feat: update wallet::Balance to use bitcoin::Amount

- update all fields `immature`, ` trusted_pending`, `unstrusted_pending`
  and `confirmed` to use the `bitcoin::Amount` instead of `u64`
- update all `impl Balance` methods to use `bitcoin::Amount`
- update all tests that relies on `keychain::Balance`

crates/chain/src/keychain.rs

@@ -14,6 +14,7 @@ use crate::{collections::BTreeMap, Append};
 
 #[cfg(feature = "miniscript")]
 mod txout_index;
+use bitcoin::Amount;
 #[cfg(feature = "miniscript")]
 pub use txout_index::*;
 
@@ -90,13 +91,13 @@ impl<K> AsRef<BTreeMap<K, u32>> for ChangeSet<K> {
 )]
 pub struct Balance {
     /// All coinbase outputs not yet matured
-    pub immature: u64,
+    pub immature: Amount,
     /// Unconfirmed UTXOs generated by a wallet tx
-    pub trusted_pending: u64,
+    pub trusted_pending: Amount,
     /// Unconfirmed UTXOs received from an external wallet
-    pub untrusted_pending: u64,
+    pub untrusted_pending: Amount,
     /// Confirmed and immediately spendable balance
-    pub confirmed: u64,
+    pub confirmed: Amount,
 }
 
 impl Balance {
@@ -104,12 +105,12 @@ impl Balance {
     ///
     /// This is the balance you can spend right now that shouldn't get cancelled via another party
     /// double spending it.
-    pub fn trusted_spendable(&self) -> u64 {
+    pub fn trusted_spendable(&self) -> Amount {
         self.confirmed + self.trusted_pending
     }
 
     /// Get the whole balance visible to the wallet.
-    pub fn total(&self) -> u64 {
+    pub fn total(&self) -> Amount {
         self.confirmed + self.trusted_pending + self.untrusted_pending + self.immature
     }
 }

crates/chain/src/spk_txout_index.rs

@@ -270,6 +270,7 @@ impl<I: Clone + Ord> SpkTxOutIndex<I> {
         self.spk_indices.get(script)
     }
 
+    // TODO: (@leonardo) Should this also be updated to return `(bitcoin::Amount, bitcoin::Amount)` instead of (u64, u64)
     /// Computes the total value transfer effect `tx` has on the script pubkeys in `range`. Value is
     /// *sent* when a script pubkey in the `range` is on an input and *received* when it is on an
     /// output. For `sent` to be computed correctly, the output being spent must have already been

crates/chain/src/tx_graph.rs

@@ -95,7 +95,7 @@ use crate::{
 use alloc::collections::vec_deque::VecDeque;
 use alloc::sync::Arc;
 use alloc::vec::Vec;
-use bitcoin::{OutPoint, Script, Transaction, TxOut, Txid};
+use bitcoin::{Amount, OutPoint, Script, Transaction, TxOut, Txid};
 use core::fmt::{self, Formatter};
 use core::{
     convert::Infallible,
@@ -1155,27 +1155,28 @@ impl<A: Anchor> TxGraph<A> {
         outpoints: impl IntoIterator<Item = (OI, OutPoint)>,
         mut trust_predicate: impl FnMut(&OI, &Script) -> bool,
     ) -> Result<Balance, C::Error> {
-        let mut immature = 0;
-        let mut trusted_pending = 0;
-        let mut untrusted_pending = 0;
-        let mut confirmed = 0;
+        let mut immature = Amount::ZERO;
+        let mut trusted_pending = Amount::ZERO;
+        let mut untrusted_pending = Amount::ZERO;
+        let mut confirmed = Amount::ZERO;
 
         for res in self.try_filter_chain_unspents(chain, chain_tip, outpoints) {
             let (spk_i, txout) = res?;
 
+            // TODO: (@leonardo) Should these operations use `bitcoin::Amount::checked_add()` instead ?
             match &txout.chain_position {
                 ChainPosition::Confirmed(_) => {
                     if txout.is_confirmed_and_spendable(chain_tip.height) {
-                        confirmed += txout.txout.value.to_sat();
+                        confirmed += txout.txout.value;
                     } else if !txout.is_mature(chain_tip.height) {
-                        immature += txout.txout.value.to_sat();
+                        immature += txout.txout.value;
                     }
                 }
                 ChainPosition::Unconfirmed(_) => {
                     if trust_predicate(&spk_i, &txout.txout.script_pubkey) {
-                        trusted_pending += txout.txout.value.to_sat();
+                        trusted_pending += txout.txout.value;
                     } else {
-                        untrusted_pending += txout.txout.value.to_sat();
+                        untrusted_pending += txout.txout.value;
                     }
                 }
             }