Contact card decompress, split, merge

buffer.go

@@ -0,0 +1,66 @@
+package meowlib
+
+import (
+	"errors"
+	"strconv"
+)
+
+func min(a, b int) int {
+	if a <= b {
+		return a
+	}
+	return b
+}
+
+func BufferSplit(buffer []byte, parts uint8) (packets [][]byte, err error) {
+	if int(parts) > len(buffer) {
+		return nil, errors.New("too many parts(" + strconv.Itoa(int(parts)) + ") for buffer len(" + strconv.Itoa(len(buffer)) + ")")
+	}
+	chunksize := int(len(buffer)/int(parts)) + 1
+	packets = make([][]byte, parts)
+	for c := 0; c < int(parts); c++ {
+		if c == 0 {
+			packets[c] = []byte{byte(c), byte(parts)}
+		} else {
+			packets[c] = []byte{byte(c)}
+		}
+	}
+	chunk := 0
+	for i := 0; i < len(buffer); i += chunksize {
+		batch := buffer[i:min(i+chunksize, len(buffer))]
+		packets[chunk] = append(packets[chunk], batch...)
+		chunk++
+	}
+	return packets, nil
+}
+
+func BufferMerge(packets [][]byte) (buffer []byte, err error) {
+	var parts int
+	found := false
+	buffer = []byte{}
+	for _, b := range packets {
+		if b[0] == 0 {
+			parts = int(b[1])
+			buffer = append(buffer, b[2:]...)
+			found = true
+			break
+		}
+	}
+	if !found {
+		return nil, errors.New("start packet not found")
+	}
+	for i := 1; i < parts; i++ {
+		found = false
+		for _, b := range packets {
+			if b[0] == byte(i) {
+				buffer = append(buffer, b[1:]...)
+				found = true
+				break
+			}
+		}
+		if !found {
+			return nil, errors.New("packet #" + strconv.Itoa(i) + " not found")
+		}
+	}
+	return buffer, nil
+}

buffer_test.go

@@ -0,0 +1,24 @@
+package meowlib
+
+import (
+	"log"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestBufferSplit(t *testing.T) {
+
+	source := []byte("Hello World, I need to slice you, but in equal parts, not the capitalist way")
+	packets, err := BufferSplit(source, 3)
+	if err != nil {
+		log.Fatalln("Failed to encode address book:", err)
+	}
+	println(len(packets))
+	destination, err := BufferMerge(packets)
+	if err != nil {
+		log.Fatalln("Failed to encode address book:", err)
+	}
+	println(string(destination))
+	assert.Equal(t, source, destination, "The two buffers should be the same.")
+}

contactcard.go

@@ -43,17 +43,53 @@ func (contact *ContactCard) Compress() ([]byte, error) {
 		return nil, err
 	}
 	var b bytes.Buffer
-	gz := gzip.NewWriter(&b)
+	gz, err := gzip.NewWriterLevel(&b, gzip.BestCompression)
+	if err != nil {
+		return nil, err
+	}
 	if _, err := gz.Write(out); err != nil {
-		log.Fatal(err)
+		return nil, err
 	}
 	if err := gz.Close(); err != nil {
-		log.Fatal(err)
+		return nil, err
 	}
 	fmt.Println(b.Bytes())
 	return b.Bytes(), nil
 }
 
+func (contact *ContactCard) Split(parts uint8) (packets [][]byte, err error) {
+	data, err := contact.Compress()
+	if err != nil {
+		return nil, err
+	}
+	return BufferSplit(data, parts)
+}
+
+func NewContactCardFromCompressed(compressed []byte) (*ContactCard, error) {
+	cc := &ContactCard{}
+	reader := bytes.NewReader([]byte(compressed))
+	gzreader, err := gzip.NewReader(reader)
+	if err != nil {
+		return nil, err
+	}
+	output, err := ioutil.ReadAll(gzreader)
+	if err != nil {
+		return nil, err
+	}
+	if err := proto.Unmarshal(output, cc); err != nil {
+		return nil, err
+	}
+	return cc, nil
+}
+
+func NewContactCardFromSplit(packets [][]byte) (*ContactCard, error) {
+	data, err := BufferMerge(packets)
+	if err != nil {
+		return nil, err
+	}
+	return NewContactCardFromCompressed(data)
+}
+
 func (contact *ContactCard) WriteCompressed(filename string) error {
 	out, err := contact.Compress()
 	if err != nil {