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/hidemyass/servers.go

@@ -0,0 +1,68 @@
+// Package hidemyass contains code to obtain the server information
+// for the HideMyAss provider.
+package hidemyass
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/updater/resolver"
+)
+
+var ErrNotEnoughServers = errors.New("not enough servers found")
+
+func GetServers(ctx context.Context, client *http.Client,
+	presolver resolver.Parallel, minServers int) (
+	servers []models.HideMyAssServer, warnings []string, err error) {
+	tcpHostToURL, udpHostToURL, err := getAllHostToURL(ctx, client)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	hosts := getUniqueHosts(tcpHostToURL, udpHostToURL)
+
+	if len(hosts) < minServers {
+		return nil, nil, fmt.Errorf("%w: %d and expected at least %d",
+			ErrNotEnoughServers, len(hosts), minServers)
+	}
+
+	hostToIPs, warnings, err := resolveHosts(ctx, presolver, hosts, minServers)
+	if err != nil {
+		return nil, warnings, err
+	}
+
+	servers = make([]models.HideMyAssServer, 0, len(hostToIPs))
+	for host, IPs := range hostToIPs {
+		tcpURL, tcp := tcpHostToURL[host]
+		udpURL, udp := udpHostToURL[host]
+
+		// These two are only used to extract the country, region and city.
+		var url, protocol string
+		if tcp {
+			url = tcpURL
+			protocol = "TCP"
+		} else if udp {
+			url = udpURL
+			protocol = "UDP"
+		}
+		country, region, city := parseOpenvpnURL(url, protocol)
+
+		server := models.HideMyAssServer{
+			Country:  country,
+			Region:   region,
+			City:     city,
+			Hostname: host,
+			IPs:      IPs,
+			TCP:      tcp,
+			UDP:      udp,
+		}
+		servers = append(servers, server)
+	}
+
+	sortServers(servers)
+
+	return servers, warnings, nil
+}