refactor

.env.example

@@ -6,3 +6,4 @@ REFRESH_TOKEN=
 # LOG_LEVEL=DEBUG|WARN|ERROR
 # ALLOWED_ORIGINS=http://localhost:3000
 # SERVER_PORT=3000
+# RT=true

.github/workflows/go.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v4
       with:
-        go-version: '1.22.4'
+        go-version: '1.25.1'
 
     - name: Build
       run: go build -v ./...

.gitignore

@@ -1 +1,2 @@
 .env**
+.idea

Dockerfile

@@ -1,17 +1,16 @@
-FROM golang:1.24 AS builder
+FROM golang:1.25.1 AS builder
 ENV CGO_ENABLED=0 GOOS=linux GOARCH=amd64
 WORKDIR /app
 COPY go.mod go.sum ./
 RUN go mod download
 COPY . .
 RUN go build -ldflags="-s -w" -o spotify-ws .
-RUN go build -ldflags="-s -w" -o healthcheck ./healthcheck/healthcheck.go
 
 FROM gcr.io/distroless/static:nonroot
 WORKDIR /app
 COPY --from=builder --chown=nonroot:nonroot /app/spotify-ws .
-COPY --from=builder --chown=nonroot:nonroot /app/healthcheck .
+
 EXPOSE 3000
-HEALTHCHECK --interval=30s --timeout=5s --start-period=5s CMD ["./healthcheck"]
+HEALTHCHECK --interval=30s --timeout=5s --start-period=5s CMD ["/spotify-ws", "-health"]
 USER nonroot:nonroot
-CMD ["./spotify-ws"]
+CMD ["/spotify-ws"]

docker-compose.dev.yaml

@@ -14,3 +14,4 @@ services:
       #- LOG_LEVEL=DEBUG
       #- ALLOWED_ORIGINS=http://localhost:3000
       #- SERVER_PORT=3000
+      #- RT=true

docker-compose.yaml

@@ -10,5 +10,6 @@ services:
       - CLIENT_SECRET=${CLIENT_SECRET}
       - CLIENT_ID=${CLIENT_ID}
       #- LOG_LEVEL=DEBUG
-      # ALLOWED_ORIGINS=http://localhost:3000
+      #- ALLOWED_ORIGINS=http://localhost:3000
-      # SERVER_PORT=3000
+      #- SERVER_PORT=3000
+      #- RT=true

go.mod

@@ -1,13 +1,9 @@
-module skidoodle/spotify-ws
+module spotify-ws
 
-go 1.24.0
+go 1.25.1
 
 require (
-	github.com/gorilla/websocket v1.5.3
 	github.com/joho/godotenv v1.5.1
-	github.com/sirupsen/logrus v1.9.3
+	golang.org/x/net v0.44.0
-	github.com/zmb3/spotify v1.3.0
+	golang.org/x/oauth2 v0.31.0
-	golang.org/x/oauth2 v0.27.0
 )
-
-require golang.org/x/sys v0.30.0 // indirect

go.sum

@@ -1,34 +1,6 @@
-cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
-github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
-github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
-github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
-github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
-github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+golang.org/x/net v0.44.0 h1:evd8IRDyfNBMBTTY5XRF1vaZlD+EmWx6x8PkhR04H/I=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+golang.org/x/net v0.44.0/go.mod h1:ECOoLqd5U3Lhyeyo/QDCEVQ4sNgYsqvCZ722XogGieY=
-github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+golang.org/x/oauth2 v0.31.0 h1:8Fq0yVZLh4j4YA47vHKFTa9Ew5XIrCP8LC6UeNZnLxo=
-github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+golang.org/x/oauth2 v0.31.0/go.mod h1:lzm5WQJQwKZ3nwavOZ3IS5Aulzxi68dUSgRHujetwEA=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/zmb3/spotify v1.3.0 h1:6Z2F1IMx0Hviq/dpf8nFwvKPppFEMXn8yfReSBVi16k=
-github.com/zmb3/spotify v1.3.0/go.mod h1:GD7AAEMUJVYc2Z7p2a2S0E3/5f/KxM/vOnErNr4j+Tw=
-golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
-golang.org/x/net v0.0.0-20190108225652-1e06a53dbb7e/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
-golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
-golang.org/x/oauth2 v0.27.0 h1:da9Vo7/tDv5RH/7nZDz1eMGS/q1Vv1N/7FCrBhI9I3M=
-golang.org/x/oauth2 v0.27.0/go.mod h1:onh5ek6nERTohokkhCD/y2cV4Do3fxFHFuAejCkRWT8=
-golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
-golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

healthcheck/go.mod

@@ -1,3 +0,0 @@
-module healthcheck
-
-go 1.24.0

healthcheck/healthcheck.go

@@ -1,24 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-	"net/http"
-	"os"
-)
-
-func main() {
-	resp, err := http.Get("http://localhost:3000/health")
-	if err != nil {
-		log.Fatalf("Error performing health check: %v", err)
-	}
-	defer resp.Body.Close()
-
-	if resp.StatusCode != http.StatusOK {
-		log.Printf("Health check failed: Status code %d", resp.StatusCode)
-		os.Exit(1)
-	}
-
-	fmt.Println("OK")
-	os.Exit(0)
-}

internal/config/config.go

@@ -0,0 +1,71 @@
+package config
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/joho/godotenv"
+)
+
+// Config holds the application configuration.
+type Config struct {
+	ServerPort     string
+	AllowedOrigins []string
+	LogLevel       slog.Level
+	RT             bool
+	Spotify        struct {
+		ClientID     string
+		ClientSecret string
+		RefreshToken string
+	}
+}
+
+// Load loads the configuration from environment variables.
+func Load() (*Config, error) {
+	if err := godotenv.Load(); err != nil {
+		slog.Warn("no .env file found, using environment variables")
+	}
+
+	cfg := &Config{}
+
+	cfg.Spotify.ClientID = os.Getenv("SPOTIFY_CLIENT_ID")
+	cfg.Spotify.ClientSecret = os.Getenv("SPOTIFY_CLIENT_SECRET")
+	cfg.Spotify.RefreshToken = os.Getenv("SPOTIFY_REFRESH_TOKEN")
+
+	if cfg.Spotify.ClientID == "" || cfg.Spotify.ClientSecret == "" || cfg.Spotify.RefreshToken == "" {
+		return nil, fmt.Errorf("spotify credentials are not set")
+	}
+
+	cfg.ServerPort = os.Getenv("SERVER_PORT")
+	if cfg.ServerPort == "" {
+		cfg.ServerPort = "3000"
+	}
+
+	allowedOrigins := os.Getenv("ALLOWED_ORIGINS")
+	if allowedOrigins != "" {
+		cfg.AllowedOrigins = strings.Split(allowedOrigins, ",")
+	}
+
+	rt, err := strconv.ParseBool(os.Getenv("RT"))
+	if err != nil {
+		cfg.RT = false
+	} else {
+		cfg.RT = rt
+	}
+
+	switch strings.ToLower(os.Getenv("LOG_LEVEL")) {
+	case "debug":
+		cfg.LogLevel = slog.LevelDebug
+	case "warn":
+		cfg.LogLevel = slog.LevelWarn
+	case "error":
+		cfg.LogLevel = slog.LevelError
+	default:
+		cfg.LogLevel = slog.LevelInfo
+	}
+
+	return cfg, nil
+}

internal/spotify/client.go

@@ -0,0 +1,74 @@
+package spotify
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+
+	"golang.org/x/oauth2"
+)
+
+const (
+	tokenURL            = "https://accounts.spotify.com/api/token"
+	currentlyPlayingURL = "https://api.spotify.com/v1/me/player/currently-playing"
+)
+
+// Client is a thread-safe client for interacting with the Spotify API.
+type Client struct {
+	httpClient *http.Client
+}
+
+// NewClient creates a new Spotify API client using the refresh token flow.
+// The returned client is safe for concurrent use.
+func NewClient(ctx context.Context, clientID, clientSecret, refreshToken string) *Client {
+	conf := &oauth2.Config{
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		Endpoint: oauth2.Endpoint{
+			TokenURL: tokenURL,
+		},
+	}
+
+	token := &oauth2.Token{
+		RefreshToken: refreshToken,
+	}
+
+	// The TokenSource is concurrency-safe and handles token refreshes automatically.
+	tokenSource := conf.TokenSource(ctx, token)
+
+	return &Client{
+		httpClient: oauth2.NewClient(ctx, tokenSource),
+	}
+}
+
+// CurrentlyPlaying fetches the user's currently playing track from the Spotify API.
+func (c *Client) CurrentlyPlaying(ctx context.Context) (*CurrentlyPlaying, error) {
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, currentlyPlayingURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if err := resp.Body.Close(); err != nil {
+			slog.Warn("failed to close spotify api response body", "error", err)
+		}
+	}()
+
+	// When nothing is playing, Spotify returns 204 No Content.
+	// We normalize this to a consistent struct response for the caller.
+	if resp.StatusCode == http.StatusNoContent {
+		return &CurrentlyPlaying{IsPlaying: false, Item: nil}, nil
+	}
+
+	var currentlyPlaying CurrentlyPlaying
+	if err := json.NewDecoder(resp.Body).Decode(&currentlyPlaying); err != nil {
+		return nil, err
+	}
+
+	return &currentlyPlaying, nil
+}

internal/spotify/model.go

@@ -0,0 +1,25 @@
+package spotify
+
+// TrackItem represents the track object from the Spotify API.
+type TrackItem struct {
+	ID         string `json:"id"`
+	Name       string `json:"name"`
+	DurationMs int    `json:"duration_ms"`
+	Artists    []struct {
+		Name string `json:"name"`
+	} `json:"artists"`
+	Album struct {
+		Images []struct {
+			URL string `json:"url"`
+		} `json:"images"`
+	} `json:"album"`
+}
+
+// CurrentlyPlaying represents the currently playing object from the Spotify API.
+// The Item field is a pointer to handle cases where nothing is playing (item is null).
+type CurrentlyPlaying struct {
+	IsPlaying  bool       `json:"is_playing"`
+	ProgressMs int        `json:"progress_ms"`
+	Timestamp  int64      `json:"timestamp"`
+	Item       *TrackItem `json:"item"`
+}

internal/websocket/handler.go

@@ -0,0 +1,47 @@
+package websocket
+
+import (
+	"log/slog"
+	"net/http"
+
+	"golang.org/x/net/websocket"
+)
+
+// newWebsocketHandler creates a new WebSocket handler closure.
+func (s *Server) newWebsocketHandler() websocket.Handler {
+	return func(ws *websocket.Conn) {
+		defer func() {
+			s.hub.unregister <- ws
+			if err := ws.Close(); err != nil {
+				slog.Warn("error while closing websocket connection", "error", err, "remoteAddr", ws.RemoteAddr())
+			}
+		}()
+
+		origin := ws.Config().Origin.String()
+		if !s.originChecker(origin) {
+			slog.Warn("origin not allowed, rejecting connection", "origin", origin)
+			return
+		}
+
+		s.hub.register <- ws
+
+		// Send the last known state immediately upon connection.
+		s.poller.SendLastState(ws)
+
+		// Block by reading from the client to detect disconnection.
+		var msg string
+		for {
+			if err := websocket.Message.Receive(ws, &msg); err != nil {
+				break // Client has disconnected.
+			}
+		}
+	}
+}
+
+// healthHandler responds to Docker health checks.
+func healthHandler(w http.ResponseWriter, _ *http.Request) {
+	w.WriteHeader(http.StatusOK)
+	if _, err := w.Write([]byte("OK")); err != nil {
+		slog.Warn("failed to write health check response", "error", err)
+	}
+}

internal/websocket/hub.go

@@ -0,0 +1,94 @@
+package websocket
+
+import (
+	"context"
+	"log/slog"
+	"spotify-ws/internal/spotify"
+	"sync"
+
+	"golang.org/x/net/websocket"
+)
+
+// Hub manages the set of active clients and broadcasts messages.
+type Hub struct {
+	clients    map[*websocket.Conn]struct{}
+	mu         sync.RWMutex
+	realtime   bool
+	register   chan *websocket.Conn
+	unregister chan *websocket.Conn
+	broadcast  chan *spotify.CurrentlyPlaying
+}
+
+// NewHub creates a new Hub.
+func NewHub(realtime bool) *Hub {
+	return &Hub{
+		clients:    make(map[*websocket.Conn]struct{}),
+		realtime:   realtime,
+		register:   make(chan *websocket.Conn),
+		unregister: make(chan *websocket.Conn),
+		broadcast:  make(chan *spotify.CurrentlyPlaying),
+	}
+}
+
+// Run starts the hub's event loop. It must be run in a separate goroutine.
+func (h *Hub) Run(ctx context.Context) {
+	slog.Info("hub started")
+	defer slog.Info("hub stopped")
+
+	for {
+		select {
+		case <-ctx.Done():
+			h.closeAllConnections()
+			return
+		case client := <-h.register:
+			h.mu.Lock()
+			h.clients[client] = struct{}{}
+			h.mu.Unlock()
+			slog.Debug("client registered", "remoteAddr", client.RemoteAddr())
+		case client := <-h.unregister:
+			h.mu.Lock()
+			if _, ok := h.clients[client]; ok {
+				delete(h.clients, client)
+			}
+			h.mu.Unlock()
+			slog.Debug("client unregistered", "remoteAddr", client.RemoteAddr())
+		case state := <-h.broadcast:
+			h.broadcastState(state)
+		}
+	}
+}
+
+// Broadcast sends a state update to all connected clients.
+func (h *Hub) Broadcast(state *spotify.CurrentlyPlaying) {
+	h.broadcast <- state
+}
+
+// broadcastState handles the actual message sending.
+func (h *Hub) broadcastState(state *spotify.CurrentlyPlaying) {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+
+	if len(h.clients) == 0 {
+		return
+	}
+
+	clientPayload := newPlaybackState(state, h.realtime)
+	for client := range h.clients {
+		go func(c *websocket.Conn) {
+			if err := websocket.JSON.Send(c, clientPayload); err != nil {
+				slog.Warn("failed to broadcast message", "error", err, "remoteAddr", c.RemoteAddr())
+			}
+		}(client)
+	}
+}
+
+// closeAllConnections closes all active client connections during shutdown.
+func (h *Hub) closeAllConnections() {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	for client := range h.clients {
+		if err := client.Close(); err != nil {
+			slog.Warn("error closing client connection during shutdown", "error", err, "remoteAddr", client.RemoteAddr())
+		}
+	}
+}

internal/websocket/poller.go

@@ -0,0 +1,108 @@
+package websocket
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+	"time"
+
+	"spotify-ws/internal/spotify"
+
+	"golang.org/x/net/websocket"
+)
+
+// Poller is responsible for fetching data from the Spotify API periodically.
+type Poller struct {
+	client    *spotify.Client
+	hub       *Hub
+	lastState *spotify.CurrentlyPlaying
+	mu        sync.RWMutex
+}
+
+// NewPoller creates a new Poller.
+func NewPoller(client *spotify.Client, hub *Hub) *Poller {
+	return &Poller{
+		client: client,
+		hub:    hub,
+	}
+}
+
+// Run starts the polling loop. It must be run in a separate goroutine.
+func (p *Poller) Run(ctx context.Context) {
+	slog.Info("poller started")
+	defer slog.Info("poller stopped")
+
+	ticker := time.NewTicker(3 * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-ticker.C:
+			p.UpdateState(ctx)
+		}
+	}
+}
+
+// UpdateState fetches the latest state, compares it, and broadcasts if needed.
+func (p *Poller) UpdateState(ctx context.Context) {
+	current, err := p.client.CurrentlyPlaying(ctx)
+	if err != nil {
+		slog.Error("failed to get currently playing track", "error", err)
+		return
+	}
+
+	p.mu.Lock()
+	hasChanged := p.hasStateChanged(current)
+	if hasChanged {
+		p.lastState = current
+	}
+	p.mu.Unlock()
+
+	if hasChanged {
+		if !p.hub.realtime {
+			trackName := "Nothing"
+			if current.Item != nil {
+				trackName = current.Item.Name
+			}
+			slog.Info("state changed, broadcasting update", "isPlaying", current.IsPlaying, "track", trackName)
+		}
+		p.hub.Broadcast(current)
+	}
+}
+
+// SendLastState sends the cached state to a single new client.
+func (p *Poller) SendLastState(ws *websocket.Conn) {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+
+	if p.lastState == nil {
+		return
+	}
+	clientPayload := newPlaybackState(p.lastState, p.hub.realtime)
+	if err := websocket.JSON.Send(ws, clientPayload); err != nil {
+		slog.Warn("failed to send initial state to client", "error", err, "remoteAddr", ws.RemoteAddr())
+	}
+}
+
+// hasStateChanged performs a robust comparison between the new and old states.
+// This function must be called within a lock.
+func (p *Poller) hasStateChanged(current *spotify.CurrentlyPlaying) bool {
+	if p.lastState == nil {
+		return true
+	}
+	if p.hub.realtime && current.IsPlaying && current.Item != nil {
+		return true
+	}
+	if p.lastState.IsPlaying != current.IsPlaying {
+		return true
+	}
+	if (p.lastState.Item == nil) != (current.Item == nil) {
+		return true
+	}
+	if p.lastState.Item != nil && current.Item != nil && p.lastState.Item.ID != current.Item.ID {
+		return true
+	}
+	return false
+}

internal/websocket/server.go

@@ -0,0 +1,106 @@
+package websocket
+
+import (
+	"context"
+	"errors"
+	"log/slog"
+	"net/http"
+	"sync"
+	"time"
+
+	"spotify-ws/internal/spotify"
+)
+
+// Server is the main application orchestrator. It owns all components
+// and manages the application's lifecycle.
+type Server struct {
+	addr          string
+	httpServer    *http.Server
+	hub           *Hub
+	poller        *Poller
+	originChecker func(string) bool
+}
+
+// NewServer creates a new, fully configured WebSocket server.
+func NewServer(addr string, allowedOrigins []string, spotifyClient *spotify.Client, realtime bool) *Server {
+	hub := NewHub(realtime)
+	poller := NewPoller(spotifyClient, hub)
+
+	// Create a closure for origin checking to keep the Server's dependencies clean.
+	originChecker := func(origin string) bool {
+		if len(allowedOrigins) == 0 {
+			return true // Allow all if not specified.
+		}
+		for _, allowedOrigin := range allowedOrigins {
+			if allowedOrigin == origin {
+				return true
+			}
+		}
+		return false
+	}
+
+	return &Server{
+		addr:          addr,
+		hub:           hub,
+		poller:        poller,
+		originChecker: originChecker,
+	}
+}
+
+// Run starts the server and its components. It blocks until the context is
+// canceled and all components have shut down gracefully.
+func (s *Server) Run(ctx context.Context) error {
+	// Do an initial state fetch before starting the server.
+	s.poller.UpdateState(ctx)
+
+	mux := http.NewServeMux()
+	mux.Handle("/", s.newWebsocketHandler())
+	mux.HandleFunc("/health", healthHandler)
+
+	s.httpServer = &http.Server{
+		Addr:    s.addr,
+		Handler: mux,
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(2) // For the hub and the poller.
+
+	go func() {
+		defer wg.Done()
+		s.hub.Run(ctx)
+	}()
+
+	go func() {
+		defer wg.Done()
+		s.poller.Run(ctx)
+	}()
+
+	// Start the HTTP server.
+	go func() {
+		if err := s.httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
+			slog.Error("http server error", "error", err)
+		}
+	}()
+
+	// Wait for shutdown signal.
+	<-ctx.Done()
+	slog.Info("shutdown signal received")
+
+	// The hub and poller will stop automatically via the context.
+	// We just need to shut down the HTTP server and wait for goroutines to finish.
+	s.shutdown()
+	wg.Wait()
+
+	return nil
+}
+
+// shutdown gracefully shuts down the HTTP server.
+func (s *Server) shutdown() {
+	slog.Info("shutting down http server")
+	shutdownCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	if err := s.httpServer.Shutdown(shutdownCtx); err != nil {
+		slog.Error("http server shutdown error", "error", err)
+	}
+}

internal/websocket/state.go

@@ -0,0 +1,29 @@
+package websocket
+
+import "spotify-ws/internal/spotify"
+
+// PlaybackState is the client-facing data structure. It conditionally omits
+// real-time data fields from JSON based on the server's mode.
+type PlaybackState struct {
+	IsPlaying  bool               `json:"is_playing"`
+	ProgressMs int                `json:"progress_ms,omitempty"`
+	Timestamp  int64              `json:"timestamp,omitempty"`
+	Item       *spotify.TrackItem `json:"item"`
+}
+
+// newPlaybackState creates a client-facing PlaybackState from the internal Spotify data.
+// It includes progress data only if the server is in real-time mode.
+func newPlaybackState(data *spotify.CurrentlyPlaying, realtime bool) PlaybackState {
+	if data == nil {
+		return PlaybackState{IsPlaying: false}
+	}
+	state := PlaybackState{
+		IsPlaying: data.IsPlaying,
+		Item:      data.Item,
+	}
+	if realtime {
+		state.ProgressMs = data.ProgressMs
+		state.Timestamp = data.Timestamp
+	}
+	return state
+}

main.go

@@ -3,364 +3,45 @@ package main
 import (
 	"context"
 	"fmt"
-	"net/http"
+	"log/slog"
 	"os"
 	"os/signal"
-	"strings"
-	"sync"
 	"syscall"
-	"time"
 
-	"github.com/gorilla/websocket"
+	"spotify-ws/internal/config"
-	"github.com/joho/godotenv"
+	"spotify-ws/internal/spotify"
-	"github.com/sirupsen/logrus"
+	"spotify-ws/internal/websocket"
-	"github.com/zmb3/spotify"
-	"golang.org/x/oauth2"
-)
-
-// Configuration holds application settings
-type Configuration struct {
-	ServerPort     string
-	AllowedOrigins []string
-	LogLevel       logrus.Level
-	Spotify        struct {
-		ClientID     string
-		ClientSecret string
-		RefreshToken string
-	}
-}
-
-var (
-	config       Configuration
-	clients      = make(map[*websocket.Conn]bool)
-	clientsMutex sync.RWMutex
-	broadcast    = make(chan *spotify.CurrentlyPlaying)
-	connectChan  = make(chan *websocket.Conn)
-
-	upgrader = websocket.Upgrader{
-		HandshakeTimeout: 10 * time.Second,
-		ReadBufferSize:   1024,
-		WriteBufferSize:  1024,
-	}
-
-	spotifyClient spotify.Client
-	tokenSource   oauth2.TokenSource
-	lastState     struct {
-		sync.RWMutex
-		track   *spotify.CurrentlyPlaying
-		playing bool
-	}
-)
-
-const (
-	defaultPort       = ":3000"
-	tokenRefreshURL   = "https://accounts.spotify.com/api/token"
-	apiRetryDelay     = 3 * time.Second
-	heartbeatInterval = 3 * time.Second
-	writeTimeout      = 10 * time.Second
 )
 
 func main() {
-	ctx, cancel := context.WithCancel(context.Background())
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
-	defer cancel()
+	defer stop()
 
-	initializeApplication()
+	if err := run(ctx); err != nil {
-	initializeSpotifyClient()
+		_, _ = fmt.Fprintf(os.Stderr, "error: %v\n", err)
-
+		os.Exit(1)
-	router := http.NewServeMux()
-	router.HandleFunc("/", connectionHandler)
-	router.HandleFunc("/health", healthHandler)
-
-	server := &http.Server{
-		Addr:    config.ServerPort,
-		Handler: router,
-	}
-
-	go trackFetcher(ctx)
-	go messageHandler(ctx)
-	go connectionManager(ctx)
-
-	startServer(server, ctx)
-	handleShutdown(server, cancel)
-}
-
-func initializeApplication() {
-	logrus.SetFormatter(&logrus.TextFormatter{
-		FullTimestamp:   true,
-		TimestampFormat: time.RFC3339,
-		ForceColors:     true,
-	})
-
-	if err := loadConfiguration(); err != nil {
-		logrus.Fatal(err)
-	}
-
-	upgrader.CheckOrigin = func(r *http.Request) bool {
-		if len(config.AllowedOrigins) == 0 {
-			return true
-		}
-		origin := r.Header.Get("Origin")
-		for _, allowed := range config.AllowedOrigins {
-			if origin == allowed {
-				return true
-			}
-		}
-		return false
 	}
 }
 
-func loadConfiguration() error {
+func run(ctx context.Context) error {
-	_ = godotenv.Load()
+	cfg, err := config.Load()
-
+	if err != nil {
-	required := map[string]*string{
+		return fmt.Errorf("failed to load config: %w", err)
-		"CLIENT_ID":     &config.Spotify.ClientID,
-		"CLIENT_SECRET": &config.Spotify.ClientSecret,
-		"REFRESH_TOKEN": &config.Spotify.RefreshToken,
 	}
 
-	for key, ptr := range required {
+	handlerOptions := &slog.HandlerOptions{Level: cfg.LogLevel}
-		value := os.Getenv(key)
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, handlerOptions))
-		if value == "" {
+	slog.SetDefault(logger)
-			return fmt.Errorf("missing required environment variable: %s", key)
+
-		}
+	spotifyClient := spotify.NewClient(ctx, cfg.Spotify.ClientID, cfg.Spotify.ClientSecret, cfg.Spotify.RefreshToken)
-		*ptr = value
+	wsServer := websocket.NewServer(":"+cfg.ServerPort, cfg.AllowedOrigins, spotifyClient, cfg.RT)
+
+	slog.Info("starting spotify-ws server", "port", cfg.ServerPort, "realtime", cfg.RT)
+
+	if err := wsServer.Run(ctx); err != nil {
+		return fmt.Errorf("server runtime error: %w", err)
 	}
 
-	config.ServerPort = defaultPort
+	slog.Info("server shut down gracefully")
-	if port := os.Getenv("SERVER_PORT"); port != "" {
-		config.ServerPort = ":" + strings.TrimLeft(port, ":")
-	}
-
-	config.AllowedOrigins = strings.Split(os.Getenv("ALLOWED_ORIGINS"), ",")
-
-	logLevel := strings.ToLower(os.Getenv("LOG_LEVEL"))
-	switch logLevel {
-	case "debug":
-		config.LogLevel = logrus.DebugLevel
-	case "warn":
-		config.LogLevel = logrus.WarnLevel
-	case "error":
-		config.LogLevel = logrus.ErrorLevel
-	default:
-		config.LogLevel = logrus.InfoLevel
-	}
-	logrus.SetLevel(config.LogLevel)
-
 	return nil
 }
-
-func initializeSpotifyClient() {
-	token := &oauth2.Token{RefreshToken: config.Spotify.RefreshToken}
-	oauthConfig := &oauth2.Config{
-		ClientID:     config.Spotify.ClientID,
-		ClientSecret: config.Spotify.ClientSecret,
-		Endpoint:     oauth2.Endpoint{TokenURL: tokenRefreshURL},
-	}
-
-	tokenSource = oauthConfig.TokenSource(context.Background(), token)
-	spotifyClient = spotify.NewClient(oauth2.NewClient(context.Background(), tokenSource))
-
-	logrus.Info("Spotify client initialized successfully")
-}
-
-func startServer(server *http.Server, _ context.Context) {
-	go func() {
-		logrus.Infof("Server starting on %s", config.ServerPort)
-		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
-			logrus.Fatalf("Server failed to start: %v", err)
-		}
-	}()
-}
-
-func handleShutdown(server *http.Server, cancel context.CancelFunc) {
-	sigChan := make(chan os.Signal, 1)
-	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
-	<-sigChan
-
-	logrus.Info("Initiating graceful shutdown...")
-	cancel()
-
-	ctx, cancelTimeout := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancelTimeout()
-
-	clientsMutex.Lock()
-	for client := range clients {
-		client.Close()
-	}
-	clientsMutex.Unlock()
-
-	if err := server.Shutdown(ctx); err != nil {
-		logrus.Errorf("Server shutdown error: %v", err)
-	}
-	logrus.Info("Server shutdown complete")
-}
-
-func connectionHandler(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("X-Source", "github.com/skidoodle/spotify-ws")
-	ws, err := upgrader.Upgrade(w, r, nil)
-	if err != nil {
-		logrus.Errorf("WebSocket upgrade failed: %v", err)
-		return
-	}
-
-	// Add client to the pool
-	clientsMutex.Lock()
-	clients[ws] = true
-	clientsMutex.Unlock()
-
-	logrus.Debugf("New client connected: %s", ws.RemoteAddr())
-
-	// Send initial state if available
-	sendInitialState(ws)
-
-	// Start monitoring the connection
-	go monitorConnection(ws)
-}
-
-func connectionManager(ctx context.Context) {
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case client := <-connectChan:
-			// Add client to the pool
-			clientsMutex.Lock()
-			clients[client] = true
-			clientsMutex.Unlock()
-
-			logrus.Debugf("New client connected: %s", client.RemoteAddr())
-
-			// Send initial state if available
-			sendInitialState(client)
-
-			// Start monitoring the connection
-			go monitorConnection(client)
-		}
-	}
-}
-
-func monitorConnection(ws *websocket.Conn) {
-	defer func() {
-		// Clean up the connection
-		clientsMutex.Lock()
-		delete(clients, ws)
-		clientsMutex.Unlock()
-
-		// Close the WebSocket connection
-		ws.Close()
-		logrus.Debugf("Client disconnected: %s", ws.RemoteAddr())
-	}()
-
-	for {
-		// Set a read deadline to detect dead connections
-		ws.SetReadDeadline(time.Now().Add(30 * time.Second))
-
-		// Attempt to read a message (even though we don't expect any)
-		_, _, err := ws.NextReader()
-		if err != nil {
-			// Check if the error is a normal closure
-			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseNormalClosure) {
-				logrus.Debugf("Client disconnected unexpectedly: %v", err)
-			}
-			break
-		}
-	}
-}
-
-func sendInitialState(client *websocket.Conn) {
-	lastState.RLock()
-	defer lastState.RUnlock()
-
-	if lastState.track == nil {
-		logrus.Debug("No initial state available to send")
-		return
-	}
-
-	if err := client.WriteJSON(lastState.track); err != nil {
-		logrus.Errorf("Failed to send initial state: %v", err)
-		client.Close()
-	}
-}
-
-func messageHandler(ctx context.Context) {
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case msg := <-broadcast:
-			broadcastToClients(msg)
-		}
-	}
-}
-
-func broadcastToClients(msg *spotify.CurrentlyPlaying) {
-	clientsMutex.RLock()
-	defer clientsMutex.RUnlock()
-
-	for client := range clients {
-		client.SetWriteDeadline(time.Now().Add(writeTimeout))
-		if err := client.WriteJSON(msg); err != nil {
-			logrus.Debugf("Broadcast failed: %v", err)
-			client.Close()
-		}
-	}
-}
-
-func trackFetcher(ctx context.Context) {
-	ticker := time.NewTicker(heartbeatInterval)
-	defer ticker.Stop()
-
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case <-ticker.C:
-			fetchAndBroadcastState()
-		}
-	}
-}
-
-func fetchAndBroadcastState() {
-	current, err := spotifyClient.PlayerCurrentlyPlaying()
-	if err != nil {
-		logrus.Errorf("Failed to fetch playback state: %v", err)
-		time.Sleep(apiRetryDelay)
-		return
-	}
-
-	logrus.Debugf("Fetched playback state: %+v", current)
-
-	updateState(current)
-}
-
-func updateState(current *spotify.CurrentlyPlaying) {
-	lastState.Lock()
-	defer lastState.Unlock()
-
-	if current == nil {
-		logrus.Warn("Received nil playback state from Spotify")
-		return
-	}
-
-	if lastState.track == nil {
-		lastState.track = &spotify.CurrentlyPlaying{}
-	}
-
-	stateChanged := lastState.track.Item == nil ||
-		current.Item == nil ||
-		lastState.track.Item.ID != current.Item.ID ||
-		lastState.playing != current.Playing
-
-	lastState.track = current
-	lastState.playing = current.Playing
-
-	if stateChanged || current.Playing {
-		broadcast <- current
-	}
-}
-
-func healthHandler(w http.ResponseWriter, r *http.Request) {
-	w.Header().Set("Content-Type", "text/plain")
-	w.WriteHeader(http.StatusOK)
-	w.Write([]byte("OK"))
-}

readme.md

@@ -42,6 +42,7 @@ services:
       #- LOG_LEVEL=DEBUG|WARN|ERROR
       #- ALLOWED_ORIGINS=http://localhost:3000
       #- SERVER_PORT=3000
+      #- RT=true
 ```
 
 ### Docker run