package postgres

import (
	"context"
	"errors"
	"time"

	"github.com/jackc/pgx/v5"

	"knowledge-governance/internal/governance"
)

// LoadBackupSchedule reads the single active backup schedule row. A missing row
// (fresh database before the seed, or a rolled-back migration) reads back as the
// defaults instead of an error, so the settings page never hard-fails.
func (s *Store) LoadBackupSchedule(ctx context.Context) (governance.BackupSchedule, error) {
	schedule := governance.BackupSchedule{
		ID:              "active",
		Enabled:         false,
		ScheduleTime:    governance.BackupScheduleDefaultTime,
		RetentionDays:   7,
		RetentionMonths: 3,
	}
	err := s.db.QueryRow(ctx, `
SELECT enabled,schedule_time,retention_days,retention_months,last_applied_at,last_applied_summary,updated_by,updated_at
FROM backup_schedule WHERE id='active'`).
		Scan(&schedule.Enabled, &schedule.ScheduleTime, &schedule.RetentionDays, &schedule.RetentionMonths,
			&schedule.LastAppliedAt, &schedule.LastAppliedSummary, &schedule.UpdatedBy, &schedule.UpdatedAt)
	if errors.Is(err, pgx.ErrNoRows) {
		return schedule, nil
	}
	if err != nil {
		return governance.BackupSchedule{}, errors.New("load backup schedule")
	}
	return schedule, nil
}

// SaveBackupSchedule upserts the schedule row. Validation belongs to the caller
// (governance.BackupSchedule.Validate); this only persists what was accepted.
func (s *Store) SaveBackupSchedule(ctx context.Context, schedule governance.BackupSchedule, updatedBy string, now time.Time) error {
	if now.IsZero() {
		return errors.New("backup schedule save requires a timestamp")
	}
	if _, err := s.db.Exec(ctx, `
INSERT INTO backup_schedule(id,enabled,schedule_time,retention_days,retention_months,updated_by,updated_at)
VALUES('active',$1,$2,$3,$4,$5,$6)
ON CONFLICT(id) DO UPDATE SET
    enabled=EXCLUDED.enabled,
    schedule_time=EXCLUDED.schedule_time,
    retention_days=EXCLUDED.retention_days,
    retention_months=EXCLUDED.retention_months,
    updated_by=EXCLUDED.updated_by,
    updated_at=EXCLUDED.updated_at`,
		schedule.Enabled, schedule.ScheduleTime, schedule.RetentionDays, schedule.RetentionMonths, updatedBy, now); err != nil {
		return errors.New("save backup schedule")
	}
	return nil
}

// MarkBackupScheduleApplied records the last successful push to the data-plane
// host (cron file + next run), which the page shows as "当前主机上的计划".
func (s *Store) MarkBackupScheduleApplied(ctx context.Context, summary string, appliedAt time.Time) error {
	if appliedAt.IsZero() {
		return errors.New("backup schedule apply requires a timestamp")
	}
	if _, err := s.db.Exec(ctx, `
UPDATE backup_schedule SET last_applied_at=$1, last_applied_summary=$2 WHERE id='active'`,
		appliedAt, summary); err != nil {
		return errors.New("mark backup schedule applied")
	}
	return nil
}