package stacks

import (
	"context"
	"testing"
	"time"
)

// R-608 (v0.261.0) — the two-way lock between the controller's own update and a guarded app update.
//
// THE GAP THIS CLOSES, measured rather than assumed: the self-updater's only busy gate was
// `backupRunning`. The app update's `backing-up` phase DOES take the backup single-flight
// (`RunAppBackupNow` → `acquireRunning`), so that one phase was already covered. `checking`,
// `safety-dump`, `pinning`, `pulling`, `starting` and `verifying` were not — and the last two are
// where the new version may already have touched the customer's data. The controller's swap restarts
// this process, and 04:30 (the default `self_update.auto_update_time`) sits inside the 02:30–05:00
// window `09` §3b Q1 proposes for automatic app updates.

// TestR608_AnyUpdatingSeesAnUpdateInFlight is the mechanism half.
//
// COMPANION RED-PROOF (run 2026-09-21): make AnyUpdating always return false. The "while updating"
// sub-test then fails — and with it the whole gate, because every caller reads this one answer.
func TestR608_AnyUpdatingSeesAnUpdateInFlight(t *testing.T) {
	m, _, _, _ := newSlice4Manager(t)

	if m.AnyUpdating() {
		t.Fatal("no update has started; AnyUpdating must be false")
	}

	release := make(chan struct{})
	m.updateHealthFn = func(context.Context, string, time.Duration) (bool, string) {
		<-release
		return true, "released"
	}
	if err := m.StartGuardedUpdate("nextcloud"); err != nil {
		t.Fatalf("start: %v", err)
	}
	deadline := time.Now().Add(3 * time.Second)
	for !m.AnyUpdating() && time.Now().Before(deadline) {
		time.Sleep(2 * time.Millisecond)
	}
	if !m.AnyUpdating() {
		t.Fatal("an update is in flight and AnyUpdating says false — the controller could swap under it")
	}
	close(release)
	waitUpdateDone(t, m, "nextcloud")
	if m.AnyUpdating() {
		t.Error("the update finished; the lock must not still be held")
	}
}

// TestR608_LockReleasesAfterHold is the one that matters most, and it is a CONSEQUENCE test.
//
// A held app is an app that could not come up. If it kept this lock, the box would never update its
// own controller again — including the release that might FIX whatever held the app. That is a worse
// failure than the one the lock prevents, and it is the kind that is silent for weeks.
//
// COMPANION RED-PROOF (run 2026-09-21): in AnyUpdating, return true when `s.updateHeld` is set as
// well as when `s.Updating` is — the plausible "a held update is still an update" reading. This test
// then fails with the lock still held after the hold.
func TestR608_LockReleasesAfterHold(t *testing.T) {
	m, _, _, _ := newSlice4Manager(t)
	m.updateHealthFn = func(context.Context, string, time.Duration) (bool, string) { return false, "crash loop" }

	if err := m.StartGuardedUpdate("nextcloud"); err != nil {
		t.Fatalf("start: %v", err)
	}
	st := waitUpdateDone(t, m, "nextcloud")
	if st.UpdatePhase != UpdatePhaseFailed {
		t.Fatalf("this fixture must end HELD, or the test proves nothing; phase=%q", st.UpdatePhase)
	}
	if m.AnyUpdating() {
		t.Error("a HELD app must not hold the self-update lock for ever")
	}
}

// TestR608_PreflightRefusesWhileTheControllerSwaps is the reverse direction, and a CONSEQUENCE test:
// the question is not "is the callback wired" but "does the button refuse".
//
// COMPANION RED-PROOF (run 2026-09-21): delete the `m.selfUpdatingNow()` block from UpdatePreflight.
// The "while swapping" sub-test then fails with `ref = <nil>` — an app update is allowed to start
// into a controller restart.
func TestR608_PreflightRefusesWhileTheControllerSwaps(t *testing.T) {
	m, _, _, _ := newSlice4Manager(t)

	if ref := m.UpdatePreflight("nextcloud"); ref != nil {
		t.Fatalf("control: with no self-update running the app update must be allowed, got %q", ref.Reason)
	}

	swapping := true
	m.SetSelfUpdatingCheck(func() bool { return swapping })

	ref := m.UpdatePreflight("nextcloud")
	if ref == nil {
		t.Fatal("while the controller swaps itself the app update must be REFUSED")
	}
	if ref.Reason != "self_updating" {
		t.Errorf("reason = %q, want %q", ref.Reason, "self_updating")
	}
	// It must carry its bundle key, or an English household reads a Hungarian refusal — R-589's
	// failure in a new place, and the reason v0.260.0 routed these through errText.
	if ref.Cause == nil {
		t.Error("the refusal must carry its key as a Cause, not only a Hungarian literal")
	}

	// And it must be TRANSIENT: once the swap ends the same app update is allowed, with no human
	// action in between. A gate that latches is an outage.
	swapping = false
	if ref := m.UpdatePreflight("nextcloud"); ref != nil {
		t.Errorf("after the swap the update must be allowed again, got %q", ref.Reason)
	}
}

// TestR608_NilChecksAreSafe — both halves default to the pre-v0.261.0 behaviour when unwired. A
// Manager built by a test fixture or a future construction path must not panic or fail closed here:
// failing closed on an UNWIRED gate would refuse every update on such a box.
func TestR608_NilChecksAreSafe(t *testing.T) {
	m, _, _, _ := newSlice4Manager(t)
	if m.selfUpdatingNow() {
		t.Error("an unwired self-update check must read false")
	}
	if ref := m.UpdatePreflight("nextcloud"); ref != nil {
		t.Errorf("an unwired gate must not refuse an update, got %q", ref.Reason)
	}
}