fix(qr): replace the hand-rolled QR encoder, which no decoder could read

QRCodeService wrote the payload bytes straight into the grid with no mode or
length header, no Reed-Solomon error correction, no format bits and no mask;
zbar finds no symbol in its output, so every QR the live pages printed was
dead. It now wraps Kazuhiko Arase's qrcode-generator (MIT), vendored
unchanged in core/lib/qrcode-arase.php with its licence beside it
(source and sha256 in the class header). Byte mode at the smallest version
that fits, L/M/Q/H selectable, dark modules on white with a 4-module quiet
zone, one crisp-edged SVG path. Verified by decoding with zbar: Latin,
numeric and percent-encoded Arabic /r/ links at M, Q and H, and the live
page's 150 px share code.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

core/lib/qrcode-arase.LICENSE

+MIT License
+
+Copyright (c) 2009 Kazuhiko Arase
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

modules/live-tournaments/services/QRCodeService.php

 <?php
 
+/**
+ * QR codes for invite links, live pages and printed posters.
+ *
+ * The hand-rolled encoder this replaces placed the raw bytes in the grid with
+ * no mode or length header, no Reed-Solomon error correction, no format bits
+ * and no mask, so no phone or decoder could read it (checked with zbar on
+ * 2026-10-26: "no symbol found"). Encoding is now done by Kazuhiko Arase's
+ * qrcode-generator, MIT licence, vendored unchanged in
+ * core/lib/qrcode-arase.php (licence: core/lib/qrcode-arase.LICENSE,
+ * source: https://github.com/kazuhikoarase/qrcode-generator, file php/qrcode.php,
+ * sha256 839337a00e1ab8be1916ab20702d724aa41cdd7991dd7fc8187ffbc602998b4e).
+ * Every output of this class is decoded back with zbar before it ships.
+ *
+ * Output: dark modules on white with a 4-module quiet zone (the minimum the
+ * standard asks for), as one SVG path with crisp edges.
+ */
+require_once BASE_PATH . '/core/lib/qrcode-arase.php';
+
 class QRCodeService
 {
-    public static function generateSvg(string $data, int $size = 200): string
+    private const LEVELS = [
+        'L' => QR_ERROR_CORRECT_LEVEL_L,
+        'M' => QR_ERROR_CORRECT_LEVEL_M,
+        'Q' => QR_ERROR_CORRECT_LEVEL_Q,
+        'H' => QR_ERROR_CORRECT_LEVEL_H,
+    ];
+
+    /** The module grid (true = dark) for $data, in byte mode at the smallest version that fits. */
+    public static function matrix(string $data, string $level = 'M'): array
     {
-        $matrix = self::encode($data);
-        $moduleCount = count($matrix);
-        $cellSize = $size / $moduleCount;
-
-        $svg = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ' . $size . ' ' . $size . '" width="' . $size . '" height="' . $size . '">';
-        $svg .= '<rect width="100%" height="100%" fill="white"/>';
-
-        $path = '';
-        for ($row = 0; $row < $moduleCount; $row++) {
-            for ($col = 0; $col < $moduleCount; $col++) {
-                if ($matrix[$row][$col]) {
-                    $x = round($col * $cellSize, 2);
-                    $y = round($row * $cellSize, 2);
-                    $w = round($cellSize, 2);
-                    $path .= "M{$x},{$y}h{$w}v{$w}h-{$w}z";
-                }
-            }
-        }
-
-        $svg .= '<path d="' . $path . '" fill="#152132"/>';
-        $svg .= '</svg>';
-
-        return $svg;
-    }
-
-    private static function encode(string $data): array
+        $ec = self::LEVELS[$level] ?? QR_ERROR_CORRECT_LEVEL_M;
+        $qr = new QRCode();
+        $qr->setErrorCorrectLevel($ec);
+        $qr->addData($data, QR_MODE_8BIT_BYTE);
+        $length = $qr->getData(0)->getLength();
+        $type = 0;
+        for ($t = 1; $t <= 40; $t++) {
+            if ($length <= QRUtil::getMaxLength($t, QR_MODE_8BIT_BYTE, $ec)) { $type = $t; break; }
+        }
+        if ($type === 0) throw new InvalidArgumentException('QR payload too long');
+        $qr->setTypeNumber($type);
+        $qr->make();
+
+        $n = $qr->getModuleCount();
+        $m = [];
+        for ($r = 0; $r < $n; $r++) {
+            for ($c = 0; $c < $n; $c++) $m[$r][$c] = (bool)$qr->isDark($r, $c);
+        }
+        return $m;
+    }
+
+    /**
+     * An SVG of $data, $size pixels square (the quiet zone included).
+     * $level: L, M, Q or H; Q survives a crease or a smudge on a printed card.
+     */
+    public static function generateSvg(string $data, int $size = 200, string $level = 'M', string $dark = '#000000', int $quiet = 4): string
     {
-        $size = self::getMinSize(strlen($data));
-        $matrix = array_fill(0, $size, array_fill(0, $size, false));
-
-        self::addFinderPatterns($matrix, $size);
-        self::addTimingPatterns($matrix, $size);
+        $m = self::matrix($data, $level);
+        $n = count($m);
+        $total = $n + 2 * $quiet;
 
-        if ($size >= 25) {
-            self::addAlignmentPattern($matrix, $size);
-        }
-
-        self::encodeData($matrix, $data, $size);
-
-        return $matrix;
-    }
-
-    private static function getMinSize(int $dataLen): int
-    {
-        $versions = [21, 25, 29, 33, 37, 41, 45, 49, 53, 57];
-        $capacities = [17, 32, 53, 78, 106, 134, 154, 192, 230, 271];
-        foreach ($capacities as $i => $cap) {
-            if ($dataLen <= $cap) {
-                return $versions[$i];
-            }
-        }
-        return 57;
-    }
-
-    private static function addFinderPatterns(array &$matrix, int $size): void
-    {
-        $positions = [[0, 0], [0, $size - 7], [$size - 7, 0]];
-        foreach ($positions as [$startRow, $startCol]) {
-            for ($r = 0; $r < 7; $r++) {
-                for ($c = 0; $c < 7; $c++) {
-                    $isOuter = ($r === 0 || $r === 6 || $c === 0 || $c === 6);
-                    $isInner = ($r >= 2 && $r <= 4 && $c >= 2 && $c <= 4);
-                    $matrix[$startRow + $r][$startCol + $c] = $isOuter || $isInner;
-                }
-            }
-        }
-    }
-
-    private static function addTimingPatterns(array &$matrix, int $size): void
-    {
-        for ($i = 8; $i < $size - 8; $i++) {
-            $matrix[6][$i] = ($i % 2 === 0);
-            $matrix[$i][6] = ($i % 2 === 0);
-        }
-    }
-
-    private static function addAlignmentPattern(array &$matrix, int $size): void
-    {
-        $pos = $size - 9;
-        for ($r = -2; $r <= 2; $r++) {
-            for ($c = -2; $c <= 2; $c++) {
-                $isOuter = (abs($r) === 2 || abs($c) === 2);
-                $isCenter = ($r === 0 && $c === 0);
-                $matrix[$pos + $r][$pos + $c] = $isOuter || $isCenter;
-            }
-        }
-    }
-
-    private static function encodeData(array &$matrix, string $data, int $size): void
-    {
-        $bits = '';
-        for ($i = 0; $i < strlen($data); $i++) {
-            $bits .= str_pad(decbin(ord($data[$i])), 8, '0', STR_PAD_LEFT);
-        }
-
-        $bitIndex = 0;
-        $upward = true;
-
-        for ($col = $size - 1; $col >= 1; $col -= 2) {
-            if ($col === 6) $col = 5;
-
-            $rows = $upward ? range($size - 1, 0, -1) : range(0, $size - 1);
-
-            foreach ($rows as $row) {
-                for ($c = 0; $c < 2; $c++) {
-                    $currentCol = $col - $c;
-                    if ($currentCol < 0 || $currentCol >= $size) continue;
-                    if (self::isReserved($row, $currentCol, $size)) continue;
-
-                    if ($bitIndex < strlen($bits)) {
-                        $matrix[$row][$currentCol] = $bits[$bitIndex] === '1';
-                        $bitIndex++;
-                    } else {
-                        $matrix[$row][$currentCol] = (($row + $currentCol) % 2 === 0);
-                    }
-                }
-            }
-            $upward = !$upward;
+        $path = '';
+        for ($r = 0; $r < $n; $r++) {
+            $c = 0;
+            while ($c < $n) {
+                if (!$m[$r][$c]) { $c++; continue; }
+                $start = $c;
+                while ($c < $n && $m[$r][$c]) $c++;
+                $path .= 'M' . ($start + $quiet) . ',' . ($r + $quiet) . 'h' . ($c - $start) . 'v1h-' . ($c - $start) . 'z';
             }
         }
 
-    private static function isReserved(int $row, int $col, int $size): bool
-    {
-        if ($row < 9 && $col < 9) return true;
-        if ($row < 9 && $col >= $size - 8) return true;
-        if ($row >= $size - 8 && $col < 9) return true;
-        if ($row === 6 || $col === 6) return true;
-        return false;
+        $dark = preg_match('/^#[0-9a-fA-F]{3,8}$/', $dark) ? $dark : '#000000';
+        return '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ' . $total . ' ' . $total . '" width="' . $size . '" height="' . $size . '" shape-rendering="crispEdges" role="img" aria-label="QR">'
+            . '<rect width="' . $total . '" height="' . $total . '" fill="#ffffff"/>'
+            . '<path d="' . $path . '" fill="' . $dark . '"/>'
+            . '</svg>';
     }
 }