refactor

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
+}