refactor: parse extension keys into proper array

pkg/versia/entity.go

@@ -24,8 +24,3 @@ type Entity struct {
 	// Extensions is a map of active extensions for the entity
 	Extensions Extensions `json:"extensions,omitempty"`
 }
-
-// Extensions represents the active extensions on an entity. For more information, see the [Spec].
-//
-// [Spec]: https://versia.pub/extensions#extension-definition
-type Extensions map[string]any

pkg/versia/extension.go

@@ -0,0 +1,41 @@
+package versia
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Extensions represents the active extensions on an entity. For more information, see the [Spec].
+//
+// [Spec]: https://versia.pub/extensions#extension-definition
+type Extensions map[ExtensionKey]any
+
+// ExtensionKey represents an extension's key. For more information see the [Spec].
+//
+// [Spec]: https://versia.pub/types#extensions
+type ExtensionKey [2]string
+
+func (e *ExtensionKey) UnmarshalText(b []byte) (err error) {
+	raw := string(b)
+
+	spl := strings.Split(raw, ":")
+	if len(spl) != 2 {
+		return InvalidExtensionKeyError{raw}
+	}
+
+	*e = [2]string{spl[0], spl[1]}
+
+	return
+}
+
+func (e ExtensionKey) MarshalText() ([]byte, error) {
+	return []byte(fmt.Sprintf("%s:%s", e[0], e[1])), nil
+}
+
+type InvalidExtensionKeyError struct {
+	Raw string
+}
+
+func (e InvalidExtensionKeyError) Error() string {
+	return fmt.Sprintf("invalid extension key: %s", e.Raw)
+}

pkg/versia/extension_test.go

@@ -0,0 +1,29 @@
+package versia
+
+import (
+	"encoding/json"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestExtensionKey_UnmarshalJSON(t *testing.T) {
+	cases := []struct {
+		Raw      string
+		Expected ExtensionKey
+		Error    bool
+	}{
+		{"\"pub.versia:Emoji\"", ExtensionKey{"pub.versia", "Emoji"}, false},
+		{"\"pub.versia\"", ExtensionKey{}, true},
+	}
+
+	for _, case_ := range cases {
+		key := ExtensionKey{}
+		err := json.Unmarshal([]byte(case_.Raw), &key)
+
+		assert.Equal(t, case_.Error, err != nil, "error assertion should match")
+
+		if !case_.Error {
+			assert.Equal(t, case_.Expected, key)
+		}
+	}
+}