rpcserver: style related changes to listunspent

rpcserver.go

@@ -684,48 +684,67 @@ func determineFeePerKw(feeEstimator lnwallet.FeeEstimator, targetConf int32,
 	}
 }
 
-// ListUnspent returns useful information about each unspent output
-// owned by the wallet, as reported by the underlying `ListUnspentWitness`;
-// the information returned is: outpoint, amount in satoshis, address,
-// address type, scriptPubKey in hex and number of confirmations.
-// The result is filtered to contain outputs whose number of confirmations
-// is between a minimum and maximum number of confirmations specified by the
-// user, with 0 meaning unconfirmed.
+// ListUnspent returns useful information about each unspent output owned by
+// the wallet, as reported by the underlying `ListUnspentWitness`; the
+// information returned is: outpoint, amount in satoshis, address, address
+// type, scriptPubKey in hex and number of confirmations.  The result is
+// filtered to contain outputs whose number of confirmations is between a
+// minimum and maximum number of confirmations specified by the user, with 0
+// meaning unconfirmed.
 func (r *rpcServer) ListUnspent(ctx context.Context,
 	in *lnrpc.ListUnspentRequest) (*lnrpc.ListUnspentResponse, error) {
+
 	minConfs := in.MinConfs
 	maxConfs := in.MaxConfs
 
-	if minConfs < 0 {
+	switch {
+	// Ensure that the user didn't attempt to specify a negative number of
+	// confirmations, as that isn't possible.
+	case minConfs < 0:
 		return nil, fmt.Errorf("min confirmations must be >= 0")
-	}
-	if minConfs > maxConfs {
+
+	// We'll also ensure that the min number of confs is strictly less than
+	// or equal to the max number of confs for sanity.
+	case minConfs > maxConfs:
 		return nil, fmt.Errorf("max confirmations must be >= min " +
 			"confirmations")
 	}
 
+	// With our arguments validated, we'll query the internal wallet for
+	// the set of UTXOs that match our query.
 	utxos, err := r.server.cc.wallet.ListUnspentWitness(minConfs, maxConfs)
 	if err != nil {
 		return nil, err
 	}
 
-	resp := &lnrpc.ListUnspentResponse{Utxos: []*lnrpc.Utxo{}}
+	resp := &lnrpc.ListUnspentResponse{
+		Utxos: make([]*lnrpc.Utxo, 0, len(utxos)),
+	}
+
 	for _, utxo := range utxos {
-		// Translate lnwallet address type to gRPC proto address type:
+		// Translate lnwallet address type to the proper gRPC proto
+		// address type.
 		var addrType lnrpc.AddressType
 		switch utxo.AddressType {
+
 		case lnwallet.WitnessPubKey:
 			addrType = lnrpc.AddressType_WITNESS_PUBKEY_HASH
+
 		case lnwallet.NestedWitnessPubKey:
 			addrType = lnrpc.AddressType_NESTED_PUBKEY_HASH
+
 		case lnwallet.UnknownAddressType:
-			rpcsLog.Warnf("[listunspent] utxo with address of unknown "+
-				"type ignored: %v", utxo.OutPoint.String())
+			rpcsLog.Warnf("[listunspent] utxo with address of "+
+				"unknown type ignored: %v",
+				utxo.OutPoint.String())
 			continue
+
 		default:
 			return nil, fmt.Errorf("invalid utxo address type")
 		}
 
+		// Now that we know we have a proper mapping to an address,
+		// we'll convert the regular outpoint to an lnrpc variant.
 		outpoint := &lnrpc.ChannelPoint{
 			FundingTxid: &lnrpc.ChannelPoint_FundingTxidStr{
 				FundingTxidStr: utxo.OutPoint.Hash.String(),
@@ -741,17 +760,26 @@ func (r *rpcServer) ListUnspent(ctx context.Context,
 			Confirmations: utxo.Confirmations,
 		}
 
+		// Finally, we'll attempt to extract the raw address from the
+		// script so we can display a human friendly address to the end
+		// user.
 		_, outAddresses, _, err := txscript.ExtractPkScriptAddrs(
-			utxo.PkScript, activeNetParams.Params)
+			utxo.PkScript, activeNetParams.Params,
+		)
 		if err != nil {
 			return nil, err
 		}
 
+		// If we can't properly locate a single address, then this was
+		// an error in our mapping, and we'll return an error back to
+		// the user.
 		if len(outAddresses) != 1 {
-			return nil, fmt.Errorf("an output was unexpectedly multisig")
+			return nil, fmt.Errorf("an output was unexpectedly " +
+				"multisig")
 		}
 
 		utxoResp.Address = outAddresses[0].String()
+
 		resp.Utxos = append(resp.Utxos, &utxoResp)
 	}
 
@@ -759,8 +787,9 @@ func (r *rpcServer) ListUnspent(ctx context.Context,
 	if maxConfs != math.MaxInt32 {
 		maxStr = " max=" + fmt.Sprintf("%d", maxConfs)
 	}
-	rpcsLog.Debugf("[listunspent] min=%v%v, generated utxos: %v",
-		minConfs, maxStr, utxos)
+
+	rpcsLog.Debugf("[listunspent] min=%v%v, generated utxos: %v", minConfs,
+		maxStr, utxos)
 
 	return resp, nil
 }