package frontend

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

//go:embed all:build
var files embed.FS

// Handler returns an http.Handler that serves the embedded SvelteKit SPA.
// Unknown paths fall back to index.html for client-side routing.
func Handler() http.Handler {
	fsys, _ := fs.Sub(files, "build")
	fileServer := http.FileServer(http.FS(fsys))

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Try to serve static file first
		path := r.URL.Path
		if path == "/" {
			path = "/index.html"
		}

		// Check if the file exists in the embedded filesystem
		cleanPath := path[1:] // Remove leading slash
		if cleanPath == "" {
			cleanPath = "index.html"
		}

		if _, err := fs.Stat(fsys, cleanPath); err != nil {
			// SPA fallback: serve index.html for client-side routing
			r.URL.Path = "/"
		}

		fileServer.ServeHTTP(w, r)
	})
}