<?php
/**
* ownCloud
*
* @author Thomas Tanghus
* @copyright 2012-2013 Thomas Tanghus <thomas@tanghus.net>
* @copyright 2012 Bart Visscher bartv@thisnet.nl
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU AFFERO GENERAL PUBLIC LICENSE
* License as published by the Free Software Foundation; either
* version 3 of the License, or any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU AFFERO GENERAL PUBLIC LICENSE for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with this library.  If not, see <http://www.gnu.org/licenses/>.
*
*/

/**
 * Class for easily tagging objects by their id
 *
 * A tag can be e.g. 'Family', 'Work', 'Chore', 'Special Occation' or
 * anything else that is either parsed from a vobject or that the user chooses
 * to add.
 * Tag names are not case-sensitive, but will be saved with the case they
 * are entered in. If a user already has a tag 'family' for a type, and
 * tries to add a tag named 'Family' it will be silently ignored.
 */

namespace OC;

class Tags implements \OCP\ITags {

	/**
	 * Tags
	 *
	 * @var array
	 */
	private $tags = array();

	/**
	 * Used for storing objectid/categoryname pairs while rescanning.
	 *
	 * @var array
	 */
	private static $relations = array();

	/**
	 * Type
	 *
	 * @var string
	 */
	private $type = null;

	/**
	 * User
	 *
	 * @var string
	 */
	private $user = null;

	const TAG_TABLE = '*PREFIX*vcategory';
	const RELATION_TABLE = '*PREFIX*vcategory_to_object';

	const TAG_FAVORITE = '_$!<Favorite>!$_';

	/**
	* Constructor.
	*
	* @param string $user The user whos data the object will operate on.
	* @param string $type
	*/
	public function __construct($user, $type, $defaultTags = array()) {
		$this->user = $user;
		$this->type = $type;
		$this->loadTags($defaultTags);
	}

	/**
	* Load tags from db.
	*
	*/
	protected function loadTags($defaultTags=array()) {
		$this->tags = array();
		$result = null;
		$sql = 'SELECT `id`, `category` FROM `' . self::TAG_TABLE . '` '
			. 'WHERE `uid` = ? AND `type` = ? ORDER BY `category`';
		try {
			$stmt = \OCP\DB::prepare($sql);
			$result = $stmt->execute(array($this->user, $this->type));
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. ', DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
		}

		if(!is_null($result)) {
			while( $row = $result->fetchRow()) {
				$this->tags[$row['id']] = $row['category'];
			}
		}

		if(count($defaultTags) > 0 && count($this->tags) === 0) {
			$this->addMultiple($defaultTags, true);
		}
		\OCP\Util::writeLog('core', __METHOD__.', tags: ' . print_r($this->tags, true),
			\OCP\Util::DEBUG);

	}

	/**
	* Check if any tags are saved for this type and user.
	*
	* @return boolean.
	*/
	public function isEmpty() {
		$sql = 'SELECT COUNT(*) FROM `' . self::TAG_TABLE . '` '
			. 'WHERE `uid` = ? AND `type` = ?';
		try {
			$stmt = \OCP\DB::prepare($sql);
			$result = $stmt->execute(array($this->user, $this->type));
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. ', DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
				return false;
			}
			return ((int)$result->fetchOne() === 0);
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}
	}

	/**
	* Get the tags for a specific user.
	*
	* This returns an array with id/name maps:
	* [
	* 	['id' => 0, 'name' = 'First tag'],
	* 	['id' => 1, 'name' = 'Second tag'],
	* ]
	*
	* @return array
	*/
	public function getTags() {
		if(!count($this->tags)) {
			return array();
		}

		$tags = array_values($this->tags);
		uasort($tags, 'strnatcasecmp');
		$tagMap = array();

		foreach($tags as $tag) {
			if($tag !== self::TAG_FAVORITE) {
				$tagMap[] = array(
					'id' => $this->array_searchi($tag, $this->tags),
					'name' => $tag
					);
			}
		}
		return $tagMap;

	}

	/**
	* Get the a list if items tagged with $tag.
	*
	* Throws an exception if the tag could not be found.
	*
	* @param string $tag Tag id or name.
	* @return array An array of object ids or false on error.
	*/
	public function getIdsForTag($tag) {
		$result = null;
		if(is_numeric($tag)) {
			$tagId = $tag;
		} elseif(is_string($tag)) {
			$tag = trim($tag);
			$tagId = $this->array_searchi($tag, $this->tags);
		}

		if($tagId === false) {
			$l10n = \OC_L10N::get('core');
			throw new \Exception(
				$l10n->t('Could not find category "%s"', $tag)
			);
		}

		$ids = array();
		$sql = 'SELECT `objid` FROM `' . self::RELATION_TABLE
			. '` WHERE `categoryid` = ?';

		try {
			$stmt = \OCP\DB::prepare($sql);
			$result = $stmt->execute(array($tagId));
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
				return false;
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}

		if(!is_null($result)) {
			while( $row = $result->fetchRow()) {
				$ids[] = (int)$row['objid'];
			}
		}

		return $ids;
	}

	/**
	* Checks whether a tag is already saved.
	*
	* @param string $name The name to check for.
	* @return bool
	*/
	public function hasTag($name) {
		return $this->in_arrayi($name, $this->tags);
	}

	/**
	* Add a new tag.
	*
	* @param string $name A string with a name of the tag
	* @return false|string the id of the added tag or false if it already exists.
	*/
	public function add($name) {
		$name = trim($name);

		if($this->hasTag($name)) {
			\OCP\Util::writeLog('core', __METHOD__.', name: ' . $name. ' exists already', \OCP\Util::DEBUG);
			return false;
		}
		try {
			$result = \OCP\DB::insertIfNotExist(
				self::TAG_TABLE,
				array(
					'uid' => $this->user,
					'type' => $this->type,
					'category' => $name,
				)
			);
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
				return false;
			} elseif((int)$result === 0) {
				\OCP\Util::writeLog('core', __METHOD__.', Tag already exists: ' . $name, \OCP\Util::DEBUG);
				return false;
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}
		$id = \OCP\DB::insertid(self::TAG_TABLE);
		\OCP\Util::writeLog('core', __METHOD__.', id: ' . $id, \OCP\Util::DEBUG);
		$this->tags[$id] = $name;
		return $id;
	}

	/**
	* Rename tag.
	*
	* @param string $from The name of the existing tag
	* @param string $to The new name of the tag.
	* @return bool
	*/
	public function rename($from, $to) {
		$from = trim($from);
		$to = trim($to);
		$id = $this->array_searchi($from, $this->tags);
		if($id === false) {
			\OCP\Util::writeLog('core', __METHOD__.', tag: ' . $from. ' does not exist', \OCP\Util::DEBUG);
			return false;
		}

		$sql = 'UPDATE `' . self::TAG_TABLE . '` SET `category` = ? '
			. 'WHERE `uid` = ? AND `type` = ? AND `id` = ?';
		try {
			$stmt = \OCP\DB::prepare($sql);
			$result = $stmt->execute(array($to, $this->user, $this->type, $id));
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
				return false;
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}
		$this->tags[$id] = $to;
		return true;
	}

	/**
	* Add a list of new tags.
	*
	* @param string[] $names A string with a name or an array of strings containing
	* the name(s) of the to add.
	* @param bool $sync When true, save the tags
	* @param int|null $id int Optional object id to add to this|these tag(s)
	* @return bool Returns false on error.
	*/
	public function addMultiple($names, $sync=false, $id = null) {
		if(!is_array($names)) {
			$names = array($names);
		}
		$names = array_map('trim', $names);
		$newones = array();
		foreach($names as $name) {
			if(($this->in_arrayi(
				$name, $this->tags) == false) && $name !== '') {
				$newones[] = $name;
			}
			if(!is_null($id) ) {
				// Insert $objectid, $categoryid  pairs if not exist.
				self::$relations[] = array('objid' => $id, 'tag' => $name);
			}
		}
		$this->tags = array_merge($this->tags, $newones);
		if($sync === true) {
			$this->save();
		}

		return true;
	}

	/**
	 * Save the list of tags and their object relations
	 */
	protected function save() {
		if(is_array($this->tags)) {
			foreach($this->tags as $tag) {
				try {
					\OCP\DB::insertIfNotExist(self::TAG_TABLE,
						array(
							'uid' => $this->user,
							'type' => $this->type,
							'category' => $tag,
						));
				} catch(\Exception $e) {
					\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
						\OCP\Util::ERROR);
				}
			}
			// reload tags to get the proper ids.
			$this->loadTags();
			// Loop through temporarily cached objectid/tagname pairs
			// and save relations.
			$tags = $this->tags;
			// For some reason this is needed or array_search(i) will return 0..?
			ksort($tags);
			foreach(self::$relations as $relation) {
				$tagId = $this->array_searchi($relation['tag'], $tags);
				\OCP\Util::writeLog('core', __METHOD__ . 'catid, ' . $relation['tag'] . ' ' . $tagId, \OCP\Util::DEBUG);
				if($tagId) {
					try {
						\OCP\DB::insertIfNotExist(self::RELATION_TABLE,
							array(
								'objid' => $relation['objid'],
								'categoryid' => $tagId,
								'type' => $this->type,
								));
					} catch(\Exception $e) {
						\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
							\OCP\Util::ERROR);
					}
				}
			}
			self::$relations = array(); // reset
		} else {
			\OCP\Util::writeLog('core', __METHOD__.', $this->tags is not an array! '
				. print_r($this->tags, true), \OCP\Util::ERROR);
		}
	}

	/**
	* Delete tags and tag/object relations for a user.
	*
	* For hooking up on post_deleteUser
	*
	* @param array
	*/
	public static function post_deleteUser($arguments) {
		// Find all objectid/tagId pairs.
		$result = null;
		try {
			$stmt = \OCP\DB::prepare('SELECT `id` FROM `' . self::TAG_TABLE . '` '
				. 'WHERE `uid` = ?');
			$result = $stmt->execute(array($arguments['uid']));
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
		}

		if(!is_null($result)) {
			try {
				$stmt = \OCP\DB::prepare('DELETE FROM `' . self::RELATION_TABLE . '` '
					. 'WHERE `categoryid` = ?');
				while( $row = $result->fetchRow()) {
					try {
						$stmt->execute(array($row['id']));
					} catch(\Exception $e) {
						\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
							\OCP\Util::ERROR);
					}
				}
			} catch(\Exception $e) {
				\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
					\OCP\Util::ERROR);
			}
		}
		try {
			$stmt = \OCP\DB::prepare('DELETE FROM `' . self::TAG_TABLE . '` '
				. 'WHERE `uid` = ?');
			$result = $stmt->execute(array($arguments['uid']));
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. ', DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__ . ', exception: '
				. $e->getMessage(), \OCP\Util::ERROR);
		}
	}

	/**
	* Delete tag/object relations from the db
	*
	* @param array $ids The ids of the objects
	* @return boolean Returns false on error.
	*/
	public function purgeObjects(array $ids) {
		if(count($ids) === 0) {
			// job done ;)
			return true;
		}
		$updates = $ids;
		try {
			$query = 'DELETE FROM `' . self::RELATION_TABLE . '` ';
			$query .= 'WHERE `objid` IN (' . str_repeat('?,', count($ids)-1) . '?) ';
			$query .= 'AND `type`= ?';
			$updates[] = $this->type;
			$stmt = \OCP\DB::prepare($query);
			$result = $stmt->execute($updates);
			if (\OCP\DB::isError($result)) {
				\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
				return false;
			}
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: ' . $e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}
		return true;
	}

	/**
	* Get favorites for an object type
	*
	* @return array An array of object ids.
	*/
	public function getFavorites() {
		try {
			return $this->getIdsForTag(self::TAG_FAVORITE);
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: ' . $e->getMessage(),
				\OCP\Util::DEBUG);
			return array();
		}
	}

	/**
	* Add an object to favorites
	*
	* @param int $objid The id of the object
	* @return boolean
	*/
	public function addToFavorites($objid) {
		if(!$this->hasTag(self::TAG_FAVORITE)) {
			$this->add(self::TAG_FAVORITE, true);
		}
		return $this->tagAs($objid, self::TAG_FAVORITE, $this->type);
	}

	/**
	* Remove an object from favorites
	*
	* @param int $objid The id of the object
	* @return boolean
	*/
	public function removeFromFavorites($objid) {
		return $this->unTag($objid, self::TAG_FAVORITE, $this->type);
	}

	/**
	* Creates a tag/object relation.
	*
	* @param int $objid The id of the object
	* @param string $tag The id or name of the tag
	* @return boolean Returns false on database error.
	*/
	public function tagAs($objid, $tag) {
		if(is_string($tag) && !is_numeric($tag)) {
			$tag = trim($tag);
			if(!$this->hasTag($tag)) {
				$this->add($tag, true);
			}
			$tagId =  $this->array_searchi($tag, $this->tags);
		} else {
			$tagId = $tag;
		}
		try {
			\OCP\DB::insertIfNotExist(self::RELATION_TABLE,
				array(
					'objid' => $objid,
					'categoryid' => $tagId,
					'type' => $this->type,
				));
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}
		return true;
	}

	/**
	* Delete single tag/object relation from the db
	*
	* @param int $objid The id of the object
	* @param string $tag The id or name of the tag
	* @return boolean
	*/
	public function unTag($objid, $tag) {
		if(is_string($tag) && !is_numeric($tag)) {
			$tag = trim($tag);
			$tagId =  $this->array_searchi($tag, $this->tags);
		} else {
			$tagId = $tag;
		}

		try {
			$sql = 'DELETE FROM `' . self::RELATION_TABLE . '` '
					. 'WHERE `objid` = ? AND `categoryid` = ? AND `type` = ?';
			$stmt = \OCP\DB::prepare($sql);
			$stmt->execute(array($objid, $tagId, $this->type));
		} catch(\Exception $e) {
			\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
				\OCP\Util::ERROR);
			return false;
		}
		return true;
	}

	/**
	* Delete tags from the
	*
	* @param string[] $names An array of tags to delete
	* @return bool Returns false on error
	*/
	public function delete($names) {
		if(!is_array($names)) {
			$names = array($names);
		}

		$names = array_map('trim', $names);

		\OCP\Util::writeLog('core', __METHOD__ . ', before: '
			. print_r($this->tags, true), \OCP\Util::DEBUG);
		foreach($names as $name) {
			$id = null;

			if($this->hasTag($name)) {
				$id = $this->array_searchi($name, $this->tags);
				unset($this->tags[$id]);
			}
			try {
				$stmt = \OCP\DB::prepare('DELETE FROM `' . self::TAG_TABLE . '` WHERE '
					. '`uid` = ? AND `type` = ? AND `category` = ?');
				$result = $stmt->execute(array($this->user, $this->type, $name));
				if (\OCP\DB::isError($result)) {
					\OCP\Util::writeLog('core', __METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result), \OCP\Util::ERROR);
				}
			} catch(\Exception $e) {
				\OCP\Util::writeLog('core', __METHOD__ . ', exception: '
					. $e->getMessage(), \OCP\Util::ERROR);
				return false;
			}
			if(!is_null($id) && $id !== false) {
				try {
					$sql = 'DELETE FROM `' . self::RELATION_TABLE . '` '
							. 'WHERE `categoryid` = ?';
					$stmt = \OCP\DB::prepare($sql);
					$result = $stmt->execute(array($id));
					if (\OCP\DB::isError($result)) {
						\OCP\Util::writeLog('core',
							__METHOD__. 'DB error: ' . \OCP\DB::getErrorMessage($result),
							\OCP\Util::ERROR);
						return false;
					}
				} catch(\Exception $e) {
					\OCP\Util::writeLog('core', __METHOD__.', exception: '.$e->getMessage(),
						\OCP\Util::ERROR);
					return false;
				}
			}
		}
		return true;
	}

	// case-insensitive in_array
	private function in_arrayi($needle, $haystack) {
		if(!is_array($haystack)) {
			return false;
		}
		return in_array(strtolower($needle), array_map('strtolower', $haystack));
	}

	// case-insensitive array_search
	private function array_searchi($needle, $haystack) {
		if(!is_array($haystack)) {
			return false;
		}
		return array_search(strtolower($needle), array_map('strtolower', $haystack));
	}
}