From 48c0f66917c0a94b2e32395f06a04581a9768319 Mon Sep 17 00:00:00 2001
From: Yuki Kishimoto <yukikishimoto@protonmail.com>
Date: Fri, 19 Jan 2024 15:43:35 +0100
Subject: [PATCH] Add `WebLN::get_balance`

---
 webln-js/src/balance.rs | 29 +++++++++++++++++++++++++++++
 webln-js/src/lib.rs     |  8 ++++++++
 webln/src/lib.rs        | 29 +++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+)
 create mode 100644 webln-js/src/balance.rs

diff --git a/webln-js/src/balance.rs b/webln-js/src/balance.rs
new file mode 100644
index 0000000..40bdf88
--- /dev/null
+++ b/webln-js/src/balance.rs
@@ -0,0 +1,29 @@
+// Copyright (c) 2024 Yuki Kishimoto
+// Distributed under the MIT software license
+
+use alloc::string::String;
+
+use wasm_bindgen::prelude::*;
+use webln::BalanceResponse;
+
+#[wasm_bindgen(js_name = BalanceResponse)]
+pub struct JsBalanceResponse {
+    inner: BalanceResponse,
+}
+
+impl From<BalanceResponse> for JsBalanceResponse {
+    fn from(inner: BalanceResponse) -> Self {
+        Self { inner }
+    }
+}
+
+#[wasm_bindgen(js_class = BalanceResponse)]
+impl JsBalanceResponse {
+    pub fn balance(&self) -> f64 {
+        self.inner.balance
+    }
+
+    pub fn currency(&self) -> Option<String> {
+        self.inner.currency.clone()
+    }
+}
diff --git a/webln-js/src/lib.rs b/webln-js/src/lib.rs
index 16b6e78..aefe104 100644
--- a/webln-js/src/lib.rs
+++ b/webln-js/src/lib.rs
@@ -14,6 +14,7 @@ use core::ops::Deref;
 use wasm_bindgen::prelude::*;
 use webln::WebLN;
 
+pub mod balance;
 pub mod error;
 pub mod get_info;
 pub mod keysend;
@@ -21,6 +22,7 @@ pub mod request_invoice;
 pub mod send_payment;
 pub mod sign_message;
 
+use self::balance::JsBalanceResponse;
 use self::error::{into_err, Result};
 use self::get_info::JsGetInfoResponse;
 use self::keysend::JsKeysendArgs;
@@ -127,4 +129,10 @@ impl JsWebLN {
             .map_err(into_err)?
             .into())
     }
+
+    /// Fetch the balance of the current account.
+    #[wasm_bindgen(js_name = getBalance)]
+    pub async fn get_balance(&self) -> Result<JsBalanceResponse> {
+        Ok(self.inner.get_balance().await.map_err(into_err)?.into())
+    }
 }
diff --git a/webln/src/lib.rs b/webln/src/lib.rs
index 9175caf..0333a0d 100644
--- a/webln/src/lib.rs
+++ b/webln/src/lib.rs
@@ -321,6 +321,15 @@ pub struct SignMessageResponse {
     pub signature: String,
 }
 
+/// Balance Response
+#[derive(Debug, Clone, PartialEq, PartialOrd)]
+pub struct BalanceResponse {
+    /// Balance
+    pub balance: f64,
+    /// Currency
+    pub currency: Option<String>,
+}
+
 /// WebLN instance
 #[derive(Debug, Clone)]
 pub struct WebLN {
@@ -539,4 +548,24 @@ impl WebLN {
             signature,
         })
     }
+
+    /// Fetch the balance of the current account.
+    pub async fn get_balance(&self) -> Result<BalanceResponse, Error> {
+        let func: Function = self.get_func(&self.webln_obj, GET_BALANCE)?;
+        let promise: Promise = Promise::resolve(&func.call0(&self.webln_obj)?);
+        let result: JsValue = JsFuture::from(promise).await?;
+        let balance_response_obj: Object =
+            result.dyn_into().map_err(|_| Error::SomethingGoneWrong)?;
+
+        // Extract data
+        let balance: f64 = self
+            .get_value_by_key(&balance_response_obj, "balance")?
+            .as_f64()
+            .ok_or_else(|| Error::TypeMismatch(String::from("expected a number [balance]")))?;
+        let currency: Option<String> = self
+            .get_value_by_key(&balance_response_obj, "currency")?
+            .as_string();
+
+        Ok(BalanceResponse { balance, currency })
+    }
 }