1 files changed, 137 insertions, 0 deletions
diff --git a/core/namespace/ORM/Repositories/CategoryRepository.php b/core/namespace/ORM/Repositories/CategoryRepository.php
new file mode 100644
index 0000000..b62485a
--- /dev/null
+++ b/core/namespace/ORM/Repositories/CategoryRepository.php
@@ -0,0 +1,137 @@
+<?php
+namespace ORM\Repositories;
+use ORM\Repository;
+use ORM\EntityInterface;
+use ORM\Entities\Category;
+
+class CategoryRepository extends Repository {
+	public static function getTableName(): string { return 'category'; }
+	public static function getClassName(): string { return 'ORM\Entities\Category'; }
+
+	#===============================================================================
+	# Get number of *posts* assigned to $Category
+	#===============================================================================
+	public function getNumberOfPosts(Category $Category): int {
+		$query = 'SELECT COUNT(id) FROM %s WHERE category = ?';
+		$query = sprintf($query, PostRepository::getTableName());
+
+		$Statement = $this->Database->prepare($query);
+		$Statement->execute([$Category->getID()]);
+
+		return $Statement->fetchColumn();
+	}
+
+	#===============================================================================
+	# Find category with parents based on primary key
+	#===============================================================================
+	public function findWithParents($id): array {
+		return $this->findWithParentsBy('id', $id);
+	}
+
+	#===============================================================================
+	# Find category with parents based on specific field comparison
+	#===============================================================================
+	public function findWithParentsBy(string $field, $value): array {
+		$query = 'WITH RECURSIVE tree AS (
+			SELECT *, 0 AS _depth FROM %s WHERE %s %s UNION
+			SELECT c.*, _depth+1 FROM %s c, tree WHERE tree.parent = c.id
+		) SELECT * FROM tree ORDER BY _depth DESC';
+
+		$table = static::getTableName();
+		$check = is_null($value) ? 'IS NULL': '= ?';
+		$query = sprintf($query, $table, $field, $check, $table);
+
+		$Statement = $this->Database->prepare($query);
+		$Statement->execute([$value]);
+
+		# TODO: Virtual column _depth shall not be fetched into the entity class
+		return $this->fetchEntities($Statement);
+	}
+
+	#===============================================================================
+	# Get paginated category tree list
+	#===============================================================================
+	public function getPaginatedTree(int $limit, int $offset = 0): array {
+		$query = 'WITH RECURSIVE tree AS (
+			SELECT *, name AS _depth FROM %s WHERE parent IS NULL UNION
+			SELECT c.*, CONCAT(_depth, "/", c.name) AS _depth FROM %s c INNER JOIN tree ON tree.id = c.parent
+		) SELECT * FROM tree ORDER BY _depth %s';
+
+		$_limit = "LIMIT $limit";
+
+		if($offset) {
+			$_limit = "LIMIT $offset,$limit";
+		}
+
+		$table = static::getTableName();
+		$query = sprintf($query, $table, $table, $_limit);
+
+		$Statement = $this->Database->prepare($query);
+		$Statement->execute();
+
+		return $this->fetchEntities($Statement);
+	}
+
+	#===============================================================================
+	# Get number of children categories assigned to $Category
+	#===============================================================================
+	public function getNumberOfChildren(Category $Category): int {
+		$query = 'WITH RECURSIVE tree AS (
+			SELECT * FROM %s WHERE id = ? UNION
+			SELECT c.* FROM %s c, tree WHERE tree.id = c.parent
+		) SELECT COUNT(id) FROM tree WHERE id != ?';
+
+		$query = sprintf($query,
+			static::getTableName(),
+			static::getTableName()
+		);
+
+		$Statement = $this->Database->prepare($query);
+		$Statement->execute([$Category->getID(), $Category->getID()]);
+
+		return $Statement->fetchColumn();
+	}
+
+	#===============================================================================
+	# Update category (and check for parent/child circular loops)
+	#===============================================================================
+	public function update(EntityInterface $Entity): bool {
+		# Entity parent might have changed *in memory*, so we re-fetch the original
+		# parent of the entity from the database and save it in a variable.
+		# TODO: Repository/Entity class should have a mechanism to detect changes!
+		$query = 'SELECT parent FROM %s WHERE id = ?';
+		$query = sprintf($query, static::getTableName());
+
+		$Statement = $this->Database->prepare($query);
+		$Statement->execute([$Entity->getID()]);
+
+		$parent = $Statement->fetchColumn();
+
+		# If parent is unchanged, circular loop check is not needed.
+		if($parent === $Entity->get('parent')) {
+			return parent::update($Entity);
+		}
+
+		$_parent = $Entity->get('parent');
+
+		# Fetch the parent of the *new* parent category and let the while loop run through
+		# the tree until either a parent of "NULL" was found or if the new parent category
+		# is a *child* of the *current* category which would cause a circular loop.
+		while($Statement->execute([$_parent]) && $_parent = $Statement->fetchColumn()) {
+			if($_parent == $Entity->get('id')) {
+				# Set parent of the *new* parent category to the *original* parent category
+				# of the *current* category (one level up) to prevent a circular loop.
+				$query = 'UPDATE %s SET parent = ? WHERE id = ?';
+				$query = sprintf($query, static::getTableName());
+
+				$UpdateStatement = $this->Database->prepare($query);
+				$UpdateStatement->execute([$parent, $Entity->get('parent')]);
+				break;
+			} else if($_parent === NULL) {
+				break;
+			}
+		}
+
+		return parent::update($Entity);
+	}
+}