Refactor (#174)

- Goal was to simplify main.go complexity
- Use common structures and interfaces for all vpn providers
- Moved files around
- Removed some alias models

internal/params/mullvad.go

@@ -1,35 +1,29 @@
 package params
 
 import (
-	"strings"
-
 	libparams "github.com/qdm12/golibs/params"
 	"github.com/qdm12/private-internet-access-docker/internal/constants"
-	"github.com/qdm12/private-internet-access-docker/internal/models"
 )
 
 // GetMullvadCountry obtains the country for the Mullvad server from the
 // environment variable COUNTRY
-func (r *reader) GetMullvadCountry() (country models.MullvadCountry, err error) {
+func (r *reader) GetMullvadCountry() (country string, err error) {
 	choices := append(constants.MullvadCountryChoices(), "")
-	s, err := r.envParams.GetValueIfInside("COUNTRY", choices)
-	return models.MullvadCountry(strings.ToLower(s)), err
+	return r.envParams.GetValueIfInside("COUNTRY", choices)
 }
 
 // GetMullvadCity obtains the city for the Mullvad server from the
 // environment variable CITY
-func (r *reader) GetMullvadCity() (country models.MullvadCity, err error) {
+func (r *reader) GetMullvadCity() (country string, err error) {
 	choices := append(constants.MullvadCityChoices(), "")
-	s, err := r.envParams.GetValueIfInside("CITY", choices)
-	return models.MullvadCity(strings.ToLower(s)), err
+	return r.envParams.GetValueIfInside("CITY", choices)
 }
 
 // GetMullvadISP obtains the ISP for the Mullvad server from the
 // environment variable ISP
-func (r *reader) GetMullvadISP() (country models.MullvadProvider, err error) {
-	choices := append(constants.MullvadProviderChoices(), "")
-	s, err := r.envParams.GetValueIfInside("ISP", choices)
-	return models.MullvadProvider(strings.ToLower(s)), err
+func (r *reader) GetMullvadISP() (isp string, err error) {
+	choices := append(constants.MullvadISPChoices(), "")
+	return r.envParams.GetValueIfInside("ISP", choices)
 }
 
 // GetMullvadPort obtains the port to reach the Mullvad server on from the