feat: real Brevo API verifier, auto-reset if campaign missing, and update existing campaign support

src/app/api/brevo/verify/route.ts

@@ -0,0 +1,64 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+export async function GET(req: NextRequest) {
+  try {
+    const { searchParams } = new URL(req.url);
+    const campaignId = searchParams.get('campaignId');
+
+    if (!campaignId) {
+      return NextResponse.json(
+        { exists: false, error: 'Chýba parameter campaignId' },
+        { status: 400 }
+      );
+    }
+
+    const apiKey = process.env.BREVO_API_KEY;
+    if (!apiKey) {
+      return NextResponse.json(
+        { exists: false, error: 'BREVO_API_KEY nie je nakonfigurovaný' },
+        { status: 500 }
+      );
+    }
+
+    const res = await fetch(`https://api.brevo.com/v3/emailCampaigns/${encodeURIComponent(campaignId)}`, {
+      method: 'GET',
+      headers: {
+        'accept': 'application/json',
+        'api-key': apiKey
+      },
+      cache: 'no-store'
+    });
+
+    if (res.status === 404) {
+      return NextResponse.json({
+        exists: false,
+        message: 'Kampaň s týmto ID v Brevo neexistuje alebo bola vymazaná.'
+      });
+    }
+
+    if (!res.ok) {
+      const errData = await res.json().catch(() => ({}));
+      return NextResponse.json({
+        exists: false,
+        error: errData.message || `Brevo API vrátilo status ${res.status}`
+      });
+    }
+
+    const data = await res.json();
+    return NextResponse.json({
+      exists: true,
+      campaignId: data.id,
+      name: data.name,
+      status: data.status,
+      subject: data.subject,
+      brevoUrl: `https://app.brevo.com/campaigns/email/edit/${data.id}`,
+      brevoListingUrl: 'https://app.brevo.com/campaigns/listing'
+    });
+  } catch (err: any) {
+    console.error('Brevo verify error:', err);
+    return NextResponse.json(
+      { exists: false, error: err.message || 'Chyba spojenia s Brevo' },
+      { status: 500 }
+    );
+  }
+}