update

server/backgrounds/handler.go

@@ -0,0 +1,140 @@
+package backgrounds
+
+import (
+	"context"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/navidrome/navidrome/consts"
+	"github.com/navidrome/navidrome/log"
+	"github.com/navidrome/navidrome/utils/cache"
+	"github.com/navidrome/navidrome/utils/random"
+	"gopkg.in/yaml.v3"
+)
+
+const (
+	//imageHostingUrl = "https://unsplash.com/photos/%s/download?fm=jpg&w=1600&h=900&fit=max"
+	imageHostingUrl     = "https://www.navidrome.org/images/%s.webp"
+	imageListURL        = "https://www.navidrome.org/images/index.yml"
+	imageListTTL        = 24 * time.Hour
+	imageCacheDir       = "backgrounds"
+	imageCacheSize      = "100MB"
+	imageCacheMaxItems  = 1000
+	imageRequestTimeout = 5 * time.Second
+)
+
+type Handler struct {
+	httpClient *cache.HTTPClient
+	cache      cache.FileCache
+}
+
+func NewHandler() *Handler {
+	h := &Handler{}
+	h.httpClient = cache.NewHTTPClient(&http.Client{Timeout: 5 * time.Second}, imageListTTL)
+	h.cache = cache.NewFileCache(imageCacheDir, imageCacheSize, imageCacheDir, imageCacheMaxItems, h.serveImage)
+	go func() {
+		_, _ = h.getImageList(log.NewContext(context.Background()))
+	}()
+	return h
+}
+
+type cacheKey string
+
+func (k cacheKey) Key() string {
+	return string(k)
+}
+
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	image, err := h.getRandomImage(r.Context())
+	if err != nil {
+		h.serveDefaultImage(w)
+		return
+	}
+	s, err := h.cache.Get(r.Context(), cacheKey(image))
+	if err != nil {
+		h.serveDefaultImage(w)
+		return
+	}
+	defer s.Close()
+
+	w.Header().Set("content-type", "image/webp")
+	_, _ = io.Copy(w, s.Reader)
+}
+
+func (h *Handler) serveDefaultImage(w http.ResponseWriter) {
+	defaultImage, _ := base64.StdEncoding.DecodeString(consts.DefaultUILoginBackgroundOffline)
+	w.Header().Set("content-type", "image/png")
+	_, _ = w.Write(defaultImage)
+}
+
+func (h *Handler) serveImage(ctx context.Context, item cache.Item) (io.Reader, error) {
+	start := time.Now()
+	image := item.Key()
+	if image == "" {
+		return nil, errors.New("empty image name")
+	}
+	c := http.Client{Timeout: imageRequestTimeout}
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, imageURL(image), nil)
+	resp, err := c.Do(req) //nolint:bodyclose // No need to close resp.Body, it will be closed via the CachedStream wrapper
+	if errors.Is(err, context.DeadlineExceeded) {
+		defaultImage, _ := base64.StdEncoding.DecodeString(consts.DefaultUILoginBackgroundOffline)
+		return strings.NewReader(string(defaultImage)), nil
+	}
+	if err != nil {
+		return nil, fmt.Errorf("could not get background image from hosting service: %w", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code getting background image from hosting service: %d", resp.StatusCode)
+	}
+	log.Debug(ctx, "Got background image from hosting service", "image", image, "elapsed", time.Since(start))
+
+	return resp.Body, nil
+}
+
+func (h *Handler) getRandomImage(ctx context.Context) (string, error) {
+	list, err := h.getImageList(ctx)
+	if err != nil {
+		return "", err
+	}
+	if len(list) == 0 {
+		return "", errors.New("no images available")
+	}
+	rnd := random.Int64N(len(list))
+	return list[rnd], nil
+}
+
+func (h *Handler) getImageList(ctx context.Context) ([]string, error) {
+	start := time.Now()
+
+	req, _ := http.NewRequestWithContext(ctx, http.MethodGet, imageListURL, nil)
+	resp, err := h.httpClient.Do(req)
+	if err != nil {
+		log.Warn(ctx, "Could not get background images from image service", err)
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	var list []string
+	dec := yaml.NewDecoder(resp.Body)
+	err = dec.Decode(&list)
+	if err != nil {
+		log.Warn(ctx, "Could not decode background images from image service", err)
+		return nil, err
+	}
+	log.Debug(ctx, "Loaded background images from image service", "total", len(list), "elapsed", time.Since(start))
+	return list, nil
+}
+
+func imageURL(imageName string) string {
+	// Discard extension
+	parts := strings.Split(imageName, ".")
+	if len(parts) > 1 {
+		imageName = parts[0]
+	}
+	return fmt.Sprintf(imageHostingUrl, imageName)
+}