package backup

import "time"

// Restore op-status (Part B): a lightweight, in-memory surface for the ASYNC restore family so the
// backups page can show a progress banner (running → success/failure) instead of blocking the HTTP
// request until the restore completes. It is display-only and mutex-guarded on the Manager's `mu`;
// it does NOT gate concurrency (that stays the restore functions' internal single-flight acquire).
// In-memory only — lost on a controller restart (same precedent as notification cooldowns); a page
// load mid-op after a restart simply shows no banner.

// RestoreOpResult is the terminal record of the most recent restore op.
type RestoreOpResult struct {
	Op         string    `json:"op"` // "restore" | "tier2-restore" | "offbox-restore"
	Stack      string    `json:"stack"`
	OK         bool      `json:"ok"`
	Message    string    `json:"message"`
	FinishedAt time.Time `json:"finished_at"`
}

// RestoreResultWindow bounds how long a finished restore still counts as "what just happened".
//
// ONE EXPRESSION, TWO SURFACES (R-351). The wizard's phase strip and the list page's banner both
// need this bound, and until now only the wizard had one — it lived in internal/web as an
// unexported constant. A second copy in the JS would be exactly the "two copies that already
// differed" shape this repo keeps paying for, so the window is defined HERE, beside the status it
// bounds, and both surfaces read it from the payload.
const RestoreResultWindow = 10 * time.Minute

// RestoreOpStatus is the shape served at GET /api/backup/restore-status.
type RestoreOpStatus struct {
	Running   bool             `json:"running"`
	Op        string           `json:"op,omitempty"`
	Stack     string           `json:"stack,omitempty"`
	StartedAt time.Time        `json:"started_at,omitempty"`
	Last      *RestoreOpResult `json:"last,omitempty"`
	// LastRecent reports whether Last finished recently enough to still be worth showing to someone
	// who was NOT watching when it happened.
	//
	// R-351, the measured defect: the banner's JS gated the terminal result on a page-local
	// `sawRunning` flag, so a restore that finished before the page was opened — or in under one
	// poll interval — was shown to nobody. The 2026-08-21 OpenGist restore finished in 8.7s and the
	// operator could not tell from any screen whether it had completed; the answer existed only in
	// a container log. A result nobody can see is the same defect class as no result at all.
	LastRecent bool `json:"last_recent,omitempty"`
}

// BeginRestoreOp marks a restore op in flight (called by the handler just before launching the
// background goroutine). Idempotent enough for display; concurrency is enforced elsewhere.
func (m *Manager) BeginRestoreOp(op, stack string) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.opRunning = true
	m.opName = op
	m.opStack = stack
	m.opStartedAt = time.Now()
}

// EndRestoreOp records the terminal result (called from the goroutine on completion, success or
// failure). Message carries the error (failure) or a human note like the scratch path (offbox).
func (m *Manager) EndRestoreOp(ok bool, message string) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.opLast = &RestoreOpResult{
		Op:         m.opName,
		Stack:      m.opStack,
		OK:         ok,
		Message:    message,
		FinishedAt: time.Now(),
	}
	m.opRunning = false
}

// RestoreStatus returns a deep copy of the current restore op-status for the page/API.
func (m *Manager) RestoreStatus() RestoreOpStatus {
	m.mu.Lock()
	defer m.mu.Unlock()
	st := RestoreOpStatus{
		Running:   m.opRunning,
		Op:        m.opName,
		Stack:     m.opStack,
		StartedAt: m.opStartedAt,
	}
	if m.opLast != nil {
		cp := *m.opLast
		st.Last = &cp
		// Recency is decided here, on the clock the result was stamped with, so neither surface has
		// to hold its own copy of the window. A zero FinishedAt is never recent — an unstamped
		// result must not be drawn as "just now".
		if !cp.FinishedAt.IsZero() {
			if d := time.Since(cp.FinishedAt); d >= 0 && d < RestoreResultWindow {
				st.LastRecent = true
			}
		}
	}
	return st
}