index.ts

import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { DynamoDBDocumentClient, GetCommand, PutCommand } from "@aws-sdk/lib-dynamodb";
import { APIGatewayProxyEvent, APIGatewayProxyResult } from "aws-lambda";
import { Endpoint, Method, Router, RouteHandler, Either } from "yatro";
import { renderCounterPage } from "./pages/counterPage";
import { LogUtil } from "./utils/log";

interface IPayload {
  event: APIGatewayProxyEvent;
}

const counterEndpoint = Endpoint.build("/");
const counterHandler: RouteHandler<IPayload, APIGatewayProxyResult, typeof counterEndpoint> = async () => {
  const client = new DynamoDBClient({});
  const dynamo = DynamoDBDocumentClient.from(client);
  const result = await dynamo.send(
    new GetCommand({
      TableName: process.env.TABLE_COUNTER!,
      Key: { key: "mycounter" },
    })
  );

  return {
    statusCode: 200,
    body: renderCounterPage(result.Item?.value || 1),
    headers: { "Content-Type": "text/html" },
  };
};

const incrementEndpoint = Endpoint.build("/increment/:value|i");
const incrementHandler: RouteHandler<IPayload, APIGatewayProxyResult, typeof incrementEndpoint> = async ({
  match: { params },
}) => {
  const client = new DynamoDBClient({});
  const dynamo = DynamoDBDocumentClient.from(client);
  await dynamo.send(
    new PutCommand({
      TableName: process.env.TABLE_COUNTER!,
      Item: { key: "mycounter", value: params.value },
    })
  );
  return { statusCode: 200, body: JSON.stringify({ value: params.value }) };
};

export const handler = async (event: APIGatewayProxyEvent): Promise<APIGatewayProxyResult> => {
  const log = new LogUtil();
  const time = Date.now();
  log.log("--------> Starting request", event.httpMethod, event.path);

  const request: IPayload = { event };
  const router = new Router<IPayload, APIGatewayProxyResult>(request)
    .get(counterEndpoint, counterHandler)
    .post(incrementEndpoint, incrementHandler);

  const url = new URL(event.path, "http://example.com");
  for (const key of Object.keys(event.queryStringParameters || {})) {
    const value = (event.queryStringParameters || {})[key];
    url.searchParams.set(key, value || "");
  }
  let resp: Either<APIGatewayProxyResult>;
  try {
    resp = await router.route(event.httpMethod as Method, url.pathname + url.search);
  } catch (e) {
    console.error(e);
    log.log("<-------- Responding for", event.httpMethod, event.path, 500, `${Date.now() - time}ms`);
    return { statusCode: 500, body: "Internal Server Error" };
  }

  log.log(
    "<-------- Responding for",
    event.httpMethod,
    event.path,
    resp.success ? resp.data.statusCode : 404,
    `${Date.now() - time}ms`
  );

  return resp.success ? resp.data : { statusCode: 404, body: "Not Found" };
};