Files
2026-08-11 00:22:54 +08:00

89 lines
2.5 KiB
Go

package store
import (
"context"
"errors"
"fmt"
"strings"
"time"
)
const SMSRateWindow = time.Hour
// SMSRateReservation is the durable result of claiming one global outbound
// SMS slot. The quota is shared by every device, SIM, transport, and caller.
type SMSRateReservation struct {
Allowed bool
Limit int
Used int
Remaining int
ResetAt time.Time
}
// ReserveSMSSend atomically claims one slot in the rolling one-hour window.
// It intentionally records submission attempts separately from SMS history so
// deleting a conversation cannot reset the global safety limit.
func (s *Store) ReserveSMSSend(
ctx context.Context,
deviceID string,
limit int,
now time.Time,
) (SMSRateReservation, error) {
if limit < 1 {
return SMSRateReservation{}, errors.New("SMS hourly limit must be positive")
}
if now.IsZero() {
now = time.Now().UTC()
} else {
now = now.UTC()
}
cutoff := now.Add(-SMSRateWindow).Unix()
result, err := s.db.ExecContext(ctx, `
INSERT INTO sms_send_attempts (device_id, created_at)
SELECT ?, ?
WHERE (
SELECT COUNT(*) FROM sms_send_attempts WHERE created_at > ?
) < ?
`, strings.TrimSpace(deviceID), now.Unix(), cutoff, limit)
if err != nil {
return SMSRateReservation{}, fmt.Errorf("reserve global SMS send slot: %w", err)
}
affected, err := result.RowsAffected()
if err != nil {
return SMSRateReservation{}, fmt.Errorf("read global SMS reservation result: %w", err)
}
status, err := s.smsRateStatus(ctx, limit, cutoff)
if err != nil {
return SMSRateReservation{}, err
}
status.Allowed = affected == 1
if status.Allowed {
// Old rows are irrelevant to enforcement. Pruning after the atomic claim
// keeps the hot index compact without creating a delete-before-insert race.
_, _ = s.db.ExecContext(ctx, `DELETE FROM sms_send_attempts WHERE created_at <= ?`, now.Add(-7*24*time.Hour).Unix())
}
return status, nil
}
func (s *Store) smsRateStatus(ctx context.Context, limit int, cutoff int64) (SMSRateReservation, error) {
var used int
var earliest *int64
if err := s.db.QueryRowContext(ctx, `
SELECT COUNT(*), MIN(created_at)
FROM sms_send_attempts
WHERE created_at > ?
`, cutoff).Scan(&used, &earliest); err != nil {
return SMSRateReservation{}, fmt.Errorf("read global SMS rate status: %w", err)
}
remaining := limit - used
if remaining < 0 {
remaining = 0
}
status := SMSRateReservation{Limit: limit, Used: used, Remaining: remaining}
if earliest != nil {
status.ResetAt = time.Unix(*earliest, 0).UTC().Add(SMSRateWindow)
}
return status, nil
}