package message

import (
	"context"
	"database/sql"
)

// RecoverOnStart 启动恢复（DEVELOPMENT 7.8）。
func (a *App) RecoverOnStart(ctx context.Context) error {
	nowMs := a.now().UnixMilli()
	graceMs := a.lim.GraceSeconds * 1000
	minExpire := nowMs + graceMs

	err := a.db.Queue.Do(ctx, func(tx *sql.Tx) error {
		if _, err := tx.Exec(`
UPDATE deliveries SET
  pushed_conn = NULL,
  expire_at = CASE
    WHEN expire_at IS NULL OR expire_at < ? THEN ?
    ELSE expire_at
  END,
  updated_at = ?
WHERE state = 'pending'`, minExpire, minExpire, nowMs); err != nil {
			return err
		}
		// 停机前在线：online_since 晚于 offline_since，或 offline_since 空而 online_since 非空
		_, err := tx.Exec(`
UPDATE endpoints SET offline_since = ?
WHERE online_since IS NOT NULL
  AND (offline_since IS NULL OR online_since > offline_since)`, nowMs)
		return err
	})
	if err != nil {
		return err
	}
	// 停机期间到点的 scheduled 立即分发
	_, err = a.DispatchDue(ctx, nowMs, 1000)
	return err
}

// CleanupOnce 处理未推送且到期的 pending，并做记录/回执/防重清理。
func (a *App) CleanupOnce(ctx context.Context, nowMs int64) error {
	err := a.db.Queue.Do(ctx, func(tx *sql.Tx) error {
		rows, err := tx.Query(`
SELECT d.seq, d.endpoint_id, d.keep, m.sender_id, m.id
FROM deliveries d
JOIN messages m ON m.seq = d.seq
WHERE d.state = 'pending' AND d.pushed_conn IS NULL
  AND d.expire_at IS NOT NULL AND d.expire_at <= ?`, nowMs)
		if err != nil {
			return err
		}
		type item struct {
			seq, keep            int64
			endpointID, senderID string
			msgID                string
		}
		var list []item
		for rows.Next() {
			var it item
			if err := rows.Scan(&it.seq, &it.endpointID, &it.keep, &it.senderID, &it.msgID); err != nil {
				_ = rows.Close()
				return err
			}
			list = append(list, it)
		}
		_ = rows.Close()

		for _, it := range list {
			state := DeliveryDropped
			reason := ReasonOffline
			if it.keep != 0 {
				state = DeliveryExpired
				reason = ReasonTTL
			}
			if err := a.finishDeliveryTx(tx, it.seq, it.endpointID, it.senderID, it.msgID, state, reason, false, nowMs); err != nil {
				return err
			}
		}

		if a.lim.RecordRetentionDays > 0 {
			cutoff := nowMs - int64(a.lim.RecordRetentionDays)*24*3600*1000
			if _, err := tx.Exec(`
DELETE FROM messages WHERE seq IN (
  SELECT seq FROM messages WHERE state = 'completed' AND created_at < ? LIMIT 5000
)`, cutoff); err != nil {
				return err
			}
		}

		if a.lim.ReceiptRetentionDays > 0 {
			cutoff := nowMs - int64(a.lim.ReceiptRetentionDays)*24*3600*1000
			if _, err := tx.Exec(`
DELETE FROM receipts WHERE receipt_id IN (
  SELECT receipt_id FROM receipts WHERE created_at < ? LIMIT 5000
)`, cutoff); err != nil {
				return err
			}
		}

		if a.lim.IdempotencyHours > 0 {
			cutoff := nowMs - int64(a.lim.IdempotencyHours)*3600*1000
			if _, err := tx.Exec(`
DELETE FROM send_keys WHERE rowid IN (
  SELECT sk.rowid FROM send_keys sk
  WHERE sk.created_at < ?
    AND NOT EXISTS (
      SELECT 1 FROM messages m WHERE m.sender_id = sk.sender_id AND m.id = sk.msg_id
    )
  LIMIT 5000
)`, cutoff); err != nil {
				return err
			}
		}
		return nil
	})
	if err != nil {
		return err
	}
	a.flushRevokes(ctx)
	return nil
}