package updater

import (
	"context"
	"fmt"
	"sort"

	"github.com/qdm12/gluetun/internal/constants/vpn"
	"github.com/qdm12/gluetun/internal/models"
	"github.com/qdm12/gluetun/internal/provider/common"
)

func (u *Updater) FetchServers(ctx context.Context, minServers int) (
	servers []models.Server, err error) {
	data, err := fetchAPI(ctx, u.client)
	if err != nil {
		return nil, fmt.Errorf("failed fetching API: %w", err)
	}

	hosts := make([]string, 0, len(data.Servers))

	for _, serverData := range data.Servers {
		openVPNHost := serverData.Hostnames.OpenVPN
		if openVPNHost != "" {
			hosts = append(hosts, openVPNHost)
		}

		wireguardHost := serverData.Hostnames.Wireguard
		if wireguardHost != "" {
			hosts = append(hosts, wireguardHost)
		}
	}

	if len(hosts) < minServers {
		return nil, fmt.Errorf("%w: %d and expected at least %d",
			common.ErrNotEnoughServers, len(hosts), minServers)
	}

	resolveSettings := parallelResolverSettings(hosts)
	hostToIPs, warnings, err := u.parallelResolver.Resolve(ctx, resolveSettings)
	for _, warning := range warnings {
		u.warner.Warn(warning)
	}
	if err != nil {
		return nil, err
	}

	if len(hostToIPs) < minServers {
		return nil, fmt.Errorf("%w: %d and expected at least %d",
			common.ErrNotEnoughServers, len(servers), minServers)
	}

	servers = make([]models.Server, 0, len(hosts))
	for _, serverData := range data.Servers {
		server := models.Server{
			Country: serverData.Country,
			City:    serverData.City,
			ISP:     serverData.ISP,
		}
		switch {
		case serverData.Hostnames.OpenVPN != "":
			server.Hostname = serverData.Hostnames.OpenVPN
			server.VPN = vpn.OpenVPN
			server.UDP = true
			server.TCP = true
			server.IPs = hostToIPs[server.Hostname]
		case serverData.Hostnames.Wireguard != "":
			server.Hostname = serverData.Hostnames.Wireguard
			server.VPN = vpn.Wireguard
			server.IPs = hostToIPs[server.Hostname]
			server.WgPubKey = serverData.WgPubKey
		default:
			warning := fmt.Sprintf("server data %v has no OpenVPN nor Wireguard hostname", serverData)
			warnings = append(warnings, warning)
		}
		servers = append(servers, server)
	}

	sort.Sort(models.SortableServers(servers))

	return servers, nil
}