TUN-2147: Implemented ScopeUnmarshaler

tunnelrpc/pogs/unmarshal.go

@@ -0,0 +1,41 @@
+package pogs
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/pkg/errors"
+)
+
+// ScopeUnmarshaler can marshal a Scope pog from JSON.
+type ScopeUnmarshaler struct {
+	Scope Scope
+}
+
+// UnmarshalJSON takes in a JSON string, and attempts to marshal it into a Scope.
+// If successful, the Scope member of this ScopeUnmarshaler is set and nil is returned.
+// If unsuccessful, returns an error.
+func (su *ScopeUnmarshaler) UnmarshalJSON(b []byte) error {
+	var scopeJSON map[string]interface{}
+	if err := json.Unmarshal(b, &scopeJSON); err != nil {
+		return errors.Wrapf(err, "cannot unmarshal %s into scopeJSON", string(b))
+	}
+
+	if group, ok := scopeJSON["group"]; ok {
+		if val, ok := group.(string); ok {
+			su.Scope = NewGroup(val)
+			return nil
+		}
+		return fmt.Errorf("JSON should have been a Scope, but the 'group' key contained %v", group)
+	}
+
+	if systemName, ok := scopeJSON["system_name"]; ok {
+		if val, ok := systemName.(string); ok {
+			su.Scope = NewSystemName(val)
+			return nil
+		}
+		return fmt.Errorf("JSON should have been a Scope, but the 'system_name' key contained %v", systemName)
+	}
+
+	return fmt.Errorf("JSON should have been an object with one root key, either 'system_name' or 'group'")
+}