initial release

.gitignore

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+*/node_modules
+package-lock.json
+.DS_Store
+*.zip

LICENSE.md

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+MIT License
+
+Copyright (c) 2024 Mike Neverov
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+![Cover Image](assets/cover.svg)
+
+This is a simple serverless application that uses AWS Lambda, Stripe and Brevo to deliver files to customers after they have made a payment via your Stripe Payment Link. 
+Because Themeforest, Gumroad and KoFi may be nice, but why not manage your own payment links and have a straight-forward user experience?
+
+## Demo
+
+TODO: Insert GitHub Video
+
+## In-depth guide
+
+You can read a detailed guide on setting this up in [my blog](neveroff.dev/blog/download-file-stripe-payment-link/).
+
+## Getting started without the guide
+
+1. Check out the repository into a local folder, open the terminal at the root folder.
+2. Do `cd email-delivery` followed by `npm install && zip -r ../email-delivery.zip .`  and then `cd ../file-delivery` followed by `npm install && zip -r ../file-delivery.zip .`. This will generate the node_modules folders necessary for Lambdas to work.
+3. Go to the AWS Console and create a new Lambda function for each of the zipped folders, using the `index.mjs` as the handler.
+4. Configure the Environment and Stage variables as per the `index.mjs` files in both file and email delivery folders.
+5. Configure the Stripe Payment Link to point to the API Gateway URL for the `file-delivery` Lambda.
+6. Configure a new Stripe Webhook on the `checkout.session.completed` event to point to the API Gateway URL for the `email-delivery` Lambda.
+7. Use the Stripe Test mode to ensure that your customer path is working as expected and an email is sent out with the file download link.
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE.md) file for details.

email-delivery/index.mjs

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+import axios from 'axios';
+import stripe from 'stripe';
+import AWS from 'aws-sdk';
+
+const s3 = new AWS.S3();
+
+export const handler = async (event) => {
+    const body = event.body;
+    const signature = event.headers['Stripe-Signature'];
+    const endpointSecret = event.stageVariables.stripe_endpoint_secret_key;
+
+    let stripeEvent;
+    let recipientEmail;
+    let redirectUrl;
+
+    try {
+        stripeEvent = stripe.webhooks.constructEvent(body, signature, endpointSecret);
+    } catch (err) {
+            console.log(`Webhook signature verification failed.`, err.message);
+        return {
+            statusCode: 400,
+            body: `Webhook Error: ${err.message}`
+        };
+    }
+
+    if (stripeEvent.type === 'checkout.session.completed') {
+        const session = stripeEvent.data.object;
+
+        if (session.payment_status === 'paid') {
+            recipientEmail = session.customer_details.email;
+
+            if (!recipientEmail) {
+                recipientEmail = process.env.fallback_email;
+            }
+
+            const params = {
+                Bucket: process.env.bucket_name,
+                Key: process.env.object_key,
+                Expires: 60 * 60 * 24 * 30 // 30 days
+            };
+            const presignedUrl = s3.getSignedUrl('getObject', params);
+            redirectUrl = `${process.env.redirect_host}${encodeURIComponent(presignedUrl)}${process.env.utm_parameters}`;
+
+            const emailBody = {
+                templateId: 1,
+                to: [{ email: recipientEmail }], // use the email from the webhook
+                params: { downloadURL: redirectUrl }
+            };
+
+            try {
+                await axios.post('https://api.sendinblue.com/v3/smtp/email', emailBody, {
+                    headers: {
+                    'accept': 'application/json',
+                    'content-type': 'application/json',
+                    'api-key': event.stageVariables.brevo_api_key
+                    }
+                });
+
+                console.log(`Email sent for session id ${session.id}`);
+            } catch (err) {
+                console.log(`Failed to send email for session id ${session.id}`, err);
+            }
+        }
+        else {
+            console.log(`Payment status is different from paid: ${session.payment_status}.`);
+            return {
+                statusCode: 400,
+                body: `Received ${stripeEvent.type}, payment status is different from paid: ${session.payment_status}, handled by ${event.stageVariables.environment} env.`
+            };
+        }
+
+    } else {
+        console.log(`Unhandled event type ${stripeEvent.type}.`);
+    }
+
+    return {
+        statusCode: 200,
+        body: `Received ${stripeEvent.type}, sent an email to ${recipientEmail} with a redirect link ${redirectUrl} handled by ${event.stageVariables.environment} env.`
+    };
+};

email-delivery/package.json

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+{
+  "dependencies": {
+    "aws-sdk": "^2.1563.0",
+    "axios": "^1.6.7",
+    "stripe": "^14.17.0"
+  }
+}

file-delivery/index.mjs

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+import Stripe from 'stripe';
+import AWS from 'aws-sdk';
+
+const s3 = new AWS.S3();
+
+export const handler = async (event) => {
+    const stripe = new Stripe(event.stageVariables.stripe_secret_api_key);
+    const sessionId = event.queryStringParameters.sessionId;
+
+    let chargeSucceeded = false;
+
+    for (let i = 0; i < 10; i++) {
+        try {
+            const session = await stripe.checkout.sessions.retrieve(sessionId);
+            if (session.payment_status === 'paid') {
+                chargeSucceeded = true;
+                break;
+            }
+        } catch (error) {
+            console.error(`Failed to retrieve session: ${error.message}. Environment: ${event.stageVariables.environment}.`);
+            return {
+                statusCode: 400,
+                body: `Failed to retrieve session: ${error.message}. Environment: ${event.stageVariables.environment}.`
+            };
+        }
+        await new Promise(resolve => setTimeout(resolve, 1000));
+    }
+
+    if (chargeSucceeded) {
+        const params = {
+            Bucket: process.env.bucket_name,
+            Key: process.env.object_key,
+            Expires: 60 * 60 * 24 * 30 // 30 days
+        };
+        const presignedUrl = s3.getSignedUrl('getObject', params);
+        const redirectUrl = `${process.env.redirect_host}${encodeURIComponent(presignedUrl)}${process.env.utm_parameters}`;
+
+        console.log(`Redirecting to ${redirectUrl} in environment ${event.stageVariables.environment}.`);
+        return {
+            statusCode: 302,
+            headers: {
+                Location: redirectUrl
+            },
+            body: ''
+        };
+    } else {
+        console.log(`Charge did not succeed for session id ${sessionId}. Environment: ${event.stageVariables.environment}.`);
+        return {
+            statusCode: 400,
+            body: `Charge did not succeed for session id ${sessionId}. Environment: ${event.stageVariables.environment}.`
+        };
+    }
+};

file-delivery/package.json

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+{
+  "dependencies": {
+    "aws-sdk": "^2.1563.0",
+    "stripe": "^14.17.0"
+  }
+}