ui: add swap component

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 69c825d..07f735a 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -63,6 +63,7 @@ set(DBB-FIRMWARE-UI-SOURCES
     ${CMAKE_SOURCE_DIR}/src/ui/components/confirm_gesture.c
     ${CMAKE_SOURCE_DIR}/src/ui/components/label.c
     ${CMAKE_SOURCE_DIR}/src/ui/components/confirm.c
+    ${CMAKE_SOURCE_DIR}/src/ui/components/confirm_swap.c
     ${CMAKE_SOURCE_DIR}/src/ui/components/keyboard_switch.c
     ${CMAKE_SOURCE_DIR}/src/ui/components/orientation_arrows.c
     ${CMAKE_SOURCE_DIR}/src/ui/components/info_centered.c
diff --git a/src/rust/bitbox-hal/src/ui.rs b/src/rust/bitbox-hal/src/ui.rs
index a305c89..5fa0e43 100644
--- a/src/rust/bitbox-hal/src/ui.rs
+++ b/src/rust/bitbox-hal/src/ui.rs
@@ -76,6 +76,9 @@ pub trait Ui {
     /// Returns `Ok(())` if the user accepts, `Err(UserAbort)` if the user rejects.
     async fn confirm(&mut self, params: &ConfirmParams<'_>) -> Result<(), UserAbort>;
 
+    /// Returns `Ok(())` if the user accepts the swap, `Err(UserAbort)` if the user rejects it.
+    async fn confirm_swap(&mut self, title: &str, from: &str, to: &str) -> Result<(), UserAbort>;
+
     async fn verify_recipient(&mut self, recipient: &str, amount: &str) -> Result<(), UserAbort>;
 
     async fn verify_total_fee(
diff --git a/src/rust/bitbox02-rust/src/hal/testing/ui.rs b/src/rust/bitbox02-rust/src/hal/testing/ui.rs
index 7b4733c..7043489 100644
--- a/src/rust/bitbox02-rust/src/hal/testing/ui.rs
+++ b/src/rust/bitbox02-rust/src/hal/testing/ui.rs
@@ -23,6 +23,11 @@ pub enum Screen {
         fee: String,
         longtouch: bool,
     },
+    Swap {
+        title: String,
+        from: String,
+        to: String,
+    },
     Recipient {
         recipient: String,
         amount: String,
@@ -102,6 +107,22 @@ impl Ui for TestingUi<'_> {
         Ok(())
     }
 
+    async fn confirm_swap(&mut self, title: &str, from: &str, to: &str) -> Result<(), UserAbort> {
+        self.screens.push(Screen::Swap {
+            title: title.into(),
+            from: from.into(),
+            to: to.into(),
+        });
+        if self
+            ._abort_nth
+            .as_ref()
+            .is_some_and(|&n| self.screens.len() - 1 == n)
+        {
+            return Err(UserAbort);
+        }
+        Ok(())
+    }
+
     async fn verify_recipient(&mut self, recipient: &str, amount: &str) -> Result<(), UserAbort> {
         self.screens.push(Screen::Recipient {
             recipient: recipient.into(),
@@ -465,4 +486,31 @@ mod tests {
         let mut ui = TestingUi::new();
         let _ = ui.quiz_mnemonic_word(&["a"], "01").await;
     }
+
+    #[async_test::test]
+    async fn test_confirm_swap_records_screen() {
+        let mut ui = TestingUi::new();
+        assert!(matches!(
+            ui.confirm_swap("Swap", "1 BTC", "2 ETH").await,
+            Ok(())
+        ));
+        assert_eq!(
+            ui.screens,
+            vec![Screen::Swap {
+                title: "Swap".into(),
+                from: "1 BTC".into(),
+                to: "2 ETH".into(),
+            }]
+        );
+    }
+
+    #[async_test::test]
+    async fn test_confirm_swap_abort() {
+        let mut ui = TestingUi::new();
+        ui.abort_nth(0);
+        assert!(matches!(
+            ui.confirm_swap("Swap", "1 BTC", "2 ETH").await,
+            Err(UserAbort)
+        ));
+    }
 }
diff --git a/src/rust/bitbox02-rust/src/hww/api/bitcoin/signtx.rs b/src/rust/bitbox02-rust/src/hww/api/bitcoin/signtx.rs
index 51a3dc1..ba1f741 100644
--- a/src/rust/bitbox02-rust/src/hww/api/bitcoin/signtx.rs
+++ b/src/rust/bitbox02-rust/src/hww/api/bitcoin/signtx.rs
@@ -3922,10 +3922,10 @@ mod tests {
                     recipient: "Test Merchant".into(),
                     amount: "12.34567890 BTC".into(),
                 },
-                Screen::Confirm {
-                    title: "SWAP".into(),
-                    body: "12.34567890 BTC\nto\n0.25 ETH".into(),
-                    longtouch: false,
+                Screen::Swap {
+                    title: "Swap".into(),
+                    from: "12.34567890 BTC".into(),
+                    to: "0.25 ETH".into(),
                 },
                 Screen::Recipient {
                     recipient: "bc1q xven xven xven xven xven xven xven xven 2ymj t8".into(),
diff --git a/src/rust/bitbox02-rust/src/hww/api/ethereum/sign.rs b/src/rust/bitbox02-rust/src/hww/api/ethereum/sign.rs
index 3a61009..1f440e0 100644
--- a/src/rust/bitbox02-rust/src/hww/api/ethereum/sign.rs
+++ b/src/rust/bitbox02-rust/src/hww/api/ethereum/sign.rs
@@ -1230,10 +1230,10 @@ mod tests {
                 recipient: "Test Merchant".into(),
                 amount: "0.530564 ETH".into(),
             },
-            Screen::Confirm {
-                title: "SWAP".into(),
-                body: "0.530564 ETH\nto\n0.25 ETH".into(),
-                longtouch: false,
+            Screen::Swap {
+                title: "Swap".into(),
+                from: "0.530564 ETH".into(),
+                to: "0.25 ETH".into(),
             },
             Screen::TotalFee {
                 total: "0.53069 ETH".into(),
@@ -1305,10 +1305,10 @@ mod tests {
                 recipient: "Test Merchant".into(),
                 amount: "57 USDT".into(),
             },
-            Screen::Confirm {
-                title: "SWAP".into(),
-                body: "57 USDT\nto\n0.25 ETH".into(),
-                longtouch: false,
+            Screen::Swap {
+                title: "Swap".into(),
+                from: "57 USDT".into(),
+                to: "0.25 ETH".into(),
             },
             Screen::TotalFee {
                 total: "57 USDT".into(),
diff --git a/src/rust/bitbox02-rust/src/hww/api/payment_request.rs b/src/rust/bitbox02-rust/src/hww/api/payment_request.rs
index 72fcc1f..c02836e 100644
--- a/src/rust/bitbox02-rust/src/hww/api/payment_request.rs
+++ b/src/rust/bitbox02-rust/src/hww/api/payment_request.rs
@@ -149,19 +149,9 @@ pub async fn user_verify(
             Memo {
                 memo: Some(memo::Memo::CoinPurchaseMemo(coin_purchase_memo)),
             } => {
-                let swap_body = format!(
-                    "{displayed_source_amount}\nto\n{}",
-                    coin_purchase_memo.amount
-                );
                 let _ = parse_coin_purchase_amount(&coin_purchase_memo.amount)?;
                 hal.ui()
-                    .confirm(&ConfirmParams {
-                        title: "SWAP",
-                        body: &swap_body,
-                        scrollable: true,
-                        accept_is_nextarrow: true,
-                        ..Default::default()
-                    })
+                    .confirm_swap("Swap", displayed_source_amount, &coin_purchase_memo.amount)
                     .await?;
             }
             _ => return Err(Error::InvalidInput),
@@ -1401,10 +1391,10 @@ mod tests {
                     recipient: "SWAPKIT (Provider)".into(),
                     amount: "0.25000000 BTC".into(),
                 },
-                Screen::Confirm {
-                    title: "SWAP".into(),
-                    body: "0.25000000 BTC\nto\n0.25 ETH".into(),
-                    longtouch: false,
+                Screen::Swap {
+                    title: "Swap".into(),
+                    from: "0.25000000 BTC".into(),
+                    to: "0.25 ETH".into(),
                 },
             ]
         );
@@ -1450,10 +1440,10 @@ mod tests {
                     recipient: "SWAPKIT (Provider)".into(),
                     amount: "0.25000000 BTC".into(),
                 },
-                Screen::Confirm {
-                    title: "SWAP".into(),
-                    body: "0.25000000 BTC\nto\n0.25 LTC".into(),
-                    longtouch: false,
+                Screen::Swap {
+                    title: "Swap".into(),
+                    from: "0.25000000 BTC".into(),
+                    to: "0.25 LTC".into(),
                 },
             ]
         );
diff --git a/src/rust/bitbox02-sys/build.rs b/src/rust/bitbox02-sys/build.rs
index 3af8091..86ea467 100644
--- a/src/rust/bitbox02-sys/build.rs
+++ b/src/rust/bitbox02-sys/build.rs
@@ -67,6 +67,7 @@ const ALLOWLIST_FNS: &[&str] = &[
     "bitbox02_smarteeprom_reset_unlock_attempts",
     "bitbox02_smarteeprom_init",
     "confirm_create",
+    "confirm_swap_create",
     "confirm_transaction_address_create",
     "confirm_transaction_fee_create",
     "atecc_attestation_sign",
@@ -259,6 +260,7 @@ const BITBOX02_SOURCES: &[&str] = &[
     "src/ui/components/confirm_gesture.c",
     "src/ui/components/confirm_transaction.c",
     "src/ui/components/confirm.c",
+    "src/ui/components/confirm_swap.c",
     "src/ui/components/empty.c",
     "src/ui/components/icon_button.c",
     "src/ui/components/image.c",
diff --git a/src/rust/bitbox02-sys/wrapper.h b/src/rust/bitbox02-sys/wrapper.h
index 22519a5..625e0ff 100644
--- a/src/rust/bitbox02-sys/wrapper.h
+++ b/src/rust/bitbox02-sys/wrapper.h
@@ -25,6 +25,7 @@
 #include <u2f/u2f_packet.h>
 #include <uart.h>
 #include <ui/components/confirm.h>
+#include <ui/components/confirm_swap.h>
 #include <ui/components/confirm_transaction.h>
 #include <ui/components/empty.h>
 #include <ui/components/label.h>
diff --git a/src/rust/bitbox02/src/hal/ui.rs b/src/rust/bitbox02/src/hal/ui.rs
index 9e3908e..eaf6680 100644
--- a/src/rust/bitbox02/src/hal/ui.rs
+++ b/src/rust/bitbox02/src/hal/ui.rs
@@ -116,6 +116,14 @@ impl<Timer: bitbox_hal::timer::Timer> Ui for BitBox02Ui<Timer> {
         }
     }
 
+    #[inline(always)]
+    async fn confirm_swap(&mut self, title: &str, from: &str, to: &str) -> Result<(), UserAbort> {
+        match crate::ui::confirm_swap(title, from, to).await {
+            crate::ui::ConfirmResponse::Approved => Ok(()),
+            crate::ui::ConfirmResponse::Cancelled => Err(UserAbort),
+        }
+    }
+
     #[inline(always)]
     async fn verify_recipient(&mut self, recipient: &str, amount: &str) -> Result<(), UserAbort> {
         match crate::ui::confirm_transaction_address(amount, recipient).await {
diff --git a/src/rust/bitbox02/src/ui/ui.rs b/src/rust/bitbox02/src/ui/ui.rs
index d6990c7..a7feea6 100644
--- a/src/rust/bitbox02/src/ui/ui.rs
+++ b/src/rust/bitbox02/src/ui/ui.rs
@@ -603,6 +603,68 @@ pub async fn confirm_transaction_address(amount: &str, address: &str) -> Confirm
     .await
 }
 
+pub async fn confirm_swap(title: &str, from: &str, to: &str) -> ConfirmResponse {
+    let _no_screensaver = crate::screen_saver::ScreensaverInhibitor::new();
+
+    // Shared between the async context and the c callback
+    struct SharedState {
+        waker: Option<Waker>,
+        result: Option<ConfirmResponse>,
+    }
+    let shared_state = Box::new(RefCell::new(SharedState {
+        waker: None,
+        result: None,
+    }));
+    let shared_state_ptr = shared_state.as_ref() as *const RefCell<SharedState> as *mut c_void;
+
+    unsafe extern "C" fn callback(result: bool, user_data: *mut c_void) {
+        let shared_state = unsafe { &*(user_data as *mut RefCell<SharedState>) };
+        let mut shared_state = shared_state.borrow_mut();
+        if shared_state.result.is_none() {
+            shared_state.result = Some(if result {
+                ConfirmResponse::Approved
+            } else {
+                ConfirmResponse::Cancelled
+            });
+            if let Some(waker) = shared_state.waker.as_ref() {
+                waker.wake_by_ref();
+            }
+        }
+    }
+
+    let component = unsafe {
+        bitbox02_sys::confirm_swap_create(
+            util::strings::str_to_cstr_vec(title).unwrap().as_ptr(), // copied in C
+            util::strings::str_to_cstr_vec(from).unwrap().as_ptr(),  // copied in C
+            util::strings::str_to_cstr_vec(to).unwrap().as_ptr(),    // copied in C
+            Some(callback),
+            shared_state_ptr, // passed to callback as `user_data`.
+        )
+    };
+
+    let mut component = Component {
+        component,
+        is_pushed: false,
+    };
+    component.screen_stack_push();
+
+    core::future::poll_fn({
+        let shared_state = &shared_state;
+        move |cx| {
+            let mut shared_state = shared_state.borrow_mut();
+
+            if let Some(result) = shared_state.result.take() {
+                Poll::Ready(result)
+            } else {
+                // Store the waker so the callback can wake up this task
+                shared_state.waker = Some(cx.waker().clone());
+                Poll::Pending
+            }
+        }
+    })
+    .await
+}
+
 pub async fn confirm_transaction_fee(amount: &str, fee: &str, longtouch: bool) -> ConfirmResponse {
     let _no_screensaver = crate::screen_saver::ScreensaverInhibitor::new();
 
diff --git a/src/rust/bitbox02/src/ui/ui_stub.rs b/src/rust/bitbox02/src/ui/ui_stub.rs
index dcf7662..f5ef5e9 100644
--- a/src/rust/bitbox02/src/ui/ui_stub.rs
+++ b/src/rust/bitbox02/src/ui/ui_stub.rs
@@ -75,6 +75,10 @@ pub async fn confirm_transaction_address(_amount: &str, _address: &str) -> Confi
     panic!("not used");
 }
 
+pub async fn confirm_swap(_title: &str, _from: &str, _to: &str) -> ConfirmResponse {
+    panic!("not used");
+}
+
 pub async fn confirm_transaction_fee(
     _amount: &str,
     _fee: &str,
diff --git a/src/rust/bitbox02/src/ui/ui_stub_c_unit_tests.rs b/src/rust/bitbox02/src/ui/ui_stub_c_unit_tests.rs
index 3603df7..b6c3746 100644
--- a/src/rust/bitbox02/src/ui/ui_stub_c_unit_tests.rs
+++ b/src/rust/bitbox02/src/ui/ui_stub_c_unit_tests.rs
@@ -90,6 +90,14 @@ pub async fn confirm_transaction_address(_amount: &str, _address: &str) -> Confi
     ConfirmResponse::Approved
 }
 
+pub async fn confirm_swap(_title: &str, _from: &str, _to: &str) -> ConfirmResponse {
+    crate::print_stdout(&format!(
+        "CONFIRM SWAP SCREEN START\nTITLE: {}\nFROM: {}\nTO: {}\nCONFIRM SWAP SCREEN END\n",
+        _title, _from, _to
+    ));
+    ConfirmResponse::Approved
+}
+
 pub async fn confirm_transaction_fee(
     _amount: &str,
     _fee: &str,
diff --git a/src/rust/bitbox03/src/ui.rs b/src/rust/bitbox03/src/ui.rs
index 867e1e3..366bff8 100644
--- a/src/rust/bitbox03/src/ui.rs
+++ b/src/rust/bitbox03/src/ui.rs
@@ -1,5 +1,6 @@
 use core::time::Duration;
 
+use alloc::format;
 use alloc::vec::Vec;
 use bitbox_hal as hal;
 use bitbox_lvgl::{
@@ -57,6 +58,21 @@ impl<Timer: bitbox_hal::timer::Timer> hal::ui::Ui for BitBox03Ui<Timer> {
             .await
     }
 
+    async fn confirm_swap(
+        &mut self,
+        title: &str,
+        from: &str,
+        to: &str,
+    ) -> Result<(), bitbox_hal::ui::UserAbort> {
+        let body = format!("from\n{from}\n\nto\n{to}");
+        self.confirm(&bitbox_hal::ui::ConfirmParams {
+            title,
+            body: &body,
+            ..Default::default()
+        })
+        .await
+    }
+
     async fn verify_recipient(
         &mut self,
         _recipient: &str,
diff --git a/src/ui/components/confirm_swap.c b/src/ui/components/confirm_swap.c
new file mode 100644
index 0000000..3c0ccec
--- /dev/null
+++ b/src/ui/components/confirm_swap.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#include "confirm_swap.h"
+#include "icon_button.h"
+#include "label.h"
+#include "ui_images.h"
+
+#include <hardfault.h>
+#include <screen.h>
+#include <string.h>
+#include <ui/fonts/arial_fonts.h>
+#include <util.h>
+
+// Empirically measured when the amount goes out of screen with the 11x10 font and we should switch
+// to the smaller 9x9 font.
+#define BIG_FONT_MAX_CHARS 19
+
+typedef struct {
+    void (*callback)(bool accepted, void* user_data);
+    void* user_data;
+} data_t;
+
+static void _render(component_t* component)
+{
+    ui_util_component_render_subcomponents(component);
+    image_arrow(
+        SCREEN_WIDTH / 2 - IMAGE_DEFAULT_ARROW_HEIGHT, 34, IMAGE_DEFAULT_ARROW_HEIGHT, ARROW_DOWN);
+}
+
+static void _cancel_cb(void* user_data)
+{
+    component_t* self = (component_t*)user_data;
+    data_t* data = (data_t*)self->data;
+    if (data->callback != NULL) {
+        data->callback(false, data->user_data);
+        data->callback = NULL;
+    }
+}
+
+static void _confirm_cb(void* user_data)
+{
+    component_t* self = (component_t*)user_data;
+    data_t* data = (data_t*)self->data;
+    if (data->callback != NULL) {
+        data->callback(true, data->user_data);
+        data->callback = NULL;
+    }
+}
+
+static const component_functions_t _component_functions = {
+    .cleanup = ui_util_component_cleanup,
+    .render = _render,
+    .on_event = NULL,
+};
+
+component_t* confirm_swap_create(
+    const char* title,
+    const char* from,
+    const char* to,
+    void (*callback)(bool accepted, void* user_data),
+    void* user_data)
+{
+    if (!callback) {
+        Abort("confirm_swap_create callback missing");
+    }
+    if (!strlens(title)) {
+        Abort("confirm_swap_create title missing");
+    }
+    if (!strlens(from)) {
+        Abort("confirm_swap_create from missing");
+    }
+    if (!strlens(to)) {
+        Abort("confirm_swap_create to missing");
+    }
+
+    component_t* confirm = malloc(sizeof(component_t));
+    if (!confirm) {
+        Abort("Error: malloc confirm swap");
+    }
+    memset(confirm, 0, sizeof(component_t));
+
+    data_t* data = malloc(sizeof(data_t));
+    if (!data) {
+        Abort("Error: malloc confirm swap data");
+    }
+    memset(data, 0, sizeof(data_t));
+    data->callback = callback;
+    data->user_data = user_data;
+
+    confirm->data = data;
+    confirm->f = &_component_functions;
+    confirm->dimension.width = SCREEN_WIDTH;
+    confirm->dimension.height = SCREEN_HEIGHT;
+
+    ui_util_add_sub_component(
+        confirm, icon_button_create(top_slider, ICON_BUTTON_CROSS, _cancel_cb, confirm));
+    ui_util_add_sub_component(
+        confirm, icon_button_create(top_slider, ICON_BUTTON_NEXT, _confirm_cb, confirm));
+
+    component_t* title_component = label_create(title, &font_font_a_11X10, CENTER_TOP, confirm);
+    ui_util_add_sub_component(confirm, title_component);
+
+    const UG_FONT* from_font = NULL;
+    if (strlen(from) > BIG_FONT_MAX_CHARS) {
+        from_font = &font_font_a_9X9;
+    }
+    const UG_FONT* to_font = NULL;
+    if (strlen(to) > BIG_FONT_MAX_CHARS) {
+        to_font = &font_font_a_9X9;
+    }
+
+    ui_util_add_sub_component(
+        confirm, label_create_offset(from, from_font, CENTER_TOP, 0, 17, confirm));
+    ui_util_add_sub_component(confirm, label_create_offset(to, to_font, CENTER, 0, 20, confirm));
+
+    return confirm;
+}
diff --git a/src/ui/components/confirm_swap.h b/src/ui/components/confirm_swap.h
new file mode 100644
index 0000000..27d2d62
--- /dev/null
+++ b/src/ui/components/confirm_swap.h
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef _UI_CONFIRM_SWAP_H
+#define _UI_CONFIRM_SWAP_H
+
+#include "ui/component.h"
+
+/**
+ * Creates a swap confirm screen.
+ * @param[in] title centered title shown in the title bar.
+ * @param[in] from source amount/value shown above the arrow.
+ * @param[in] to destination amount/value shown below the arrow.
+ * @param[in] callback The callback triggered when the user accepts or rejects. Is called at most
+ * once.
+ * @param[in] user_data Passed to `callback`.
+ */
+component_t* confirm_swap_create(
+    const char* title,
+    const char* from,
+    const char* to,
+    void (*callback)(bool accepted, void* user_data),
+    void* user_data);
+
+#endif