impl config State and config Interval

config/config.go

@@ -1,7 +1,35 @@
 package config
 
-import "errors"
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+)
+
+type Config struct {
+	Interval Duration
+	States   []State
+}
+
+var live Config
 
 func Refresh() error {
-	return errors.New("not impl")
+	configPath, ok := os.LookupEnv("CONFIG")
+	if !ok {
+		configPath = "./config.json"
+	}
+	b, err := ioutil.ReadFile(configPath)
+	if err != nil {
+		return err
+	}
+	var c Config
+	if err := json.Unmarshal(b, &c); err != nil {
+		return err
+	}
+	live = c
+	return nil
+}
+
+func Get() Config {
+	return live
 }

config/duration.go

@@ -0,0 +1,25 @@
+package config
+
+import (
+	"encoding/json"
+	"time"
+)
+
+type Duration time.Duration
+
+func (d Duration) Get() time.Duration {
+	return time.Duration(d)
+}
+
+func (d *Duration) UnmarshalJSON(b []byte) error {
+	var s string
+	if err := json.Unmarshal(b, &s); err != nil {
+		return err
+	}
+	d2, err := time.ParseDuration(s)
+	if err != nil {
+		return err
+	}
+	*d = Duration(d2)
+	return nil
+}

config/state.go

@@ -0,0 +1,27 @@
+package config
+
+import (
+	"encoding/json"
+	"errors"
+)
+
+type State string
+
+var States = map[int]State{
+	27006: "NC",
+	84058: "UT",
+}
+
+func (state *State) UnmarshalJSON(b []byte) error {
+	var s string
+	if err := json.Unmarshal(b, &s); err != nil {
+		return err
+	}
+	for k := range States {
+		if string(States[k]) == s {
+			*state = States[k]
+			return nil
+		}
+	}
+	return errors.New("unknown state " + s)
+}