Maintenance: refactor servers updater code

- Require at least 80% of number of servers now to pass
- Each provider is in its own package with a common structure
- Unzip package with unzipper interface
- Openvpn package with extraction and download functions

internal/updater/providers/windscribe/api.go

@@ -0,0 +1,61 @@
+package windscribe
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net"
+	"net/http"
+	"strconv"
+	"time"
+)
+
+var (
+	ErrHTTPStatusCodeNotOK   = errors.New("HTTP status code not OK")
+	ErrUnmarshalResponseBody = errors.New("failed unmarshaling response body")
+)
+
+type apiData struct {
+	Data []regionData `json:"data"`
+}
+
+type regionData struct {
+	Region string      `json:"name"`
+	Groups []groupData `json:"groups"`
+}
+
+type groupData struct {
+	City  string       `json:"city"`
+	Nodes []serverData `json:"nodes"`
+}
+
+type serverData struct {
+	Hostname  string `json:"hostname"`
+	OpenvpnIP net.IP `json:"ip2"`
+}
+
+func fetchAPI(ctx context.Context, client *http.Client) (
+	data apiData, err error) {
+	const baseURL = "https://assets.windscribe.com/serverlist/mob-v2/1/"
+	cacheBreaker := time.Now().Unix()
+	url := baseURL + strconv.Itoa(int(cacheBreaker))
+
+	request, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return data, err
+	}
+
+	response, err := client.Do(request)
+	if err != nil {
+		return data, err
+	}
+	defer response.Body.Close()
+
+	decoder := json.NewDecoder(response.Body)
+	if err := decoder.Decode(&data); err != nil {
+		return data, fmt.Errorf("%w: %s", ErrUnmarshalResponseBody, err)
+	}
+
+	return data, nil
+}

internal/updater/providers/windscribe/servers.go

@@ -0,0 +1,47 @@
+// Package windscribe contains code to obtain the server information
+// for the Windscribe provider.
+package windscribe
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+var ErrNotEnoughServers = errors.New("not enough servers found")
+
+func GetServers(ctx context.Context, client *http.Client, minServers int) (
+	servers []models.WindscribeServer, err error) {
+	data, err := fetchAPI(ctx, client)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, regionData := range data.Data {
+		region := regionData.Region
+		for _, group := range regionData.Groups {
+			city := group.City
+			for _, node := range group.Nodes {
+				server := models.WindscribeServer{
+					Region:   region,
+					City:     city,
+					Hostname: node.Hostname,
+					IP:       node.OpenvpnIP,
+				}
+				servers = append(servers, server)
+			}
+		}
+	}
+
+	if len(servers) < minServers {
+		return nil, fmt.Errorf("%w: %d and expected at least %d",
+			ErrNotEnoughServers, len(servers), minServers)
+	}
+
+	sortServers(servers)
+
+	return servers, nil
+}

internal/updater/providers/windscribe/sort.go

@@ -0,0 +1,19 @@
+package windscribe
+
+import (
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func sortServers(servers []models.WindscribeServer) {
+	sort.Slice(servers, func(i, j int) bool {
+		if servers[i].Region == servers[j].Region {
+			if servers[i].City == servers[j].City {
+				return servers[i].Hostname < servers[j].Hostname
+			}
+			return servers[i].City < servers[j].City
+		}
+		return servers[i].Region < servers[j].Region
+	})
+}

internal/updater/providers/windscribe/string.go

@@ -0,0 +1,14 @@
+package windscribe
+
+import "github.com/qdm12/gluetun/internal/models"
+
+func Stringify(servers []models.WindscribeServer) (s string) {
+	s = "func WindscribeServers() []models.WindscribeServer {\n"
+	s += "	return []models.WindscribeServer{\n"
+	for _, server := range servers {
+		s += "		" + server.String() + ",\n"
+	}
+	s += "	}\n"
+	s += "}"
+	return s
+}