Print every line at full price and take the discount off once, in euros

Second correction to the same block, and this one came from the right place: a
line reading 202,50 beside "Rabatt 10 %" does not say whether the discount is
in that number or still to come. It was unreadable, and unreadable on the one
figure a customer checks.

Lines are at full price now. Discounts are still entered per line — that is
where they belong and where somebody decides them — but they are summed and
shown once, in euros, under a subtotal that the "Gesamt netto" column adds up
to. Subtotal, one subtraction, VAT, total: a sum anybody can follow without
being told which figures are already adjusted.

The gross line-total column is gone and a gross UNIT price takes its place.
Full-price gross totals would sum to 315,60 against a total of 288,60 — the
same contradiction in a different column. Nobody adds up unit prices, and a
consumer reading this wants to know what one of the things costs.

lineTotal() and adjustmentLabel() went with it. Nothing calls them any more,
and a helper kept for a layout that no longer exists is the next person's
wrong turn.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/Services/Billing/InvoiceMath.php

@@ -39,49 +39,6 @@ final class InvoiceMath
         return (int) round($unitNetCents * $quantityMilli / 1000);
     }
 
-    /**
-     * A line's net after its own discount or surcharge.
-     *
-     * Per line rather than per invoice, so the columns add up. With one
-     * discount applied under the table, the gross column summed to more than
-     * the total — the reader who checks a column found a document that does not
-     * agree with itself, and had no way to know which figure was the real one.
-     *
-     * @param  array{type:string, value:int}|null  $adjustment
-     */
-    public static function lineTotal(int $unitNetCents, int $quantityMilli, ?array $adjustment = null): int
-    {
-        $net = self::lineNet($unitNetCents, $quantityMilli);
-
-        if ($adjustment === null) {
-            return $net;
-        }
-
-        return $net + self::adjustment($net, (string) $adjustment['type'], (int) $adjustment['value']);
-    }
-
-    /**
-     * "Rabatt 10 %" or "Aufschlag 15,00" — the label printed under a line.
-     *
-     * Built here rather than in the template so the wording and the sign can
-     * never disagree with the arithmetic they describe.
-     *
-     * @param  array{type:string, value:int}|null  $adjustment
-     */
-    public static function adjustmentLabel(?array $adjustment): ?string
-    {
-        if ($adjustment === null || (int) $adjustment['value'] === 0) {
-            return null;
-        }
-
-        $value = (int) $adjustment['value'];
-        $word = $value < 0 ? __('invoice.discount') : __('invoice.surcharge');
-
-        return $adjustment['type'] === self::PERCENT
-            ? $word.' '.rtrim(rtrim(number_format(abs($value) / 100, 2, ',', '.'), '0'), ',').' %'
-            : $word.' '.self::money(abs($value));
-    }
-
     /**
      * A discount or surcharge, as a signed amount in cents.
      *
@@ -108,33 +65,49 @@ final class InvoiceMath
     /**
      * Every figure the document shows, from the lines and one adjustment.
      *
-     * @param  array<int, array{unit_net_cents:int, quantity_milli:int}>  $lines
+     * @param  array<int, array{unit_net_cents:int, quantity_milli:int, adjustment?:array{type:string, value:int}}>  $lines
      * @param  array{type:string, value:int}|null  $adjustment
-     * @return array{lines_net:int, adjustment:int, net:int, tax:int, gross:int}
+     * @return array{subtotal:int, lines_net:int, adjustment:int, net:int, tax:int, gross:int}
      */
     public static function totals(array $lines, ?array $adjustment, int $rateBasisPoints): array
     {
-        $linesNet = 0;
+        // The subtotal is the sum of the FULL line prices — the column the
+        // reader can add up on the page. Discounts are collected separately and
+        // shown as one figure beneath it.
+        //
+        // Printing each line already reduced was the previous attempt, and it
+        // was worse: a line reading 202,50 next to "Rabatt 10 %" leaves the
+        // reader unable to tell whether the discount is in that number or still
+        // to come. Full price, then one subtraction, is a sum anybody can
+        // follow.
+        $subtotal = 0;
+        $lineDiscounts = 0;
 
         foreach ($lines as $line) {
-            // Each line's own discount is inside its total, so the column the
+            $full = self::lineNet((int) $line['unit_net_cents'], (int) $line['quantity_milli']);
-            // reader adds up is the column the sum is taken from.
+            $subtotal += $full;
-            $linesNet += self::lineTotal(
+
-                (int) $line['unit_net_cents'],
+            if (! empty($line['adjustment'])) {
-                (int) $line['quantity_milli'],
+                $lineDiscounts += self::adjustment(
-                $line['adjustment'] ?? null,
+                    $full,
-            );
+                    (string) $line['adjustment']['type'],
+                    (int) $line['adjustment']['value'],
+                );
+            }
         }
 
-        $adjusted = $adjustment === null
+        // An adjustment on the whole document, on top of any on the lines.
+        $wide = $adjustment === null
             ? 0
-            : self::adjustment($linesNet, (string) $adjustment['type'], (int) $adjustment['value']);
+            : self::adjustment($subtotal, (string) $adjustment['type'], (int) $adjustment['value']);
 
-        $net = $linesNet + $adjusted;
+        $adjusted = $lineDiscounts + $wide;
+        $net = $subtotal + $adjusted;
         $tax = self::tax($net, $rateBasisPoints);
 
         return [
-            'lines_net' => $linesNet,
+            'subtotal' => $subtotal,
+            'lines_net' => $subtotal,   // kept: older snapshots read this name
             'adjustment' => $adjusted,
             'net' => $net,
             'tax' => $tax,

app/Services/Billing/SampleInvoice.php

@@ -84,8 +84,8 @@ final class SampleInvoice
             ],
         ];
 
-        // No invoice-wide adjustment on the specimen: the discount sits on the
+        // The discount is entered on the line it belongs to and shown once, in
-        // line it belongs to, which is what keeps the columns adding up.
+        // euros, beneath the subtotal — the lines themselves stay at full price.
         $totals = InvoiceMath::totals($lines, null, $rate) + ['rate_basis_points' => $rate];
 
         return [
@@ -105,6 +105,7 @@ final class SampleInvoice
                 'issued_on' => now()->local()->format('d.m.Y'),
                 'due_on' => now()->local()->addDays((int) CompanyProfile::get('payment_days', 14))->format('d.m.Y'),
                 'currency' => 'EUR',
+                'adjustment_label' => 'Rabatt',
                 'salutation' => 'Sehr geehrte Damen und Herren,',
                 'intro' => 'wir erlauben uns, für die im Folgenden aufgeführten Leistungen in Rechnung zu stellen.',
                 'payment_terms' => trim((string) CompanyProfile::get('payment_terms')) !== ''

lang/de/invoice.php

@@ -18,6 +18,8 @@ return [
 
     'discount' => 'Rabatt',
     'surcharge' => 'Aufschlag',
+    'col_unit_gross' => 'Einzelpreis brutto',
+    'subtotal' => 'Zwischensumme',
     'adjustment' => 'Rabatt',
     'net' => 'Nettobetrag',
     'tax' => 'Umsatzsteuer :rate %',

lang/en/invoice.php

@@ -18,6 +18,8 @@ return [
 
     'discount' => 'Discount',
     'surcharge' => 'Surcharge',
+    'col_unit_gross' => 'Unit price gross',
+    'subtotal' => 'Subtotal',
     'adjustment' => 'Discount',
     'net' => 'Net amount',
     'tax' => 'VAT :rate %',

resources/views/pdf/invoice.blade.php

@@ -83,41 +83,52 @@
         <td style="width:41%; border-bottom:0.2mm solid #b4b4be;">{{ __('invoice.col_description') }}</td>
         <td style="width:12%; text-align:right; border-bottom:0.2mm solid #b4b4be;">{{ __('invoice.col_quantity') }}</td>
         <td style="width:14%; text-align:right; border-bottom:0.2mm solid #b4b4be;">{{ __('invoice.col_unit_net') }}</td>
+        {{-- A unit price, not a line total. Nobody adds up unit prices, so this
+             column cannot contradict the sum — which a full-price gross TOTAL
+             column would, by 315,60 against 288,60. --}}
+        <td style="width:13%; text-align:right; border-bottom:0.2mm solid #b4b4be;">{{ __('invoice.col_unit_gross') }}</td>
         <td style="width:13%; text-align:right; border-bottom:0.2mm solid #b4b4be;">{{ __('invoice.col_total_net') }}</td>
-        <td style="width:13%; text-align:right; border-bottom:0.2mm solid #b4b4be;">{{ __('invoice.col_total_gross') }}</td>
     </tr>
     @foreach ($lines as $index => $line)
         @php
-            // The line's own discount is inside its total, so this column adds
+            // Full price throughout. The discount is collected and shown once,
-            // up to the sum printed beneath it. With one discount applied under
+            // in euros, beneath the subtotal — a line printed already-reduced
-            // the table, it did not.
+            // leaves the reader guessing whether it is reduced.
-            $net = InvoiceMath::lineTotal((int) $line['unit_net_cents'], (int) $line['quantity_milli'], $line['adjustment'] ?? null);
+            $rate = (int) ($totals['rate_basis_points'] ?? 2000);
-            $gross = $net + InvoiceMath::tax($net, (int) ($totals['rate_basis_points'] ?? 2000));
+            $net = InvoiceMath::lineNet((int) $line['unit_net_cents'], (int) $line['quantity_milli']);
-            $adjustmentLabel = InvoiceMath::adjustmentLabel($line['adjustment'] ?? null);
+            $unitGross = (int) $line['unit_net_cents'] + InvoiceMath::tax((int) $line['unit_net_cents'], $rate);
         @endphp
         <tr>
             <td style="border-bottom:0.1mm solid #e9e9ee;">{{ $index + 1 }}</td>
-            <td style="border-bottom:0.1mm solid #e9e9ee;">{{ $line['description'] ?? '' }}@foreach (($line['details'] ?? []) as $detail)<br><span style="color:#6e6e7a;">{{ $detail }}</span>@endforeach@if ($adjustmentLabel)<br><span style="color:#b8500a;">{{ $adjustmentLabel }}</span>@endif</td>
+            <td style="border-bottom:0.1mm solid #e9e9ee;">{{ $line['description'] ?? '' }}@foreach (($line['details'] ?? []) as $detail)<br><span style="color:#6e6e7a;">{{ $detail }}</span>@endforeach</td>
             <td style="text-align:right; border-bottom:0.1mm solid #e9e9ee;">{{ InvoiceMath::quantity((int) $line['quantity_milli']) }}@if (! empty($line['unit'])) {{ $line['unit'] }}@endif</td>
             <td style="text-align:right; border-bottom:0.1mm solid #e9e9ee;">{{ InvoiceMath::money((int) $line['unit_net_cents']) }}</td>
+            <td style="text-align:right; border-bottom:0.1mm solid #e9e9ee;">{{ InvoiceMath::money($unitGross) }}</td>
             <td style="text-align:right; border-bottom:0.1mm solid #e9e9ee;">{{ InvoiceMath::money($net) }}</td>
-            <td style="text-align:right; border-bottom:0.1mm solid #e9e9ee;">{{ InvoiceMath::money($gross) }}</td>
         </tr>
     @endforeach
 </table>
 
 <table cellpadding="3" cellspacing="0" style="width:100%; margin-top:4mm; font-size:9pt;">
+    {{-- The subtotal is what the "Gesamt netto" column adds up to. Without it
+         the discount below has nothing to be a discount OF, which is exactly
+         what made the previous version unreadable. --}}
     @if (! empty($totals['adjustment']))
         <tr>
             <td style="width:60%;"></td>
-            <td style="width:25%;">{{ $meta['adjustment_label'] ?? __('invoice.adjustment') }}</td>
+            <td style="width:25%;">{{ __('invoice.subtotal') }}</td>
-            <td style="width:15%; text-align:right;">{{ InvoiceMath::money((int) $totals['adjustment']) }}</td>
+            <td style="width:15%; text-align:right;">{{ InvoiceMath::money((int) ($totals['subtotal'] ?? 0)) }}</td>
+        </tr>
+        <tr>
+            <td></td>
+            <td>{{ $meta['adjustment_label'] ?? __('invoice.adjustment') }}</td>
+            <td style="text-align:right;">{{ InvoiceMath::money((int) $totals['adjustment']) }}</td>
         </tr>
     @endif
     <tr>
-        <td></td>
+        <td style="width:60%;"></td>
-        <td>{{ __('invoice.net') }}</td>
+        <td style="width:25%;">{{ __('invoice.net') }}</td>
-        <td style="text-align:right;">{{ InvoiceMath::money((int) ($totals['net'] ?? 0)) }}</td>
+        <td style="width:15%; text-align:right;">{{ InvoiceMath::money((int) ($totals['net'] ?? 0)) }}</td>
     </tr>
     <tr>
         <td></td>

tests/Feature/Billing/InvoiceMathTest.php

@@ -91,41 +91,46 @@ it('formats money and quantities the way the document reads them', function () {
         ->and(InvoiceMath::quantity(250))->toBe('0,25');
 });
 
-it('puts a line’s discount inside that line, so the columns add up', function () {
+it('shows lines at full price and takes the discount off once, in euros', function () {
-    // The reason it moved off the summary block. With one discount under the
+    // Two attempts got here. Applying one discount under the table left the
-    // table, the gross column summed to more than the total — a document that
+    // gross column summing to more than the total; printing each line already
-    // does not agree with itself, and no way for the reader to know which
+    // reduced left a line reading 202,50 beside "Rabatt 10 %" with no way to
-    // figure is the real one.
+    // tell whether the discount was in that number or still to come. Full
+    // price, a subtotal, one subtraction — a sum anybody can follow.
     $lines = [
         ['unit_net_cents' => 1900, 'quantity_milli' => 1000],
         ['unit_net_cents' => 9000, 'quantity_milli' => 2500, 'adjustment' => ['type' => InvoiceMath::PERCENT, 'value' => -1000]],
     ];
 
-    $columnNet = 0;
+    $column = 0;
-    $columnGross = 0;
 
     foreach ($lines as $line) {
-        $net = InvoiceMath::lineTotal($line['unit_net_cents'], $line['quantity_milli'], $line['adjustment'] ?? null);
+        $column += InvoiceMath::lineNet($line['unit_net_cents'], $line['quantity_milli']);
-        $columnNet += $net;
-        $columnGross += $net + InvoiceMath::tax($net, 2000);
     }
 
     $totals = InvoiceMath::totals($lines, null, 2000);
 
-    expect($columnNet)->toBe($totals['net'])
+    // The column the reader can add up on the page IS the subtotal.
-        ->and($columnGross)->toBe($totals['gross'])
+    expect($column)->toBe($totals['subtotal'])
-        // 225,00 less 10 % is 202,50; plus 19,00 is 221,50.
+        ->and($totals['subtotal'])->toBe(24400)
-        ->and($totals['net'])->toBe(22150);
+        ->and($totals['adjustment'])->toBe(-2250)
+        ->and($totals['net'])->toBe(22150)
+        ->and($totals['net'] + $totals['tax'])->toBe($totals['gross']);
 });
 
-it('labels an adjustment so the words cannot disagree with the arithmetic', function () {
+it('adds up discounts from several lines into one figure', function () {
-    expect(InvoiceMath::adjustmentLabel(['type' => InvoiceMath::PERCENT, 'value' => -1000]))
+    // Each line can carry its own, and the document shows their sum. Printing
-        ->toBe(__('invoice.discount').' 10 %')
+    // three separate discount rows under the table is a summary block nobody
-        ->and(InvoiceMath::adjustmentLabel(['type' => InvoiceMath::PERCENT, 'value' => 1550]))
+    // reads.
-        ->toBe(__('invoice.surcharge').' 15,5 %')
+    $lines = [
-        ->and(InvoiceMath::adjustmentLabel(['type' => InvoiceMath::AMOUNT, 'value' => -2500]))
+        ['unit_net_cents' => 10000, 'quantity_milli' => 1000, 'adjustment' => ['type' => InvoiceMath::PERCENT, 'value' => -1000]],
-        ->toBe(__('invoice.discount').' 25,00')
+        ['unit_net_cents' => 5000, 'quantity_milli' => 1000, 'adjustment' => ['type' => InvoiceMath::AMOUNT, 'value' => -500]],
-        // Nothing at all rather than "Rabatt 0,00", which reads as a mistake.
+        ['unit_net_cents' => 2000, 'quantity_milli' => 1000],
-        ->and(InvoiceMath::adjustmentLabel(['type' => InvoiceMath::AMOUNT, 'value' => 0]))->toBeNull()
+    ];
-        ->and(InvoiceMath::adjustmentLabel(null))->toBeNull();
+
+    $totals = InvoiceMath::totals($lines, null, 2000);
+
+    expect($totals['subtotal'])->toBe(17000)
+        ->and($totals['adjustment'])->toBe(-1500)
+        ->and($totals['net'])->toBe(15500);
 });