Websocket for real-time updates of projects

backend/go.mod

@@ -6,6 +6,8 @@ require github.com/gofiber/fiber/v2 v2.51.0
 
 require (
 	github.com/andybalholm/brotli v1.0.5 // indirect
+	github.com/fasthttp/websocket v1.5.3 // indirect
+	github.com/gofiber/websocket/v2 v2.2.1 // indirect
 	github.com/google/uuid v1.4.0 // indirect
 	github.com/klauspost/compress v1.16.7 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
@@ -13,6 +15,7 @@ require (
 	github.com/mattn/go-runewidth v0.0.15 // indirect
 	github.com/philhofer/fwd v1.1.2 // indirect
 	github.com/rivo/uniseg v0.2.0 // indirect
+	github.com/savsgio/gotils v0.0.0-20230208104028-c358bd845dee // indirect
 	github.com/tinylib/msgp v1.1.8 // indirect
 	github.com/valyala/bytebufferpool v1.0.0 // indirect
 	github.com/valyala/fasthttp v1.50.0 // indirect

backend/go.sum

@@ -1,7 +1,11 @@
 github.com/andybalholm/brotli v1.0.5 h1:8uQZIdzKmjc/iuPu7O2ioW48L81FgatrcpfFmiq/cCs=
 github.com/andybalholm/brotli v1.0.5/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
+github.com/fasthttp/websocket v1.5.3 h1:TPpQuLwJYfd4LJPXvHDYPMFWbLjsT91n3GpWtCQtdek=
+github.com/fasthttp/websocket v1.5.3/go.mod h1:46gg/UBmTU1kUaTcwQXpUxtRwG2PvIZYeA8oL6vF3Fs=
 github.com/gofiber/fiber/v2 v2.51.0 h1:JNACcZy5e2tGApWB2QrRpenTWn0fq0hkFm6k0C86gKQ=
 github.com/gofiber/fiber/v2 v2.51.0/go.mod h1:xaQRZQJGqnKOQnbQw+ltvku3/h8QxvNi8o6JiJ7Ll0U=
+github.com/gofiber/websocket/v2 v2.2.1 h1:C9cjxvloojayOp9AovmpQrk8VqvVnT8Oao3+IUygH7w=
+github.com/gofiber/websocket/v2 v2.2.1/go.mod h1:Ao/+nyNnX5u/hIFPuHl28a+NIkrqK7PRimyKaj4JxVU=
 github.com/google/uuid v1.4.0 h1:MtMxsa51/r9yyhkyLsVeVt0B+BGQZzpQiTQ4eHZ8bc4=
 github.com/google/uuid v1.4.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
 github.com/klauspost/compress v1.16.7 h1:2mk3MPGNzKyxErAw8YaohYh69+pa4sIQSC0fPGCFR9I=
@@ -19,6 +23,8 @@ github.com/philhofer/fwd v1.1.2 h1:bnDivRJ1EWPjUIRXV5KfORO897HTbpFAQddBdE8t7Gw=
 github.com/philhofer/fwd v1.1.2/go.mod h1:qkPdfjR2SIEbspLqpe1tO4n5yICnr2DY7mqEx2tUTP0=
 github.com/rivo/uniseg v0.2.0 h1:S1pD9weZBuJdFmowNwbpi7BJ8TNftyUImj/0WQi72jY=
 github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJtxc=
+github.com/savsgio/gotils v0.0.0-20230208104028-c358bd845dee h1:8Iv5m6xEo1NR1AvpV+7XmhI4r39LGNzwUL4YpMuL5vk=
+github.com/savsgio/gotils v0.0.0-20230208104028-c358bd845dee/go.mod h1:qwtSXrKuJh/zsFQ12yEE89xfCrGKK63Rr7ctU/uCo4g=
 github.com/tinylib/msgp v1.1.8 h1:FCXC1xanKO4I8plpHGH2P7koL/RzZs12l/+r7vakfm0=
 github.com/tinylib/msgp v1.1.8/go.mod h1:qkpG+2ldGg4xRFmx+jfTvZPxfGFhi64BcnL9vkCm/Tw=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=

backend/handlers/main.go

@@ -12,6 +12,7 @@ func v1Router(router fiber.Router) error {
 	tagsRouter(router.Group("/tags"))
 	viewsRouter(router.Group("/views"))
 	filtersRouter(router.Group("/filters"))
+	wsRouter(router.Group("/ws"))
 	return nil
 }
 

backend/handlers/projects.go

@@ -83,9 +83,22 @@ func CreateProject(c *fiber.Ctx) error {
 
 	projectsLastEdit = time.Now().Truncate(time.Second);
 
-	return c.Status(fiber.StatusCreated).JSON(fiber.Map{
+	if err = c.Status(fiber.StatusCreated).JSON(fiber.Map{
 		"id": id,
+	}); err != nil {
+		return err;
+	}
+
+	p.ID = id;
+
+	publish(fiber.Map{
+		"object": "project",
+		"action": "create",
+		"id": id,
+		"value": p,
 	})
+
+	return nil;
 }
 
 func UpdateProject(c *fiber.Ctx) error {
@@ -113,7 +126,18 @@ func UpdateProject(c *fiber.Ctx) error {
 
 	projectsLastEdit = time.Now().Truncate(time.Second);
 
-	return c.SendStatus(fiber.StatusNoContent)
+	if err = c.SendStatus(fiber.StatusNoContent); err != nil {
+		return err;
+	}
+
+	publish(fiber.Map{
+		"object": "project",
+		"action": "update",
+		"id": id,
+		"value": p,
+})
+
+	return nil;
 }
 
 func DeleteProject(c *fiber.Ctx) error {
@@ -136,7 +160,17 @@ func DeleteProject(c *fiber.Ctx) error {
 
 	projectsLastEdit = time.Now().Truncate(time.Second);
 
-	return c.SendStatus(fiber.StatusNoContent)
+	if err = c.SendStatus(fiber.StatusNoContent); err != nil {
+		return err;
+	}
+
+	publish(fiber.Map{
+		"object": "project",
+		"action": "delete",
+		"id": id,
+	})
+
+	return nil;
 }
 
 func GetProjectCards(c *fiber.Ctx) error {

backend/handlers/ws.go

@@ -0,0 +1,57 @@
+package handlers
+
+import (
+	"encoding/json"
+	"log"
+
+	"github.com/gofiber/fiber/v2"
+	"github.com/gofiber/websocket/v2"
+)
+
+var (
+	subscribers = make(map[*websocket.Conn]bool)
+)
+
+func wsRouter(router fiber.Router) error {
+	router.Use("/", upgradeWebsocket)
+	router.Get("/", websocket.New(handleWebsocket))
+	return nil;
+}
+
+func upgradeWebsocket(c *fiber.Ctx) error {
+	if websocket.IsWebSocketUpgrade(c) {
+		c.Locals("allowed", true)
+		return c.Next()
+	}
+	return fiber.ErrUpgradeRequired
+}
+
+func handleWebsocket(c *websocket.Conn) {
+	subscribers[c] = true
+	defer func() {
+		delete(subscribers, c)
+		c.Close()
+	}()
+
+	for {
+		_, _, err := c.ReadMessage()
+		if err != nil {
+			return
+		}
+	}
+}
+
+func publish(content fiber.Map) {
+	jsonMessage, err := json.Marshal(content)
+	if err != nil {
+		log.Println("Error marshalling JSON:", err)
+		return
+	}
+
+	for s := range subscribers {
+		if err := s.WriteMessage(websocket.TextMessage, jsonMessage); err != nil {
+			log.Println("Error writing to websocket:", err)
+			s.Close()
+		}
+	}
+}

frontend/src/lib/api/websocket.ts

@@ -0,0 +1,62 @@
+import Project, { projects } from '$lib/types/Project';
+import { hasPendingRequests } from '$lib/utils/api';
+import { toastWarning } from '$lib/utils/toasts';
+import { get } from 'svelte/store';
+
+let socket: WebSocket;
+
+export function connectWebSocket() {
+	socket = new WebSocket('ws://localhost:3000/api/v1/ws');
+
+	socket.onopen = () => {
+		console.log('WebSocket connected');
+	};
+
+	socket.onclose = () => {
+		console.log('WebSocket disconnected');
+		toastWarning(
+			'WebSocket disconnected',
+			'You may experience sync issues. You can try to reload the page.'
+		);
+
+		const reconnectTimer = setTimeout(() => {
+			connectWebSocket();
+			clearTimeout(reconnectTimer);
+		}, 5000);
+	};
+
+	socket.onerror = (err) => {
+		console.error('WebSocket error:', err);
+	};
+
+	socket.onmessage = async (event) => {
+		const parsed = JSON.parse(event.data);
+		while (hasPendingRequests()) {
+			await new Promise((resolve) => setTimeout(resolve, 100));
+		}
+		applyMessage(parsed);
+	};
+}
+
+function applyMessage(data: any) {
+	switch (data.object) {
+		case 'project':
+			applyProject(data);
+			break;
+		default:
+			console.log('Unknown object:', data);
+	}
+}
+
+function applyProject(data: any) {
+	switch (data.action) {
+		case 'create':
+			if (get(projects).find((p) => p.id === data.id)) break;
+		case 'update':
+			Project.parse(data.value);
+			break;
+		case 'delete':
+			projects.set(get(projects).filter((p) => p.id !== data.id));
+			break;
+	}
+}

frontend/src/lib/utils/api.ts

@@ -1,26 +1,55 @@
 import axios, { Axios, type AxiosResponse } from 'axios';
-import { toastAlert } from './toasts';
 import { setupCache } from 'axios-cache-interceptor';
+import { toastAlert } from './toasts';
 // import { env } from '$env/dynamic/public';
 
 // const backend = env.PUBLIC_BACKEND_URL || 'http://localhost:3000';
-const backend = 'http://localhost:3000';
+const backendUrl = 'http://localhost:3000';
 
-export default setupCache(
-	new Axios({
-		...axios.defaults,
-		baseURL: backend + '/api',
-		validateStatus: () => true,
-		headers: {
-			'Content-Type': 'application/json'
-		}
-	}),
-	{
-		interpretHeader: true,
-		modifiedSince: true
+let pendingRequests = 0;
+
+export function hasPendingRequests() {
+	return pendingRequests > 0;
+}
+
+const axiosInstance = new Axios({
+	...axios.defaults,
+	baseURL: backendUrl + '/api',
+	validateStatus: () => true,
+	headers: {
+		'Content-Type': 'application/json'
+	}
+});
+
+const cachedInstance = setupCache(axiosInstance, {
+	interpretHeader: true,
+	modifiedSince: true
+});
+
+axiosInstance.interceptors.request.use(
+	(config) => {
+		pendingRequests++;
+		return config;
+	},
+	(error) => {
+		pendingRequests--;
+		return Promise.reject(error);
 	}
 );
 
+axiosInstance.interceptors.response.use(
+	(response) => {
+		pendingRequests--;
+		return response;
+	},
+	(error) => {
+		pendingRequests--;
+		return Promise.reject(error);
+	}
+);
+
+export default axiosInstance;
+
 export function processError(response: AxiosResponse<any, any>, message: string = '') {
 	let title = `${response.status} ${response.statusText}`;
 	let subtitle = message;

frontend/src/lib/utils/toasts.ts

@@ -1,18 +1,29 @@
 import { toast } from '@zerodevx/svelte-toast';
 
 export function toastAlert(title: string, subtitle: string = '', persistant: boolean = false) {
-    toast.push(
-        `<strong>${title}</strong><br>${subtitle}`,
-        {
-            theme: {
-                '--toastBackground': '#ff4d4f',
-                '--toastBarBackground': '#d32f2f',
-                '--toastColor': '#fff',
-            },
-            initial: persistant ? 0 : 1,
-            next: 0,
-            duration: 10000,
-            pausable: true,
-        },
-    ) 
-}
+	toast.push(`<strong>${title}</strong><br>${subtitle}`, {
+		theme: {
+			'--toastBackground': '#ff4d4f',
+			'--toastBarBackground': '#d32f2f',
+			'--toastColor': '#fff'
+		},
+		initial: persistant ? 0 : 1,
+		next: 0,
+		duration: 10000,
+		pausable: true
+	});
+}
+
+export function toastWarning(title: string, subtitle: string = '', persistant: boolean = false) {
+	toast.push(`<strong>${title}</strong><br>${subtitle}`, {
+		theme: {
+			'--toastBackground': '#faad14',
+			'--toastBarBackground': '#d48806',
+			'--toastColor': '#fff'
+		},
+		initial: persistant ? 0 : 1,
+		next: 0,
+		duration: 5000,
+		pausable: true
+	});
+}

frontend/src/routes/+page.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
 	import projectsApi from '$lib/api/projectsApi';
+	import { connectWebSocket } from '$lib/api/websocket';
 	import Project, { projects } from '$lib/types/Project';
 	import { SvelteToast } from '@zerodevx/svelte-toast';
 	import { onMount } from 'svelte';
@@ -8,6 +9,8 @@
 	onMount(async () => {
 		await projectsApi.getAll();
 	});
+
+	connectWebSocket();
 </script>
 
 <section>