Change get_balance to return in categories.

Add type balance with add, display traits. Change affected tests.
Update `CHANGELOG.md`

src/types.rs

@@ -227,7 +227,7 @@ pub struct TransactionDetails {
     /// Sent value (sats)
     /// Sum of owned inputs of this transaction.
     pub sent: u64,
-    /// Fee value (sats) if available.
+    /// Fee value (sats) if confirmed.
     /// The availability of the fee depends on the backend. It's never `None` with an Electrum
     /// Server backend, but it could be `None` with a Bitcoin RPC node without txindex that receive
     /// funds while offline.
@@ -262,6 +262,65 @@ impl BlockTime {
     }
 }
 
+/// Balance differentiated in various categories
+#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Clone, Default)]
+pub struct Balance {
+    /// All coinbase outputs not yet matured
+    pub immature: u64,
+    /// Unconfirmed UTXOs generated by a wallet tx
+    pub trusted_pending: u64,
+    /// Unconfirmed UTXOs received from an external wallet
+    pub untrusted_pending: u64,
+    /// Confirmed and immediately spendable balance
+    pub confirmed: u64,
+}
+
+impl Balance {
+    /// Get sum of trusted_pending and confirmed coins
+    pub fn get_spendable(&self) -> u64 {
+        self.confirmed + self.trusted_pending
+    }
+
+    /// Get the whole balance visible to the wallet
+    pub fn get_total(&self) -> u64 {
+        self.confirmed + self.trusted_pending + self.untrusted_pending + self.immature
+    }
+}
+
+impl std::fmt::Display for Balance {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{{ immature: {}, trusted_pending: {}, untrusted_pending: {}, confirmed: {} }}",
+            self.immature, self.trusted_pending, self.untrusted_pending, self.confirmed
+        )
+    }
+}
+
+impl std::ops::Add for Balance {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self {
+            immature: self.immature + other.immature,
+            trusted_pending: self.trusted_pending + other.trusted_pending,
+            untrusted_pending: self.untrusted_pending + other.untrusted_pending,
+            confirmed: self.confirmed + other.confirmed,
+        }
+    }
+}
+
+impl std::iter::Sum for Balance {
+    fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
+        iter.fold(
+            Balance {
+                ..Default::default()
+            },
+            |a, b| a + b,
+        )
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;