package web

import (
	"fmt"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/stacks"
)

// updateState is the three-way answer to "is this app running what the catalog currently pins?".
//
// THREE values, and the third is the entire safety property — the same shape, and the same lesson,
// as AppConfig.DesiredState (R-166):
//
//	ABSENT MEANS UNKNOWN. IT NEVER MEANS "UP TO DATE".
//
// Every app.yaml written before v0.233.0 carries no installed_images, so unknown is the common value
// on upgrade. An implementation that fell through to "Naprakész" would tell every customer on the
// fleet that their months-old app is current — a confident wrong answer, which is worse than none.
type updateState int

const (
	updateUnknown updateState = iota // nothing recorded, or nothing to compare against
	updateCurrent                    // every service runs exactly what the template pins
	updateBehind                     // at least one service does not
)

// compareInstalledToTemplate answers the question WITHOUT touching the network.
//
// NO REGISTRY QUERY, deliberately: a customer's box must not depend on reaching eight upstream
// registries to render a page. The comparison is therefore reference-to-reference — what the
// container was created from, against what the CATALOG currently offers.
//
// ⚠ IT COMPARES AGAINST Stack.CatalogImages, NEVER Stack.TemplateImages, AND v0.235.0 IS WHY.
// Since the freeze, a pinned app's LIVE docker-compose.yml is rendered from its own stored
// definition once the catalog moves past it — so the live file names the OLD version, installed
// would equal template, and this function would answer „Naprakész" on precisely the apps that are
// behind. It would invert the feature silently, with every test still green, because the two fields
// have the same type and shape. CatalogImages is read from the syncer's git clone instead.
//
// KNOWN LIMITATION, stated rather than hidden (see 09-update-architecture.md and the register row):
// 23 of the catalog's 66 distinct pins FLOAT (postgres:16-alpine, mariadb:11.6, …). For those the
// reference can be identical while the image behind it has moved upstream — measured live in
// SPIKE-app-update-2026-09-01 §5, where mariadb:11.4 and mariadb:12.3 had both already moved. Those
// apps will read "Naprakész" when they may not be. Closing that needs a registry query and a digest
// comparison, which is deferred.
func compareInstalledToTemplate(s stacks.Stack) updateState {
	if !s.Deployed || s.Protected || s.Orphaned {
		// Not deployed: nothing is running. Protected: infra is ours, not the customer's to update.
		// Orphaned: the template is gone from the catalog, so there is nothing to be current WITH.
		return updateUnknown
	}
	if s.AppConfig == nil || len(s.AppConfig.InstalledImages) == 0 {
		return updateUnknown // legacy app.yaml — no record was ever written
	}
	if len(s.CatalogImages) == 0 {
		return updateUnknown // no readable catalog template — cannot tell, so say nothing
	}
	if len(s.AppConfig.InstalledImages) != len(s.CatalogImages) {
		// A service was added or removed by the template. That IS a change the customer's running
		// stack has not taken up.
		return updateBehind
	}
	for svc, want := range s.CatalogImages {
		got, ok := s.AppConfig.InstalledImages[svc]
		if !ok || got.Ref != want {
			return updateBehind
		}
	}
	return updateCurrent
}

// updateBadgeAt is the pure form: `now` is injected so the age is a testable contract rather than a
// property of the clock. updateBadge (the funcmap entry) is the one-line wrapper.
//
// It returns a *MetaBadge and calls the EXISTING meta_badge partial — no new markup and no new CSS.
// metabadge.go's own comment asks for exactly that of its second user, and this is it.
func updateBadgeAt(s stacks.Stack, now time.Time) *MetaBadge {
	switch compareInstalledToTemplate(s) {
	case updateCurrent:
		return &MetaBadge{
			Label: "Naprakész",
			Class: "tag-ok",
			Title: "Ez az alkalmazás a legfrissebb elérhető változatot futtatja.",
		}
	case updateBehind:
		label := "Frissítés elérhető"
		if days, ok := s.Meta.CatalogSinceAge(now); ok {
			if days == 0 {
				label += " — ma"
			} else {
				label += fmt.Sprintf(" — %d napja", days)
			}
		}
		return &MetaBadge{
			Label: label,
			Class: "tag-warn",
			Title: "Újabb változat érhető el ehhez az alkalmazáshoz. " +
				"A frissítés indításához nyomd meg a Frissítés gombot.",
		}
	default:
		// UNKNOWN renders NOTHING. Not a grey "ismeretlen" pill: a badge on an app we cannot judge
		// is a question the customer cannot answer, and the record fills itself in on the next
		// restart or update anyway.
		return nil
	}
}

// updateBadge is the funcmap entry. NO version number appears in any string it produces — the
// operator ruled that a household cannot act on "26.05.2", only on "you are behind, by this long".
// Version strings stay in the logs, the API and the hub.
//
// It is INFORMATION ONLY. It is wired to no action, and the Frissítés button is untouched.
func updateBadge(s stacks.Stack) *MetaBadge { return updateBadgeAt(s, time.Now().UTC()) }