1 files changed, 77 insertions, 0 deletions
diff --git a/storage/filter/filter.go b/storage/filter/filter.go
new file mode 100644
index 0000000..52ecbfd
--- /dev/null
+++ b/storage/filter/filter.go
@@ -0,0 +1,77 @@
+package filter
+
+import (
+	"bytes"
+	"code.laria.me/petrific/objects"
+	"code.laria.me/petrific/storage"
+	"errors"
+	"os/exec"
+)
+
+type Filter interface {
+	Transform([]byte) ([]byte, error)
+}
+
+type PipeFilter []string
+
+var emptyCommand = errors.New("Need at least one argument for pipeFilter")
+
+func (pf PipeFilter) Transform(b []byte) ([]byte, error) {
+	if len(pf) == 0 {
+		return []byte{}, emptyCommand
+	}
+
+	cmd := exec.Command(pf[0], pf[1:]...)
+
+	buf := new(bytes.Buffer)
+	cmd.Stdout = buf
+	cmd.Stdin = bytes.NewReader(b)
+
+	if err := cmd.Run(); err != nil {
+		return []byte{}, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+type FilterStorage struct {
+	Base           storage.Storage
+	Decode, Encode Filter
+}
+
+func (filt FilterStorage) Get(id objects.ObjectId) ([]byte, error) {
+	data, err := filt.Base.Get(id)
+	if err != nil {
+		return data, err
+	}
+
+	if filt.Decode == nil {
+		return data, nil
+	}
+
+	return filt.Decode.Transform(data)
+}
+
+func (filt FilterStorage) Has(id objects.ObjectId) (bool, error) {
+	return filt.Base.Has(id)
+}
+
+func (filt FilterStorage) Set(id objects.ObjectId, typ objects.ObjectType, raw []byte) error {
+	if filt.Encode != nil {
+		var err error
+		raw, err = filt.Encode.Transform(raw)
+		if err != nil {
+			return err
+		}
+	}
+
+	return filt.Base.Set(id, typ, raw)
+}
+
+func (filt FilterStorage) List(typ objects.ObjectType) ([]objects.ObjectId, error) {
+	return filt.Base.List(typ)
+}
+
+func (filt FilterStorage) Close() error {
+	return filt.Base.Close()
+}