From bf152adbefb25a7d9718c1d0210b83dd65a9d63e Mon Sep 17 00:00:00 2001
From: James Hillyerd <james@hillyerd.com>
Date: Wed, 4 Apr 2018 21:40:53 -0700
Subject: [PATCH] Use enum for MailboxNaming for #33

---
 pkg/config/config.go       | 30 +++++++++++++++++++++++++++---
 pkg/policy/address.go      |  2 +-
 pkg/policy/address_test.go |  8 ++++----
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/pkg/config/config.go b/pkg/config/config.go
index e1501d8..ecd5971 100644
--- a/pkg/config/config.go
+++ b/pkg/config/config.go
@@ -1,6 +1,7 @@
 package config
 
 import (
+	"fmt"
 	"log"
 	"os"
 	"strings"
@@ -29,10 +30,33 @@ var (
 	BuildDate = ""
 )
 
-// Root wraps all other configurations.
+// mbNaming represents a mailbox naming strategy.
+type mbNaming int
+
+// Mailbox naming strategies.
+const (
+	UnknownNaming mbNaming = iota
+	LocalNaming
+	FullNaming
+)
+
+// Decode a naming strategy from string.
+func (n *mbNaming) Decode(v string) error {
+	switch strings.ToLower(v) {
+	case "local":
+		*n = LocalNaming
+	case "full":
+		*n = FullNaming
+	default:
+		return fmt.Errorf("Unknown MailboxNaming strategy: %q", v)
+	}
+	return nil
+}
+
+// Root contains global configuration, and structs with for specific sub-systems.
 type Root struct {
-	LogLevel      string `required:"true" default:"info" desc:"debug, info, warn, or error"`
-	MailboxNaming string `required:"true" default:"local" desc:"local or full"`
+	LogLevel      string   `required:"true" default:"info" desc:"debug, info, warn, or error"`
+	MailboxNaming mbNaming `required:"true" default:"local" desc:"local or full"`
 	SMTP          SMTP
 	POP3          POP3
 	Web           Web
diff --git a/pkg/policy/address.go b/pkg/policy/address.go
index ce06d09..de9e8a7 100644
--- a/pkg/policy/address.go
+++ b/pkg/policy/address.go
@@ -25,7 +25,7 @@ func (a *Addressing) ExtractMailbox(address string) (string, error) {
 	if err != nil {
 		return "", err
 	}
-	if a.Config.MailboxNaming == "local" {
+	if a.Config.MailboxNaming == config.LocalNaming {
 		return local, nil
 	}
 	if domain == "" {
diff --git a/pkg/policy/address_test.go b/pkg/policy/address_test.go
index 82d417d..2956dd3 100644
--- a/pkg/policy/address_test.go
+++ b/pkg/policy/address_test.go
@@ -123,8 +123,8 @@ func TestShouldStoreDomain(t *testing.T) {
 }
 
 func TestExtractMailboxValid(t *testing.T) {
-	localPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: "local"}}
-	fullPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: "full"}}
+	localPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.LocalNaming}}
+	fullPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.FullNaming}}
 
 	testTable := []struct {
 		input string // Input to test
@@ -251,8 +251,8 @@ func TestExtractMailboxValid(t *testing.T) {
 }
 
 func TestExtractMailboxInvalid(t *testing.T) {
-	localPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: "local"}}
-	fullPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: "full"}}
+	localPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.LocalNaming}}
+	fullPolicy := policy.Addressing{Config: &config.Root{MailboxNaming: config.FullNaming}}
 	// Test local mailbox naming policy.
 	localInvalidTable := []struct {
 		input, msg string