refactor: move distro id to separate file

distro/id.go

@@ -0,0 +1,63 @@
+package distro
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ID of the distro
+type ID int
+
+const (
+	// Ubuntu https://ubuntu.com/
+	Ubuntu ID = iota
+	// CentOS https://www.centos.org/
+	CentOS
+	// Debian https://www.debian.org/
+	Debian
+	// OracleLinux https://www.oracle.com/linux/
+	OracleLinux
+)
+
+var IDs = []ID{
+	Ubuntu, CentOS, Debian, OracleLinux,
+}
+
+var nameStrings = [...]string{
+	"Ubuntu",
+	"CentOS",
+	"Debian",
+	"OracleLinux",
+}
+
+func NewID(name string) (id ID, err error) {
+	err = id.UnmarshalTOML([]byte(name))
+	return
+}
+
+func (id ID) String() string {
+	return nameStrings[id]
+}
+
+// UnmarshalTOML is for support github.com/naoina/toml
+func (id *ID) UnmarshalTOML(data []byte) (err error) {
+	name := strings.Trim(string(data), `"`)
+	if strings.EqualFold(name, "Ubuntu") {
+		*id = Ubuntu
+	} else if strings.EqualFold(name, "CentOS") {
+		*id = CentOS
+	} else if strings.EqualFold(name, "Debian") {
+		*id = Debian
+	} else if strings.EqualFold(name, "OracleLinux") {
+		*id = OracleLinux
+	} else {
+		err = fmt.Errorf("distro %s is unsupported", name)
+	}
+	return
+}
+
+// MarshalTOML is for support github.com/naoina/toml
+func (id ID) MarshalTOML() (data []byte, err error) {
+	data = []byte(`"` + id.String() + `"`)
+	return
+}