// Package adminui serves the compiled management console from the API binary.
package adminui

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

//go:embed all:dist
var assets embed.FS

func Handler() http.Handler {
	root, _ := fs.Sub(assets, "dist")
	files := http.FileServer(http.FS(root))
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet && r.Method != http.MethodHead {
			w.Header().Set("Allow", "GET, HEAD")
			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
			return
		}
		name := strings.TrimPrefix(path.Clean("/"+r.URL.Path), "/")
		if strings.HasPrefix(name, ".") || strings.Contains(name, "/.") {
			http.NotFound(w, r)
			return
		}
		if _, err := fs.Stat(root, "index.html"); err != nil {
			http.Error(w, "Management console not built. Run npm --prefix web/admin run build, then rebuild the Go executable.", http.StatusServiceUnavailable)
			return
		}
		if name != "" && name != "." {
			if info, err := fs.Stat(root, name); err == nil && !info.IsDir() {
				files.ServeHTTP(w, r)
				return
			}
		}
		if path.Ext(name) != "" || strings.HasPrefix(name, "assets/") {
			http.NotFound(w, r)
			return
		}
		index, err := fs.ReadFile(root, "index.html")
		if err != nil {
			http.Error(w, "Management console unavailable", http.StatusServiceUnavailable)
			return
		}
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Header().Set("Cache-Control", "no-cache")
		w.WriteHeader(http.StatusOK)
		if r.Method != http.MethodHead {
			_, _ = w.Write(index)
		}
	})
}