feat: Adding audio player + music to play

server/main.go

@@ -1,10 +1,14 @@
 package main
 
 import (
+	"encoding/json"
 	"io/fs"
 	"log"
 	"net/http"
 	"os"
+	"path/filepath"
+	"sort"
+	"strings"
 
 	"countrygame/web"
 )
@@ -24,19 +28,31 @@ func main() {
 		os.Exit(0)
 	}
 
+	// Background music: .mp3 files read live from this folder, so adding a track needs no rebuild.
+	musicDir := os.Getenv("MUSIC_DIR")
+	if musicDir == "" {
+		musicDir = "music"
+	}
+
 	root, err := fs.Sub(web.Files, ".")
 	if err != nil {
 		log.Fatal(err)
 	}
 
+	log.Printf("country game listening on :%s (music folder %q)", port, musicDir)
+	log.Fatal(http.ListenAndServe(":"+port, newMux(root, musicDir)))
+}
+
+// newMux serves the embedded game, /healthz, and the music folder under /music/.
+func newMux(root fs.FS, musicDir string) *http.ServeMux {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("ok"))
 	})
+	mux.HandleFunc("/music/index.json", musicIndex(musicDir))
+	mux.Handle("/music/", http.StripPrefix("/music/", noCache(http.FileServer(noListing{http.Dir(musicDir)}))))
 	mux.Handle("/", noCache(http.FileServer(http.FS(root))))
-
-	log.Printf("country game listening on :%s", port)
-	log.Fatal(http.ListenAndServe(":"+port, mux))
+	return mux
 }
 
 // noCache keeps iteration simple: data and scripts are always revalidated.
@@ -46,3 +62,43 @@ func noCache(next http.Handler) http.Handler {
 		next.ServeHTTP(w, r)
 	})
 }
+
+// noListing hides directory listings and dot files: only the tracks themselves are served.
+type noListing struct{ fs http.FileSystem }
+
+func (n noListing) Open(name string) (http.File, error) {
+	if strings.Contains(filepath.Base(name), "..") || strings.HasPrefix(filepath.Base(name), ".") {
+		return nil, os.ErrNotExist
+	}
+	f, err := n.fs.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	if info, err := f.Stat(); err != nil || info.IsDir() {
+		f.Close()
+		return nil, os.ErrNotExist
+	}
+	return f, nil
+}
+
+// musicIndex lists the playable tracks: non-empty .mp3 files (the empty placeholder is skipped), sorted by name.
+// A missing folder is not an error: the game simply shows an empty tape deck.
+func musicIndex(dir string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		tracks := []string{}
+		entries, _ := os.ReadDir(dir)
+		for _, e := range entries {
+			name := e.Name()
+			if e.IsDir() || strings.HasPrefix(name, ".") || !strings.EqualFold(filepath.Ext(name), ".mp3") {
+				continue
+			}
+			if info, err := e.Info(); err == nil && info.Size() > 0 {
+				tracks = append(tracks, name)
+			}
+		}
+		sort.Strings(tracks)
+		w.Header().Set("Content-Type", "application/json")
+		w.Header().Set("Cache-Control", "no-store")
+		json.NewEncoder(w).Encode(map[string]any{"tracks": tracks})
+	}
+}