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Fix duplicate IDs for multiple footnote references #6

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Merged
merged 1 commit into from
Nov 28, 2025
Merged

Fix duplicate IDs for multiple footnote references #6

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52 changes: 49 additions & 3 deletions src/Renderer/HtmlRenderer.php
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Original file line number Diff line number Diff line change
Expand Up @@ -942,17 +942,24 @@ protected function renderFootnotesSection(): string
foreach ($renderedContents as $number => $content) {
$html .= '<li id="fn' . $number . '">' . "\n";

// Find the label for this footnote number to get ref count
$label = array_search($number, $this->footnoteNumbers, true);
$refCount = $label !== false ? ($this->footnoteRefCounts[$label] ?? 1) : 1;

// Generate backlinks - multiple if footnote referenced multiple times
$backlinks = $this->generateBacklinks($number, $refCount);

// Add backlink - if content ends with </p>, insert before it
// Otherwise add as separate paragraph
if ($content !== '' && preg_match('/^(.*)(<\/p>\n?)$/s', $content, $matches)) {
$content = $matches[1] . '<a href="#fnref' . $number . '" role="doc-backlink">↩︎</a></p>';
$content = $matches[1] . $backlinks . '</p>';
$html .= $content . "\n";
} else {
// Content doesn't end with paragraph (e.g., code block or empty)
if ($content !== '') {
$html .= $content . "\n";
}
$html .= '<p><a href="#fnref' . $number . '" role="doc-backlink">↩︎</a></p>' . "\n";
$html .= '<p>' . $backlinks . '</p>' . "\n";
}

$html .= '</li>' . "\n";
Expand All @@ -964,6 +971,32 @@ protected function renderFootnotesSection(): string
return $html;
}

/**
* Generate backlink(s) for a footnote
*
* @param int $number Footnote number
* @param int $refCount Number of times footnote was referenced
*/
protected function generateBacklinks(int $number, int $refCount): string
{
if ($refCount <= 1) {
// Single reference - simple backlink
return '<a href="#fnref' . $number . '" role="doc-backlink">↩︎</a>';
}

// Multiple references - generate numbered backlinks
$links = [];
for ($i = 1; $i <= $refCount; $i++) {
$refId = 'fnref' . $number;
if ($i > 1) {
$refId .= '-' . $i;
}
$links[] = '<a href="#' . $refId . '" role="doc-backlink">↩︎<sup>' . $i . '</sup></a>';
}

return implode(' ', $links);
}

protected function renderFootnoteRef(FootnoteRef $node): string
{
$label = $node->getLabel();
Expand All @@ -975,8 +1008,21 @@ protected function renderFootnoteRef(FootnoteRef $node): string
}
$number = $this->footnoteNumbers[$label];

// Track reference count for this footnote to generate unique IDs
if (!isset($this->footnoteRefCounts[$label])) {
$this->footnoteRefCounts[$label] = 0;
}
$this->footnoteRefCounts[$label]++;
$refCount = $this->footnoteRefCounts[$label];

// Generate unique ID: fnref1 for first, fnref1-2 for second, etc.
$refId = 'fnref' . $number;
if ($refCount > 1) {
$refId .= '-' . $refCount;
}

// Format: <a id="fnref1" href="#fn1" role="doc-noteref"><sup>1</sup></a>
return '<a id="fnref' . $number . '" href="#fn' . $number . '" role="doc-noteref"><sup>' . $number . '</sup></a>';
return '<a id="' . $refId . '" href="#fn' . $number . '" role="doc-noteref"><sup>' . $number . '</sup></a>';
}

protected function renderMath(Math $node): string
Expand Down
56 changes: 56 additions & 0 deletions tests/TestCase/DjotConverterTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2380,4 +2380,60 @@ public function testBackticksWithClosingFenceIsCodeBlock(): void
$this->assertStringContainsString('<pre><code class="language-python">', $result);
$this->assertStringContainsString('x = y + 3', $result);
}

/**
* Test that multiple references to the same footnote get unique IDs
*
* Fix for GitHub issue jgm/djot#348: Multiple calls to the same note
* should generate unique HTML-compliant IDs with suffixes.
*/
public function testMultipleFootnoteReferencesGetUniqueIds(): void
{
$djot = <<<'DJOT'
First ref[^note].

Second ref[^note].

Third ref[^note].

[^note]: The footnote.
DJOT;

$result = $this->converter->convert($djot);

// Each reference should have a unique ID
$this->assertStringContainsString('id="fnref1"', $result);
$this->assertStringContainsString('id="fnref1-2"', $result);
$this->assertStringContainsString('id="fnref1-3"', $result);

// All should link to the same footnote
$this->assertSame(3, substr_count($result, 'href="#fn1"'));

// Footnote should have multiple backlinks
$this->assertStringContainsString('href="#fnref1"', $result);
$this->assertStringContainsString('href="#fnref1-2"', $result);
$this->assertStringContainsString('href="#fnref1-3"', $result);

// Single footnote (no duplicates)
$this->assertSame(1, substr_count($result, 'id="fn1"'));
}

public function testSingleFootnoteReferenceNoSuffix(): void
{
$djot = <<<'DJOT'
Single ref[^note].

[^note]: The footnote.
DJOT;

$result = $this->converter->convert($djot);

// Single reference - no suffix needed
$this->assertStringContainsString('id="fnref1"', $result);
$this->assertStringNotContainsString('fnref1-', $result);

// Simple backlink without numbering
$this->assertStringContainsString('href="#fnref1"', $result);
$this->assertStringNotContainsString('<sup>1</sup></a> <a', $result);
}
}
6 changes: 3 additions & 3 deletions tests/official/footnotes.test
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Original file line number Diff line number Diff line change
Expand Up @@ -13,13 +13,13 @@ test[^a] and another[^foo_bar].
another ref to the first note[^a].
.
<p>test<a id="fnref1" href="#fn1" role="doc-noteref"><sup>1</sup></a> and another<a id="fnref2" href="#fn2" role="doc-noteref"><sup>2</sup></a>.</p>
<p>another ref to the first note<a id="fnref1" href="#fn1" role="doc-noteref"><sup>1</sup></a>.</p>
<p>another ref to the first note<a id="fnref1-2" href="#fn1" role="doc-noteref"><sup>1</sup></a>.</p>
<section role="doc-endnotes">
<hr>
<ol>
<li id="fn1">
<p>This is a note.</p>
<p>Second paragraph.<a href="#fnref1" role="doc-backlink">↩︎</a></p>
<p>Second paragraph.<a href="#fnref1" role="doc-backlink">↩︎<sup>1</sup></a> <a href="#fnref1-2" role="doc-backlink">↩︎<sup>2</sup></a></p>
</li>
<li id="fn2">
<pre><code>code
Expand Down Expand Up @@ -85,7 +85,7 @@ text[^footnote].
<p>very long footnote<a id="fnref2" href="#fn2" role="doc-noteref"><sup>2</sup></a><a href="#fnref1" role="doc-backlink">↩︎</a></p>
</li>
<li id="fn2">
<p>bla bla<a id="fnref2" href="#fn2" role="doc-noteref"><sup>2</sup></a><a href="#fnref2" role="doc-backlink">↩︎</a></p>
<p>bla bla<a id="fnref2-2" href="#fn2" role="doc-noteref"><sup>2</sup></a><a href="#fnref2" role="doc-backlink">↩︎<sup>1</sup></a> <a href="#fnref2-2" role="doc-backlink">↩︎<sup>2</sup></a></p>
</li>
</ol>
</section>
Expand Down