// Command unibus_admin is the web administration panel for the unibus message
// bus. It is a single Go binary that (a) serves an embedded Mantine SPA and (b)
// exposes a small REST API. The binary holds the operator's ADMIN identity and
// mediates every privileged action against the unibus control plane (signing
// each request) and, when given direct store access, the bus user allowlist. The
// browser never signs, never speaks NATS, and never sees a private key.
package main

import (
	"context"
	"flag"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	cs "fn-registry/functions/cybersecurity"

	"github.com/enmanuel/unibus/pkg/membership"

	"github.com/enmanuel/unibus_admin/internal/admin"
)

func main() {
	var (
		bind         = flag.String("bind", "127.0.0.1", "interface to bind the admin HTTP server to (loopback by default; Caddy fronts it)")
		port         = flag.String("port", "8480", "admin HTTP port")
		ctrlURL      = flag.String("ctrl-url", "http://127.0.0.1:8470", "primary unibus control-plane base URL")
		ctrlURLs     = flag.String("ctrl-urls", "", "comma-separated ADDITIONAL control-plane base URLs (cluster failover)")
		natsURL      = flag.String("nats-url", "nats://127.0.0.1:4250", "primary NATS URL")
		natsURLs     = flag.String("nats-urls", "", "comma-separated ADDITIONAL NATS seed URLs (cluster failover)")
		caPath       = flag.String("ca", "", "bus CA cert path; set to talk TLS+nkey to a secured bus (empty = plaintext dev)")
		nodesCSV     = flag.String("nodes", "", "cluster nodes to probe for /healthz as name=url,name=url (default: derive one from --ctrl-url)")
		identityFile = flag.String("identity-file", "", "path to the admin identity JSON file (0600). Mutually exclusive with --identity-pass")
		identityPass = flag.String("identity-pass", "", "pass(1) entry holding the admin identity JSON, e.g. unibus/operator-identity")
		dbPath       = flag.String("db", "", "membership SQLite path for the Users tab (single-node/dev). Empty = Users tab read-only-unavailable unless --mock")
		mock         = flag.Bool("mock", false, "serve sample data instead of talking to the bus (UI iteration)")
	)
	flag.Parse()

	log.SetFlags(log.LstdFlags | log.Lmsgprefix)
	log.SetPrefix("[unibus_admin] ")

	files, err := spaFS()
	if err != nil {
		log.Fatalf("embed SPA: %v", err)
	}

	var repo admin.Repo
	if *mock {
		repo = admin.NewMockRepo()
		log.Printf("MODE: mock (sample data, no bus connection)")
	} else {
		id, err := loadIdentity(*identityFile, *identityPass)
		if err != nil {
			log.Fatalf("%v", err)
		}
		var store membership.Store
		backend := "none"
		if *dbPath != "" {
			store, err = membership.Open(*dbPath)
			if err != nil {
				log.Fatalf("open membership store %q: %v", *dbPath, err)
			}
			defer store.Close()
			backend = "sqlite"
			log.Printf("users backend: sqlite %s", *dbPath)
		} else {
			log.Printf("users backend: none (Users tab degraded; pass --db for single-node user management)")
		}

		nodes := parseNodes(*nodesCSV, *ctrlURL)
		busRepo, err := admin.NewBusRepo(admin.BusConfig{
			Identity:     id,
			NatsURL:      *natsURL,
			CtrlURL:      *ctrlURL,
			CtrlURLs:     splitCSV(*ctrlURLs),
			NatsURLs:     splitCSV(*natsURLs),
			CAPath:       *caPath,
			Nodes:        nodes,
			Store:        store,
			StoreBackend: backend,
		})
		if err != nil {
			log.Fatalf("%v", err)
		}
		defer busRepo.Close()
		repo = busRepo
		me := busRepo.Me(context.Background())
		log.Printf("admin endpoint: %s", me.Endpoint)
		log.Printf("control plane: %s (+%d failover)", *ctrlURL, len(splitCSV(*ctrlURLs)))
		log.Printf("cluster nodes probed: %d", len(nodes))
		tls := "OFF (plaintext dev)"
		if *caPath != "" {
			tls = "ON (CA " + *caPath + ")"
		}
		log.Printf("bus TLS+nkey: %s", tls)
	}

	srv := admin.NewServer(repo, files)
	addr := *bind + ":" + *port
	httpSrv := &http.Server{
		Addr:              addr,
		Handler:           srv,
		ReadHeaderTimeout: 10 * time.Second,
	}

	go func() {
		log.Printf("admin panel: http://%s", addr)
		if err := httpSrv.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("http server: %v", err)
		}
	}()

	stop := make(chan os.Signal, 1)
	signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM)
	<-stop
	log.Printf("shutting down...")
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	_ = httpSrv.Shutdown(ctx)
	log.Printf("bye")
}

// loadIdentity resolves the admin identity from exactly one of --identity-file or
// --identity-pass.
func loadIdentity(file, passEntry string) (cs.Identity, error) {
	switch {
	case file != "" && passEntry != "":
		return cs.Identity{}, errFlag("set only one of --identity-file or --identity-pass")
	case file != "":
		return admin.LoadIdentityFromFile(file)
	case passEntry != "":
		return admin.LoadIdentityFromPass(passEntry)
	default:
		return cs.Identity{}, errFlag("an identity is required: pass --identity-file <path> or --identity-pass <entry> (or run with --mock)")
	}
}

type flagErr string

func (e flagErr) Error() string { return string(e) }
func errFlag(s string) error    { return flagErr("unibus_admin: " + s) }

// parseNodes builds the cluster probe list from a name=url CSV, falling back to a
// single node derived from the primary control-plane URL when none is given.
func parseNodes(csv, ctrlURL string) []admin.NodeTarget {
	var out []admin.NodeTarget
	for _, item := range splitCSV(csv) {
		name, url, ok := strings.Cut(item, "=")
		if !ok {
			// Bare URL: name it by its host.
			out = append(out, admin.NodeTarget{Name: hostOf(item), URL: item})
			continue
		}
		out = append(out, admin.NodeTarget{Name: strings.TrimSpace(name), URL: strings.TrimSpace(url)})
	}
	if len(out) == 0 && ctrlURL != "" {
		out = append(out, admin.NodeTarget{Name: hostOf(ctrlURL), URL: ctrlURL})
	}
	return out
}

func hostOf(url string) string {
	s := url
	s = strings.TrimPrefix(s, "https://")
	s = strings.TrimPrefix(s, "http://")
	if i := strings.IndexAny(s, ":/"); i >= 0 {
		s = s[:i]
	}
	if s == "" {
		return "node"
	}
	return s
}

func splitCSV(s string) []string {
	var out []string
	for _, p := range strings.Split(s, ",") {
		if p = strings.TrimSpace(p); p != "" {
			out = append(out, p)
		}
	}
	return out
}