From 94c895aedcb0fc20949d65547f6ab3f1b3f92f69 Mon Sep 17 00:00:00 2001
From: Jeremy Klein <jklein24@gmail.com>
Date: Wed, 15 Nov 2023 10:59:05 -0800
Subject: [PATCH] Add displayDecimals to the currency object.

This helps the sender display the receiving currency amount correctly in their UI.

Protocol: https://github.com/uma-universal-money-address/protocol/pull/7
---
 src/currency.rs | 21 +++++++++++++++++++++
 src/uma_test.rs |  1 +
 2 files changed, 22 insertions(+)

diff --git a/src/currency.rs b/src/currency.rs
index b108b04..f5fe90f 100644
--- a/src/currency.rs
+++ b/src/currency.rs
@@ -2,13 +2,34 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 pub struct Currency {
+    // The ISO 4217 currency code of the currency (eg. USD).
     pub code: String,
+
+    // The full display name of the currency (eg. US Dollars).
     pub name: String,
+
+    // The symbol of the currency (eg. $ for USD).
     pub symbol: String,
+
+    // The estimated millisatoshis per smallest "unit" of this currency (eg. 1 cent in USD).
     #[serde(rename = "multiplier")]
     pub millisatoshi_per_unit: i64,
+
+    // The minimum amount of the currency that can be sent in a single transaction. This is in the
+    // smallest unit of the currency (eg. cents for USD).
     #[serde(rename = "minSendable")]
     pub min_sendable: i64,
+
+    // The maximum amount of the currency that can be sent in a single transaction. This is in the
+    // smallest unit of the currency (eg. cents for USD).
     #[serde(rename = "maxSendable")]
     pub max_sendable: i64,
+
+    // The number of digits after the decimal point for display on the sender side. For example,
+    // in USD, by convention, there are 2 digits for cents - $5.95. in this case, `displayDecimals`
+    // would be 2. Note that the multiplier is still always in the smallest unit (cents). This field
+    // is only for display purposes. The sender should assume zero if this field is omitted, unless
+    // they know the proper display format of the target currency.
+    #[serde(rename = "displayDecimals")]
+    pub display_decimals: Option<i64>,
 }
diff --git a/src/uma_test.rs b/src/uma_test.rs
index 8b32b01..260ea63 100644
--- a/src/uma_test.rs
+++ b/src/uma_test.rs
@@ -148,6 +148,7 @@ mod tests {
             millisatoshi_per_unit: 34150,
             min_sendable: 1,
             max_sendable: 10000000,
+            display_decimals: Some(2),
         }];
 
         let response = get_lnurlp_response(