chore(all): return concrete types, accept interfaces

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

internal/portforward/interfaces.go

@@ -0,0 +1,30 @@
+package portforward
+
+import (
+	"context"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+type PortAllower interface {
+	SetAllowedPort(ctx context.Context, port uint16, intf string) (err error)
+	RemoveAllowedPort(ctx context.Context, port uint16) (err error)
+}
+
+type statusManager interface {
+	GetStatus() (status models.LoopStatus)
+	SetStatus(status models.LoopStatus)
+	ApplyStatus(ctx context.Context, status models.LoopStatus) (
+		outcome string, err error)
+}
+
+type StateManager interface {
+	GetSettings() (settings settings.PortForwarding)
+	SetSettings(ctx context.Context,
+		settings settings.PortForwarding) (outcome string)
+	GetPortForwarded() (port uint16)
+	SetPortForwarded(port uint16)
+	GetStartData() (startData StartData)
+	SetStartData(startData StartData)
+}