1 files changed, 222 insertions, 0 deletions
diff --git a/packfile/objects.go b/packfile/objects.go
new file mode 100644
index 0000000..3c77a33
--- /dev/null
+++ b/packfile/objects.go
@@ -0,0 +1,222 @@
+package packfile
+
+import (
+	"bytes"
+	"compress/zlib"
+	"crypto/sha1"
+	"encoding/hex"
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"time"
+)
+
+type Object interface {
+	Type() string
+	Hash() string
+}
+
+type Hash []byte
+
+func (h Hash) String() string {
+	return hex.EncodeToString(h)
+}
+
+type Commit struct {
+	Tree      Hash
+	Parents   []Hash
+	Author    Signature
+	Committer Signature
+	Message   string
+	hash      string
+}
+
+func NewCommit(b []byte) (*Commit, error) {
+	o := &Commit{hash: calculateHash("commit", b)}
+
+	lines := bytes.Split(b, []byte{'\n'})
+	for i := range lines {
+		if len(lines[i]) > 0 {
+			var err error
+
+			split := bytes.SplitN(lines[i], []byte{' '}, 2)
+			switch string(split[0]) {
+			case "tree":
+				o.Tree = make([]byte, 20)
+				_, err = hex.Decode(o.Tree, split[1])
+			case "parent":
+				h := make([]byte, 20)
+				_, err = hex.Decode(h, split[1])
+				if err == nil {
+					o.Parents = append(o.Parents, h)
+				}
+			case "author":
+				o.Author = NewSignature(split[1])
+			case "committer":
+				o.Committer = NewSignature(split[1])
+			}
+
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			o.Message = string(bytes.Join(append(lines[i+1:]), []byte{'\n'}))
+			break
+		}
+	}
+
+	return o, nil
+}
+
+func (o *Commit) Type() string {
+	return "commit"
+}
+
+func (o *Commit) Hash() string {
+	return o.hash
+}
+
+type Signature struct {
+	Name  string
+	Email string
+	When  time.Time
+}
+
+func NewSignature(signature []byte) Signature {
+	ret := Signature{}
+	if len(signature) == 0 {
+		return ret
+	}
+
+	from := 0
+	state := 'n' // n: name, e: email, t: timestamp, z: timezone
+	for i := 0; ; i++ {
+		var c byte
+		var end bool
+		if i < len(signature) {
+			c = signature[i]
+		} else {
+			end = true
+		}
+
+		switch state {
+		case 'n':
+			if c == '<' || end {
+				if i == 0 {
+					break
+				}
+				ret.Name = string(signature[from : i-1])
+				state = 'e'
+				from = i + 1
+			}
+		case 'e':
+			if c == '>' || end {
+				ret.Email = string(signature[from:i])
+				i++
+				state = 't'
+				from = i + 1
+			}
+		case 't':
+			if c == ' ' || end {
+				t, err := strconv.ParseInt(string(signature[from:i]), 10, 64)
+				if err == nil {
+					ret.When = time.Unix(t, 0)
+				}
+				end = true
+			}
+		}
+
+		if end {
+			break
+		}
+	}
+
+	return ret
+}
+
+func (s *Signature) String() string {
+	return fmt.Sprintf("%q <%s> @ %s", s.Name, s.Email, s.When)
+}
+
+type Tree struct {
+	Entries []TreeEntry
+	hash    string
+}
+
+type TreeEntry struct {
+	Name string
+	Hash string
+}
+
+func NewTree(b []byte) (*Tree, error) {
+	o := &Tree{hash: calculateHash("tree", b)}
+
+	if len(b) == 0 {
+		return o, nil
+	}
+
+	zr, e := zlib.NewReader(bytes.NewBuffer(b))
+	if e == nil {
+		defer zr.Close()
+		var err error
+		b, err = ioutil.ReadAll(zr)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	body := b
+	for {
+		split := bytes.SplitN(body, []byte{0}, 2)
+		split1 := bytes.SplitN(split[0], []byte{' '}, 2)
+
+		o.Entries = append(o.Entries, TreeEntry{
+			Name: string(split1[1]),
+			Hash: fmt.Sprintf("%x", split[1][0:20]),
+		})
+
+		body = split[1][20:]
+		if len(split[1]) == 20 {
+			break
+		}
+	}
+
+	return o, nil
+}
+
+func (o *Tree) Type() string {
+	return "tree"
+}
+
+func (o *Tree) Hash() string {
+	return o.hash
+}
+
+type Blob struct {
+	Len  int
+	hash string
+}
+
+func NewBlob(b []byte) (*Blob, error) {
+	return &Blob{Len: len(b), hash: calculateHash("blob", b)}, nil
+}
+
+func (o *Blob) Type() string {
+	return "blob"
+}
+
+func (o *Blob) Hash() string {
+	return o.hash
+}
+
+func calculateHash(objType string, content []byte) string {
+	header := []byte(objType)
+	header = append(header, ' ')
+	header = strconv.AppendInt(header, int64(len(content)), 10)
+	header = append(header, 0)
+	header = append(header, content...)
+
+	return fmt.Sprintf("%x", sha1.Sum(header))
+}
+
+type ContentCallback func(hash string, content []byte)