feat(protonvpn): updater finds more servers using app-version linux-vpn

internal/provider/protonvpn/updater/version.go

@@ -7,15 +7,18 @@ import (
 	"io"
 	"net/http"
 	"regexp"
+	"sort"
 	"strings"
 	"time"
+
+	"golang.org/x/mod/semver"
 )
 
-// getMostRecentStableTag finds the most recent proton-account stable tag version,
+// getMostRecentStableWebAccountTag finds the most recent proton-account stable tag version,
 // in order to use it in the x-pm-appversion http request header. Because if we do
 // fall behind on versioning, Proton doesn't like it because they like to create
 // complications where there is no need for it. Hence this function.
-func getMostRecentStableTag(ctx context.Context, client *http.Client) (version string, err error) {
+func getMostRecentStableWebAccountTag(ctx context.Context, client *http.Client) (version string, err error) {
 	page := 1
 	regexVersion := regexp.MustCompile(`^proton-account@(\d+\.\d+\.\d+\.\d+)$`)
 	for ctx.Err() == nil {
@@ -69,3 +72,45 @@ func getMostRecentStableTag(ctx context.Context, client *http.Client) (version s
 
 	return "", fmt.Errorf("%w (queried %d pages)", context.Canceled, page)
 }
+
+// getMostRecentStableVPNGtkAppTag finds the latest proton-vpn-gtk-app semver tag,
+// in order to use it in the x-pm-appversion http request header ONLY to fetch servers
+// data. Because if we do fall behind on versioning, Proton doesn't like it because they like
+// to create complications where there is no need for it. Hence this function.
+func getMostRecentStableVPNGtkAppTag(ctx context.Context, client *http.Client) (version string, err error) {
+	const url = "https://api.github.com/repos/ProtonVPN/proton-vpn-gtk-app/tags?per_page=30"
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return "", fmt.Errorf("creating request: %w", err)
+	}
+	request.Header.Set("Accept", "application/vnd.github.v3+json")
+
+	response, err := client.Do(request)
+	if err != nil {
+		return "", err
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("%w: %s", ErrHTTPStatusCodeNotOK, response.Status)
+	}
+
+	decoder := json.NewDecoder(response.Body)
+	var data []struct {
+		Name string `json:"name"`
+	}
+	err = decoder.Decode(&data)
+	if err != nil {
+		return "", fmt.Errorf("decoding JSON response: %w", err)
+	}
+
+	// Sort tags by semver. Invalid tags are placed at the end and we ignore them.
+	// Yes, proton does push invalid semver tag names sometimes. Good job yet again.
+	sort.Slice(data, func(i, j int) bool {
+		return semver.Compare(data[i].Name, data[j].Name) > 0
+	})
+
+	version = "linux-vpn@" + data[0].Name[1:] // remove leading v
+	return version, nil
+}