package webapp

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

//go:embed static/*
var assets embed.FS

func Handler() http.Handler {
	static, err := fs.Sub(assets, "static")
	if err != nil {
		panic(err)
	}
	files := http.FileServer(http.FS(static))

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path == "/" {
			serveIndex(w, r, static)
			return
		}
		if strings.HasPrefix(r.URL.Path, "/assets/") {
			http.StripPrefix("/assets/", files).ServeHTTP(w, r)
			return
		}
		http.NotFound(w, r)
	})
}

func serveIndex(w http.ResponseWriter, r *http.Request, static fs.FS) {
	content, err := fs.ReadFile(static, "index.html")
	if err != nil {
		http.Error(w, "web app unavailable", http.StatusInternalServerError)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	_, _ = w.Write(content)
}