(wip) rework configuration to support multiple frontends

pkg/conf/config.go

@@ -0,0 +1,62 @@
+// Package conf contains alias for map encoded configuration
+// and structure unmarshaller
+package conf
+
+import (
+	"errors"
+
+	"github.com/mitchellh/mapstructure"
+	"github.com/rs/zerolog"
+)
+
+// TagName is a tag name, used for decoder customization
+const TagName = "cfg"
+
+// ErrNilConfigMap returned if unmarshalling map is nil and could not be
+// decoded into structure
+var ErrNilConfigMap = errors.New("unable to process nil map")
+
+// MapConfig is just alias for map[string]any
+type MapConfig map[string]any
+
+// MarshalZerologObject writes map into zerolog event
+func (m MapConfig) MarshalZerologObject(e *zerolog.Event) {
+	e.Fields(map[string]any(m))
+}
+
+// Unmarshal decodes receiver map into provided structure.
+// Decoder configured to automatically unmarshal inherited structures,
+// convert string-ed duration (1s, 2m, 3h...) into time.Duration and
+// string representation IP into net.IP.
+// Tag used for decode customization is conf.TagName.
+func (m MapConfig) Unmarshal(into any) (err error) {
+	if m != nil {
+		if len(m) > 0 {
+			conf := &mapstructure.DecoderConfig{
+				DecodeHook: mapstructure.ComposeDecodeHookFunc(
+					mapstructure.StringToTimeDurationHookFunc(),
+					mapstructure.StringToIPHookFunc(),
+				),
+				Squash:  true,
+				Result:  into,
+				TagName: TagName,
+			}
+			var decoder *mapstructure.Decoder
+			if decoder, err = mapstructure.NewDecoder(conf); err == nil {
+				err = decoder.Decode(m)
+			}
+		}
+	} else {
+		err = ErrNilConfigMap
+	}
+	return
+}
+
+type NamedMapConfig struct {
+	Name   string
+	Config MapConfig
+}
+
+func (nm NamedMapConfig) MarshalZerologObject(e *zerolog.Event) {
+	e.Str("name", nm.Name).Dict("config", zerolog.Dict().EmbedObject(nm.Config))
+}