chore(all): return concrete types, accept interfaces

- Remove exported interfaces unused locally
- Define interfaces to accept arguments
- Return concrete types, not interfaces

internal/openvpn/auth.go

@@ -6,10 +6,6 @@ import (
 	"strings"
 )
 
-type AuthWriter interface {
-	WriteAuthFile(user, password string) error
-}
-
 // WriteAuthFile writes the OpenVPN auth file to disk with the right permissions.
 func (c *Configurator) WriteAuthFile(user, password string) error {
 	file, err := os.Open(c.authFilePath)

internal/openvpn/config.go

@@ -5,10 +5,6 @@ import (
 	"strings"
 )
 
-type Writer interface {
-	WriteConfig(lines []string) error
-}
-
 func (c *Configurator) WriteConfig(lines []string) error {
 	file, err := os.OpenFile(c.configPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
 	if err != nil {

internal/openvpn/extract/extractor.go

@@ -1,16 +1,5 @@
 package extract
 
-import (
-	"github.com/qdm12/gluetun/internal/models"
-)
-
-var _ Interface = (*Extractor)(nil)
-
-type Interface interface {
-	Data(filepath string) (lines []string,
-		connection models.Connection, err error)
-}
-
 type Extractor struct{}
 
 func New() *Extractor {

internal/openvpn/openvpn.go

@@ -5,14 +5,6 @@ import (
 	"github.com/qdm12/golibs/command"
 )
 
-var _ Interface = (*Configurator)(nil)
-
-type Interface interface {
-	VersionGetter
-	AuthWriter
-	Writer
-}
-
 type Configurator struct {
 	logger       Infoer
 	cmder        command.RunStarter

internal/openvpn/version.go

@@ -8,11 +8,6 @@ import (
 	"strings"
 )
 
-type VersionGetter interface {
-	Version24(ctx context.Context) (version string, err error)
-	Version25(ctx context.Context) (version string, err error)
-}
-
 func (c *Configurator) Version24(ctx context.Context) (version string, err error) {
 	return c.version(ctx, binOpenvpn24)
 }