package api

import (
	"log"
	"mime"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"
)

func init() {
	// Ensure common types are known (some distros are sparse by default)
	_ = mime.AddExtensionType(".js", "application/javascript; charset=utf-8")
	_ = mime.AddExtensionType(".css", "text/css; charset=utf-8")
	_ = mime.AddExtensionType(".html", "text/html; charset=utf-8")
	_ = mime.AddExtensionType(".map", "application/json; charset=utf-8")
}

func (s *Server) MountStatic(dir string, baseURL string) {
	if dir == "" {
		return
	}
	if baseURL == "" {
		baseURL = "/"
	}
	s.mux.Handle(baseURL, s.staticHandler(dir, baseURL))
	if !strings.HasSuffix(baseURL, "/") {
		s.mux.Handle(baseURL+"/", s.staticHandler(dir, baseURL))
	}
}

func (s *Server) ListenFrontendHTTP(addr, dir, baseURL string) error {
	if dir == "" || addr == "" {
		return nil
	}
	log.Printf("frontend listening on %s (dir=%s base=%s)", addr, dir, baseURL)
	mx := http.NewServeMux()
	mx.Handle(baseURL, s.staticHandler(dir, baseURL))
	if !strings.HasSuffix(baseURL, "/") {
		mx.Handle(baseURL+"/", s.staticHandler(dir, baseURL))
	}
	server := &http.Server{
		Addr:              addr,
		Handler:           mx,
		ReadHeaderTimeout: 5 * time.Second,
	}
	return server.ListenAndServe()
}

func (s *Server) staticHandler(dir, baseURL string) http.Handler {
	if baseURL == "" {
		baseURL = "/"
	}
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		s.secureHeaders(w)

		up := strings.TrimPrefix(r.URL.Path, baseURL)
		if up == "" || strings.HasSuffix(r.URL.Path, "/") {
			up = "index.html"
		}
		full := filepath.Join(dir, filepath.FromSlash(up))
		if !strings.HasPrefix(filepath.Clean(full), filepath.Clean(dir)) {
			http.NotFound(w, r)
			return
		}

		// Serve file if it exists, else SPA-fallback to index.html
		if st, err := os.Stat(full); err == nil && !st.IsDir() {
			// Set Content-Type explicitly based on extension
			if ctype := mime.TypeByExtension(filepath.Ext(full)); ctype != "" {
				w.Header().Set("Content-Type", ctype)
			}
			http.ServeFile(w, r, full)
			return
		}
		fallback := filepath.Join(dir, "index.html")
		if _, err := os.Stat(fallback); err == nil {
			w.Header().Set("Content-Type", "text/html; charset=utf-8")
			http.ServeFile(w, r, fallback)
			return
		}
		http.NotFound(w, r)
	})
}