import { FastifyInstance } from 'fastify';
import fp from 'fastify-plugin';
import Caching from '@fastify/caching';

declare module 'fastify' {
  interface FastifyContextConfig {
    serverCache?: {
      key?: string;
      ttl: number;
    };
  }
}

export default fp(async function (fastify: FastifyInstance) {

  fastify.register(Caching,{
    expiresIn: 10000,
    privacy: Caching.privacy.PUBLIC,
    // TODO: default is a mem cache, should use redis cache for prod, for example
  })
  .addHook('onRoute', (routeOptions) => {
    const { config } = routeOptions;

    if (config?.serverCache) {

      const { key, ttl = 10000 } = config.serverCache;

      // set or add our handler to the route preHandler hook
      Object.entries({
        preHandler: (request, reply, done) => {
          fastify.cache.get(key || encodeURIComponent(request.raw.url), (err, cached) => {
            if (err) {
              // TODO: handle error
              done();
              return;
            }
            if (cached?.item) {
              console.log('from cache');
              reply.send(cached.item);
            } else {
              console.log('getting fresh data');
            }
            
            done();
          });

          return reply;
        },
        onSend: (request, _reply, payload, done) => {
          fastify.cache.set(key || encodeURIComponent(request.raw.url), payload, ttl, () => {done();});
        },
      }).forEach(([hook, handler]) => {
        if (!routeOptions[hook]) {
          routeOptions[hook] = [handler]
          return
        }
        if (Array.isArray(routeOptions[hook])) {
          routeOptions[hook].push(handler)
          return
        }
        routeOptions[hook] = [routeOptions[hook], handler]
      })
    }
  })
});