chore: users can leave federations with zero balance

src/fedimint.rs

@@ -116,7 +116,7 @@ impl Wallet {
 
     pub async fn connect_to_joined_federations(&self) -> anyhow::Result<()> {
         // Note: We're intentionally locking the clients mutex earlier than
-        // necessary so that the lock is held while we're reading the data directory.
+        // necessary so that the lock is held while we're accessing the data directory.
         let mut clients = self.clients.lock().await;
 
         // List all files in the data directory.
@@ -154,9 +154,9 @@ impl Wallet {
         Ok(())
     }
 
-    pub async fn join_federation(&self, invite_code: InviteCode) -> anyhow::Result<()> {
+    pub async fn join_federation(&self, invite_code: InviteCode) -> anyhow::Result<WalletView> {
         // Note: We're intentionally locking the clients mutex earlier than
-        // necessary so that the lock is held while we're reading the data directory.
+        // necessary so that the lock is held while we're accessing the data directory.
         let mut clients = self.clients.lock().await;
 
         let federation_id = invite_code.federation_id();
@@ -167,7 +167,7 @@ impl Wallet {
 
         // Short-circuit if we're already connected to this federation.
         if federation_data_dir.is_dir() {
-            return Ok(());
+            return Ok(Self::get_current_state(clients).await);
         }
 
         let db: Database = RocksDb::open(federation_data_dir)?.into();
@@ -176,7 +176,44 @@ impl Wallet {
 
         clients.insert(federation_id, client);
 
-        Ok(())
+        Ok(Self::get_current_state(clients).await)
+    }
+
+    // TODO: Call `ClientModule::leave()` for every module.
+    // https://docs.rs/fedimint-client/0.4.2/fedimint_client/module/trait.ClientModule.html#method.leave
+    // Currently it isn't implemented for the `LightningClientModule`, so for now we're just checking
+    // that the client has a zero balance.
+    pub async fn leave_federation(
+        &self,
+        federation_id: FederationId,
+    ) -> anyhow::Result<WalletView> {
+        // Note: We're intentionally locking the clients mutex earlier than
+        // necessary so that the lock is held while we're accessing the data directory.
+        let mut clients = self.clients.lock().await;
+
+        if let Some(client) = clients.remove(&federation_id) {
+            if client.get_balance().await.msats != 0 {
+                // Re-insert the client back into the clients map.
+                clients.insert(federation_id, client);
+
+                return Err(anyhow::anyhow!(
+                    "Cannot leave federation with non-zero balance: {}",
+                    federation_id
+                ));
+            }
+
+            client.shutdown().await;
+
+            let federation_data_dir = self
+                .fedimint_clients_data_dir
+                .join(federation_id.to_string());
+
+            if federation_data_dir.is_dir() {
+                std::fs::remove_dir_all(federation_data_dir)?;
+            }
+        }
+
+        Ok(Self::get_current_state(clients).await)
     }
 
     async fn get_current_state(

src/routes/bitcoin_wallet.rs

@@ -1,7 +1,7 @@
-use std::str::FromStr;
+use std::{str::FromStr, sync::Arc};
 
 use fedimint_core::{
-    config::{ClientConfig, META_FEDERATION_NAME_KEY},
+    config::{ClientConfig, FederationId, META_FEDERATION_NAME_KEY},
     invite_code::InviteCode,
     Amount,
 };
@@ -42,6 +42,10 @@ pub enum Message {
     JoinFederation(InviteCode),
     JoinedFederation(InviteCode),
 
+    LeaveFederation(FederationId),
+    LeftFederation((FederationId, WalletView)),
+    FailedToLeaveFederation((FederationId, Arc<anyhow::Error>)),
+
     Send(send::Message),
     Receive(receive::Message),
 
@@ -161,7 +165,9 @@ impl Page {
 
                 Task::stream(async_stream::stream! {
                     match wallet.join_federation(invite_code.clone()).await {
-                        Ok(()) => {
+                        Ok(wallet_view) => {
+                            yield app::Message::UpdateWalletView(wallet_view);
+
                             yield app::Message::AddToast(Toast {
                                 title: "Joined federation".to_string(),
                                 body: "You have successfully joined the federation.".to_string(),
@@ -196,6 +202,38 @@ impl Page {
 
                 Task::none()
             }
+            Message::LeaveFederation(federation_id) => {
+                let wallet = self.connected_state.wallet.clone();
+
+                Task::future(async move {
+                    match wallet.leave_federation(federation_id).await {
+                        Ok(wallet_view) => app::Message::Routes(super::Message::BitcoinWalletPage(
+                            Message::LeftFederation((federation_id, wallet_view)),
+                        )),
+                        Err(err) => app::Message::Routes(super::Message::BitcoinWalletPage(
+                            Message::FailedToLeaveFederation((federation_id, Arc::from(err))),
+                        )),
+                    }
+                })
+            }
+            Message::LeftFederation((_federation_id, wallet_view)) => {
+                Task::done(app::Message::UpdateWalletView(wallet_view))
+                    .chain(Task::done(app::Message::Routes(super::Message::Navigate(
+                        RouteName::BitcoinWallet(SubrouteName::List),
+                    ))))
+                    .chain(Task::done(app::Message::AddToast(Toast {
+                        title: "Left federation".to_owned(),
+                        body: "You have successfully left the federation.".to_owned(),
+                        status: ToastStatus::Good,
+                    })))
+            }
+            Message::FailedToLeaveFederation((_federation_id, _err)) => {
+                Task::done(app::Message::AddToast(Toast {
+                    title: "Failed to leave federation".to_owned(),
+                    body: "Could not leave federation.".to_owned(),
+                    status: ToastStatus::Bad,
+                }))
+            }
             Message::Send(send_message) => {
                 if let Subroute::Send(send_page) = &mut self.subroute {
                     send_page.update(send_message)
@@ -444,6 +482,25 @@ impl FederationDetails {
             );
         }
 
+        let has_zero_balance = self.view.balance.msats == 0;
+
+        if !has_zero_balance {
+            container = container.push(
+                Text::new("Must have a zero balance in this federation in order to leave.")
+                    .size(20),
+            );
+        }
+
+        container = container.push(
+            icon_button("Leave Federation", SvgIcon::Delete, PaletteColor::Danger).on_press_maybe(
+                has_zero_balance.then(|| {
+                    app::Message::Routes(super::Message::BitcoinWalletPage(
+                        Message::LeaveFederation(self.view.federation_id),
+                    ))
+                }),
+            ),
+        );
+
         container = container.push(
             icon_button("Back", SvgIcon::ArrowBack, PaletteColor::Background).on_press(
                 app::Message::Routes(super::Message::Navigate(RouteName::BitcoinWallet(