2 files changed, 157 insertions, 2 deletions

diff --git a/config/config.go b/config/config.go
index a2b5012..bffb125 100644
--- a/config/config.go
+++ b/config/config.go
@@ -2,8 +2,11 @@
 package config
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
+
+	"gopkg.in/src-d/go-git.v4/plumbing/format/config"
 )
 
 const (
@@ -27,17 +30,24 @@ var (
 )
 
 // Config contains the repository configuration
+// https://www.kernel.org/pub/software/scm/git/docs/git-config.html
 type Config struct {
 	Core struct {
 		IsBare bool
 	}
 	Remotes map[string]*RemoteConfig
+
+	// contains the raw information of a config file, the main goal is preserve
+	// the parsed information from the original format, to avoid miss not
+	// supported properties
+	raw *config.Config
 }
 
 // NewConfig returns a new empty Config
 func NewConfig() *Config {
 	return &Config{
 		Remotes: make(map[string]*RemoteConfig, 0),
+		raw:     config.New(),
 	}
 }
 
@@ -56,11 +66,82 @@ func (c *Config) Validate() error {
 	return nil
 }
 
+const (
+	remoteSection = "remote"
+	coreSection   = "core"
+	fetchKey      = "fetch"
+	urlKey        = "url"
+	bareKey       = "bare"
+)
+
+// Unmarshal parses a git-config file and stores it
+func (c *Config) Unmarshal(b []byte) error {
+	r := bytes.NewBuffer(b)
+	d := config.NewDecoder(r)
+
+	c.raw = config.New()
+	if err := d.Decode(c.raw); err != nil {
+		return err
+	}
+
+	c.unmarshalCore()
+	c.unmarshalRemotes()
+	return nil
+}
+
+func (c *Config) unmarshalCore() {
+	s := c.raw.Section(coreSection)
+	if s.Options.Get(bareKey) == "true" {
+		c.Core.IsBare = true
+	}
+}
+
+func (c *Config) unmarshalRemotes() {
+	s := c.raw.Section(remoteSection)
+	for _, sub := range s.Subsections {
+		r := &RemoteConfig{}
+		r.unmarshal(sub)
+
+		c.Remotes[r.Name] = r
+	}
+}
+
+// Marshal returns Config encoded as a git-config file
+func (c *Config) Marshal() ([]byte, error) {
+	c.marshalCore()
+	c.marshalRemotes()
+
+	buf := bytes.NewBuffer(nil)
+	if err := config.NewEncoder(buf).Encode(c.raw); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func (c *Config) marshalCore() {
+	s := c.raw.Section(coreSection)
+	s.SetOption(bareKey, fmt.Sprintf("%t", c.Core.IsBare))
+}
+
+func (c *Config) marshalRemotes() {
+	s := c.raw.Section(remoteSection)
+	s.Subsections = make(config.Subsections, len(c.Remotes))
+
+	var i int
+	for _, r := range c.Remotes {
+		s.Subsections[i] = r.marshal()
+		i++
+	}
+}
+
 // RemoteConfig contains the configuration for a given repository
 type RemoteConfig struct {
 	Name  string
 	URL   string
 	Fetch []RefSpec
+
+	raw *config.Subsection
 }
 
 // Validate validate the fields and set the default values
@@ -79,3 +160,33 @@ func (c *RemoteConfig) Validate() error {
 
 	return nil
 }
+
+func (c *RemoteConfig) unmarshal(s *config.Subsection) {
+	c.raw = s
+
+	fetch := []RefSpec{}
+	for _, f := range c.raw.Options.GetAll(fetchKey) {
+		rs := RefSpec(f)
+		if rs.IsValid() {
+			fetch = append(fetch, rs)
+		}
+	}
+
+	c.Name = c.raw.Name
+	c.URL = c.raw.Option(urlKey)
+	c.Fetch = fetch
+}
+
+func (c *RemoteConfig) marshal() *config.Subsection {
+	if c.raw == nil {
+		c.raw = &config.Subsection{}
+	}
+
+	c.raw.Name = c.Name
+	c.raw.SetOption(urlKey, c.URL)
+	for _, rs := range c.Fetch {
+		c.raw.SetOption(fetchKey, rs.String())
+	}
+
+	return c.raw
+}
diff --git a/config/config_test.go b/config/config_test.go
index f2539d0..2bcefe4 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -6,7 +6,51 @@ type ConfigSuite struct{}
 
 var _ = Suite(&ConfigSuite{})
 
-func (s *ConfigSuite) TestConfigValidateInvalidRemote(c *C) {
+func (s *ConfigSuite) TestUnmarshall(c *C) {
+	input := []byte(`[core]
+        bare = true
+[remote "origin"]
+        url = git@github.com:mcuadros/go-git.git
+        fetch = +refs/heads/*:refs/remotes/origin/*
+[branch "master"]
+        remote = origin
+        merge = refs/heads/master
+`)
+
+	cfg := NewConfig()
+	err := cfg.Unmarshal(input)
+	c.Assert(err, IsNil)
+
+	c.Assert(cfg.Core.IsBare, Equals, true)
+	c.Assert(cfg.Remotes, HasLen, 1)
+	c.Assert(cfg.Remotes["origin"].Name, Equals, "origin")
+	c.Assert(cfg.Remotes["origin"].URL, Equals, "git@github.com:mcuadros/go-git.git")
+	c.Assert(cfg.Remotes["origin"].Fetch, DeepEquals, []RefSpec{"+refs/heads/*:refs/remotes/origin/*"})
+}
+
+func (s *ConfigSuite) TestUnmarshallMarshall(c *C) {
+	input := []byte(`[core]
+	bare = true
+	custom = ignored
+[remote "origin"]
+	url = git@github.com:mcuadros/go-git.git
+	fetch = +refs/heads/*:refs/remotes/origin/*
+	mirror = true
+[branch "master"]
+	remote = origin
+	merge = refs/heads/master
+`)
+
+	cfg := NewConfig()
+	err := cfg.Unmarshal(input)
+	c.Assert(err, IsNil)
+
+	output, err := cfg.Marshal()
+	c.Assert(err, IsNil)
+	c.Assert(output, DeepEquals, input)
+}
+
+func (s *ConfigSuite) TestValidateInvalidRemote(c *C) {
 	config := &Config{
 		Remotes: map[string]*RemoteConfig{
 			"foo": {Name: "foo"},
@@ -16,7 +60,7 @@ func (s *ConfigSuite) TestConfigValidateInvalidRemote(c *C) {
 	c.Assert(config.Validate(), Equals, ErrRemoteConfigEmptyURL)
 }
 
-func (s *ConfigSuite) TestConfigValidateInvalidKey(c *C) {
+func (s *ConfigSuite) TestValidateInvalidKey(c *C) {
 	config := &Config{
 		Remotes: map[string]*RemoteConfig{
 			"bar": {Name: "foo"},