Workshop: Build serverless edge applications with Cloudflare Workers and Fauna

import { Client, fql, FaunaError } from 'fauna';

export interface Env {
  FAUNA_SECRET: string;
}

interface RequestBody {
  operation: 'create' | 'update' | 'delete';
  id?: string; // Only required for "update" and "delete" operations
  fields?: Record<string, any>; // Data fields for "create" and "update" operations
}

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
    // Extract the method from the request
    const { method } = request;

    switch (method) {
      case 'GET':
        return getAllProducts(env);
      case 'POST':
        const body = (await request.json()) as RequestBody;
        return createNewProduct(body, env);
      default:
        return new Response('Method Not Allowed', { status: 405 });
    }
  }
}

async function getAllProducts(env: Env): Promise<Response> {
  // Custom GET logic here (e.g., fetching data from Fauna)
  const client = new Client({ secret: env.FAUNA_SECRET });
  try {
    const result = await client.query(fql`
      Product.all()
    `);
    return new Response(JSON.stringify(result.data));
  } catch (error) {
    if (error instanceof FaunaError) {
      return new Response(error.message, { status: 500 });
    }
    return new Response('An error occurred', { status: 500 });
  }
}

async function createNewProduct(body: any, env: Env): Promise<Response> {
  const { name, price, description, category, stock } = body;

  if (!name || !price || !description || !category || !stock) {
    return new Response('Missing required fields', { status: 400 });
  }

  const client = new Client({ secret: env.FAUNA_SECRET });
  try {
    // Custom POST logic here (e.g., storing data to Fauna)
    const result = await client.query(fql`
      // Get the category by name. We can use .first() here because we know that the category
      // name is unique.
      let category = Category.byName(${category}).first()
      // If the category does not exist, abort the query.
      if (category == null) abort("Category does not exist.")
        // Create the product with the given values.
        let args = { name: ${name}, price: ${price}, stock: ${stock}, description: ${description}, category: category }
        let product: Any = Product.create(args)
        // Use projection to only return the fields you need.
        product {
          id,
          name,
          price,
          description,
          stock,
          category {
            id,
            name,
            description
          }
        }
    `);
    return new Response(JSON.stringify(result.data));
  } catch (error) {
    console.error(error);
    return new Response('An error occurred', { status: 500 });
  }
}