gluetun/internal/updater/providers.go

package updater

import (
	"context"
	"encoding/json"
	"fmt"

	"github.com/qdm12/gluetun-servers/pkg/models"
)

func (u *Updater) updateProvider(ctx context.Context, providerName string,
	manifest manifest, minRatio float64,
) (err error) {
	providerFilepath := manifest.providerToFilepath[providerName]
	providerFileURL := buildProviderFileURL(providerName, providerFilepath)

	var data models.Servers
	err = u.fetchJSON(ctx, providerFileURL, &data)
	if err != nil {
		return fmt.Errorf("downloading provider file %s: %w", providerFileURL, err)
	}

	existingServersCount := u.storage.GetServersCount(providerName)
	minServers := int(minRatio * float64(existingServersCount))
	servers := data.Servers
	if len(servers) < minServers {
		return fmt.Errorf("provider %s has not enough servers from downloaded file: got %d and expected at least %d",
			providerName, len(servers), minServers)
	}

	for _, server := range servers {
		err := server.HasMinimumInformation()
		if err != nil {
			serverJSON, jsonErr := json.Marshal(server)
			if jsonErr != nil {
				panic(jsonErr)
			}
			return fmt.Errorf("server %s has not enough information: %w", serverJSON, err)
		}
	}

	if u.storage.ServersAreEqual(providerName, servers) {
		return nil
	}

	// Note the servers variable must NOT BE MUTATED after this call,
	// since the implementation does not deep copy the servers.
	// TODO set in storage in provider updater directly, server by server,
	// to avoid accumulating server data in memory.
	err = u.storage.SetServers(providerName, servers)
	if err != nil {
		return fmt.Errorf("setting servers to storage: %w", err)
	}
	return nil
}