package static

import (
	"io/fs"
	"net/http"
	"path"
)

type SPAHandler struct {
	assets fs.FS
	files  http.Handler
}

func NewSPAHandler() (http.Handler, error) {
	sub, err := fs.Sub(DistFS, "dist")
	if err != nil {
		return nil, err
	}
	return &SPAHandler{
		assets: sub,
		files:  http.FileServer(http.FS(sub)),
	}, nil
}

func (h *SPAHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	requested := path.Clean(r.URL.Path)
	if requested == "." || requested == "/" {
		h.serveIndex(w, r)
		return
	}
	candidate := requested[1:]
	if candidate == "" {
		h.serveIndex(w, r)
		return
	}
	if file, err := h.assets.Open(candidate); err == nil {
		_ = file.Close()
		h.files.ServeHTTP(w, r)
		return
	}
	h.serveIndex(w, r)
}

func (h *SPAHandler) serveIndex(w http.ResponseWriter, r *http.Request) {
	index, err := fs.ReadFile(h.assets, "index.html")
	if err != nil {
		http.Error(w, "index.html not found", http.StatusNotFound)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write(index)
}