feat(listmonk): schedule weekly transactional emails

.gitignore

@@ -1,2 +1,3 @@
 .env
-node_modules/
+node_modules/
+.qodo

src/formHandler.js

@@ -10,6 +10,12 @@ export async function submitToListmonk(req, res) {
     const listmonkBaseUrl = process.env.LISTMONK_BASE_URL;
     const listId = parseInt(process.env.LIST_ID, 10);
 
+    const welcomeTemplateId = parseInt(process.env.PRESET_CAMPAIGN_ID, 10);
+    const week1TemplateId = parseInt(process.env.TEMPLATE_ID_WEEK_1, 10);
+    const week2TemplateId = parseInt(process.env.TEMPLATE_ID_WEEK_2, 10);
+    const week3TemplateId = parseInt(process.env.TEMPLATE_ID_WEEK_3, 10);
+    const week4TemplateId = parseInt(process.env.TEMPLATE_ID_WEEK_4, 10);
+
     // Encode username and password as base64
     const auth = Buffer.from(`${listmonkUsername}:${listmonkPassword}`).toString('base64');
 
@@ -40,6 +46,50 @@ export async function submitToListmonk(req, res) {
         }
     }
 
+    async function scheduleTransactionalEmails(email, name, message, auth, baseUrl) {
+        const MAX_TIMEOUT_MS = 2147483647;
+
+        const SCHEDULES = [
+            { delayMs: 7 * 24 * 60 * 60 * 1000, templateId: week1TemplateId },  // 1 week
+            { delayMs: 14 * 24 * 60 * 60 * 1000, templateId: week2TemplateId }, // 2 weeks
+            { delayMs: 21 * 24 * 60 * 60 * 1000, templateId: week3TemplateId }, // 3 weeks
+            {
+                delayMs: Math.min(28 * 24 * 60 * 60 * 1000, MAX_TIMEOUT_MS),    // 4 weeks (capped)
+                templateId: week4TemplateId
+            }
+        ];
+
+        for (const { delayMs, templateId } of SCHEDULES) {
+            setTimeout(async () => {
+                const payload = {
+                    template_id: templateId,
+                    subscriber_emails: [email],
+                    from_email: "Janek <janek@melonion.me>",
+                    data: { name, message }
+                };
+
+                try {
+                    const res = await fetch(`${baseUrl}/tx`, {
+                        method: 'POST',
+                        headers: {
+                            'Content-Type': 'application/json',
+                            'Authorization': `Basic ${auth}`
+                        },
+                        body: JSON.stringify(payload)
+                    });
+
+                    if (!res.ok) {
+                        console.error(`Error sending email with template ${templateId}:`, await res.text());
+                    } else {
+                        console.log(`Email sent with template ${templateId}`);
+                    }
+                } catch (err) {
+                    console.error(`Error dispatching scheduled email for template ${templateId}:`, err);
+                }
+            }, delayMs);
+        }
+    }
+
     try {
         // Add subscriber
         const response = await fetchWithRetry(listmonkSubscriberUrl, {
@@ -49,7 +99,7 @@ export async function submitToListmonk(req, res) {
                 'Authorization': `Basic ${auth}`
             },
             body: JSON.stringify(payload),
-        },12);
+        }, 12);
 
         if (!response.ok) {
             const errorBody = await response.text();
@@ -59,33 +109,36 @@ export async function submitToListmonk(req, res) {
         const result = await response.json();
         console.log('Subscriber added successfully:', result);
 
-        // Send transactional email
+        // Send welcome message immediately
         const transactionalUrl = `${listmonkBaseUrl}/tx`;
         const txPayload = {
-          template_id: parseInt(process.env.PRESET_CAMPAIGN_ID, 10),
+            template_id: welcomeTemplateId,
-          subscriber_emails: [ email ],
+            subscriber_emails: [email],
-          from_email: "Janek <janek@melonion.me>",
+            from_email: "Janek <janek@melonion.me>",
-          data: { name, message }
+            data: { name, message }
         };
-        
+
         const txResponse = await fetchWithRetry(transactionalUrl, {
-          method: 'POST',
+            method: 'POST',
-          headers: {
+            headers: {
-            'Content-Type': 'application/json',
+                'Content-Type': 'application/json',
-            'Authorization': `Basic ${auth}`
+                'Authorization': `Basic ${auth}`
-          },
+            },
-          body: JSON.stringify(txPayload)
+            body: JSON.stringify(txPayload)
         }, 12);
-        
+
         if (!txResponse.ok) {
-          const errorBody = await txResponse.text();
+            const errorBody = await txResponse.text();
-          throw new Error(`Listmonk TX error: ${txResponse.statusText}. ${errorBody}`);
+            throw new Error(`Listmonk TX error: ${txResponse.statusText}. ${errorBody}`);
         }
 
         const dispatchResult = await txResponse.json();
-        console.log('tx dispatched successfully:', dispatchResult);
+        console.log('Welcome email dispatched successfully:', dispatchResult);
 
-        res.status(200).json({ message: 'Subscription and welcome email sent successfully!', result });
+        // Schedule the remaining follow-up emails
+        await scheduleTransactionalEmails(email, name, message, auth, listmonkBaseUrl);
+
+        res.status(200).json({ message: 'Subscription and emails scheduled successfully!', result });
 
     } catch (error) {
         console.error('Error submitting to Listmonk:', error);