webui4frpc/internal/httpapi/server.go

// Package httpapi serves the web UI and REST API.
package httpapi

import (
	"bytes"
	"context"
	"embed"
	"encoding/json"
	"fmt"
	"io"
	"io/fs"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"webui4frpc/internal/cluster"
	"webui4frpc/internal/process"
	"webui4frpc/internal/store"
)

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

// Handler bundles dependencies for the HTTP API.
type Handler struct {
	Store    *store.Store
	Process  *process.Manager
	WorkDir  string
	BinDir   string
	User     string
	Password string

	// InstallBinary downloads and activates a frpc binary. Set by the app to
	// avoid an import cycle with the install package.
	InstallBinary func(version string) (path, ver string, err error)
	// BinaryPath resolves the current worker binary.
	BinaryPath func() string
	// RunInstall is a hook to trigger canary tasks after canvas save.
	SyncWorkers func()
	// Cluster is the peer-to-peer binary registry (M6). Nil disables M6 routes.
	Cluster *cluster.Registry
	// Ring is the token-ring engine (M6). Nil disables ring routes.
	Ring *cluster.Engine
	// SelfAddr is this node's reachable listen address (from -addr), used for
	// cluster discovery so peers can reach back for binary exchange.
	SelfAddr string
}

const (
	healthzPath = "/healthz"
	apiPrefix   = "/api/manager"
)

// NewServeMux builds the full HTTP handler.
func NewServeMux(h *Handler) (http.Handler, error) {
	mux := http.NewServeMux()

	auth := func(next http.HandlerFunc) http.HandlerFunc {
		return func(w http.ResponseWriter, r *http.Request) {
			u, p, ok := r.BasicAuth()
			if !ok || u != h.User || p != h.Password {
				w.Header().Set("WWW-Authenticate", `Basic realm="webui-frpc"`)
				w.WriteHeader(http.StatusUnauthorized)
				return
			}
			next(w, r)
		}
	}

	mux.HandleFunc(healthzPath, func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	})

	// API routes (basic auth).
	mux.HandleFunc(apiPrefix+"/status", auth(h.handleStatus))
	mux.HandleFunc(apiPrefix+"/canvas", auth(h.handleCanvasSave))
	mux.HandleFunc(apiPrefix+"/settings", auth(func(w http.ResponseWriter, r *http.Request) {
		if r.Method == http.MethodPut {
			h.handleSettingsPut(w, r)
			return
		}
		h.handleSettingsGet(w, r)
	}))
	mux.HandleFunc(apiPrefix+"/binary/status", auth(h.handleBinaryStatus))
	mux.HandleFunc(apiPrefix+"/binary/install", auth(h.handleBinaryInstall))

	// Profile lifecycle routes.
	mux.HandleFunc(apiPrefix+"/profiles/", auth(h.handleProfile))
	mux.HandleFunc(apiPrefix+"/remotes", auth(h.handleRemoteUpsert))
	mux.HandleFunc(apiPrefix+"/remotes/", auth(h.handleRemoteDelete))

	// M6: cluster nodes + per-node cached versions (UI + discovery).
	mux.HandleFunc(apiPrefix+"/cluster/nodes", auth(h.handleClusterNodes))
	mux.HandleFunc(apiPrefix+"/cluster/cache", auth(h.handleClusterCache))
	mux.HandleFunc(apiPrefix+"/cluster/token", auth(h.handleClusterToken))
	mux.HandleFunc(apiPrefix+"/cluster/ring", auth(h.handleClusterRing))
	mux.HandleFunc(apiPrefix+"/cluster/join", auth(h.handleClusterJoin))
	mux.HandleFunc(apiPrefix+"/cluster/task", auth(h.handleClusterTask))
	mux.HandleFunc(apiPrefix+"/cluster/node-remove", auth(h.handleNodeRemove))
	mux.HandleFunc(apiPrefix+"/cluster/create", auth(h.handleClusterCreate))
	mux.HandleFunc(apiPrefix+"/cluster/join-ring", auth(h.handleClusterJoinRing))

	// M6: peer-to-peer binary exchange endpoint (Basic Auth, same creds).
	// Not under /api so peers hit it directly; auth still applied.
	mux.HandleFunc("/frpc/", auth(h.handleFrpcBinary))

	// Static assets (also basic auth) under /.
	// The SPA shell is served behind the SAME Basic Auth as the API (plan:
	// "healthz 免认证，其余 Basic Auth"). Without this, the browser loads the
	// page without a 401 challenge, never caches credentials, and every
	// same-origin /api/* fetch (credentials:"same-origin") gets 401 — so the
	// SPA renders but all data pages read as empty ("集群未启动"). Wrapping /
	// in auth makes the browser prompt once, cache the Basic header for the
	// origin, and send it on every subsequent asset + API request.
	mux.HandleFunc("/", auth(h.handleStatic))

	return mux, nil
}

// handleStatic serves the embedded web build. Paths map to dist files; / and
// unknown paths serve index.html for SPA routing. The SPA uses hash-based
// routing, so returning index.html for "/" is enough — a redirect here would
// loop (the hash fragment never reaches the server).
func (h *Handler) handleStatic(w http.ResponseWriter, r *http.Request) {
	sub, err := fs.Sub(distFS, "dist")
	if err != nil {
		http.Error(w, "assets unavailable", http.StatusInternalServerError)
		return
	}
	name := strings.TrimPrefix(r.URL.Path, "/")
	if name == "" {
		name = "index.html"
	}
	data, err := fs.ReadFile(sub, name)
	if err != nil {
		// SPA fallback: any non-file path serves index.html.
		data, err = fs.ReadFile(sub, "index.html")
		if err != nil {
			http.NotFound(w, r)
			return
		}
		name = "index.html"
	}
	if ct := contentTypeFor(name); ct != "" {
		w.Header().Set("Content-Type", ct)
	}
	_, _ = w.Write(data)
}

func contentTypeFor(name string) string {
	switch {
	case strings.HasSuffix(name, ".html"):
		return "text/html; charset=utf-8"
	case strings.HasSuffix(name, ".js"):
		return "application/javascript"
	case strings.HasSuffix(name, ".css"):
		return "text/css"
	case strings.HasSuffix(name, ".svg"):
		return "image/svg+xml"
	case strings.HasSuffix(name, ".png"):
		return "image/png"
	case strings.HasSuffix(name, ".ico"):
		return "image/x-icon"
	default:
		return ""
	}
}

// proxyState is a per-proxy status row reported by the local frpc admin
// API (GET /api/status). Status is one of frpc's proxy phases:
// new | wait start | start error | running | check failed | closed.
type proxyState struct {
	Name       string `json:"name"`
	Type       string `json:"type"`
	Status     string `json:"status"`
	Err        string `json:"err,omitempty"`
	LocalAddr  string `json:"local_addr"`
	RemoteAddr string `json:"remote_addr"`
}

func (h *Handler) handleStatus(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		methodNotAllowed(w)
		return
	}
	locals, _ := h.Store.ListLocals()
	remotes, _ := h.Store.ListRemotes()
	settings, _ := h.Store.Settings()

	type profileStatus struct {
		Name     string          `json:"name"`
		Enabled  bool            `json:"enabled"`
		Status   process.Status  `json:"process"`
		HasProc  bool            `json:"hasProcess"`
		Forwards []store.Forward `json:"forwards"`
		// ConnState is the derived frps connection state:
		// connected | connecting | failed | not_started | disabled.
		ConnState string `json:"connState"`
		// AdminEnabled is true when the remote configures a local frpc admin
		// API (adminPort > 0); then ProxyStates reflects real proxy health.
		AdminEnabled bool         `json:"adminEnabled"`
		ProxyStates  []proxyState `json:"proxyStates,omitempty"`
		// GroupCount is the number of distinct LB groups across this remote's
		// forwards (M3 display).
		GroupCount int `json:"groupCount,omitempty"`
	}

	profiles := make([]profileStatus, 0, len(remotes))
	binary := ""
	if h.BinaryPath != nil {
		binary = h.BinaryPath()
	}
	for _, rv := range remotes {
		st, has := h.Process.Status(rv.Name)
		fwd, _ := h.Store.LinksForRemote(rv.Name)
		p := profileStatus{
			Name: rv.Name, Enabled: rv.Enabled, Status: st, HasProc: has, Forwards: fwd,
			AdminEnabled: rv.AdminPort > 0,
			GroupCount:   groupCountOf(locals, fwd),
		}
		if rv.AdminPort > 0 {
			// Query the local frpc admin API for true per-proxy state.
			if states, err := fetchProxyStates(rv.AdminAddr, rv.AdminPort, rv.AdminUser, rv.AdminPassword); err == nil {
				p.ProxyStates = states
			}
		}
		// Prefer admin-derived conn state; fall back to log inference.
		if p.AdminEnabled && len(p.ProxyStates) > 0 {
			p.ConnState = connStateAdmin(p.ProxyStates)
		} else {
			p.ConnState = connStateOf(h.Process.LogPath(rv.Name), rv.Enabled, st)
		}
		profiles = append(profiles, p)
	}

	// Local status: each local plus its forwarding targets and whether each
	// target's worker is healthy (running).
	type localTargetStatus struct {
		Remote      string `json:"remote"`
		RemotePort  int    `json:"remotePort"`
		WorkerState string `json:"workerState"`
	}
	type localStatus struct {
		Local   store.Local         `json:"local"`
		Targets []localTargetStatus `json:"targets"`
	}

	localStatuses := make([]localStatus, 0, len(locals))
	for _, l := range locals {
		targets, err := h.Store.LinksForLocal(l.Name)
		if err != nil {
			targets = nil
		}
		ts := make([]localTargetStatus, 0, len(targets))
		for _, tg := range targets {
			st, _ := h.Process.Status(tg.Remote)
			ts = append(ts, localTargetStatus{
				Remote:      tg.Remote,
				RemotePort:  tg.RemotePort,
				WorkerState: st.State,
			})
		}
		localStatuses = append(localStatuses, localStatus{Local: l, Targets: ts})
	}

	resp := map[string]any{
		"version":     "0.1.0",
		"workDir":     h.WorkDir,
		"settings":    settings,
		"services":    locals,
		"remotes":     remotes,
		"binaryPath":  binary,
		"profiles":    profiles,
		"localStatus": localStatuses,
	}
	writeJSON(w, http.StatusOK, resp)
}

// handleClusterNodes reports registered cluster nodes and their cached frpc
// versions (M6). Used by discovery and the frontend cluster page.
func (h *Handler) handleClusterNodes(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		methodNotAllowed(w)
		return
	}
	if h.Cluster == nil {
		http.Error(w, "cluster registry not enabled", http.StatusNotFound)
		return
	}
	// Self node goes first so a querier can identify us by Nodes[0]. The
	// version we advertise is the newest locally cached frpc (falling back to
	// the configured binary path), so peers can bootstrap the same version.
	type nodeResp struct {
		Addr    string   `json:"addr"`
		Cache   []string `json:"cache,omitempty"`
		Version string   `json:"version,omitempty"`
	}
	out := make([]nodeResp, 0, 1+len(h.Cluster.NodeList()))
	ver := ""
	if cs := h.Cluster.CachedVersions(); len(cs) > 0 {
		ver = cs[len(cs)-1]
	} else if h.BinaryPath != nil {
		ver = frpcVersionOf(h.BinaryPath())
	}
	out = append(out, nodeResp{Addr: h.SelfAddr, Cache: h.Cluster.CachedVersions(), Version: ver})
	for _, n := range h.Cluster.NodeList() {
		out = append(out, nodeResp{Addr: n.Addr, Version: n.Version, Cache: n.Cache})
	}
	writeJSON(w, http.StatusOK, map[string]any{"nodes": out})
}

// handleFrpcBinary serves a cached frpc binary to peer nodes over
// GET /frpc/{version}. Basic Auth is required (same creds as the manager).
func (h *Handler) handleFrpcBinary(w http.ResponseWriter, r *http.Request) {
	if h.Cluster == nil {
		http.NotFound(w, r)
		return
	}
	name := strings.TrimPrefix(r.URL.Path, "/frpc/")
	if name == "" || strings.Contains(name, "/") || strings.Contains(name, "..") {
		http.Error(w, "bad version", http.StatusBadRequest)
		return
	}
	path, checksum, err := h.Cluster.Provide(name)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	f, err := os.Open(path)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	defer f.Close()
	w.Header().Set("Content-Type", "application/octet-stream")
	w.Header().Set("X-Frpc-SHA256", checksum)
	_, _ = io.Copy(w, f)
}

// handleClusterCache lists cached frpc versions (GET) or prunes (POST {keep:N}).
func (h *Handler) handleClusterCache(w http.ResponseWriter, r *http.Request) {
	if h.Cluster == nil {
		http.Error(w, "cluster registry not enabled", http.StatusNotFound)
		return
	}
	switch r.Method {
	case http.MethodGet:
		writeJSON(w, http.StatusOK, map[string]any{"cache": h.Cluster.CacheInfo()})
	case http.MethodPost:
		var req struct {
			Keep int `json:"keep"`
		}
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			http.Error(w, "parse json: "+err.Error(), http.StatusBadRequest)
			return
		}
		if req.Keep < 0 || req.Keep > 50 {
			http.Error(w, "keep in [0,50]", http.StatusBadRequest)
			return
		}
		removed := h.Cluster.PruneCache(req.Keep)
		writeJSON(w, http.StatusOK, map[string]any{"removed": removed, "cache": h.Cluster.CacheInfo()})
	default:
		methodNotAllowed(w)
	}
}

// handleClusterToken receives the circulating token (POST), lets the ring
// engine process it, returns the updated token so the caller can forward it.
func (h *Handler) handleClusterToken(w http.ResponseWriter, r *http.Request) {
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	if r.Method != http.MethodPost {
		methodNotAllowed(w)
		return
	}
	// Heartbeat ping: empty body (no token) is a liveness check from the
	// leader's predecessor — answer 200 without processing.
	if r.Body == nil {
		w.WriteHeader(http.StatusOK)
		return
	}
	body, _ := io.ReadAll(r.Body)
	if len(bytes.TrimSpace(body)) == 0 {
		w.WriteHeader(http.StatusOK)
		return
	}
	var tk cluster.Token
	if err := json.Unmarshal(body, &tk); err != nil {
		http.Error(w, "parse token: "+err.Error(), http.StatusBadRequest)
		return
	}
	updated, err := h.Ring.OnToken(context.Background(), &tk)
	if err != nil {
		http.Error(w, "token process: "+err.Error(), http.StatusInternalServerError)
		return
	}
	// OnToken returns nil when it drops a stale/duplicate token: the token is
	// dead, do NOT hand a nil token onward (would nil-panic in Send/Forward).
	if updated == nil {
		w.WriteHeader(http.StatusOK)
		return
	}
	// Onward forwarding is ASYNC: acknowledge receipt immediately (the
	// token is a relay baton, not a synchronous RPC chain). If we forwarded
	// synchronously, a slow next hop would make this handler hang for the
	// upstream client timeout, which would recursively stall the whole ring.
	nextTK := *updated
	if h.Ring.IsLeader() {
		go func() { _ = h.Ring.Send(context.Background(), &nextTK) }()
	} else {
		go func() { _ = h.Ring.Forward(context.Background(), &nextTK) }()
	}
	writeJSON(w, http.StatusOK, updated)
}

// handleClusterRing reports the local ring engine state snapshot (frontend).
func (h *Handler) handleClusterRing(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		methodNotAllowed(w)
		return
	}
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	writeJSON(w, http.StatusOK, h.Ring.Snapshot())
}

// handleClusterJoin accepts a newcomer join request: the target node inserts
// the newcomer after itself in the ring and returns the updated ring state
// for the newcomer to adopt.
func (h *Handler) handleClusterJoin(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		methodNotAllowed(w)
		return
	}
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	var ji cluster.JoinInfo
	if err := json.NewDecoder(r.Body).Decode(&ji); err != nil {
		http.Error(w, "parse join: "+err.Error(), http.StatusBadRequest)
		return
	}
	wasSingle := len(h.Ring.State().Nodes) <= 1
	state := h.Ring.JoinNode(ji)
	writeJSON(w, http.StatusOK, map[string]any{"state": state})
	// Kick off the token cycle AFTER the newcomer has adopted (respond first,
	// then start in background so the new node is no longer single when the
	// token reaches it).
	if wasSingle && h.Ring.IsLeader() {
		go func() {
			time.Sleep(800 * time.Millisecond)
			h.Ring.StartRing(context.Background())
		}()
	}
}

// handleClusterTask accepts a new forward request (intermediate config:
// local/remote/link) and submits it to the ring as a pending task.
func (h *Handler) handleClusterTask(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		methodNotAllowed(w)
		return
	}
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	var req struct {
		Local  store.Local  `json:"local"`
		Remote store.Remote `json:"remote"`
		Link   store.Link   `json:"link"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "parse task: "+err.Error(), http.StatusBadRequest)
		return
	}
	tk := h.Ring.SubmitTask(req.Local, req.Remote, req.Link)
	writeJSON(w, http.StatusOK, map[string]any{"task": tk})
}

// handleNodeRemove publishes a node-removal command via the token; the
// target node self-removes when the command reaches it.
func (h *Handler) handleNodeRemove(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		methodNotAllowed(w)
		return
	}
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	var req struct {
		ID string `json:"id"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "parse: "+err.Error(), http.StatusBadRequest)
		return
	}
	if req.ID == "" {
		http.Error(w, "node id required", http.StatusBadRequest)
		return
	}
	tk := h.Ring.RemoveNode(req.ID)
	writeJSON(w, http.StatusOK, map[string]any{"task": tk})
}

// handleClusterCreate reseeds this node as a fresh standalone leader (the
// runtime "创建集群" path). Refuses with 409 if this node is still a
// multi-node member — reseeding mid-cluster would split the ring.
func (h *Handler) handleClusterCreate(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		methodNotAllowed(w)
		return
	}
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	if err := h.Ring.CreateCluster(); err != nil {
		http.Error(w, err.Error(), http.StatusConflict)
		return
	}
	writeJSON(w, http.StatusOK, h.Ring.Snapshot())
}

// handleClusterJoinRing is the runtime "加入集群" path: this node joins the
// cluster at the given peer address (newcomer-side — it POSTs its own
// JoinInfo to the peer's /cluster/join and adopts the returned state).
// Synchronous so the UI gets a real success/failure; capped at 10s (the
// peer dial itself times out at 8s). Refuses 409 if already a multi-node
// member (would split the ring).
func (h *Handler) handleClusterJoinRing(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		methodNotAllowed(w)
		return
	}
	if h.Ring == nil {
		http.Error(w, "ring engine not enabled", http.StatusNotFound)
		return
	}
	var req struct {
		Addr string `json:"addr"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "parse: "+err.Error(), http.StatusBadRequest)
		return
	}
	if req.Addr == "" {
		http.Error(w, "addr required", http.StatusBadRequest)
		return
	}
	if h.Ring.IsMember() {
		http.Error(w, "already a multi-node cluster member; leave first", http.StatusConflict)
		return
	}
	jc, cancel := context.WithTimeout(r.Context(), 10*time.Second)
	defer cancel()
	if err := h.Ring.JoinRingAddr(jc, req.Addr); err != nil {
		http.Error(w, "join failed: "+err.Error(), http.StatusBadGateway)
		return
	}
	writeJSON(w, http.StatusOK, h.Ring.Snapshot())
}

// handleClusterJoin accepts a newcomer join request: the target node inserts
// the newcomer after itself in the ring and returns the updated ring state
// for the newcomer to adopt.
// .../bin/frpc-0.71.0/frpc. Empty when not a versioned cache path.
func frpcVersionOf(binPath string) string {
	dir := filepath.Dir(binPath)
	base := filepath.Base(dir)
	if strings.HasPrefix(base, "frpc-") {
		return strings.TrimPrefix(base, "frpc-")
	}
	return ""
}

// connStateOf derives the frps connection state from the local worker process
// state plus a probe of its log. We never control the remote frps: the worker is
// our local frpc; "connected" means frpc has successfully logged in to frps.
// - disabled      -> remote disabled, worker not started
// - running+login -> frpc logged in to frps (connected)
// - running       -> frpc up but not yet logged in (connecting)
// - starting/restarting -> connecting
// - crashed/exit nonzero -> failed
// - stopped clean / no worker -> not_started
func connStateOf(workerLog string, enabled bool, st process.Status) string {
	if !enabled {
		return "disabled"
	}
	switch st.State {
	case "running":
		tail, _ := tailFile(workerLog, 64*1024)
		if tail != "" {
			// frpc prints "login to server success" once the control link is up.
			if strings.Contains(tail, "login to server success") ||
				strings.Contains(tail, "start proxy success") {
				return "connected"
			}
			if strings.Contains(tail, "login to server error") ||
				strings.Contains(tail, "connect to server error") ||
				strings.Contains(tail, "connect server error") {
				return "failed"
			}
		}
		return "connecting"
	case "starting", "restarting":
		return "connecting"
	case "crashed":
		return "failed"
	case "stopped":
		if st.ExitCode != 0 || st.Err != "" {
			return "failed"
		}
		return "not_started"
	default:
		return "not_started"
	}
}

// fetchProxyStates queries a worker's local frpc admin API (webServer) for
// true per-proxy status: GET /api/status returns a map keyed by proxy type,
// each value a list of { name, type, status, err, local_addr, remote_addr }.
// status is one of frpc's proxy phases:
//
//	new | wait start | start error | running | check failed | closed
func fetchProxyStates(addr string, port int, user, pass string) ([]proxyState, error) {
	if addr == "" {
		addr = "127.0.0.1"
	}
	url := fmt.Sprintf("http://%s:%d/api/status", addr, port)
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	req.SetBasicAuth(user, pass)
	cli := &http.Client{Timeout: 3 * time.Second}
	resp, err := cli.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		_, _ = io.Copy(io.Discard, resp.Body)
		return nil, fmt.Errorf("admin status HTTP %d", resp.StatusCode)
	}
	body, err := io.ReadAll(io.LimitReader(resp.Body, 4<<20))
	if err != nil {
		return nil, err
	}
	var m map[string][]proxyState
	if err := json.Unmarshal(body, &m); err != nil {
		return nil, err
	}
	var out []proxyState
	for _, arr := range m {
		out = append(out, arr...)
	}
	return out, nil
}

// connStateAdmin derives the overall worker connection state from the per-proxy
// states reported by the local frpc admin API.
func connStateAdmin(states []proxyState) string {
	if len(states) == 0 {
		return "connecting"
	}
	anyRunning := false
	for _, s := range states {
		switch s.Status {
		case "running":
			anyRunning = true
		case "wait start":
			return "connecting"
		}
	}
	if anyRunning {
		return "connected"
	}
	return "failed"
}

// groupCountOf returns the number of distinct non-empty LB groups a remote
// participates in, by mapping each forward's service back to its local.
func groupCountOf(locals []store.Local, fwd []store.Forward) int {
	groupByLocal := map[string]string{}
	for _, l := range locals {
		if l.LBGroup != "" {
			groupByLocal[l.Name] = l.LBGroup
		}
	}
	seen := map[string]bool{}
	for _, f := range fwd {
		if g := groupByLocal[f.Service]; g != "" {
			seen[g] = true
		}
	}
	return len(seen)
}

func methodNotAllowed(w http.ResponseWriter) {
	http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
}

func writeJSON(w http.ResponseWriter, code int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(code)
	_ = fmtJSONEncode(w, v)
}

func fmtJSONEncode(w http.ResponseWriter, v any) error {
	return json.NewEncoder(w).Encode(v)
}