Serialize/Deserialize collections

Signed-off-by: Thomas Fossati <[email protected]>

collection.go

@@ -5,6 +5,7 @@ package cmw
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 
 	"github.com/fxamacker/cbor/v2"
@@ -14,6 +15,39 @@ type Collection struct {
 	m map[any]CMW
 }
 
+type CollectionSerialization uint
+
+const (
+	UnknownCollectionSerialization = CollectionSerialization(iota)
+	CollectionSerializationJSON
+	CollectionSerializationCBOR
+)
+
+func (o *Collection) Deserialize(b []byte) error {
+	switch b[0] {
+	case 0x7b: // '{'
+		return o.UnmarshalJSON(b)
+	default:
+		return o.UnmarshalCBOR(b)
+	}
+}
+
+func (o *Collection) Serialize() ([]byte, error) {
+	s, err := o.detectSerialization()
+	if err != nil {
+		return nil, err
+	}
+
+	switch s {
+	case CollectionSerializationCBOR:
+		return o.MarshalCBOR()
+	case CollectionSerializationJSON:
+		return o.MarshalJSON()
+	default:
+		return nil, errors.New("unsupported serialization")
+	}
+}
+
 // GetMap returns a pointer to the internal map
 func (o *Collection) GetMap() map[any]CMW {
 	return o.m
@@ -129,3 +163,32 @@ func (o *Collection) UnmarshalJSON(b []byte) error {
 
 	return nil
 }
+
+func (o Collection) detectSerialization() (CollectionSerialization, error) {
+	rec := make(map[CollectionSerialization]bool)
+
+	s := UnknownCollectionSerialization
+
+	for k, v := range o.m {
+		switch v.serialization {
+		case CBORArray, CBORTag:
+			s = CollectionSerializationCBOR
+			rec[s] = true
+		case JSONArray:
+			s = CollectionSerializationJSON
+			rec[s] = true
+		default:
+			return UnknownCollectionSerialization,
+				fmt.Errorf(
+					"serialization not defined for collection item with k %v", k,
+				)
+		}
+	}
+
+	if len(rec) != 1 {
+		return UnknownCollectionSerialization,
+			errors.New("CMW collection has items with incompatible serializations")
+	}
+
+	return s, nil
+}

collection_test.go

@@ -62,7 +62,7 @@ func Test_Collection_JSON_Serialize_ok(t *testing.T) {
 
 	tv.SetItem("b", b)
 
-	actual, err := tv.MarshalJSON()
+	actual, err := tv.Serialize()
 	assert.NoError(t, err)
 
 	assert.JSONEq(t, string(expected), string(actual))
@@ -124,7 +124,7 @@ func Test_Collection_CBOR_Serialize_ok(t *testing.T) {
 
 	expected := mustReadFile(t, "testdata/collection-cbor-ok-2.cbor")
 
-	b, err := tv.MarshalCBOR()
+	b, err := tv.Serialize()
 	assert.NoError(t, err)
 	assert.Equal(t, expected, b)
 }
@@ -147,3 +147,41 @@ func Test_Collection_CBOR_Deserialize_and_iterate(t *testing.T) {
 		}
 	}
 }
+
+func Test_Collection_detectSerialization_fail(t *testing.T) {
+	var tv Collection
+
+	var a CMW
+	a.SetMediaType("application/vnd.a")
+	a.SetValue([]byte{0x61})
+	a.SetSerialization(JSONArray)
+
+	tv.SetItem("a", a)
+
+	var b CMW
+	b.SetMediaType("application/vnd.b")
+	b.SetValue([]byte{0x62})
+	b.SetSerialization(CBORArray)
+
+	tv.SetItem("b", b)
+
+	s, err := tv.detectSerialization()
+	assert.EqualError(t, err, "CMW collection has items with incompatible serializations")
+	assert.Equal(t, UnknownCollectionSerialization, s)
+}
+
+func Test_Collection_Deserialize_JSON_ok(t *testing.T) {
+	tv := mustReadFile(t, "testdata/collection-ok.json")
+
+	var c Collection
+	err := c.Deserialize(tv)
+	assert.NoError(t, err)
+}
+
+func Test_Collection_Deserialize_CBOR_ok(t *testing.T) {
+	tv := mustReadFile(t, "testdata/collection-cbor-ok.cbor")
+
+	var c Collection
+	err := c.Deserialize(tv)
+	assert.NoError(t, err)
+}