Feat/prerender and state (#8)

* pre-load data behind link elements on hover

* Enable SSR and prerendering of pages in 'auto' mode

* merge relay & regulator state in /api/state

This helps when updating relays and receiving state of relays and regulator state (idle,
heating or cooling) after emitting relay change.

src/lib/components/Navigation.svelte

@@ -20,7 +20,7 @@ const routes: Array<IRoute> = [{
 
 <ul class="navigation-cards" on:click>
   {#each routes as route}
-    <a href={route.path}>
+    <a href={route.path} data-sveltekit-preload-data="hover">
       <li>
         <span>{ route.name }</span>
 

src/lib/components/RelayControls.svelte

@@ -7,13 +7,13 @@
   export let relays: IRelaysDTO[] = [];
   const dispatch = createEventDispatcher();
 
-  function toggleRelay(controls: string) {
+  async function toggleRelay(controls: string) {
     const url = `/api/relay/${controls}`;
     const options = {
       method: 'POST'
     };
 
-    fetch(url, options)
+    await fetch(url, options)
       .then((resp) => resp.json())
       .then((response) => {
         const changedRelay = relays.findIndex((relay) => relay.pin === response.pin);

src/routes/+layout.ts

@@ -0,0 +1,16 @@
+// if you want to generate a static html file
+// for your page.
+// Documentation: https://kit.svelte.dev/docs/page-options#prerender
+export const prerender = 'auto';
+
+// if you want to Generate a SPA
+// you have to set ssr to false.
+// This is not the case (so set as true or comment the line)
+// Documentation: https://kit.svelte.dev/docs/page-options#ssr
+export const ssr = true;
+
+// How to manage the trailing slashes in the URLs
+// the URL for about page witll be /about with 'ignore' (default)
+// the URL for about page witll be /about/ with 'always'
+// https://kit.svelte.dev/docs/page-options#trailingslash
+export const trailingSlash = 'ignore';

src/routes/+page.server.ts

@@ -1,28 +1,51 @@
 import { BREWLOGGER_HOST } from '$env/static/private';
-import type { PageServerLoad } from './$types';
-import type { ISensorDTO } from '../lib/interfaces/ISensorDTO'
+import type { PageServerLoad, RequestEvent } from './$types';
+import type { ISensorDTO } from '../lib/interfaces/ISensorDTO';
 import { IRelaysDTO } from '../lib/interfaces/IRelaysDTO';
 import { IStateDTO } from '../lib/interfaces/IStateDTO';
 
 const sensorsUrl = `${BREWLOGGER_HOST}/api/sensors`;
-const relaysUrl = `${BREWLOGGER_HOST}/api/relays`;
-const stateUrl = `${BREWLOGGER_HOST}/api/regulator`;
+export const prerender = true; // explicitly pre-render
 
-async function getFromEndpoint(endpoint: string)  {
-  return fetch(endpoint)
+async function fetchSensors(fetch: Fetch): Promise<ISensorDTO[]> {
+  return fetch(sensorsUrl)
     .then((resp) => resp.json())
+    .then((data) => data?.sensors || [])
     .catch((error) => {
-      console.error('Failed to fetch endpoint:', endpoint);
+      console.error('failed to fetch sensors.');
       console.error(error);
-      return null
+      return null;
     });
 }
 
-export const load: PageServerLoad = async () => {
-  const [sensorsResp, relaysResp, stateResp] = await Promise.all([getFromEndpoint(sensorsUrl), getFromEndpoint(relaysUrl), getFromEndpoint(stateUrl)]);
-  const sensors: ISensorDTO[] = sensorsResp?.sensors || []
-  const relays: IRelaysDTO[] = relaysResp?.relays || []
-  const state: IStateDTO = stateResp
+// calls internal sveltekit api endpoint.
+// this allows unified response in svelte app, even
+// though it requires multiple calls to regulator server
+async function fetchState(fetch: Fetch) {
+  return fetch('/api/state')
+    .then((resp) => resp.json())
+    .catch((error) => {
+      console.error('failed to fetch state');
+      console.error(error);
+      return null;
+    });
+}
+
+type Fetch = typeof fetch;
+type HandleFetch = {
+  event: RequestEvent;
+  request: Request;
+  fetch: Fetch;
+};
+
+export const load: PageServerLoad = async (input: HandleFetch) => {
+  const [stateResponse, sensorsResponse] = await Promise.all([
+    fetchState(input.fetch),
+    fetchSensors(input.fetch)
+  ]);
+  const sensors: ISensorDTO[] = sensorsResponse || [];
+  const relays: IRelaysDTO[] = stateResponse?.relays || [];
+  const regulator: IStateDTO = stateResponse?.regulator;
 
   const inside = sensors.find((sensor: ISensorDTO) => sensor.location === 'inside');
   const outside = sensors.find((sensor: ISensorDTO) => sensor.location === 'outside');
@@ -30,7 +53,6 @@ export const load: PageServerLoad = async () => {
   return {
     inside: inside || null,
     outside: outside || null,
-    relays,
-    state
+    state: { regulator, relays }
   };
 };

src/routes/+page.svelte

@@ -8,14 +8,13 @@
 
   export let data: PageData;
   const { inside, outside } = data;
-  let { relays, state } = data;
+  let { relays, regulator } = data.state;
 
-  const updateState = () =>
-    setTimeout(() => {
-      fetch('/api/state')
-        .then((resp) => resp.json())
-        .then((response: IStateDTO) => (state = response));
-    }, 100);
+  const updateState = () => {
+    fetch('/api/state')
+      .then((resp) => resp.json())
+      .then((response: IStateDTO) => ({ relays, regulator } = response));
+    }
 </script>
 
 <Logo />
@@ -23,7 +22,12 @@
 <div class="vertical-grid">
   <BrewProgress />
 
-  <VerticalSensorDisplay {inside} {outside} {relays} {state} />
+  <VerticalSensorDisplay
+    inside="{inside}"
+    outside="{outside}"
+    relays="{relays}"
+    state="{regulator}"
+  />
 
   <RelayControls bind:relays="{relays}" on:relaySwitched="{updateState}" />
 </div>

src/routes/api/state/+server.ts

@@ -1,9 +1,19 @@
 import { json, RequestEvent } from '@sveltejs/kit';
 import { BREWLOGGER_HOST } from '$env/static/private';
 import type { RequestHandler } from './$types';
+import { IRelaysDTO } from '../../../lib/interfaces/IRelaysDTO';
 
-export const GET = (async (event: RequestEvent) => {
-  return fetch(BREWLOGGER_HOST + '/api/regulator')
+async function fetchRegulator(): Promise<Response | IRelaysDTO[]> {
+  return fetch(BREWLOGGER_HOST + '/api/regulator').then((resp) => resp.json());
+}
+
+async function fetchRelays(): Promise<Response | IRelaysDTO[]> {
+  return fetch(BREWLOGGER_HOST + '/api/relays')
     .then((resp) => resp.json())
-    .then((response) => json(response));
+    .then((data) => data?.relays || []);
+}
+
+export const GET = (async () => {
+  const [regulatorState, relaysState] = await Promise.all([fetchRegulator(), fetchRelays()]);
+  return json({ regulator: regulatorState, relays: relaysState });
 }) satisfies RequestHandler;

src/routes/brews/+page.svelte

@@ -17,7 +17,7 @@
   <ul>
     {#each brews as brew}
     <li class="brew">
-      <a href="{path(brew.date)}">
+      <a href="{path(brew.date)}" data-sveltekit-preload-data="hover">
         <img src="/images/{brew.image}" alt="Beer label of {brew.beer.name}" />
 
         <div class="details">

src/routes/brews/[date]/+page.server.ts

@@ -4,8 +4,9 @@ import { fetchHumidity, fetchTemperature } from '../../../lib/server/graphQueryG
 import type { PageLoad } from './$types';
 
 async function fetchGraphData(brew) {
-  const start = new Date(brew.date * 1000 - 86400000);
-  const end = new Date(brew.date * 1000 + 4838400000);
+  const { date } = brew;
+  const start = new Date(date * 1000 - 86400000);
+  const end = new Date(date * 1000 + 4838400000);
   const size = 200;
 
   const [temperature, humidity] = await Promise.all([
@@ -13,10 +14,7 @@ async function fetchGraphData(brew) {
     fetchHumidity(start, end, size)
   ]);
 
-  return {
-    temperature,
-    humidity
-  };
+  return { temperature, humidity };
 }
 
 export const load = (async ({ params }) => {