feat(gui-client): Tauri welcome screen (#4013)

Closes #3961 

No tests yet, might be tricky to test since it's all I/O. 
I cued it off the device ID being generated, so it will have a minor
merge conflict with #3920

```[tasklist]
### Before merging
- [ ] UI polish, or disable the welcome screen temporarily
```

<img width="664" alt="image"
src="https://github.com/firezone/firezone/assets/13400041/d5def59c-b075-4135-91e5-85f9f9212fa5">

---------

Co-authored-by: Jamil Bou Kheir <jamilbk@users.noreply.github.com>

rust/connlib/shared/src/device_id.rs

@@ -2,6 +2,12 @@ use anyhow::{Context, Result};
 use std::fs;
 use std::io::Write;
 
+pub struct DeviceId {
+    /// True iff the device ID was not found on disk and we had to generate it, meaning this is the app's first run since installing.
+    pub is_first_time: bool,
+    pub id: String,
+}
+
 /// Returns the device ID, generating it and saving it to disk if needed.
 ///
 /// Per <https://github.com/firezone/firezone/issues/2697> and <https://github.com/firezone/firezone/issues/2711>,
@@ -10,7 +16,7 @@ use std::io::Write;
 /// Returns: The UUID as a String, suitable for sending verbatim to `connlib_client_shared::Session::connect`.
 ///
 /// Errors: If the disk is unwritable when initially generating the ID, or unwritable when re-generating an invalid ID.
-pub fn get() -> Result<String> {
+pub fn get() -> Result<DeviceId> {
     let dir = imp::path().context("Failed to compute path for firezone-id file")?;
     let path = dir.join("firezone-id.json");
 
@@ -19,9 +25,12 @@ pub fn get() -> Result<String> {
         .ok()
         .and_then(|s| serde_json::from_str::<DeviceIdJson>(&s).ok())
     {
-        let device_id = j.device_id();
-        tracing::debug!(?device_id, "Loaded device ID from disk");
-        return Ok(device_id);
+        let id = j.device_id();
+        tracing::debug!(?id, "Loaded device ID from disk");
+        return Ok(DeviceId {
+            is_first_time: false,
+            id,
+        });
     }
 
     // Couldn't read, it's missing or invalid, generate a new one and save it.
@@ -39,9 +48,12 @@ pub fn get() -> Result<String> {
     file.write(|f| f.write_all(content.as_bytes()))
         .context("Failed to write firezone-id file")?;
 
-    let device_id = j.device_id();
-    tracing::debug!(?device_id, "Saved device ID to disk");
-    Ok(j.device_id())
+    let id = j.device_id();
+    tracing::debug!(?id, "Saved device ID to disk");
+    Ok(DeviceId {
+        is_first_time: true,
+        id,
+    })
 }
 
 #[derive(serde::Deserialize, serde::Serialize)]

rust/gui-client/src-tauri/src/client.rs

@@ -16,6 +16,7 @@ mod resolvers;
 mod settings;
 mod updates;
 mod uptime;
+mod welcome;
 
 #[cfg(target_os = "windows")]
 mod wintun_install;

rust/gui-client/src-tauri/src/client/gui.rs

@@ -8,7 +8,7 @@ use crate::client::{
     settings::{self, AdvancedSettings},
     Failure,
 };
-use anyhow::{anyhow, bail, Context, Result};
+use anyhow::{bail, Context, Result};
 use arc_swap::ArcSwap;
 use connlib_client_shared::{file_logger, ResourceDescription};
 use connlib_shared::{keypair, messages::ResourceId, LoginUrl, BUNDLE_ID};
@@ -209,6 +209,7 @@ pub(crate) fn run(cli: &client::Cli) -> Result<(), Error> {
             settings::apply_advanced_settings,
             settings::reset_advanced_settings,
             settings::get_advanced_settings,
+            crate::client::welcome::sign_in,
         ])
         .system_tray(tray)
         .on_system_tray_event(|app, event| {
@@ -430,6 +431,7 @@ pub(crate) enum ControllerRequest {
     Fail(Failure),
     GetAdvancedSettings(oneshot::Sender<AdvancedSettings>),
     SchemeRequest(SecretString),
+    SignIn,
     SystemTrayMenu(TrayMenuEvent),
     TunnelReady,
     UpdateAvailable(client::updates::Release),
@@ -618,6 +620,17 @@ impl Controller {
                 .handle_deep_link(&url)
                 .await
                 .context("Couldn't handle deep link")?,
+            Req::SignIn | Req::SystemTrayMenu(TrayMenuEvent::SignIn) => {
+                if let Some(req) = self.auth.start_sign_in()? {
+                    let url = req.to_url(&self.advanced_settings.auth_base_url);
+                    self.refresh_system_tray_menu()?;
+                    os::open_url(&self.app, &url)?;
+                    self.app
+                        .get_window("welcome")
+                        .context("Couldn't get handle to Welcome window")?
+                        .hide()?;
+                }
+            }
             Req::SystemTrayMenu(TrayMenuEvent::CancelSignIn) => {
                 if self.session.is_some() {
                     // If the user opened the menu, then sign-in completed, then they
@@ -648,13 +661,6 @@ impl Controller {
             Req::SystemTrayMenu(TrayMenuEvent::Resource { id }) => self
                 .copy_resource(&id)
                 .context("Couldn't copy resource to clipboard")?,
-            Req::SystemTrayMenu(TrayMenuEvent::SignIn) => {
-                if let Some(req) = self.auth.start_sign_in()? {
-                    let url = req.to_url(&self.advanced_settings.auth_base_url);
-                    self.refresh_system_tray_menu()?;
-                    os::open_url(&self.app, &url)?;
-                }
-            }
             Req::SystemTrayMenu(TrayMenuEvent::SignOut) => {
                 tracing::info!("User asked to sign out");
                 self.sign_out()?;
@@ -759,7 +765,7 @@ impl Controller {
         let win = self
             .app
             .get_window(id)
-            .ok_or_else(|| anyhow!("getting handle to `{id}` window"))?;
+            .context("Couldn't get handle to `{id}` window")?;
 
         win.show()?;
         win.unminimize()?;
@@ -779,6 +785,14 @@ async fn run_controller(
     let device_id =
         connlib_shared::device_id::get().context("Failed to read / create device ID")?;
 
+    if device_id.is_first_time {
+        let win = app
+            .get_window("welcome")
+            .context("Couldn't get handle to Welcome window")?;
+        win.show()?;
+    }
+    let device_id = device_id.id;
+
     let mut controller = Controller {
         advanced_settings,
         app,

rust/gui-client/src-tauri/src/client/settings.rs

@@ -82,12 +82,15 @@ pub(crate) async fn get_advanced_settings(
     managed: tauri::State<'_, Managed>,
 ) -> Result<AdvancedSettings, String> {
     let (tx, rx) = oneshot::channel();
-    if let Err(e) = managed
+    if let Err(error) = managed
         .ctlr_tx
         .send(ControllerRequest::GetAdvancedSettings(tx))
         .await
     {
-        tracing::error!("couldn't request advanced settings from controller task: {e}");
+        tracing::error!(
+            ?error,
+            "couldn't request advanced settings from controller task"
+        );
     }
     Ok(rx.await.unwrap())
 }

rust/gui-client/src-tauri/src/client/welcome.rs

@@ -0,0 +1,12 @@
+//! Everything related to the Welcome window
+
+use crate::client::gui::{ControllerRequest, Managed};
+
+// Tauri requires a `Result` here, maybe in case the managed state can't be retrieved
+#[tauri::command]
+pub(crate) async fn sign_in(managed: tauri::State<'_, Managed>) -> anyhow::Result<(), String> {
+    if let Err(error) = managed.ctlr_tx.send(ControllerRequest::SignIn).await {
+        tracing::error!(?error, "Couldn't request `Controller` to begin signing in");
+    }
+    Ok(())
+}

rust/gui-client/src-tauri/tauri.conf.json

@@ -65,7 +65,17 @@
         "resizable": true,
         "width": 640,
         "height": 480,
-        "visible": true
+        "visible": false
+      },
+      {
+        "label": "welcome",
+        "title": "Welcome",
+        "url": "welcome.html",
+        "fullscreen": false,
+        "resizable": true,
+        "width": 640,
+        "height": 480,
+        "visible": false
       }
     ]
   }

rust/gui-client/src/welcome.html

@@ -0,0 +1,33 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <link rel="stylesheet" href="output.css" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>Welcome to Firezone</title>
+    <script src="./flowbite.min.js" defer></script>
+    <script type="module" src="welcome.js" defer></script>
+  </head>
+
+  <body class="bg-neutral-100 text-neutral-900">
+    <div class="container mx-auto">
+      <div class="flex justify-center mt-8">
+        <h1 class="text-3xl font-bold">Welcome to Firezone.</h1>
+      </div>
+      <p class="mt-8 flex justify-center">Sign in below to get started.</p>
+      <img
+        src="logo.png"
+        alt="Firezone Logo"
+        class="mt-8 rounded-full w-48 h-48 mx-auto bg-white shadow border-2 border-black"
+      />
+      <div class="flex justify-center mt-8">
+        <button
+          class="text-white bg-accent-450 hover:bg-accent-700 font-medium rounded text-lg w-full sm:w-auto px-5 py-2.5 text-center"
+          id="sign-in"
+        >
+          Sign in
+        </button>
+      </div>
+    </div>
+  </body>
+</html>

rust/gui-client/src/welcome.ts

@@ -0,0 +1,18 @@
+import "./tauri_stub.js";
+
+const invoke = window.__TAURI__.tauri.invoke;
+
+const signInBtn = <HTMLButtonElement>(
+  document.getElementById("sign-in")
+);
+
+async function sign_in() {
+  console.log("Signing in...");
+  invoke("sign_in")
+    .then(() => {})
+    .catch((e: Error) => {
+      console.error(e);
+    });
+}
+
+signInBtn.addEventListener("click", (e) => sign_in());

rust/linux-client/src/main.rs

@@ -28,7 +28,7 @@ async fn main() -> Result<()> {
     // AKA "Device ID", not the Firezone slug
     let firezone_id = match cli.firezone_id {
         Some(id) => id,
-        None => connlib_shared::device_id::get().context("Could not get `firezone_id` from CLI, could not read it from disk, could not generate it and save it to disk")?,
+        None => connlib_shared::device_id::get().context("Could not get `firezone_id` from CLI, could not read it from disk, could not generate it and save it to disk")?.id,
     };
 
     let (private_key, public_key) = keypair();