Added related tag suggesting on tag click

public_html/media/css/core.css

@@ -320,6 +320,28 @@ ul.tagit input {
 	height: auto !important;
 	margin: -4px 0 !important;
 }
+.related-tags {
+	padding: 0.5em;
+	background: rgba(255,255,255,0.7);
+	border-radius: 3px;
+	margin: 0.4em 0 0.2em 0;
+	font-size: 95%;
+}
+.related-tags ul {
+	list-style-type: none;
+	margin: 0;
+	padding: 0;
+	display: block;
+	overflow: hidden;
+}
+.related-tags p {
+	float: left;
+	margin: 0 1em 0 0;
+}
+.related-tags li {
+	display: inline-block;
+	margin: 0 1em 0 0;
+}
 
 
 
@@ -427,7 +449,6 @@ blockquote>*:last-child {
 }
 
 .ui-state-default,
-.ui-widget-content .ui-state-default,
-.ui-widget-header .ui-state-default {
+.ui-state-default a {
 	color: hsla(0,70%,45%,0.8) !important;
 }

public_html/media/js/core.js

@@ -268,11 +268,52 @@ $(function()
 	});
 });
 
-function attachTagIt(element)
+function attachTagIt(target)
 {
 	var tagItOptions =
 	{
 		caseSensitive: false,
+		onTagClicked: function(e, ui)
+		{
+			var targetTagit = ui.tag.parents('.tagit');
+			options = { tag: ui.tagLabel };
+			if (targetTagit.siblings('.related-tags:eq(0)').data('for') == options.tag)
+			{
+				targetTagit.siblings('.related-tags').slideUp(function()
+				{
+					$(this).remove();
+				});
+				return;
+			}
+
+			$.getJSON('/tags-related?json', options, function(data)
+			{
+				var list = $('<ul>');
+				$.each(data.tags.slice(0, 10), function(i, tag)
+				{
+					var link = $('<a>');
+					link.attr('href', '#');
+					link.text('#' + tag.name);
+					link.click(function(e)
+					{
+						e.preventDefault();
+						target.tagit('createTag', tag.name);
+					});
+					list.append(link.wrap('<li/>').parent());
+				});
+				targetTagit.siblings('.related-tags').slideUp(function()
+				{
+					$(this).remove();
+				});
+				var div = $('<div>');
+				div.data('for', options.tag);
+				div.addClass('related-tags');
+				div.append('<p>Related tags:</p>');
+				div.append(list);
+				div.insertAfter(targetTagit).hide().slideDown();
+			});
+		},
+
 		autocomplete:
 		{
 			source:
@@ -295,8 +336,8 @@ function attachTagIt(element)
 		}
 	};
 
-	tagItOptions.placeholderText = element.attr('placeholder');
-	element.tagit(tagItOptions);
+	tagItOptions.placeholderText = target.attr('placeholder');
+	target.tagit(tagItOptions);
 }
 
 

src/Controllers/TagController.php

@@ -66,6 +66,28 @@ class TagController
 				}, $tags));
 	}
 
+	/**
+	* @route /tags-related
+	*/
+	public function relatedAction()
+	{
+		PrivilegesHelper::confirmWithException(Privilege::ListTags);
+
+		$suppliedTag = InputHelper::get('tag');
+
+		$tags = TagSearchService::getRelatedTagRows($suppliedTag, 10, 1);
+
+		$this->context->transport->tags =
+			array_values(array_map(
+				function($tag)
+				{
+					return [
+						'name' => $tag['name'],
+						'count' => $tag['post_count']
+					];
+				}, $tags));
+	}
+
 	/**
 	* @route /tag/merge
 	*/

src/Models/SearchServices/TagSearchService.php

@@ -9,6 +9,63 @@ class TagSearchService extends AbstractSearchService
 		$stmt->addColumn(new Sql\AliasFunctor(new Sql\CountFunctor('post_tag.post_id'), 'post_count'));
 	}
 
+	public static function getRelatedTagRows($parentTagName, $limit)
+	{
+		$parentTagEntity = TagModel::findByName($parentTagName, false);
+		if (empty($parentTagEntity))
+			return [];
+		$parentTagId = $parentTagEntity->id;
+
+		//get tags that appear with selected tag along with their occurence frequency
+		$stmt = (new Sql\SelectStatement)
+			->setTable('tag')
+			->addColumn('tag.*')
+			->addColumn(new Sql\AliasFunctor(new Sql\CountFunctor('post_tag.post_id'), 'post_count'))
+			->addInnerJoin('post_tag', new Sql\EqualsFunctor('post_tag.tag_id', 'tag.id'))
+			->setGroupBy('tag.id')
+			->setOrderBy('post_count', Sql\SelectStatement::ORDER_DESC)
+			->setLimit($limit + 1, 0)
+			->setCriterion(new Sql\ExistsFunctor((new Sql\SelectStatement)
+				->setTable('post_tag pt2')
+				->setCriterion((new Sql\ConjunctionFunctor)
+					->add(new Sql\EqualsFunctor('pt2.post_id', 'post_tag.post_id'))
+					->add(new Sql\EqualsFunctor('pt2.tag_id', new Sql\Binding($parentTagId)))
+				)));
+
+		$rows1 = [];
+		foreach (Database::fetchAll($stmt) as $row)
+			$rows1[$row['id']] = $row;
+
+		//get the same tags, but this time - get global occurence frequency
+		$stmt = (new Sql\SelectStatement)
+			->setTable('tag')
+			->addColumn('tag.*')
+			->addColumn(new Sql\AliasFunctor(new Sql\CountFunctor('post_tag.post_id'), 'post_count'))
+			->addInnerJoin('post_tag', new Sql\EqualsFunctor('post_tag.tag_id', 'tag.id'))
+			->setCriterion(Sql\InFunctor::fromArray('tag.id', Sql\Binding::fromArray(array_keys($rows1))))
+			->setGroupBy('tag.id');
+
+		$rows2 = [];
+		foreach (Database::fetchAll($stmt) as $row)
+			$rows2[$row['id']] = $row;
+
+		$rows = [];
+		foreach ($rows1 as $i => $row)
+		{
+			//multiply own occurences by two because we are going to subtract them
+			$row['sort'] = $row['post_count'] * 2;
+			//subtract global occurencecount
+			$row['sort'] -= isset($rows2[$i]) ? $rows2[$i]['post_count'] : 0;
+
+			if ($row['id'] != $parentTagId)
+				$rows []= $row;
+		}
+
+		usort($rows, function($a, $b) { return intval($b['sort']) - intval($a['sort']); });
+
+		return $rows;
+	}
+
 	public static function getMostUsedTag()
 	{
 		$stmt = (new Sql\SelectStatement)