package backup

import (
	"encoding/json"
	"os"
	"sort"
	"time"
)

// R-550 (operator ruling "fix", 2026-09-17) — the restore record survives a restart.
//
// A DESIGN REVERSED, AND RECORDED AS SUCH. opstatus.go was deliberately in-memory ("same precedent as
// notification cooldowns"). Chaos night round 10 measured the cost: a restore accepted at 23:26:08Z,
// the box hard-reset four seconds later, and afterwards the status answered the Go zero value — the
// household had pressed a button, been told it started, and could never learn whether it finished.
// The operator reversed the choice for the RESTORE RECORD ONLY; notification cooldowns stay in memory.
//
// Shape: one JSON file in the controller's state directory (DataDir, beside settings.json), written
// atomically (atomicWrite: tmp + rename) at BOTH ends of an op. At startup a record still marked
// running is, by construction, a restore nothing is running any more: it becomes a terminal failure
// (Interrupted, RestoreInterruptedMessage) and a per-app notice that stays until that app's next
// restore. LoadRestoreRecord reports the conversion ONCE, so the caller raises restore_interrupted once.
//
// No path set (tests that build a bare Manager, a box with backup disabled) = the old in-memory
// behaviour, silently: persistence is a property of the wired controller, not of every Manager.

// RestoreInterruptedMessage is what the household reads when the box stopped mid-restore.
const RestoreInterruptedMessage = "A visszaállítás megszakadt (a doboz újraindult) — indítsd el újra."

// restoreRecordFile is the on-disk shape.
type restoreRecordFile 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"`
	Interrupted map[string]RestoreOpResult `json:"interrupted,omitempty"`
}

// SetRestoreRecordPath wires persistence. Call before LoadRestoreRecord and before serving requests.
func (m *Manager) SetRestoreRecordPath(path string) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.opRecordPath = path
}

// LoadRestoreRecord restores the record at startup. It returns the restore that was interrupted by the
// stop — non-nil exactly once per interruption — so the caller can log it and raise restore_interrupted.
func (m *Manager) LoadRestoreRecord() *RestoreOpResult {
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.opRecordPath == "" {
		return nil
	}
	b, err := os.ReadFile(m.opRecordPath)
	if err != nil {
		if !os.IsNotExist(err) && m.logger != nil {
			m.logger.Printf("[WARN] [backup] restore record unreadable (%v) — starting with no restore history", err)
		}
		return nil
	}
	var rec restoreRecordFile
	if err := json.Unmarshal(b, &rec); err != nil {
		if m.logger != nil {
			m.logger.Printf("[WARN] [backup] restore record corrupt (%v) — starting with no restore history", err)
		}
		return nil
	}
	m.opLast = rec.Last
	m.opInterrupted = rec.Interrupted
	if !rec.Running || rec.Stack == "" {
		if m.logger != nil && len(m.opInterrupted) > 0 {
			m.logger.Printf("[INFO] [backup] restore record loaded: %d interrupted restore notice(s) still shown", len(m.opInterrupted))
		}
		return nil
	}
	res := RestoreOpResult{
		Op: rec.Op, Stack: rec.Stack, OK: false,
		Message: RestoreInterruptedMessage, FinishedAt: time.Now(), Interrupted: true,
	}
	m.opLast = &res
	if m.opInterrupted == nil {
		m.opInterrupted = map[string]RestoreOpResult{}
	}
	m.opInterrupted[rec.Stack] = res
	m.opRunning = false
	if m.logger != nil {
		m.logger.Printf("[WARN] [backup] restore of %s (%s, started %s) was INTERRUPTED by a controller stop — recorded as failed; the household is told to run it again",
			rec.Stack, rec.Op, rec.StartedAt.Format(time.RFC3339))
	}
	m.persistRestoreRecordLocked()
	out := res
	return &out
}

// InterruptedRestore reports the standing interrupted-restore notice for one app, if any.
func (m *Manager) InterruptedRestore(stack string) (RestoreOpResult, bool) {
	m.mu.Lock()
	defer m.mu.Unlock()
	r, ok := m.opInterrupted[stack]
	return r, ok
}

// InterruptedRestores lists every standing notice, sorted by app, for the restore page.
func (m *Manager) InterruptedRestores() []RestoreOpResult {
	m.mu.Lock()
	defer m.mu.Unlock()
	out := make([]RestoreOpResult, 0, len(m.opInterrupted))
	for _, r := range m.opInterrupted {
		out = append(out, r)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Stack < out[j].Stack })
	return out
}

// persistRestoreRecordLocked writes the current op-status. Caller holds m.mu. A failed write is logged
// and the in-memory status carries on — the page still works for this process's lifetime.
func (m *Manager) persistRestoreRecordLocked() {
	if m.opRecordPath == "" {
		return
	}
	rec := restoreRecordFile{
		Running: m.opRunning, Op: m.opName, Stack: m.opStack, StartedAt: m.opStartedAt,
		Last: m.opLast, Interrupted: m.opInterrupted,
	}
	b, err := json.Marshal(rec)
	if err == nil {
		err = atomicWrite(m.opRecordPath, b, 0o600)
	}
	if err != nil && m.logger != nil {
		m.logger.Printf("[WARN] [backup] could not persist the restore record to %s: %v (kept in memory)", m.opRecordPath, err)
	}
}