Setup for differnet types of compression for Writer

Added some TODOs

internal/compression/gzip.go

@@ -15,23 +15,21 @@ type gzipInit struct {
 
 //Gzip is a decompressor for gzip type compression. Uses zlib for compression and decompression
 type Gzip struct {
-	CompressionLevel int32
-	HasCustomWindow  bool
-	HasStrategies    bool
+	gzipInit
+	HasCustomWindow bool
+	HasStrategies   bool
 }
 
 //NewGzipCompressorWithOptions creates a new gzip compressor/decompressor with options read from the given reader.
 func NewGzipCompressorWithOptions(r io.Reader) (*Gzip, error) {
 	var gzip Gzip
-	var init gzipInit
-	err := binary.Read(r, binary.LittleEndian, &init)
+	err := binary.Read(r, binary.LittleEndian, &gzip.gzipInit)
 	if err != nil {
 		return nil, err
 	}
-	gzip.CompressionLevel = init.CompressionLevel
 	//TODO: proper support for window size and strategies
-	gzip.HasCustomWindow = init.WindowSize != 15
-	gzip.HasStrategies = init.Strategies != 0 && init.Strategies != 1
+	gzip.HasCustomWindow = gzip.WindowSize != 15
+	gzip.HasStrategies = gzip.Strategies != 0 && gzip.Strategies != 1
 	return &gzip, nil
 }
 
@@ -58,9 +56,6 @@ func (g *Gzip) Compress(data []byte) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	err = wrt.Flush()
-	if err != nil {
-		return nil, err
-	}
+	wrt.Close()
 	return buf.Bytes(), nil
 }

internal/compression/lz4.go

@@ -35,3 +35,21 @@ func (l *Lz4) Decompress(r io.Reader) ([]byte, error) {
 	_, err := io.Copy(&buf, rdr)
 	return buf.Bytes(), err
 }
+
+//Compress implements compression.Compress
+func (l *Lz4) Compress(data []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w := lz4.NewWriter(&buf)
+	if l.HC {
+		err := w.Apply(lz4.CompressionLevelOption(lz4.Level9))
+		if err != nil {
+			return nil, err
+		}
+	}
+	_, err := w.Write(data)
+	if err != nil {
+		return nil, err
+	}
+	w.Close()
+	return buf.Bytes(), nil
+}

internal/compression/lzma.go

@@ -23,3 +23,18 @@ func (l *Lzma) Decompress(rdr io.Reader) ([]byte, error) {
 	}
 	return buf.Bytes(), nil
 }
+
+//Compress implements compression.Compress
+func (l *Lzma) Compress(data []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w, err := lzma.NewWriter(&buf)
+	if err != nil {
+		return nil, err
+	}
+	_, err = w.Write(data)
+	if err != nil {
+		return nil, err
+	}
+	w.Close()
+	return buf.Bytes(), nil
+}

internal/compression/xz.go

@@ -53,3 +53,23 @@ func (x *Xz) Decompress(rdr io.Reader) ([]byte, error) {
 	}
 	return buf.Bytes(), nil
 }
+
+//Compress implements compression.Compress
+func (x *Xz) Compress(data []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w, err := xz.NewWriter(&buf)
+	if err != nil {
+		return nil, err
+	}
+	w.DictCap = int(x.DictionarySize)
+	err = w.Verify()
+	if err != nil {
+		return nil, err
+	}
+	_, err = w.Write(data)
+	if err != nil {
+		return nil, err
+	}
+	w.Close()
+	return buf.Bytes(), nil
+}

internal/compression/zstd.go

@@ -34,3 +34,18 @@ func (z *Zstd) Decompress(r io.Reader) ([]byte, error) {
 	_, err = io.Copy(&buf, rdr)
 	return buf.Bytes(), err
 }
+
+//Compress impelements compression.Compress
+func (z *Zstd) Compress(data []byte) ([]byte, error) {
+	var buf bytes.Buffer
+	w, err := zstd.NewWriter(&buf, zstd.WithEncoderLevel(zstd.EncoderLevel(z.CompressionLevel)))
+	if err != nil {
+		return nil, err
+	}
+	_, err = w.Write(data)
+	if err != nil {
+		return nil, err
+	}
+	w.Close()
+	return buf.Bytes(), nil
+}