Add category system to categorize posts (readme)

This commit implements a new category system to categorize posts. Each
category can have an unlimited number of nested children categories. A
single post don't necessarily need to be in a category, but it can.

Each category can have a full content body like posts or pages, so you
have enough space to describe the content of your categories.

Please note that you need to have at least the following MySQL/MariaDB
versions to use the category system, because it uses "WITH RECURSIVE"
database queries, the so-called "Common-Table-Expressions (CTE)".

MariaDB: 10.2.2
MySQL: 8.0

See: https://mariadb.com/kb/en/with/
See: https://dev.mysql.com/doc/refman/8.0/en/with.html

6 files changed, 178 insertions, 0 deletions

diff --git a/theme/admin/html/category/delete.php b/theme/admin/html/category/delete.php
new file mode 100644
index 0000000..635e9a8
--- /dev/null
+++ b/theme/admin/html/category/delete.php
@@ -0,0 +1,6 @@
+<main id="main-content">
+<h1><i class="fa fa-trash-o"></i><?=$Language->text('delete_category')?></h1>
+<p><?=$Language->text('delete_category_desc')?></p>
+
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/category/form.php b/theme/admin/html/category/form.php
new file mode 100644
index 0000000..2cb7b20
--- /dev/null
+++ b/theme/admin/html/category/form.php
@@ -0,0 +1,112 @@
+<?php
+function categorySelectList($category_tree, $selected = NULL, $current = NULL, $prefix = '') {
+	foreach($category_tree as $category) {
+		$option = '<option value="%s"%s>%s%s [%d]</option>';
+		$select = ($category['ID'] == $selected) ? ' selected' : '';
+		$select = ($category['ID'] == $current) ? ' disabled' : $select;
+
+		printf($option, $category['ID'], $select, $prefix, escapeHTML($category['NAME']), $category['ID']);
+
+		if(isset($category['CHILDS'])) {
+			# If there are children, call self and pass children array.
+			(__FUNCTION__)($category['CHILDS'], $selected, $current, $prefix.'– ');
+		}
+	}
+}
+?>
+<?php if($FORM['INFO']): ?>
+	<div id="message-list-wrapper">
+		<ul id="message-list">
+			<?php foreach($FORM['INFO'] as $message): ?>
+				<li><?=$message?></li>
+			<?php endforeach ?>
+		</ul>
+	</div>
+<?php endif ?>
+
+<form action="" method="POST">
+	<input type="hidden" name="token" value="<?=$FORM['TOKEN']?>" />
+
+<?php if($FORM['TYPE'] !== 'DELETE'): ?>
+	<div class="form-grid">
+		<label for="form_name">
+			<i class="fa fa-tag"></i><?=$Language->text('label_name')?></label>
+
+		<div class="form-grid-item first">
+			<input id="form_name" name="name" value="<?=escapeHTML($FORM['DATA']['NAME'])?>" />
+		</div>
+
+		<label for="form_slug">
+			<i class="fa fa-link"></i><?=$Language->text('label_slug')?></label>
+
+		<div class="form-grid-item">
+			<input id="form_slug" name="slug" value="<?=escapeHTML($FORM['DATA']['SLUG'])?>" />
+		</div>
+
+		<label for="form_category_parent">
+			<i class="fa fa-tags"></i><?=$Language->text('label_category_parent')?></label>
+
+		<div class="form-grid-item">
+			<select id="form_category_parent" name="parent">
+				<option value="">[ –– <?=$Language->text('label_category')?> –– ]</option>
+				<?=categorySelectList($FORM['CATEGORY_TREE'], $FORM['DATA']['PARENT'], $FORM['DATA']['ID']);?>
+			</select>
+		</div>
+
+		<label for="form_time_insert">
+			<i class="fa fa-clock-o"></i><?=$Language->text('label_insert')?></label>
+
+		<div class="form-grid-item">
+			<input id="form_time_insert" name="time_insert" placeholder="YYYY-MM-DD HH:II:SS" value="<?=escapeHTML($FORM['DATA']['TIME_INSERT'])?>" />
+		</div>
+
+		<label for="form_time_update">
+			<i class="fa fa-pencil"></i><?=$Language->text('label_update')?></label>
+
+		<div class="form-grid-item">
+			<input id="form_time_update" name="time_update" placeholder="<?=escapeHTML($FORM['DATA']['TIME_UPDATE'] ?: 'CURRENT_TIMESTAMP')?>" value="" />
+		</div>
+	</div>
+
+	<div id="content-editor-wrapper" class="form-border-box">
+		<div id="button-list-wrapper">
+			<ul id="markdown-list" class="button-list markdown">
+				<li data-markdown="bold" class="fa fa-bold" title="<?=$Language->text('markdown_bold')?>"></li>
+				<li data-markdown="italic" class="fa fa-italic" title="<?=$Language->text('markdown_italic')?>"></li>
+				<li data-markdown="heading" class="fa fa-header" title="<?=$Language->text('markdown_heading')?>"></li>
+				<li data-markdown="link" class="fa fa-link" title="<?=$Language->text('markdown_link')?>"></li>
+				<li data-markdown="image" class="fa fa-picture-o" title="<?=$Language->text('markdown_image')?>"></li>
+				<li data-markdown="code" class="fa fa-code" title="<?=$Language->text('markdown_code')?>"></li>
+				<li data-markdown="quote" class="fa fa-quote-right" title="<?=$Language->text('markdown_quote')?>"></li>
+				<li data-markdown="list_ul" class="fa fa-list-ul" title="<?=$Language->text('markdown_list_ul')?>"></li>
+				<li data-markdown="list_ol" class="fa fa-list-ol" title="<?=$Language->text('markdown_list_ol')?>"></li>
+			</ul>
+		</div>
+		<textarea id="content-editor" name="body" placeholder="[…]"><?=escapeHTML($FORM['DATA']['BODY'])?></textarea>
+	</div>
+	<div id="emoticon-list-wrapper" class="form-border-box background padding">
+		<ul id="emoticon-list" class="button-list emoticons">
+			<?php foreach(getUnicodeEmoticons() as $emoticon => $explanation):?>
+				<li data-emoticon="<?=$emoticon?>" title="<?=$explanation?>"><?=$emoticon?></li>
+			<?php endforeach; ?>
+		</ul>
+	</div>
+	<div class="form-border-box background padding">
+		<input id="form_argv" name="argv" maxlength="250" placeholder="[ARGUMENT_ONE=foo|ARGUMENT_TWO=bar …]" value="<?=escapeHTML($FORM['DATA']['ARGV'])?>" />
+	</div>
+<?php else: ?>
+	<div class="form-border-box background padding">
+		<?=$HTML?>
+	</div>
+<?php endif; ?>
+
+	<div class="form-border-box background padding">
+		<?php if($FORM['TYPE'] === 'INSERT'): ?>
+			<input id="insert-button" type="submit" name="insert" value="<?=$Language->text('insert')?>" />
+		<?php elseif($FORM['TYPE'] === 'UPDATE'): ?>
+			<input id="update-button" type="submit" name="update" value="<?=$Language->text('update')?>" />
+		<?php elseif($FORM['TYPE'] === 'DELETE'): ?>
+			<input id="delete-button" type="submit" name="delete" value="<?=$Language->text('delete')?>" data-text="<?=$Language->text('sure')?>" />
+		<?php endif; ?>
+	</div>
+</form>
diff --git a/theme/admin/html/category/index.php b/theme/admin/html/category/index.php
new file mode 100644
index 0000000..e2c35a4
--- /dev/null
+++ b/theme/admin/html/category/index.php
@@ -0,0 +1,15 @@
+<main id="main-content" class="wide">
+<h1><i class="fa fa-tags"></i><?=$Language->text('category_overview')?></h1>
+<p class="actions-before"><?=$Language->text('overview_category_desc')?></p>
+<ul class="actions">
+	<li><a href="<?=Application::getAdminURL('category/insert.php')?>" title="<?=$Language->text('insert_category')?>"><i class="fa fa-plus"></i><?=$Language->text('insert')?></a></li>
+</ul>
+
+<div class="item-container category grid">
+	<?php foreach($LIST['CATEGORIES'] as $category): ?>
+		<?php echo $category; ?>
+	<?php endforeach; ?>
+</div>
+
+<?=$PAGINATION['HTML']?>
+</main>
diff --git a/theme/admin/html/category/insert.php b/theme/admin/html/category/insert.php
new file mode 100644
index 0000000..be9fdfe
--- /dev/null
+++ b/theme/admin/html/category/insert.php
@@ -0,0 +1,6 @@
+<main id="main-content">
+<h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('insert_category')?></h1>
+<p><?=$Language->text('insert_category_desc')?></p>
+
+<?=$HTML?>
+</main>
diff --git a/theme/admin/html/category/item.php b/theme/admin/html/category/item.php
new file mode 100644
index 0000000..05212e7
--- /dev/null
+++ b/theme/admin/html/category/item.php
@@ -0,0 +1,33 @@
+<article class="item">
+	<header>
+		<h2><i class="fa fa-tag"></i><?=escapeHTML($CATEGORY['ATTR']['NAME'])?></h2>
+		<div>
+			<span class="brackets item-id">#<?=$CATEGORY['ATTR']['ID']?></span>
+			<time class="brackets" datetime="<?=$CATEGORY['ATTR']['TIME_INSERT']?>"><?=parseDatetime($CATEGORY['ATTR']['TIME_INSERT'], $Language->text('date_format'))?></time>
+			<span class="brackets"><?=$Language->text('posts')?>: <?=$COUNT['POST']?></span>
+			<span class="brackets"><?=$Language->text('categories')?>: <?=$COUNT['CHILDREN']?></span>
+		</div>
+	</header>
+	<blockquote cite="<?=$CATEGORY['URL']?>">
+		<?php if(isset($CATEGORY['FILE']['LIST'][0])): ?>
+			<img class="item-image" src="<?=$CATEGORY['FILE']['LIST'][0]?>" alt="" />
+		<?php endif; ?>
+		<p><?=excerpt($CATEGORY['BODY']['HTML']())?></p>
+	</blockquote>
+
+	<?php if($CATEGORY['ARGV']): ?>
+		<ul class="arguments">
+			<?php foreach($CATEGORY['ARGV'] as $argument => $value): ?>
+				<li><strong><?=$argument?>:</strong> <span><?=escapeHTML($value)?></span></li>
+			<?php endforeach; ?>
+		</ul>
+	<?php endif; ?>
+
+	<footer>
+		<ul>
+			<li><a href="<?=$CATEGORY['URL']?>" target="_blank" title="<?=$Language->text('select_category')?>"><i class="fa fa-external-link"></i><span class="hidden"><?=$Language->text('select_category')?></span></a></li>
+			<li><a href="<?=Application::getAdminURL("category/update.php?id={$CATEGORY['ATTR']['ID']}")?>" title="<?=$Language->text('update_category')?>"><i class="fa fa-pencil-square-o"></i><span class="hidden"><?=$Language->text('update_category')?></span></a></li>
+			<li><a href="<?=Application::getAdminURL("category/delete.php?id={$CATEGORY['ATTR']['ID']}")?>" title="<?=$Language->text('delete_category')?>"><i class="fa fa-trash-o"></i><span class="hidden"><?=$Language->text('delete_category')?></span></a></li>
+		</ul>
+	</footer>
+</article>
diff --git a/theme/admin/html/category/update.php b/theme/admin/html/category/update.php
new file mode 100644
index 0000000..fefaa18
--- /dev/null
+++ b/theme/admin/html/category/update.php
@@ -0,0 +1,6 @@
+<main id="main-content">
+<h1><i class="fa fa-pencil-square-o"></i><?=$Language->text('update_category')?></h1>
+<p><?=$Language->text('update_category_desc')?></p>
+
+<?=$HTML?>
+</main>