register and balances accept bpi

ledger/balances.go

@@ -9,6 +9,23 @@ type Balances map[string]Balance
 
 type Balance map[Currency]float64
 
+func (balances Balances) WithBPIs(bpis BPIs) Balances {
+	result := make(Balances)
+	for k, v := range balances {
+		if _, ok := result[k]; !ok {
+			result[k] = make(Balance)
+		}
+		for k2, v2 := range v {
+			scalar := 1.0
+			if k2 != USD {
+				scalar = bpis[k2].Lookup("9")
+			}
+			result[k][USD] += v2 * scalar
+		}
+	}
+	return result
+}
+
 func (balances Balances) PushAll(other Balances) {
 	for k, v := range other {
 		if _, ok := balances[k]; !ok {