	var i int
+	for _, r := range m.Submodules {
+		s.Subsections[i] = r.marshal()
+		i++
+	}
+
+	buf := bytes.NewBuffer(nil)
+	if err := format.NewEncoder(buf).Encode(m.raw); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+// Submodule defines a submodule
+type Submodule struct {
+	// Name module name
+	Name string
+	// Path defines the path, relative to the top-level directory of the Git
+	// working tree,
+	Path string
+	// URL defines a URL from which the submodule repository can be cloned.
+	URL string
+	// Branch is a remote branch name for tracking updates in the upstream
+	// submodule. Optional value.
+	Branch string
+
+	// raw representation of the subsection, filled by marshal or unmarshal are
+	// called
+	raw *format.Subsection
+}
+
+// Validate validate the fields and set the default values
+func (m *Submodule) Validate() error {
+	if m.Path == "" {
+		return ErrModuleEmptyPath
+	}
+
+	if m.URL == "" {
+		return ErrModuleEmptyURL
+	}
+
+	return nil
+}
+
+func (m *Submodule) unmarshal(s *format.Subsection) {
+	m.raw = s
+
+	m.Name = m.raw.Name
+	m.Path = m.raw.Option(pathKey)
+	m.URL = m.raw.Option(urlKey)
+	m.Branch = m.raw.Option(branchKey)
+}
+
+func (m *Submodule) marshal() *format.Subsection {
+	if m.raw == nil {
+		m.raw = &format.Subsection{}
+	}
+
+	m.raw.Name = m.Name
+	if m.raw.Name == "" {
+		m.raw.Name = m.Path
+	}
+
+	m.raw.SetOption(pathKey, m.Path)
+	m.raw.SetOption(urlKey, m.URL)
+
+	if m.Branch != "" {
+		m.raw.SetOption(branchKey, m.Branch)
+	}
+
+	return m.raw
+}