AWS Lambda code receiving API Gateway information for SNS notifications

index.js

const AWS = require('aws-sdk');
const sns = new AWS.SNS({ apiVersion: '2010-03-31' });

exports.handler = async (event, context) => {
    let body;
    let statusCode = '200';
    const { origin } = event.headers;
    const acceptedOrigins = ['http://localhost:8080', 'https://mywebsite.com']; // PLACE PROPER WEBSITE ORIGIN
    const headers = {
        'Access-Control-Allow-Headers': 'Content-Type',
        'Access-Control-Allow-Origin': acceptedOrigins.includes(origin) ? origin : acceptedOrigins[1],
        'Access-Control-Allow-Methods': 'POST,OPTIONS'
    };

    try {
        const { method } = event.requestContext.http;
        switch (method) {
            case 'OPTIONS':
                break;
            case 'POST':
                statusCode = '201';
                const { name, email, phone_number } = JSON.parse(event.body);
                
                await sns.publish({
                    Message: `Name: ${name}\nEmail: ${email}\nPhone Number: ${phone_number}`,
                    TopicArn: 'arn:aws:sns:' // PLACE PROPER TOPIC ARN HERE
                }).promise();
                break;
            default:
                throw new Error(`Unsupported method "${method}"`);
        }
    } catch (err) {
        statusCode = '400';
        body = err.message;
    } finally {
        body = JSON.stringify(body);
    }

    return {
        statusCode,
        body,
        headers,
    };
};