add transparent only API

lib/src/lightwallet.rs

@@ -2168,34 +2168,41 @@ impl LightWallet {
         println!("{}: Selecting notes", now() - start_time);
         let target_value = Amount::from_u64(total_value).unwrap() + DEFAULT_FEE ;
           // Select the candidate notes that are eligible to be spent
-          let notes: Vec<_> = self.txs.read().unwrap().iter()
-          .map(|(txid, tx)| tx.notes.iter().map(move |note| (*txid, note)))
-          .flatten()
-          .filter_map(|(txid, note)| {
-            // Filter out notes that are already spent
-            if note.spent.is_some() || note.unconfirmed_spent.is_some() {
-                None
-            } else {
-                // Get the spending key for the selected fvk, if we have it
-                let extsk = self.zkeys.read().unwrap().iter()
-                    .find(|zk| zk.extfvk == note.extfvk)
-                    .and_then(|zk| zk.extsk.clone());
-                SpendableNote::from(txid, note, anchor_offset, &extsk)
-            }
-        })
-        .scan(0, |running_total, spendable| {
-
-            let value = spendable.note.value;
-            let ret = if *running_total < u64::from(target_value) {
-                Some(spendable)
-            } else {
-                None
-            };
-            *running_total = *running_total + value;
-            ret
-        })
-        .collect();
+          let mut candidate_notes: Vec<_> = if transparent_only {
+            vec![]
+        } else {
+            self.txs.read().unwrap().iter()
+                .map(|(txid, tx)| tx.notes.iter().map(move |note| (*txid, note)))
+                .flatten()
+                .filter_map(|(txid, note)| {
+                    // Filter out notes that are already spent
+                    if note.spent.is_some() || note.unconfirmed_spent.is_some() {
+                        None
+                    } else {
+                        // Get the spending key for the selected fvk, if we have it
+                        let extsk = self.zkeys.read().unwrap().iter()
+                            .find(|zk| zk.extfvk == note.extfvk)
+                            .and_then(|zk| zk.extsk.clone());
+                        SpendableNote::from(txid, note, anchor_offset, &extsk)
+                    }
+                }).collect()
+        };
 
+        // Sort by highest value-notes first.
+        candidate_notes.sort_by(|a, b| b.note.value.cmp(&a.note.value));
+        // Select the minimum number of notes required to satisfy the target value
+        let notes: Vec<_> = candidate_notes.iter()
+            .scan(0, |running_total, spendable| {
+                let value = spendable.note.value;
+                let ret = if *running_total < u64::from(target_value) {
+                    Some(spendable)
+                } else {
+                    None
+                };
+                *running_total = *running_total + value;
+                ret
+            })
+            .collect();
         let mut builder = Builder::new(height);
 
         // A note on t addresses