package backup

// R-49, operator ruling D21 = B (2026-10-22): a template may mark a named volume `excluded` (a pure cache the app
// rebuilds by itself — Immich's machine-learning model cache, 62 % of its off-site copy). Such a volume is never
// dumped, so it is in no recovery unit: not on the drive's copy, not on the second drive, not off-site. Its last tar
// is removed by DumpAppVolumes' stale-tar clean-up. A restore then finds no tar for it and leaves the volume as the
// app makes it (Immich downloads its models again). The rule and its guards: appbackup.ExcludedDockerVolumes.

// volumeExclusionProvider is implemented by the production stack adapter (cmd/controller); test fakes need not.
type volumeExclusionProvider interface {
	GetExcludedDockerVolumes(name string) []string
}

// dumpableVolumes is the stack's named Docker volumes minus the ones its template excludes.
func (m *Manager) dumpableVolumes(stackName string) []string {
	all := m.stackProvider.GetDockerVolumes(stackName)
	ex, ok := m.stackProvider.(volumeExclusionProvider)
	if !ok || len(all) == 0 {
		return all
	}
	skip := map[string]bool{}
	for _, v := range ex.GetExcludedDockerVolumes(stackName) {
		skip[v] = true
	}
	if len(skip) == 0 {
		return all
	}
	out := make([]string, 0, len(all))
	for _, v := range all {
		if skip[v] {
			m.logger.Printf("[INFO] [backup] Volume %s/%s is excluded by the template (a cache the app rebuilds) — not dumped (R-49)", stackName, v)
			continue
		}
		out = append(out, v)
	}
	return out
}