Check for duplicate recipient addresses

gui/src/app/state/spend/step.rs

@@ -43,12 +43,33 @@ pub trait Step {
 
 pub struct ChooseRecipients {
     recipients: Vec<Recipient>,
+    is_valid: bool,
+    is_duplicate: bool,
 }
 
 impl std::default::Default for ChooseRecipients {
     fn default() -> Self {
         Self {
             recipients: vec![Recipient::default()],
+            is_valid: false,
+            is_duplicate: false,
+        }
+    }
+}
+
+impl ChooseRecipients {
+    fn check_valid(&mut self) {
+        self.is_valid = !self.recipients.is_empty();
+        self.is_duplicate = false;
+        for (i, recipient) in self.recipients.iter().enumerate() {
+            if !recipient.valid() {
+                self.is_valid = false;
+            }
+            if !self.is_duplicate {
+                self.is_duplicate = self.recipients[..i]
+                    .iter()
+                    .any(|r| r.address.value == recipient.address.value);
+            }
         }
     }
 }
@@ -74,6 +95,8 @@ impl Step for ChooseRecipients {
                 }
                 _ => {}
             }
+
+            self.check_valid();
         }
         Command::none()
     }
@@ -102,7 +125,8 @@ impl Step for ChooseRecipients {
                     .map(|r| r.amount().unwrap_or(0_u64))
                     .sum(),
             ),
-            !self.recipients.iter().any(|recipient| !recipient.valid()),
+            self.is_valid,
+            self.is_duplicate,
         )
     }
 }

gui/src/app/view/spend/step.rs

@@ -27,6 +27,7 @@ pub fn choose_recipients_view(
     recipients: Vec<Element<Message>>,
     total_amount: Amount,
     is_valid: bool,
+    duplicate: bool,
 ) -> Element<Message> {
     modal(
         false,
@@ -49,11 +50,17 @@ pub fn choose_recipients_view(
         Some(
             Container::new(
                 Row::new()
+                    .spacing(20)
                     .align_items(Alignment::Center)
                     .push(
                         Container::new(text(format!("{}", total_amount)).bold())
                             .width(Length::Fill),
                     )
+                    .push_maybe(if duplicate {
+                        Some(text("Two recipient addresses are the same").style(color::WARNING))
+                    } else {
+                        None
+                    })
                     .push(if is_valid {
                         button::primary(None, "Next")
                             .on_press(Message::Next)