nbg and auto fill GEL exchange rate

asxpio.rb

@@ -28,6 +28,7 @@ if ENV['DATABASE_URL']
   require_relative 'lib/invoice'
   require_relative 'lib/ltc_rate'
   require_relative 'lib/ltc_qr'
+  require_relative 'lib/gel_rate'
   require_relative 'lib/invoice_pdf'
 else
   $logger.warn('DATABASE_URL not set — invoicing disabled')
@@ -65,6 +66,20 @@ class AsxpioWeb < Sinatra::Base
         request.env['HTTP_X_REAL_IP'] ||
         request.ip
     end
+
+    # Exchange rate for display: full captured precision (up to 8 dp), trailing
+    # zeros trimmed, padded to at least min_dp. Mirrors InvoicePdf#fmt_rate so
+    # the HTML and PDF agree. (4 dp matches the NBG's GEL quoting.)
+    def fmt_rate(value, min_dp = 4)
+      frac = BigDecimal(value.to_s).round(8).to_s('F').split('.').last.sub(/0+$/, '')
+      whole = BigDecimal(value.to_s).to_i
+      "#{whole}.#{frac.ljust(min_dp, '0')}"
+    end
+
+    # LTC amount: up to 8 dp, trailing zeros trimmed, no padding.
+    def fmt_ltc(value)
+      BigDecimal(value.to_s).round(8).to_s('F').sub(/(\.\d*?)0+$/, '\1').sub(/\.$/, '')
+    end
   end
 
   before do
@@ -169,6 +184,30 @@ class AsxpioWeb < Sinatra::Base
     end
   end
 
+  # Official GEL rate from the National Bank of Georgia for the new-invoice
+  # form's "Fetch official" button. The rate is GEL per 1 unit of the invoice
+  # currency (USD/EUR), so it tracks the form's selected currency. Pass date=
+  # for a past invoice (NBG rolls back to the last published rate on
+  # weekends/holidays). GEL invoices have a trivial rate of 1 — no fetch needed.
+  get '/admin/gel-rate' do
+    content_type :json
+    currency = params[:currency].to_s.upcase
+    currency = 'USD' if currency.empty?
+    date = params[:date].to_s.strip
+
+    if currency == 'GEL'
+      return { rate: '1', currency: 'GEL', date: date }.to_json
+    end
+
+    begin
+      rate = GelRate.fetch(currency, date: date.empty? ? nil : date)
+      { rate: rate.to_s('F').sub(/(\.\d*?)0+$/, '\1').sub(/\.$/, ''), currency: currency, date: date }.to_json
+    rescue GelRate::Error => e
+      status 502
+      { error: e.message }.to_json
+    end
+  end
+
   get '/admin/invoices/new' do
     @page_title  = 'New invoice — admin'
     @noindex     = true

lib/gel_rate.rb

@@ -0,0 +1,61 @@
+require 'net/http'
+require 'json'
+require 'uri'
+require 'date'
+require 'bigdecimal'
+
+# Fetches the official GEL exchange rate from the National Bank of Georgia.
+# https://nbg.gov.ge/en/monetary-policy/currency
+#
+# API: GET .../currencies/en/json/?currencies=USD&date=YYYY-MM-DD
+# Response is a top-level array; rate is quoted per `quantity` units, so the
+# per-unit rate is rate / quantity. NBG returns the rate valid on or before the
+# requested date (weekends/holidays roll back to the last published rate).
+module GelRate
+  ENDPOINT = 'https://nbg.gov.ge/gw/api/ct/monetarypolicy/currencies/en/json/'.freeze
+  TIMEOUT = 6 # seconds
+
+  class Error < StandardError; end
+
+  module_function
+
+  # Returns a BigDecimal: how many GEL per 1 unit of `currency` on `date`.
+  # `date` may be a Date or YYYY-MM-DD string; omitted ⇒ latest published rate.
+  def fetch(currency = 'USD', date: nil)
+    currency = currency.to_s.upcase
+    uri = URI(ENDPOINT)
+    query = { currencies: currency }
+    query[:date] = normalize_date(date) if date
+    uri.query = URI.encode_www_form(query)
+
+    res = Net::HTTP.start(uri.host, uri.port, use_ssl: true,
+                          open_timeout: TIMEOUT, read_timeout: TIMEOUT) do |http|
+      http.get(uri.request_uri, 'Accept' => 'application/json')
+    end
+    raise Error, "NBG HTTP #{res.code}" unless res.is_a?(Net::HTTPSuccess)
+
+    data = JSON.parse(res.body)
+    entry = Array(data).first or raise Error, 'Empty NBG response'
+    cur = Array(entry['currencies']).find { |c| c['code'] == currency } \
+      or raise Error, "No #{currency} in NBG response"
+
+    rate = BigDecimal(cur.fetch('rate').to_s)
+    qty  = BigDecimal(cur.fetch('quantity', 1).to_s)
+    raise Error, 'NBG quantity is zero' if qty.zero?
+
+    (rate / qty).round(8)
+  rescue JSON::ParserError => e
+    raise Error, "Bad JSON from NBG: #{e.message}"
+  rescue Net::OpenTimeout, Net::ReadTimeout
+    raise Error, 'NBG timed out'
+  rescue KeyError => e
+    raise Error, "Missing field in NBG response: #{e.message}"
+  end
+
+  def normalize_date(date)
+    d = date.is_a?(Date) ? date : Date.parse(date.to_s)
+    d.strftime('%Y-%m-%d')
+  rescue ArgumentError
+    raise Error, "Invalid date: #{date}"
+  end
+end

lib/invoice_pdf.rb

@@ -210,7 +210,7 @@ class InvoicePdf
       ['Total',    "#{@invoice.currency} #{fmt_money(total)}"]
     ]
     if @invoice.currency != 'GEL'
-      rows << ["In GEL (rate #{fmt_money(@invoice.gel_rate)})", "GEL #{fmt_money(@invoice.total_gel)}"]
+      rows << ["In GEL (rate #{fmt_rate(@invoice.gel_rate)})", "GEL #{fmt_money(@invoice.total_gel)}"]
     end
 
     pdf.bounding_box([pdf.bounds.right - 270, pdf.cursor], width: 270) do
@@ -277,7 +277,7 @@ class InvoicePdf
             pdf.text "Amount: #{fmt_ltc(amount)} LTC", style: :bold
             if @invoice.ltc_rate
               pdf.fill_color COLOR_MUTED
-              pdf.text "(rate 1 LTC = #{fmt_money(@invoice.ltc_rate)} #{@invoice.currency} at issue)", size: 8
+              pdf.text "(rate 1 LTC = #{fmt_rate(@invoice.ltc_rate)} #{@invoice.currency} at issue)", size: 8
               pdf.fill_color COLOR_TEXT
             end
             pdf.move_down 3
@@ -329,6 +329,17 @@ class InvoicePdf
     BigDecimal(value.to_s).round(8).to_s('F').sub(/(\.\d*?)0+$/, '\\1').sub(/\.$/, '')
   end
 
+  # Exchange rate: keep full captured precision (up to 8 dp), trim trailing
+  # zeros, but pad to at least `min_dp` so it reads as a rate. GEL/USD rates are
+  # quoted to 4 dp by the NBG, so the default min is 4.
+  def fmt_rate(value, min_dp: 4)
+    s = BigDecimal(value.to_s).round(8).to_s('F')
+    int, frac = s.split('.')
+    frac = (frac || '').sub(/0+$/, '')
+    frac = frac.ljust(min_dp, '0')
+    "#{with_thousands("#{int}.00").split('.').first}.#{frac}"
+  end
+
   def fmt_qty(value)
     bd = BigDecimal(value.to_s)
     bd.frac.zero? ? bd.to_i.to_s : bd.to_s('F')

public/admin-invoice-form.js

@@ -59,8 +59,11 @@
         }
     }
 
+    const gelRateCcy = document.getElementById('gel-rate-ccy');
     function syncCcyLabel() {
-        if (rateCcy && currencySel) rateCcy.textContent = currencySel.value;
+        const ccy = currencySel ? currencySel.value : 'USD';
+        if (rateCcy) rateCcy.textContent = ccy;
+        if (gelRateCcy) gelRateCcy.textContent = ccy;
     }
     syncCcyLabel();
     if (currencySel) currencySel.addEventListener('change', syncCcyLabel);
@@ -85,4 +88,38 @@
                 .catch(() => { rateStatus.textContent = ' network error'; });
         });
     }
+
+    // --- Official GEL rate from NBG -------------------------------------
+    const gelFetchBtn = document.getElementById('fetch-gel-rate');
+    const gelStatus = document.getElementById('gel-rate-status');
+    const issuedInput = document.getElementById('issued_on');
+
+    if (gelFetchBtn) {
+        gelFetchBtn.addEventListener('click', function () {
+            const ccy = currencySel ? currencySel.value : 'USD';
+            const params = new URLSearchParams({ currency: ccy });
+            // Past invoice ⇒ fetch the rate as published for the issued date.
+            if (issuedInput && issuedInput.value && issuedInput.value < today()) {
+                params.set('date', issuedInput.value);
+            }
+            gelStatus.textContent = ' fetching…';
+            fetch('/admin/gel-rate?' + params.toString(), { headers: { Accept: 'application/json' } })
+                .then((r) => r.json().then((j) => ({ ok: r.ok, j })))
+                .then(({ ok, j }) => {
+                    if (!ok) { gelStatus.textContent = ' ' + (j.error || 'failed'); return; }
+                    if (gelRateInput) gelRateInput.value = j.rate;
+                    gelStatus.textContent = params.has('date')
+                        ? ' ✓ official ' + params.get('date')
+                        : ' ✓ official (latest)';
+                })
+                .catch(() => { gelStatus.textContent = ' network error'; });
+        });
+    }
+
+    function today() {
+        const d = new Date();
+        const m = String(d.getMonth() + 1).padStart(2, '0');
+        const day = String(d.getDate()).padStart(2, '0');
+        return d.getFullYear() + '-' + m + '-' + day;
+    }
 })();

views/admin/invoices/new.erb

@@ -48,8 +48,10 @@
                 </select>
             </div>
             <div class="field">
-                <label for="gel_rate">GEL rate</label>
+                <label for="gel_rate">GEL rate (GEL per 1 <span id="gel-rate-ccy">unit</span>)</label>
                 <input type="text" id="gel_rate" name="gel_rate" value="<%= @form_values[:gel_rate] %>" placeholder="2.9500" inputmode="decimal" required />
+                <button type="button" id="fetch-gel-rate" class="link-button">↻ Fetch official (NBG)</button>
+                <span id="gel-rate-status" class="optional"></span>
             </div>
         </div>
 

views/admin/invoices/show.erb

@@ -16,7 +16,7 @@
         <% if @invoice.ltc? %>
             <dt>LTC</dt>
             <dd class="mono">
-                <% if (amt = @invoice.ltc_amount_due) %><%= amt.to_s('F').sub(/\.?0+$/, '') %> LTC<% if @invoice.ltc_rate %> @ <%= '%.2f' % @invoice.ltc_rate %> <%= @invoice.currency %><% end %><br /><% end %>
+                <% if (amt = @invoice.ltc_amount_due) %><%= amt.to_s('F').sub(/\.?0+$/, '') %> LTC<% if @invoice.ltc_rate %> @ <%= @invoice.ltc_rate.to_s('F').sub(/(\.\d*?)0+$/, '\1').sub(/\.$/, '') %> <%= @invoice.currency %><% end %><br /><% end %>
                 <span style="word-break:break-all;"><%= @invoice.ltc_address %></span>
             </dd>
         <% end %>

views/invoice_public.erb

@@ -9,6 +9,12 @@
         <dt>Issued</dt><dd class="mono"><%= @invoice.issued_on.strftime('%Y-%m-%d') %></dd>
         <dt>Due</dt><dd class="mono"><%= @invoice.due_on.strftime('%Y-%m-%d') %></dd>
         <dt>Total</dt><dd class="mono"><%= @invoice.currency %> <%= '%.2f' % @invoice.total %></dd>
+        <% unless @invoice.currency == 'GEL' %>
+            <dt>In GEL</dt><dd class="mono">GEL <%= '%.2f' % @invoice.total_gel %> <span class="optional">@ <%= fmt_rate(@invoice.gel_rate) %></span></dd>
+        <% end %>
+        <% if @invoice.ltc? && (ltc = @invoice.ltc_amount_due) %>
+            <dt>In LTC</dt><dd class="mono"><%= fmt_ltc(ltc) %> LTC<% if @invoice.ltc_rate %> <span class="optional">@ <%= fmt_rate(@invoice.ltc_rate) %> <%= @invoice.currency %></span><% end %></dd>
+        <% end %>
         <dt>Status</dt><dd><span class="badge badge-<%= @invoice.status %>"><%= @invoice.status %></span></dd>
     </dl>
 </section>