NexaVPN/desktop-client/src/App.tsx

import { FormEvent, useEffect, useState } from "react";
import { invoke } from "@tauri-apps/api/core";

type EnrollmentState = {
  assignedIp: string;
  resources: string[];
  profileRevision: number;
  gatewayEndpoint: string;
  profilePath: string;
  lastSyncTime: string;
  tunnelStrategy: string;
};

function formatInvokeError(err: unknown, fallback: string) {
  if (typeof err === "string" && err.trim().length > 0) {
    return err;
  }

  if (err instanceof Error && err.message.trim().length > 0) {
    return err.message;
  }

  return fallback;
}

export function App() {
  const [serverUrl, setServerUrl] = useState("http://localhost");
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const [connected, setConnected] = useState(false);
  const [state, setState] = useState<EnrollmentState | null>(null);

  useEffect(() => {
    void invoke<EnrollmentState | null>("load_state")
      .then((value) => {
        if (value) {
          setState(value);
        }
      })
      .catch(() => undefined);
  }, []);

  async function onSubmit(event: FormEvent) {
    event.preventDefault();
    setLoading(true);
    setError(null);

    try {
      const result = await invoke<EnrollmentState>("enroll_device", {
        payload: { serverUrl, username, password }
      });
      setState(result);
    } catch (err) {
      setError(formatInvokeError(err, "Enrollment failed"));
    } finally {
      setLoading(false);
    }
  }

  async function toggleConnection() {
    const command = connected ? "disconnect_tunnel" : "connect_tunnel";
    try {
      await invoke(command);
      setConnected((value) => !value);
      setError(null);
    } catch (err) {
      setError(formatInvokeError(err, "Tunnel action failed"));
    }
  }

  return (
    <div className="client-shell">
      <div className="hero">
        <p className="eyebrow">NexaVPN</p>
        <h1>Private access without manual WireGuard setup.</h1>
        <p className="lede">
          Enter your VPN address, username, and password. NexaVPN provisions and stores the profile for you.
        </p>
      </div>

      {!state ? (
        <form className="panel" onSubmit={onSubmit}>
          <label>
            VPN server address
            <input value={serverUrl} onChange={(event) => setServerUrl(event.target.value)} />
          </label>
          <label>
            Username
            <input value={username} onChange={(event) => setUsername(event.target.value)} />
          </label>
          <label>
            Password
            <input type="password" value={password} onChange={(event) => setPassword(event.target.value)} />
          </label>
          {error ? <div className="error">{error}</div> : null}
          <button disabled={loading} type="submit">
            {loading ? "Provisioning..." : "Sign in"}
          </button>
        </form>
      ) : (
        <div className="panel status">
          <div className="status-row">
            <div>
              <p className="eyebrow">Connection</p>
              <h2>{connected ? "Connected" : "Disconnected"}</h2>
            </div>
            <button onClick={toggleConnection}>{connected ? "Disconnect" : "Connect"}</button>
          </div>
          <div className="details">
            <div>
              <span>Assigned VPN IP</span>
              <strong>{state.assignedIp}</strong>
            </div>
            <div>
              <span>Gateway</span>
              <strong>{state.gatewayEndpoint}</strong>
            </div>
            <div>
              <span>Profile revision</span>
              <strong>{state.profileRevision}</strong>
            </div>
            <div>
              <span>Last sync</span>
              <strong>{state.lastSyncTime}</strong>
            </div>
          </div>
          <div className="details">
            <div>
              <span>Profile path</span>
              <strong>{state.profilePath}</strong>
            </div>
            <div>
              <span>Tunnel strategy</span>
              <strong>{state.tunnelStrategy}</strong>
            </div>
          </div>
          {error ? <div className="error">{error}</div> : null}
          <div>
            <p className="eyebrow">Allowed resources</p>
            <ul className="resource-list">
              {state.resources.map((resource) => (
                <li key={resource}>{resource}</li>
              ))}
            </ul>
          </div>
        </div>
      )}
    </div>
  );
}