package api

import (
	"net/http"
	"os"
	"path/filepath"
	"strings"
)

// MountStatic serves files from dir under baseURL. If baseURL == "/", it serves root.
// Directory listings are disabled. Unknown paths fall back to index.html (SPA).
func (s *Server) MountStatic(dir string, baseURL string) {
	if dir == "" {
		return
	}
	if baseURL == "" {
		baseURL = "/"
	}
	fs := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		s.secureHeaders(w)
		// normalize path inside dir
		up := strings.TrimPrefix(r.URL.Path, baseURL)
		if up == "" || strings.HasSuffix(r.URL.Path, "/") {
			up = "index.html"
		}
		full := filepath.Join(dir, filepath.FromSlash(up))
		// prevent path escape
		if !strings.HasPrefix(filepath.Clean(full), filepath.Clean(dir)) {
			http.NotFound(w, r)
			return
		}
		// serve if exists, else SPA fallback
		if st, err := os.Stat(full); err == nil && !st.IsDir() {
			http.ServeFile(w, r, full)
			return
		}
		fallback := filepath.Join(dir, "index.html")
		if _, err := os.Stat(fallback); err == nil {
			http.ServeFile(w, r, fallback)
			return
		}
		http.NotFound(w, r)
	})
	// Root or subpath
	if baseURL == "/" {
		s.mux.Handle("/", fs)
	} else {
		if !strings.HasSuffix(baseURL, "/") {
			baseURL += "/"
		}
		s.mux.Handle(baseURL, fs)
		s.mux.Handle(baseURL+"", fs) // ensure exact mount works
	}
}