Add admin UI

internal/admin/static.go

@@ -0,0 +1,62 @@
+package admin
+
+import (
+	"embed"
+	"io"
+	"io/fs"
+	"net/http"
+	"path"
+	"strings"
+)
+
+//go:embed all:dist
+var frontendAssets embed.FS
+
+// serveSPA serves the frontend SPA with fallback to index.html for client-side routing.
+func (s *AdminServer) serveSPA() http.Handler {
+	// Get the dist subdirectory from embedded files
+	distFS, err := fs.Sub(frontendAssets, "dist")
+	if err != nil {
+		s.logger.Error("failed to access frontend assets", "error", err)
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			http.Error(w, "Admin UI not available", http.StatusNotFound)
+		})
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Path comes in without /admin prefix due to StripPrefix
+		urlPath := r.URL.Path
+		if urlPath == "" || urlPath == "/" {
+			urlPath = "index.html"
+		} else {
+			// Remove leading slash
+			urlPath = strings.TrimPrefix(urlPath, "/")
+		}
+
+		// Clean the path
+		cleanPath := path.Clean(urlPath)
+
+		// Try to open the file
+		file, err := distFS.Open(cleanPath)
+		if err != nil {
+			// File not found, serve index.html for SPA routing
+			cleanPath = "index.html"
+			file, err = distFS.Open(cleanPath)
+			if err != nil {
+				http.Error(w, "Not found", http.StatusNotFound)
+				return
+			}
+		}
+		defer file.Close()
+
+		// Get file info for content type detection
+		info, err := file.Stat()
+		if err != nil {
+			http.Error(w, "Internal error", http.StatusInternalServerError)
+			return
+		}
+
+		// Serve the file
+		http.ServeContent(w, r, cleanPath, info.ModTime(), file.(io.ReadSeeker))
+	})
+}