Show available balance on wallet page

.env.example

@@ -1,2 +1,3 @@
 EJABBERD_API_URL='https://xmpp.kosmos.org/api'
 LNDHUB_API_URL='http://10.1.1.163:3023'
+LNDHUB_PUBLIC_URL='https://lndhub.kosmos.org'

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

app/views/wallet/index.html.erb

@@ -1,14 +1,20 @@
-<section>
+<section class="w-full grid grid-cols-1 md:grid-cols-2">
+  <div>
     <h2>Wallet</h2>
     <p>
       Send and receive BTC via the Lightning Network.
     </p>
+  </div>
+  <p class="font-mono mt-4 md:text-right md:mt-0">
+  <% if @balance %>
+    <span class="text-xl"><%= @balance %> sats</span><br>
+    <span class="text-sm text-gray-500">Available balance</span>
+  <% end %>
+  </p>
 </section>
 
 <section>
-  <h3>
-    Blue Wallet
-  </h3>
+  <h3>Blue Wallet</h3>
   <p>
     You can connect
     <%= link_to "Blue Wallet", "https://bluewallet.io",