Show available balance on wallet page

app/controllers/wallet_controller.rb

@@ -2,11 +2,12 @@ require "rqrcode"
 
 class WalletController < ApplicationController
   before_action :require_user_signed_in
+  before_action :authenticate_with_lndhub
 
   def index
     @current_section = :wallet
 
-    @wallet_url = "lndhub://#{current_user.ln_login}:#{current_user.ln_password}@https://lndhub.kosmos.org"
+    @wallet_url = "lndhub://#{current_user.ln_login}:#{current_user.ln_password}@#{ENV['LNDHUB_PUBLIC_URL']}"
 
     qrcode = RQRCode::QRCode.new(@wallet_url)
     @svg = qrcode.as_svg(
@@ -16,6 +17,37 @@ class WalletController < ApplicationController
       standalone: true,
       use_path: true
     )
+
+    @balance = fetch_balance rescue nil
   end
 
+  private
+
+  def authenticate_with_lndhub
+    if session["ln_auth_token"].present?
+      @ln_auth_token = session["ln_auth_token"]
+    else
+      res = Faraday.post("#{ENV["LNDHUB_API_URL"]}/auth?type=auth",
+                         { login: current_user.ln_login, password: current_user.ln_password }.to_json,
+                         "Content-Type" => "application/json",
+                         "Accept" => "application/json")
+
+      credentials = JSON.parse(res.body)
+      session["ln_auth_token"] = credentials["access_token"]
+      @ln_auth_token = credentials["access_token"]
+    end
+  rescue
+    # TODO add exception tracking
+  end
+
+  def fetch_balance
+      res = Faraday.get("#{ENV["LNDHUB_API_URL"]}/balance", {}, {
+        "Content-Type" => "application/json",
+        "Accept" => "application/json",
+        "Authorization" => "Bearer #{@ln_auth_token}"
+      })
+
+      data = JSON.parse(res.body)
+      data["BTC"]["AvailableBalance"]
+  end
 end