setup: auto-download official installer for existing launchers too

src/setup.rs

@@ -22,6 +22,7 @@ pub enum Message {
     // Install stage
     Back,
     SourceChanged(String),
+    AutoDownload,
     PreparePressed,
     PrepareDone(Result<PathBuf, String>),
     InstallPressed,
@@ -224,6 +225,34 @@ fn update(state: &mut State, message: Message) -> Task<Message> {
             state.source = s;
             Task::none()
         }
+        Message::AutoDownload => {
+            // Auto-start download for launchers with an official installer URL
+            let url = state.source.clone();
+            if url.is_empty() {
+                return Task::none();
+            }
+            state.stage = Stage::Busy;
+            let display_name = state
+                .launcher
+                .as_ref()
+                .map(|l| l.display.clone())
+                .unwrap_or_else(|| "installer".to_string());
+            state.status = format!("Downloading {} installer…", display_name);
+            if let Ok(mut p) = state.download.lock() {
+                *p = DownloadProgress::default();
+            }
+            let name = state
+                .launcher
+                .as_ref()
+                .expect("launcher set")
+                .name
+                .clone();
+            let progress = state.download.clone();
+            Task::perform(
+                async_blocking(move || download_blocking(&url, &name, progress)),
+                Message::PrepareDone,
+            )
+        }
         Message::PreparePressed => {
             let src = state.source.trim().to_string();
             if src.is_empty() {
@@ -821,10 +850,17 @@ pub fn run(config: &Config, launcher: &Launcher) -> Result<()> {
             ..Default::default()
         })
         .run_with(move || {
-            (
-                State::new_install(config.clone(), launcher.clone()),
-                Task::none(),
-            )
+            let has_url = launcher.installer_url.is_some();
+            let mut state = State::new_install(config.clone(), launcher.clone());
+            if has_url {
+                state.source = launcher.installer_url.unwrap_or_default();
+            }
+            let init_task = if has_url {
+                Task::done(Message::AutoDownload)
+            } else {
+                Task::none()
+            };
+            (state, init_task)
         })
         .map_err(|e| anyhow::anyhow!("iced: {e}"))
 }