emailsignature.lib.php

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<?php
/* Copyright (C) 2026 Frédéric France      <frederic.france@free.fr>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/>.
 */
 
function dolCheckSignatureQuality($html)
{
  $html = (string) $html;
 
  // Tunable thresholds
  $maximg = getDolGlobalInt('SIGNATURE_QUALITY_MAX_IMG', 3);
  $maximgwidth = getDolGlobalInt('SIGNATURE_QUALITY_MAX_IMG_WIDTH', 600);
  $maxtextlen = getDolGlobalInt('SIGNATURE_QUALITY_MAX_TEXT_LEN', 600);
  $maxlinks = getDolGlobalInt('SIGNATURE_QUALITY_MAX_LINKS', 5);
  $mincharsperimg = getDolGlobalInt('SIGNATURE_QUALITY_MIN_CHARS_PER_IMG', 60);
  $mintextlen = getDolGlobalInt('SIGNATURE_QUALITY_MIN_TEXT_LEN', 20);
 
  // Fixed penalty weights (kept internal so the 0..100 scale stays meaningful)
  $w = array(
    'script_tag' => 60,
    'style_block' => 10,
    'non_absolute_url' => 25,
    'text_image_ratio_error' => 55,
    'text_image_ratio_warning' => 12,
    'image_count_error' => 20,
    'image_count_warning' => 10,
    'image_alt_per_image' => 5,
    'image_alt_cap' => 15,
    'image_weight' => 10,
    'link_count' => 10,
    'text_length' => 10,
    'contact_info' => 20,
    'fixed_width' => 5,
  );
 
  // A signature with almost no real text (and no image) can never be more than this
  $insufficientcontentcap = 35;
 
  $codes = array(
    'content', 'script_tag', 'style_block', 'non_absolute_url', 'text_image_ratio',
    'image_count', 'image_alt', 'image_weight', 'link_count', 'text_length',
    'contact_info', 'fixed_width',
  );
  $checks = array();
  foreach ($codes as $code) {
    $checks[$code] = array('status' => 'ok', 'weight' => 0);
  }
  $score = 100;
 
  $set = function (string $code, string $status, int $weight) use (&$checks, &$score) {
    $checks[$code] = array('status' => $status, 'weight' => $weight);
    $score -= $weight;
  };
 
  // Plain text length, ignoring the content of <script>/<style> blocks
  $htmlnoscript = preg_replace('/<(script|style)\b[^>]*>.*?<\/\1>/is', ' ', $html);
  $text = dol_string_nohtmltag((string) $htmlnoscript, 1, 'UTF-8', 0, 1);
  $text = trim((string) preg_replace('/\s+/u', ' ', (string) $text));
  $textlen = function_exists('mb_strlen') ? mb_strlen($text, 'UTF-8') : strlen($text);
  $wordcount = preg_match_all('/\p{L}{2,}/u', $text);
 
  // Collect <img> tags
  $matches = array();
  preg_match_all('/<img\b[^>]*>/i', $html, $matches);
  $imgtags = $matches[0];
  $nbimg = count($imgtags);
 
  // Nothing usable at all: this is not a signature
  if ($textlen == 0 && $nbimg == 0) {
    $checks['content']['status'] = 'error';
    $checks['text_image_ratio']['status'] = 'error';
    $checks['text_length']['status'] = 'error';
    $checks['contact_info']['status'] = 'error';
    return array('score' => 0, 'grade' => 'poor', 'checks' => $checks);
  }
 
  // Real content: a text-only signature must carry at least a couple of words (a name)
  $insufficientcontent = ($nbimg == 0 && ($textlen < $mintextlen || $wordcount < 2));
  if ($insufficientcontent) {
    $set('content', 'error', 0);
  }
 
  // Executable / non portable markup
  if (preg_match('/<script\b/i', $html)) {
    $set('script_tag', 'error', $w['script_tag']);
  }
  if (preg_match('/<style\b/i', $html) || preg_match('/<link\b[^>]*stylesheet/i', $html)) {
    $set('style_block', 'warning', $w['style_block']);
  }
 
  // Per image inspection
  $nbimgnoalt = 0;
  $hasnonabsolute = false;
  $hasheavyimg = false;
  foreach ($imgtags as $tag) {
    $src = '';
    if (preg_match('/\ssrc\s*=\s*("|\')(.*?)\1/is', $tag, $ms)) {
      $src = trim(html_entity_decode($ms[2], ENT_QUOTES, 'UTF-8'));
    }
    // Accepted: https://... , protocol relative //... , inline data:
    if ($src === '' || (!preg_match('#^(https:)?//#i', $src) && strpos($src, 'data:') !== 0)) {
      $hasnonabsolute = true;
    }
    if (strpos($src, 'data:') === 0) {
      $hasheavyimg = true; // inline base64 is reloaded in every single mail
    }
    if (!preg_match('/\salt\s*=\s*("|\')(.*?)\1/is', $tag) && !preg_match('/\salt\s*=\s*[^"\'\s>]+/i', $tag)) {
      $nbimgnoalt++;
    }
    if (preg_match('/\swidth\s*=\s*("|\')?\s*(\d+)/i', $tag, $mw) && (int) $mw[2] > $maximgwidth) {
      $hasheavyimg = true;
    }
    if (preg_match('/width\s*:\s*(\d+)\s*px/i', $tag, $mw2) && (int) $mw2[1] > $maximgwidth) {
      $hasheavyimg = true;
    }
  }
 
  if ($hasnonabsolute) {
    $set('non_absolute_url', 'error', $w['non_absolute_url']);
  }
 
  // Balance between real text and images
  if ($nbimg > 0) {
    $ratio = $textlen / $nbimg;
    if ($textlen < 10 || $ratio < 20) {
      $set('text_image_ratio', 'error', $w['text_image_ratio_error']);
    } elseif ($ratio < $mincharsperimg) {
      $set('text_image_ratio', 'warning', $w['text_image_ratio_warning']);
    }
  }
 
  // Too many images
  if ($nbimg > 2 * $maximg) {
    $set('image_count', 'error', $w['image_count_error']);
  } elseif ($nbimg > $maximg) {
    $set('image_count', 'warning', $w['image_count_warning']);
  }
 
  // Images without alt text
  if ($nbimgnoalt > 0) {
    $set('image_alt', 'warning', min($w['image_alt_cap'], $nbimgnoalt * $w['image_alt_per_image']));
  }
 
  // Heavy / oversized images
  if ($hasheavyimg) {
    $set('image_weight', 'warning', $w['image_weight']);
  }
 
  // Too many links
  $nblinks = preg_match_all('/<a\b[^>]*\shref\s*=/i', $html);
  if ($nblinks > $maxlinks) {
    $set('link_count', 'warning', $w['link_count']);
  }
 
  // Overly long text
  if ($textlen > $maxtextlen) {
    $set('text_length', 'warning', $w['text_length']);
  }
 
  // No reachable contact detail
  $hascontact = (preg_match('/mailto:/i', $html) || preg_match('/tel:/i', $html)
    || preg_match('/[\w.+-]+@[\w-]+\.[\w.-]+/', $text) || preg_match('/[\w.+-]+@[\w-]+\.[\w.-]+/', $html));
  if (!$hascontact) {
    $set('contact_info', 'warning', $w['contact_info']);
  }
 
  // Oversized fixed layout width (breaks on mobile)
  $fixedwidth = false;
  if (preg_match_all('/<(?:table|td|div)\b[^>]*\swidth\s*=\s*("|\')?\s*(\d+)/i', $html, $mfw)) {
    foreach ($mfw[2] as $wv) {
      if ((int) $wv > $maximgwidth) {
        $fixedwidth = true;
        break;
      }
    }
  }
  if ($fixedwidth) {
    $set('fixed_width', 'warning', $w['fixed_width']);
  }
 
  if ($insufficientcontent) {
    $score = min($score, $insufficientcontentcap);
  }
 
  $score = max(0, min(100, $score));
 
  if ($score >= 85) {
    $grade = 'excellent';
  } elseif ($score >= 65) {
    $grade = 'good';
  } elseif ($score >= 40) {
    $grade = 'fair';
  } else {
    $grade = 'poor';
  }
 
  return array('score' => (int) $score, 'grade' => $grade, 'checks' => $checks);
}
 
 
function dolGetSignatureQualityBadge($html, $outputlangs = null)
{
  global $langs;
 
  if (!is_object($outputlangs)) {
    $outputlangs = $langs;
  }
  $outputlangs->load('users');
 
  if (trim((string) $html) === '') {
    return '';
  }
 
  $res = dolCheckSignatureQuality($html);
 
  $gradecolors = array(
    'excellent' => '#1a9850',
    'good' => '#66bd63',
    'fair' => '#f46d43',
    'poor' => '#d73027',
  );
  $color = isset($gradecolors[$res['grade']]) ? $gradecolors[$res['grade']] : '#999999';
  $gradelabel = $outputlangs->trans('SignatureQuality'.ucfirst($res['grade']));
 
  $out = '<div class="signaturequalityscore paddingtop">';
  $out .= '<span class="badge" style="background-color: '.$color.';" title="'.dol_escape_htmltag($outputlangs->trans('SignatureQualityTooltip')).'">';
  $out .= dol_escape_htmltag($outputlangs->trans('SignatureQuality')).': '.dol_escape_htmltag($gradelabel).' &mdash; '.((int) $res['score']).'/100';
  $out .= '</span>';
 
  $issues = array();
  foreach ($res['checks'] as $code => $check) {
    if ($check['status'] === 'ok') {
      continue;
    }
    $key = 'SignatureCheck'.str_replace(' ', '', ucwords(str_replace('_', ' ', $code)));
    $advkey = 'SignatureAdvice'.str_replace(' ', '', ucwords(str_replace('_', ' ', $code)));
    $icon = ($check['status'] === 'error' ? img_picto('', 'error') : img_picto('', 'warning'));
    $issues[] = '<li>'.$icon.' <strong>'.dol_escape_htmltag($outputlangs->trans($key)).'</strong> &mdash; '.dol_escape_htmltag($outputlangs->trans($advkey)).'</li>';
  }
 
  if (count($issues)) {
    $out .= ' <details class="signaturequalitydetails inline-block">';
    $out .= '<summary class="cursorpointer">'.dol_escape_htmltag($outputlangs->trans('SignatureQualityDetails')).'</summary>';
    $out .= '<ul class="nomargin">'.implode('', $issues).'</ul>';
    $out .= '</details>';
  } else {
    $out .= ' <span class="opacitymedium">'.dol_escape_htmltag($outputlangs->trans('SignatureQualityNoIssue')).'</span>';
  }
 
  $out .= '</div>';
 
  return $out;
}