From e332b4710ae88cc341b2c4ea04c4208911d16f70 Mon Sep 17 00:00:00 2001
From: Aidan Woods <aidantwoods@gmail.com>
Date: Mon, 4 May 2020 22:02:20 +0100
Subject: [PATCH 1/4] Add HeaderSlug configurable

Adds HeaderSlug configurable, with the option for the slug function
to be customised.

Co-authored-by: netniV <netniv@hotmail.com>
---
 src/Components/Blocks/Header.php           | 10 +++-
 src/Components/Blocks/SetextHeader.php     | 10 +++-
 src/Configurables/HeaderSlug.php           | 64 ++++++++++++++++++++++
 tests/ParsedownTest.php                    |  2 +
 tests/data/slug_heading.html               | 10 ++++
 tests/data/slug_heading.md                 | 24 ++++++++
 tests/src/Configurables/HeaderSlugTest.php | 38 +++++++++++++
 7 files changed, 156 insertions(+), 2 deletions(-)
 create mode 100644 src/Configurables/HeaderSlug.php
 create mode 100644 tests/data/slug_heading.html
 create mode 100644 tests/data/slug_heading.md
 create mode 100644 tests/src/Configurables/HeaderSlugTest.php

diff --git a/src/Components/Blocks/Header.php b/src/Components/Blocks/Header.php
index ae2180c..cbdfae1 100644
--- a/src/Components/Blocks/Header.php
+++ b/src/Components/Blocks/Header.php
@@ -5,6 +5,7 @@ namespace Erusev\Parsedown\Components\Blocks;
 use Erusev\Parsedown\AST\Handler;
 use Erusev\Parsedown\AST\StateRenderable;
 use Erusev\Parsedown\Components\Block;
+use Erusev\Parsedown\Configurables\HeaderSlug;
 use Erusev\Parsedown\Configurables\StrictMode;
 use Erusev\Parsedown\Html\Renderables\Element;
 use Erusev\Parsedown\Parsedown;
@@ -96,9 +97,16 @@ final class Header implements Block
         return new Handler(
             /** @return Element */
             function (State $State) {
+                $HeaderSlug = $State->get(HeaderSlug::class);
+                $attributes = (
+                    $HeaderSlug->isEnabled()
+                    ? ['id' => $HeaderSlug->transform($this->text())]
+                    : []
+                );
+
                 return new Element(
                     'h' . \strval($this->level()),
-                    [],
+                    $attributes,
                     $State->applyTo(Parsedown::line($this->text(), $State))
                 );
             }
diff --git a/src/Components/Blocks/SetextHeader.php b/src/Components/Blocks/SetextHeader.php
index 4e1a5df..dbdf04b 100644
--- a/src/Components/Blocks/SetextHeader.php
+++ b/src/Components/Blocks/SetextHeader.php
@@ -6,6 +6,7 @@ use Erusev\Parsedown\AST\Handler;
 use Erusev\Parsedown\AST\StateRenderable;
 use Erusev\Parsedown\Components\AcquisitioningBlock;
 use Erusev\Parsedown\Components\Block;
+use Erusev\Parsedown\Configurables\HeaderSlug;
 use Erusev\Parsedown\Html\Renderables\Element;
 use Erusev\Parsedown\Parsedown;
 use Erusev\Parsedown\Parsing\Context;
@@ -88,9 +89,16 @@ final class SetextHeader implements AcquisitioningBlock
         return new Handler(
             /** @return Element */
             function (State $State) {
+                $HeaderSlug = $State->get(HeaderSlug::class);
+                $attributes = (
+                    $HeaderSlug->isEnabled()
+                    ? ['id' => $HeaderSlug->transform($this->text())]
+                    : []
+                );
+
                 return new Element(
                     'h' . \strval($this->level()),
-                    [],
+                    $attributes,
                     $State->applyTo(Parsedown::line($this->text(), $State))
                 );
             }
diff --git a/src/Configurables/HeaderSlug.php b/src/Configurables/HeaderSlug.php
new file mode 100644
index 0000000..a2e75eb
--- /dev/null
+++ b/src/Configurables/HeaderSlug.php
@@ -0,0 +1,64 @@
+<?php
+
+namespace Erusev\Parsedown\Configurables;
+
+use Erusev\Parsedown\Configurable;
+
+final class HeaderSlug implements Configurable
+{
+    /** @var bool */
+    private $enabled = false;
+
+    /** @var \Closure(string):string */
+    private $slugCallback;
+
+    /**
+     * @param bool $enabled
+     * @param (\Closure(string):string)|null $slugCallback
+     */
+    public function __construct($enabled, $slugCallback = null)
+    {
+        $this->enabled = $enabled;
+
+        if (! isset($slugCallback)) {
+            $this->slugCallback = function (string $text): string {
+                $slug = \mb_strtolower($text);
+                $slug = \str_replace(' ', '-', $slug);
+                $slug = \preg_replace('/[^\p{L}\p{N}\p{M}-]+/u', '', $slug);
+
+                return $slug;
+            };
+        } else {
+            $this->slugCallback = $slugCallback;
+        }
+    }
+
+    /** @return bool */
+    public function isEnabled()
+    {
+        return $this->enabled;
+    }
+
+    public function transform(string $text): string
+    {
+        return ($this->slugCallback)($text);
+    }
+
+    /** @param \Closure(string):string $slugCallback */
+    public static function withCallback($slugCallback): self
+    {
+        return new self(true, $slugCallback);
+    }
+
+    /** @return self */
+    public static function enabled()
+    {
+        return new self(true);
+    }
+
+    /** @return self */
+    public static function initial()
+    {
+        return new self(false);
+    }
+}
diff --git a/tests/ParsedownTest.php b/tests/ParsedownTest.php
index d463279..f0833c5 100755
--- a/tests/ParsedownTest.php
+++ b/tests/ParsedownTest.php
@@ -6,6 +6,7 @@ use Erusev\Parsedown\Components\Blocks\Markup as BlockMarkup;
 use Erusev\Parsedown\Components\Inlines\Markup as InlineMarkup;
 use Erusev\Parsedown\Configurables\BlockTypes;
 use Erusev\Parsedown\Configurables\Breaks;
+use Erusev\Parsedown\Configurables\HeaderSlug;
 use Erusev\Parsedown\Configurables\InlineTypes;
 use Erusev\Parsedown\Configurables\SafeMode;
 use Erusev\Parsedown\Configurables\StrictMode;
@@ -59,6 +60,7 @@ class ParsedownTest extends TestCase
             new SafeMode(\substr($test, 0, 3) === 'xss'),
             new StrictMode(\substr($test, 0, 6) === 'strict'),
             new Breaks(\substr($test, 0, 14) === 'breaks_enabled'),
+            new HeaderSlug(\substr($test, 0, 4) === 'slug'),
         ]));
 
         $actualMarkup = $Parsedown->toHtml($markdown);
diff --git a/tests/data/slug_heading.html b/tests/data/slug_heading.html
new file mode 100644
index 0000000..d379bb4
--- /dev/null
+++ b/tests/data/slug_heading.html
@@ -0,0 +1,10 @@
+<h1 id="foo">foo</h1>
+<h1 id="foo-bar">foo bar</h1>
+<h1 id="foobar">foo_bar</h1>
+<h1 id="foobar">foo+bar</h1>
+<h1 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h1>
+<h2 id="foo">foo</h2>
+<h2 id="foo-bar">foo bar</h2>
+<h2 id="foobar">foo_bar</h2>
+<h2 id="foobar">foo+bar</h2>
+<h2 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h2>
\ No newline at end of file
diff --git a/tests/data/slug_heading.md b/tests/data/slug_heading.md
new file mode 100644
index 0000000..01f66d6
--- /dev/null
+++ b/tests/data/slug_heading.md
@@ -0,0 +1,24 @@
+# foo
+
+# foo bar
+
+# foo_bar
+
+# foo+bar
+
+# 2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි
+
+foo
+---
+
+foo bar
+---
+
+foo_bar
+---
+
+foo+bar
+---
+
+2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි
+---
\ No newline at end of file
diff --git a/tests/src/Configurables/HeaderSlugTest.php b/tests/src/Configurables/HeaderSlugTest.php
new file mode 100644
index 0000000..7b4806a
--- /dev/null
+++ b/tests/src/Configurables/HeaderSlugTest.php
@@ -0,0 +1,38 @@
+<?php
+
+namespace Erusev\Parsedown\Tests\Configurables;
+
+use Erusev\Parsedown\Configurables\HeaderSlug;
+use Erusev\Parsedown\State;
+use PHPUnit\Framework\TestCase;
+
+final class HeaderSlugTest extends TestCase
+{
+    /**
+     * @return void
+     * @throws \PHPUnit\Framework\ExpectationFailedException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
+     */
+    public function testNamedConstructor()
+    {
+        $State = new State([HeaderSlug::enabled()]);
+
+        $this->assertSame(true, $State->get(HeaderSlug::class)->isEnabled());
+    }
+    /**
+     * @return void
+     * @throws \PHPUnit\Framework\ExpectationFailedException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
+     */
+    public function testCustomCallback()
+    {
+        $HeaderSlug = HeaderSlug::withCallback(function (string $t): string {
+            return \preg_replace('/[^A-Za-z0-9]++/', '_', $t);
+        });
+
+        $this->assertSame(
+            'foo_bar',
+            $HeaderSlug->transform('foo bar')
+        );
+    }
+}

From d8bf07535c7621b6994c9cb2196c996a9b9acc01 Mon Sep 17 00:00:00 2001
From: Aidan Woods <aidantwoods@gmail.com>
Date: Mon, 4 May 2020 22:37:38 +0100
Subject: [PATCH 2/4] Strip superscripts and divisions from eventual slug

As suggested by @Ayesh

Co-authored-by: Ayesh Karunaratne <ayesh@ayesh.me>
---
 src/Configurables/HeaderSlug.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Configurables/HeaderSlug.php b/src/Configurables/HeaderSlug.php
index a2e75eb..103faeb 100644
--- a/src/Configurables/HeaderSlug.php
+++ b/src/Configurables/HeaderSlug.php
@@ -24,7 +24,7 @@ final class HeaderSlug implements Configurable
             $this->slugCallback = function (string $text): string {
                 $slug = \mb_strtolower($text);
                 $slug = \str_replace(' ', '-', $slug);
-                $slug = \preg_replace('/[^\p{L}\p{N}\p{M}-]+/u', '', $slug);
+                $slug = \preg_replace('/[^\p{L}\p{Nd}\p{Nl}\p{M}-]+/u', '', $slug);
 
                 return $slug;
             };

From 4e99e29d286b057d6c89baf746fd721096445fe9 Mon Sep 17 00:00:00 2001
From: Aidan Woods <aidantwoods@gmail.com>
Date: Tue, 5 May 2020 19:11:02 +0100
Subject: [PATCH 3/4] Trim leading and trailing hyphens from slug

---
 src/Configurables/HeaderSlug.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/Configurables/HeaderSlug.php b/src/Configurables/HeaderSlug.php
index 103faeb..2f32699 100644
--- a/src/Configurables/HeaderSlug.php
+++ b/src/Configurables/HeaderSlug.php
@@ -25,6 +25,7 @@ final class HeaderSlug implements Configurable
                 $slug = \mb_strtolower($text);
                 $slug = \str_replace(' ', '-', $slug);
                 $slug = \preg_replace('/[^\p{L}\p{Nd}\p{Nl}\p{M}-]+/u', '', $slug);
+                $slug = \trim($slug, '-');
 
                 return $slug;
             };

From 8764512c23f2a68565bc8060117dc65f9c89fd9c Mon Sep 17 00:00:00 2001
From: Aidan Woods <aidantwoods@gmail.com>
Date: Tue, 5 May 2020 19:42:32 +0100
Subject: [PATCH 4/4] Add SlugRegister so IDs are not duplicated

---
 src/Components/Blocks/Header.php           |  4 +-
 src/Components/Blocks/SetextHeader.php     |  4 +-
 src/Configurables/HeaderSlug.php           | 43 +++++++++++++++++++--
 src/Configurables/SlugRegister.php         | 44 ++++++++++++++++++++++
 tests/data/slug_heading.html               | 13 ++++---
 tests/data/slug_heading.md                 |  2 +
 tests/src/Configurables/HeaderSlugTest.php | 24 +++++++++++-
 7 files changed, 121 insertions(+), 13 deletions(-)
 create mode 100644 src/Configurables/SlugRegister.php

diff --git a/src/Components/Blocks/Header.php b/src/Components/Blocks/Header.php
index cbdfae1..c3859fe 100644
--- a/src/Components/Blocks/Header.php
+++ b/src/Components/Blocks/Header.php
@@ -6,6 +6,7 @@ use Erusev\Parsedown\AST\Handler;
 use Erusev\Parsedown\AST\StateRenderable;
 use Erusev\Parsedown\Components\Block;
 use Erusev\Parsedown\Configurables\HeaderSlug;
+use Erusev\Parsedown\Configurables\SlugRegister;
 use Erusev\Parsedown\Configurables\StrictMode;
 use Erusev\Parsedown\Html\Renderables\Element;
 use Erusev\Parsedown\Parsedown;
@@ -98,9 +99,10 @@ final class Header implements Block
             /** @return Element */
             function (State $State) {
                 $HeaderSlug = $State->get(HeaderSlug::class);
+                $Register = $State->get(SlugRegister::class);
                 $attributes = (
                     $HeaderSlug->isEnabled()
-                    ? ['id' => $HeaderSlug->transform($this->text())]
+                    ? ['id' => $HeaderSlug->transform($Register, $this->text())]
                     : []
                 );
 
diff --git a/src/Components/Blocks/SetextHeader.php b/src/Components/Blocks/SetextHeader.php
index dbdf04b..482e37a 100644
--- a/src/Components/Blocks/SetextHeader.php
+++ b/src/Components/Blocks/SetextHeader.php
@@ -7,6 +7,7 @@ use Erusev\Parsedown\AST\StateRenderable;
 use Erusev\Parsedown\Components\AcquisitioningBlock;
 use Erusev\Parsedown\Components\Block;
 use Erusev\Parsedown\Configurables\HeaderSlug;
+use Erusev\Parsedown\Configurables\SlugRegister;
 use Erusev\Parsedown\Html\Renderables\Element;
 use Erusev\Parsedown\Parsedown;
 use Erusev\Parsedown\Parsing\Context;
@@ -90,9 +91,10 @@ final class SetextHeader implements AcquisitioningBlock
             /** @return Element */
             function (State $State) {
                 $HeaderSlug = $State->get(HeaderSlug::class);
+                $Register = $State->get(SlugRegister::class);
                 $attributes = (
                     $HeaderSlug->isEnabled()
-                    ? ['id' => $HeaderSlug->transform($this->text())]
+                    ? ['id' => $HeaderSlug->transform($Register, $this->text())]
                     : []
                 );
 
diff --git a/src/Configurables/HeaderSlug.php b/src/Configurables/HeaderSlug.php
index 2f32699..a0bc3c3 100644
--- a/src/Configurables/HeaderSlug.php
+++ b/src/Configurables/HeaderSlug.php
@@ -12,12 +12,19 @@ final class HeaderSlug implements Configurable
     /** @var \Closure(string):string */
     private $slugCallback;
 
+    /** @var \Closure(string,int):string */
+    private $duplicationCallback;
+
     /**
      * @param bool $enabled
      * @param (\Closure(string):string)|null $slugCallback
+     * @param (\Closure(string, int):string)|null $duplicationCallback
      */
-    public function __construct($enabled, $slugCallback = null)
-    {
+    public function __construct(
+        $enabled,
+        $slugCallback = null,
+        $duplicationCallback = null
+    ) {
         $this->enabled = $enabled;
 
         if (! isset($slugCallback)) {
@@ -32,6 +39,14 @@ final class HeaderSlug implements Configurable
         } else {
             $this->slugCallback = $slugCallback;
         }
+
+        if (! isset($duplicationCallback)) {
+            $this->duplicationCallback = function (string $slug, int $duplicateNumber): string {
+                return $slug . '-' . \strval($duplicateNumber-1);
+            };
+        } else {
+            $this->duplicationCallback = $duplicationCallback;
+        }
     }
 
     /** @return bool */
@@ -40,9 +55,23 @@ final class HeaderSlug implements Configurable
         return $this->enabled;
     }
 
-    public function transform(string $text): string
+    public function transform(SlugRegister $SlugRegister, string $text): string
     {
-        return ($this->slugCallback)($text);
+        $slug = ($this->slugCallback)($text);
+
+        if ($SlugRegister->slugCount($slug) > 0) {
+            $newSlug = ($this->duplicationCallback)($slug, $SlugRegister->mutatingIncrement($slug));
+
+            while ($SlugRegister->slugCount($newSlug) > 0) {
+                $newSlug = ($this->duplicationCallback)($slug, $SlugRegister->mutatingIncrement($slug));
+            }
+
+            return $newSlug;
+        }
+
+        $SlugRegister->mutatingIncrement($slug);
+
+        return $slug;
     }
 
     /** @param \Closure(string):string $slugCallback */
@@ -51,6 +80,12 @@ final class HeaderSlug implements Configurable
         return new self(true, $slugCallback);
     }
 
+    /** @param \Closure(string,int):string $duplicationCallback */
+    public static function withDuplicationCallback($duplicationCallback): self
+    {
+        return new self(true, null, $duplicationCallback);
+    }
+
     /** @return self */
     public static function enabled()
     {
diff --git a/src/Configurables/SlugRegister.php b/src/Configurables/SlugRegister.php
new file mode 100644
index 0000000..1a659e0
--- /dev/null
+++ b/src/Configurables/SlugRegister.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace Erusev\Parsedown\Configurables;
+
+use Erusev\Parsedown\MutableConfigurable;
+
+final class SlugRegister implements MutableConfigurable
+{
+    /** @var array<string, int> */
+    private $register;
+
+    /**
+     * @param array<string, int> $register
+     */
+    public function __construct(array $register = [])
+    {
+        $this->register = $register;
+    }
+
+    /** @return self */
+    public static function initial()
+    {
+        return new self;
+    }
+
+    public function mutatingIncrement(string $slug): int
+    {
+        if (! isset($this->register[$slug])) {
+            $this->register[$slug] = 0;
+        }
+
+        return ++$this->register[$slug];
+    }
+
+    public function slugCount(string $slug): int
+    {
+        return $this->register[$slug] ?? 0;
+    }
+
+    public function isolatedCopy(): self
+    {
+        return new self($this->register);
+    }
+}
diff --git a/tests/data/slug_heading.html b/tests/data/slug_heading.html
index d379bb4..56b6021 100644
--- a/tests/data/slug_heading.html
+++ b/tests/data/slug_heading.html
@@ -1,10 +1,11 @@
 <h1 id="foo">foo</h1>
 <h1 id="foo-bar">foo bar</h1>
 <h1 id="foobar">foo_bar</h1>
-<h1 id="foobar">foo+bar</h1>
+<h1 id="foobar-1">foo+bar-1</h1>
+<h1 id="foobar-2">foo+bar</h1>
 <h1 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h1>
-<h2 id="foo">foo</h2>
-<h2 id="foo-bar">foo bar</h2>
-<h2 id="foobar">foo_bar</h2>
-<h2 id="foobar">foo+bar</h2>
-<h2 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h2>
\ No newline at end of file
+<h2 id="foo-1">foo</h2>
+<h2 id="foo-bar-1">foo bar</h2>
+<h2 id="foobar-3">foo_bar</h2>
+<h2 id="foobar-4">foo+bar</h2>
+<h2 id="2rer0ගම්මැද්ද-v-force-ඉනොවේශන්-නේෂන්-සඳහා-එවූ-නි-1">2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි</h2>
\ No newline at end of file
diff --git a/tests/data/slug_heading.md b/tests/data/slug_heading.md
index 01f66d6..2317bb5 100644
--- a/tests/data/slug_heading.md
+++ b/tests/data/slug_heading.md
@@ -4,6 +4,8 @@
 
 # foo_bar
 
+# foo+bar-1
+
 # foo+bar
 
 # 2rer*(0👍ගම්මැද්ද V FORCE ඉනොවේශන් නේෂන් සඳහා එවූ නි
diff --git a/tests/src/Configurables/HeaderSlugTest.php b/tests/src/Configurables/HeaderSlugTest.php
index 7b4806a..e831a70 100644
--- a/tests/src/Configurables/HeaderSlugTest.php
+++ b/tests/src/Configurables/HeaderSlugTest.php
@@ -3,6 +3,7 @@
 namespace Erusev\Parsedown\Tests\Configurables;
 
 use Erusev\Parsedown\Configurables\HeaderSlug;
+use Erusev\Parsedown\Configurables\SlugRegister;
 use Erusev\Parsedown\State;
 use PHPUnit\Framework\TestCase;
 
@@ -19,6 +20,7 @@ final class HeaderSlugTest extends TestCase
 
         $this->assertSame(true, $State->get(HeaderSlug::class)->isEnabled());
     }
+
     /**
      * @return void
      * @throws \PHPUnit\Framework\ExpectationFailedException
@@ -32,7 +34,27 @@ final class HeaderSlugTest extends TestCase
 
         $this->assertSame(
             'foo_bar',
-            $HeaderSlug->transform('foo bar')
+            $HeaderSlug->transform(SlugRegister::initial(), 'foo bar')
+        );
+    }
+
+    /**
+     * @return void
+     * @throws \PHPUnit\Framework\ExpectationFailedException
+     * @throws \SebastianBergmann\RecursionContext\InvalidArgumentException
+     */
+    public function testCustomDuplicationCallback()
+    {
+        $HeaderSlug = HeaderSlug::withDuplicationCallback(function (string $t, int $n): string {
+            return $t . '_' . \strval($n-1);
+        });
+
+        $SlugRegister = new SlugRegister;
+        $HeaderSlug->transform($SlugRegister, 'foo bar');
+
+        $this->assertSame(
+            'foo-bar_1',
+            $HeaderSlug->transform($SlugRegister, 'foo bar')
         );
     }
 }