<?php
/**
 * Elgg users
 * Functions to manage multiple or single users in an Elgg install
 *
 * @package Elgg
 * @subpackage Core
 * @author Curverider Ltd
 * @link http://elgg.org/
 */

/// Map a username to a cached GUID
$USERNAME_TO_GUID_MAP_CACHE = array();

/// Map a user code to a cached GUID
$CODE_TO_GUID_MAP_CACHE = array();

/**
 * ElggUser
 *
 * Representation of a "user" in the system.
 *
 * @package Elgg
 * @subpackage Core
 */
class ElggUser extends ElggEntity
	implements Friendable {
	/**
	 * Initialise the attributes array.
	 * This is vital to distinguish between metadata and base parameters.
	 *
	 * Place your base parameters here.
	 */
	protected function initialise_attributes() {
		parent::initialise_attributes();

		$this->attributes['type'] = "user";
		$this->attributes['name'] = "";
		$this->attributes['username'] = "";
		$this->attributes['password'] = "";
		$this->attributes['salt'] = "";
		$this->attributes['email'] = "";
		$this->attributes['language'] = "";
		$this->attributes['code'] = "";
		$this->attributes['banned'] = "no";
		$this->attributes['tables_split'] = 2;
	}

	/**
	 * Construct a new user entity, optionally from a given id value.
	 *
	 * @param mixed $guid If an int, load that GUID.
	 * 	If a db row then will attempt to load the rest of the data.
	 * @throws Exception if there was a problem creating the user.
	 */
	function __construct($guid = null) {
		$this->initialise_attributes();

		if (!empty($guid)) {
			// Is $guid is a DB row - either a entity row, or a user table row.
			if ($guid instanceof stdClass) {
				// Load the rest
				if (!$this->load($guid->guid)) {
					throw new IOException(sprintf(elgg_echo('IOException:FailedToLoadGUID'), get_class(), $guid->guid));
				}
			}

			// See if this is a username
			else if (is_string($guid)) {
				$guid = get_user_by_username($guid);
				foreach ($guid->attributes as $key => $value) {
					$this->attributes[$key] = $value;
				}
			}

			// Is $guid is an ElggUser? Use a copy constructor
			else if ($guid instanceof ElggUser) {
				foreach ($guid->attributes as $key => $value) {
					$this->attributes[$key] = $value;
				}
			}

			// Is this is an ElggEntity but not an ElggUser = ERROR!
			else if ($guid instanceof ElggEntity) {
				throw new InvalidParameterException(elgg_echo('InvalidParameterException:NonElggUser'));
			}

			// We assume if we have got this far, $guid is an int
			else if (is_numeric($guid)) {
				if (!$this->load($guid)) {
					IOException(sprintf(elgg_echo('IOException:FailedToLoadGUID'), get_class(), $guid));
				}
			}

			else {
				throw new InvalidParameterException(elgg_echo('InvalidParameterException:UnrecognisedValue'));
			}
		}
	}

	/**
	 * Override the load function.
	 * This function will ensure that all data is loaded (were possible), so
	 * if only part of the ElggUser is loaded, it'll load the rest.
	 *
	 * @param int $guid
	 * @return true|false
	 */
	protected function load($guid) {
		// Test to see if we have the generic stuff
		if (!parent::load($guid)) {
			return false;
		}

		// Check the type
		if ($this->attributes['type']!='user') {
			throw new InvalidClassException(sprintf(elgg_echo('InvalidClassException:NotValidElggStar'), $guid, get_class()));
		}

		// Load missing data
		$row = get_user_entity_as_row($guid);
		if (($row) && (!$this->isFullyLoaded())) {
			// If $row isn't a cached copy then increment the counter
			$this->attributes['tables_loaded'] ++;
		}

		// Now put these into the attributes array as core values
		$objarray = (array) $row;
		foreach($objarray as $key => $value) {
			$this->attributes[$key] = $value;
		}

		return true;
	}

	/**
	 * Saves this user to the database.
	 * @return true|false
	 */
	public function save() {
		// Save generic stuff
		if (!parent::save()) {
			return false;
		}

		// Now save specific stuff
		return create_user_entity($this->get('guid'), $this->get('name'), $this->get('username'), $this->get('password'), $this->get('salt'), $this->get('email'), $this->get('language'), $this->get('code'));
	}

	/**
	 * User specific override of the entity delete method.
	 *
	 * @return bool
	 */
	public function delete() {
		global $USERNAME_TO_GUID_MAP_CACHE, $CODE_TO_GUID_MAP_CACHE;
		
		// clear cache
		if (isset($USERNAME_TO_GUID_MAP_CACHE[$this->username])) {
			unset($USERNAME_TO_GUID_MAP_CACHE[$this->username]);
		}
		if (isset($CODE_TO_GUID_MAP_CACHE[$this->code])) {
			unset($CODE_TO_GUID_MAP_CACHE[$this->code]);
		}
		
		// Delete owned data
		clear_annotations_by_owner($this->guid);
		clear_metadata_by_owner($this->guid);
		clear_user_files($this);

		// Delete entity
		return parent::delete();
	}

	/**
	 * Ban this user.
	 *
	 * @param string $reason Optional reason
	 */
	public function ban($reason = "") {
		return ban_user($this->guid, $reason);
	}

	/**
	 * Unban this user.
	 */
	public function unban()	{
		return unban_user($this->guid);
	}

	/**
	 * Is this user banned or not?
	 *
	 * @return bool
	 */
	public function isBanned() {
		return $this->banned == 'yes';
	}

	/**
	 * Get sites that this user is a member of
	 *
	 * @param string $subtype Optionally, the subtype of result we want to limit to
	 * @param int $limit The number of results to return
	 * @param int $offset Any indexing offset
	 */
	function getSites($subtype="", $limit = 10, $offset = 0) {
		// return get_site_users($this->getGUID(), $subtype, $limit, $offset);
		return get_user_sites($this->getGUID(), $subtype, $limit, $offset);
	}

	/**
	 * Add this user to a particular site
	 *
	 * @param int $site_guid The guid of the site to add it to
	 * @return true|false
	 */
	function addToSite($site_guid) {
		// return add_site_user($this->getGUID(), $site_guid);
		return add_site_user($site_guid, $this->getGUID());
	}

	/**
	 * Remove this user from a particular site
	 *
	 * @param int $site_guid The guid of the site to remove it from
	 * @return true|false
	 */
	function removeFromSite($site_guid) {
		//return remove_site_user($this->getGUID(), $site_guid);
		return remove_site_user($site_guid, $this->getGUID());
	}

	/**
	 * Adds a user to this user's friends list
	 *
	 * @param int $friend_guid The GUID of the user to add
	 * @return true|false Depending on success
	 */
	function addFriend($friend_guid) {
		return user_add_friend($this->getGUID(), $friend_guid);
	}

	/**
	 * Removes a user from this user's friends list
	 *
	 * @param int $friend_guid The GUID of the user to remove
	 * @return true|false Depending on success
	 */
	function removeFriend($friend_guid) {
		return user_remove_friend($this->getGUID(), $friend_guid);
	}

	/**
	 * Determines whether or not this user is a friend of the currently logged in user
	 *
	 * @return true|false
	 */
	function isFriend() {
		return user_is_friend(get_loggedin_userid(), $this->getGUID());
	}

	/**
	 * Determines whether this user is friends with another user
	 *
	 * @param int $user_guid The GUID of the user to check is on this user's friends list
	 * @return true|false
	 */
	function isFriendsWith($user_guid) {
		return user_is_friend($this->getGUID(), $user_guid);
	}

	/**
	 * Determines whether or not this user is on another user's friends list
	 *
	 * @param int $user_guid The GUID of the user to check against
	 * @return true|false
	 */
	function isFriendOf($user_guid) {
		return user_is_friend($user_guid, $this->getGUID());
	}

	/**
	 * Retrieves a list of this user's friends
	 *
	 * @param string $subtype Optionally, the subtype of user to filter to (leave blank for all)
	 * @param int $limit The number of users to retrieve
	 * @param int $offset Indexing offset, if any
	 * @return array|false Array of ElggUsers, or false, depending on success
	 */
	function getFriends($subtype = "", $limit = 10, $offset = 0) {
		return get_user_friends($this->getGUID(), $subtype, $limit, $offset);
	}

	/**
	 * Retrieves a list of people who have made this user a friend
	 *
	 * @param string $subtype Optionally, the subtype of user to filter to (leave blank for all)
	 * @param int $limit The number of users to retrieve
	 * @param int $offset Indexing offset, if any
	 * @return array|false Array of ElggUsers, or false, depending on success
	 */
	function getFriendsOf($subtype = "", $limit = 10, $offset = 0) {
		return get_user_friends_of($this->getGUID(), $subtype, $limit, $offset);
	}

	/**
	 * Get an array of ElggObjects owned by this user.
	 *
	 * @param string $subtype The subtype of the objects, if any
	 * @param int $limit Number of results to return
	 * @param int $offset Any indexing offset
	 */
	public function getObjects($subtype="", $limit = 10, $offset = 0) {
		return get_user_objects($this->getGUID(), $subtype, $limit, $offset);
	}

	/**
	 * Get an array of ElggObjects owned by this user's friends.
	 *
	 * @param string $subtype The subtype of the objects, if any
	 * @param int $limit Number of results to return
	 * @param int $offset Any indexing offset
	 */
	public function getFriendsObjects($subtype = "", $limit = 10, $offset = 0) {
		return get_user_friends_objects($this->getGUID(), $subtype, $limit, $offset);
	}

	/**
	 * Counts the number of ElggObjects owned by this user
	 *
	 * @param string $subtype The subtypes of the objects, if any
	 * @return int The number of ElggObjects
	 */
	public function countObjects($subtype = "") {
		return count_user_objects($this->getGUID(), $subtype);
	}

	/**
	 * Get the collections associated with a user.
	 *
	 * @param string $subtype Optionally, the subtype of result we want to limit to
	 * @param int $limit The number of results to return
	 * @param int $offset Any indexing offset
	 * @return unknown
	 */
	public function getCollections($subtype="", $limit = 10, $offset = 0) {
		return get_user_collections($this->getGUID(), $subtype, $limit, $offset);
	}

	/**
	 * If a user's owner is blank, return its own GUID as the owner
	 *
	 * @return int User GUID
	 */
	function getOwner() {
		if ($this->owner_guid == 0) {
			return $this->getGUID();
		}

		return $this->owner_guid;
	}

	// EXPORTABLE INTERFACE ////////////////////////////////////////////////////////////

	/**
	 * Return an array of fields which can be exported.
	 */
	public function getExportableValues() {
		return array_merge(parent::getExportableValues(), array(
			'name',
			'username',
			'language',
		));
	}
}

/**
 * Return the user specific details of a user by a row.
 *
 * @param int $guid
 */
function get_user_entity_as_row($guid) {
	global $CONFIG;

	$guid = (int)$guid;
	return get_data_row("SELECT * from {$CONFIG->dbprefix}users_entity where guid=$guid");
}

/**
 * Create or update the extras table for a given user.
 * Call create_entity first.
 *
 * @param int $guid
 * @param string $name
 * @param string $description
 * @param string $url
 */
function create_user_entity($guid, $name, $username, $password, $salt, $email, $language, $code) {
	global $CONFIG;

	$guid = (int)$guid;
	$name = sanitise_string($name);
	$username = sanitise_string($username);
	$password = sanitise_string($password);
	$salt = sanitise_string($salt);
	$email = sanitise_string($email);
	$language = sanitise_string($language);
	$code = sanitise_string($code);

	$row = get_entity_as_row($guid);
	if ($row) {
		// Exists and you have access to it

		if ($exists = get_data_row("SELECT guid from {$CONFIG->dbprefix}users_entity where guid = {$guid}")) {
			$result = update_data("UPDATE {$CONFIG->dbprefix}users_entity set name='$name', username='$username', password='$password', salt='$salt', email='$email', language='$language', code='$code', last_action = ". time() ." where guid = {$guid}");
			if ($result != false) {
				// Update succeeded, continue
				$entity = get_entity($guid);
				if (trigger_elgg_event('update',$entity->type,$entity)) {
					return $guid;
				} else {
					$entity->delete();
				}
			}
		} else {
			// Update failed, attempt an insert.
			$result = insert_data("INSERT into {$CONFIG->dbprefix}users_entity (guid, name, username, password, salt, email, language, code) values ($guid, '$name', '$username', '$password', '$salt', '$email', '$language', '$code')");
			if ($result!==false) {
				$entity = get_entity($guid);
				if (trigger_elgg_event('create',$entity->type,$entity)) {
					return $guid;
				} else {
					$entity->delete(); //delete_entity($guid);
				}
			}
		}
	}

	return false;
}

/**
 * Disables all of a user's entities
 *
 * @param int $owner_guid The owner GUID
 * @return true|false Depending on success
 */
function disable_user_entities($owner_guid) {
	global $CONFIG;
	$owner_guid = (int) $owner_guid;
	if ($entity = get_entity($owner_guid)) {
		if (trigger_elgg_event('disable',$entity->type,$entity)) {
			if ($entity->canEdit()) {
				$res = update_data("UPDATE {$CONFIG->dbprefix}entities set enabled='no' where owner_guid={$owner_guid} or container_guid = {$owner_guid}");
				return $res;
			}
		}
	}

	return false;
}

/**
 * Ban a user
 *
 * @param int $user_guid The user guid
 * @param string $reason A reason
 */
function ban_user($user_guid, $reason = "") {
	global $CONFIG;

	$user_guid = (int)$user_guid;
	$reason = sanitise_string($reason);

	$user = get_entity($user_guid);

	if (($user) && ($user->canEdit()) && ($user instanceof ElggUser)) {
		if (trigger_elgg_event('ban', 'user', $user)) {
			// Add reason
			if ($reason) {
				create_metadata($user_guid, 'ban_reason', $reason,'', 0, ACCESS_PUBLIC);
			}

			// Set ban flag
			return update_data("UPDATE {$CONFIG->dbprefix}users_entity set banned='yes' where guid=$user_guid");
		}
	}

	return false;
}

/**
 * Unban a user.
 *
 * @param int $user_guid Unban a user.
 */
function unban_user($user_guid) {
	global $CONFIG;

	$user_guid = (int)$user_guid;

	$user = get_entity($user_guid);

	if (($user) && ($user->canEdit()) && ($user instanceof ElggUser)) {
		if (trigger_elgg_event('unban', 'user', $user)) {
			create_metadata($user_guid, 'ban_reason', '','', 0, ACCESS_PUBLIC);
			return update_data("UPDATE {$CONFIG->dbprefix}users_entity set banned='no' where guid=$user_guid");
		}
	}

	return false;
}

/**
 * THIS FUNCTION IS DEPRECATED.
 *
 * Delete a user's extra data.
 *
 * @param int $guid
 */
function delete_user_entity($guid) {
	system_message(sprintf(elgg_echo('deprecatedfunction'), 'delete_user_entity'));

	return 1; // Always return that we have deleted one row in order to not break existing code.
}

/**
 * Get the sites this user is part of
 *
 * @param int $user_guid The user's GUID
 * @param int $limit Number of results to return
 * @param int $offset Any indexing offset
 * @return false|array On success, an array of ElggSites
 */
function get_user_sites($user_guid, $limit = 10, $offset = 0) {
	$user_guid = (int)$user_guid;
	$limit = (int)$limit;
	$offset = (int)$offset;

	return get_entities_from_relationship("member_of_site", $user_guid, false, "site", "", 0, "time_created desc", $limit, $offset);
}

/**
 * Adds a user to another user's friends list.
 *
 * @param int $user_guid The GUID of the friending user
 * @param int $friend_guid The GUID of the user to friend
 * @return true|false Depending on success
 */
function user_add_friend($user_guid, $friend_guid) {
	$user_guid = (int) $user_guid;
	$friend_guid = (int) $friend_guid;
	if ($user_guid == $friend_guid) {
		return false;
	}
	if (!$friend = get_entity($friend_guid)) {
		return false;
	}
	if (!$user = get_entity($user_guid)) {
		return false;
	}
	if ((!($user instanceof ElggUser)) || (!($friend instanceof ElggUser))) {
		return false;
	}
	return add_entity_relationship($user_guid, "friend", $friend_guid);
}

/**
 * Removes a user from another user's friends list.
 *
 * @param int $user_guid The GUID of the friending user
 * @param int $friend_guid The GUID of the user on the friends list
 * @return true|false Depending on success
 */
function user_remove_friend($user_guid, $friend_guid) {
	global $CONFIG;

	$user_guid = (int) $user_guid;
	$friend_guid = (int) $friend_guid;

	// perform cleanup for access lists.
	$collections = get_user_access_collections($user_guid);
	foreach ($collections as $collection) {
		remove_user_from_access_collection($friend_guid, $collection->id);
	}

	return remove_entity_relationship($user_guid, "friend", $friend_guid);
}

/**
 * Determines whether or not a user is another user's friend.
 *
 * @param int $user_guid The GUID of the user
 * @param int $friend_guid The GUID of the friend
 * @return true|false
 */
function user_is_friend($user_guid, $friend_guid) {
	return check_entity_relationship($user_guid, "friend", $friend_guid);
}

/**
 * Obtains a given user's friends
 *
 * @param int $user_guid The user's GUID
 * @param string $subtype The subtype of users, if any
 * @param int $limit Number of results to return (default 10)
 * @param int $offset Indexing offset, if any
 * @return false|array Either an array of ElggUsers or false, depending on success
 */
function get_user_friends($user_guid, $subtype = "", $limit = 10, $offset = 0) {
	return get_entities_from_relationship("friend",$user_guid,false,"user",$subtype,0,"time_created desc",$limit,$offset);
}

/**
 * Obtains the people who have made a given user a friend
 *
 * @param int $user_guid The user's GUID
 * @param string $subtype The subtype of users, if any
 * @param int $limit Number of results to return (default 10)
 * @param int $offset Indexing offset, if any
 * @return false|array Either an array of ElggUsers or false, depending on success
 */
function get_user_friends_of($user_guid, $subtype = "", $limit = 10, $offset = 0) {
	return get_entities_from_relationship("friend",$user_guid,true,"user",$subtype,0,"time_created desc",$limit,$offset);
}

/**
 * Obtains a list of objects owned by a user
 *
 * @param int $user_guid The GUID of the owning user
 * @param string $subtype Optionally, the subtype of objects
 * @param int $limit The number of results to return (default 10)
 * @param int $offset Indexing offset, if any
 * @param int $timelower The earliest time the entity can have been created. Default: all
 * @param int $timeupper The latest time the entity can have been created. Default: all
 * @return false|array An array of ElggObjects or false, depending on success
 */
function get_user_objects($user_guid, $subtype = "", $limit = 10, $offset = 0, $timelower = 0, $timeupper = 0) {
	$ntt = get_entities('object',$subtype, $user_guid, "time_created desc", $limit, $offset,false,0,$user_guid,$timelower, $timeupper);
	return $ntt;
}

/**
 * Counts the objects (optionally of a particular subtype) owned by a user
 *
 * @param int $user_guid The GUID of the owning user
 * @param string $subtype Optionally, the subtype of objects
 * @param int $timelower The earliest time the entity can have been created. Default: all
 * @param int $timeupper The latest time the entity can have been created. Default: all
 * @return int The number of objects the user owns (of this subtype)
 */
function count_user_objects($user_guid, $subtype = "", $timelower = 0, $timeupper = 0) {
	$total = get_entities('object', $subtype, $user_guid, "time_created desc", null, null, true, 0, $user_guid,$timelower,$timeupper);
	return $total;
}

/**
 * Displays a list of user objects of a particular subtype, with navigation.
 *
 * @see elgg_view_entity_list
 *
 * @param int $user_guid The GUID of the user
 * @param string $subtype The object subtype
 * @param int $limit The number of entities to display on a page
 * @param true|false $fullview Whether or not to display the full view (default: true)
 * @param true|false $viewtypetoggle Whether or not to allow gallery view (default: true)
 * @param true|false $pagination Whether to display pagination (default: true)
 * @param int $timelower The earliest time the entity can have been created. Default: all
 * @param int $timeupper The latest time the entity can have been created. Default: all
 * @return string The list in a form suitable to display
 */
function list_user_objects($user_guid, $subtype = "", $limit = 10, $fullview = true, $viewtypetoggle = true, $pagination = true, $timelower = 0, $timeupper = 0) {
	$offset = (int) get_input('offset');
	$limit = (int) $limit;
	$count = (int) count_user_objects($user_guid, $subtype,$timelower,$timeupper);
	$entities = get_user_objects($user_guid, $subtype, $limit, $offset, $timelower, $timeupper);

	return elgg_view_entity_list($entities, $count, $offset, $limit, $fullview, $viewtypetoggle, $pagination);
}

/**
 * Obtains a list of objects owned by a user's friends
 *
 * @param int $user_guid The GUID of the user to get the friends of
 * @param string $subtype Optionally, the subtype of objects
 * @param int $limit The number of results to return (default 10)
 * @param int $offset Indexing offset, if any
 * @param int $timelower The earliest time the entity can have been created. Default: all
 * @param int $timeupper The latest time the entity can have been created. Default: all
 * @return false|array An array of ElggObjects or false, depending on success
 */
function get_user_friends_objects($user_guid, $subtype = "", $limit = 10, $offset = 0, $timelower = 0, $timeupper = 0) {
	if ($friends = get_user_friends($user_guid, "", 999999, 0)) {
		$friendguids = array();
		foreach($friends as $friend) {
			$friendguids[] = $friend->getGUID();
		}
		return get_entities('object',$subtype,$friendguids, "time_created desc", $limit, $offset, false, 0, $friendguids, $timelower, $timeupper);
	}
	return false;
}

/**
 * Counts the number of objects owned by a user's friends
 *
 * @param int $user_guid The GUID of the user to get the friends of
 * @param string $subtype Optionally, the subtype of objects
 * @param int $timelower The earliest time the entity can have been created. Default: all
 * @param int $timeupper The latest time the entity can have been created. Default: all
 * @return int The number of objects
 */
function count_user_friends_objects($user_guid, $subtype = "", $timelower = 0, $timeupper = 0) {
	if ($friends = get_user_friends($user_guid, "", 999999, 0)) {
		$friendguids = array();
		foreach($friends as $friend) {
			$friendguids[] = $friend->getGUID();
		}
		return get_entities('object',$subtype,$friendguids, "time_created desc", null, null, true, 0, $friendguids, $timelower, $timeupper);
	}
	return 0;
}

/**
 * Displays a list of a user's friends' objects of a particular subtype, with navigation.
 *
 * @see elgg_view_entity_list
 *
 * @param int $user_guid The GUID of the user
 * @param string $subtype The object subtype
 * @param int $limit The number of entities to display on a page
 * @param true|false $fullview Whether or not to display the full view (default: true)
 * @param true|false $viewtypetoggle Whether or not to allow you to flip to gallery mode (default: true)
 * @param true|false $pagination Whether to display pagination (default: true)
 * @param int $timelower The earliest time the entity can have been created. Default: all
 * @param int $timeupper The latest time the entity can have been created. Default: all
 * @return string The list in a form suitable to display
 */
function list_user_friends_objects($user_guid, $subtype = "", $limit = 10, $fullview = true, $viewtypetoggle = true, $pagination = true, $timelower = 0, $timeupper = 0) {
	$offset = (int) get_input('offset');
	$limit = (int) $limit;
	$count = (int) count_user_friends_objects($user_guid, $subtype, $timelower, $timeupper);
	$entities = get_user_friends_objects($user_guid, $subtype, $limit, $offset, $timelower, $timeupper);

	return elgg_view_entity_list($entities, $count, $offset, $limit, $fullview, $viewtypetoggle, $pagination);
}

/**
 * Get user objects by an array of metadata
 *
 * @param int $user_guid The GUID of the owning user
 * @param string $subtype Optionally, the subtype of objects
 * @paran array $metadata An array of metadata
 * @param int $limit The number of results to return (default 10)
 * @param int $offset Indexing offset, if any
 * @return false|array An array of ElggObjects or false, depending on success
 */
function get_user_objects_by_metadata($user_guid, $subtype = "", $metadata = array(), $limit = 0, $offset = 0) {
	return get_entities_from_metadata_multi($metadata,"object",$subtype,$user_guid,$limit,$offset);
}

/**
 * Get a user object from a GUID.
 *
 * This function returns an ElggUser from a given GUID.
 * @param int $guid The GUID
 * @return ElggUser|false
 */
function get_user($guid) {
	// Fixes "Exception thrown without stack frame" when db_select fails
	if (!empty($guid)) {
		$result = get_entity($guid);
	}

	if ((!empty($result)) && (!($result instanceof ElggUser))) {
		//throw new InvalidClassException(sprintf(elgg_echo('InvalidClassException:NotValidElggStar'), $guid, 'ElggUser'));
		return false;
	}

	if (!empty($result)) {
		return $result;
	}

	return false;
}

/**
 * Get user by username
 *
 * @param string $username The user's username
 * @return ElggUser|false Depending on success
 */
function get_user_by_username($username) {
	global $CONFIG, $USERNAME_TO_GUID_MAP_CACHE;

	$username = sanitise_string($username);
	$access = get_access_sql_suffix('e');

	// Caching
	if ( (isset($USERNAME_TO_GUID_MAP_CACHE[$username])) && (retrieve_cached_entity($USERNAME_TO_GUID_MAP_CACHE[$username])) ) {
		return retrieve_cached_entity($USERNAME_TO_GUID_MAP_CACHE[$username]);
	}

	$row = get_data_row("SELECT e.* from {$CONFIG->dbprefix}users_entity u join {$CONFIG->dbprefix}entities e on e.guid=u.guid where u.username='$username' and $access ");
	if ($row) {
		$USERNAME_TO_GUID_MAP_CACHE[$username] = $row->guid;
		return new ElggUser($row);
	}

	return false;
}

/**
 * Get user by session code
 *
 * @param string $code The session code
 * @return ElggUser|false Depending on success
 */
function get_user_by_code($code) {
	global $CONFIG, $CODE_TO_GUID_MAP_CACHE;

	$code = sanitise_string($code);

	$access = get_access_sql_suffix('e');

	// Caching
	if ( (isset($CODE_TO_GUID_MAP_CACHE[$code])) && (retrieve_cached_entity($CODE_TO_GUID_MAP_CACHE[$code])) ) {
		return retrieve_cached_entity($CODE_TO_GUID_MAP_CACHE[$code]);
	}

	$row = get_data_row("SELECT e.* from {$CONFIG->dbprefix}users_entity u join {$CONFIG->dbprefix}entities e on e.guid=u.guid where u.code='$code' and $access");
	if ($row) {
		$CODE_TO_GUID_MAP_CACHE[$code] = $row->guid;
		return new ElggUser($row);
	}

	return false;
}

/**
 * Get an array of users from their
 *
 * @param string $email Email address.
 * @return Array of users
 */
function get_user_by_email($email) {
	global $CONFIG;

	$email = sanitise_string($email);

	$access = get_access_sql_suffix('e');

	$query = "SELECT e.* from {$CONFIG->dbprefix}entities e join {$CONFIG->dbprefix}users_entity u on e.guid=u.guid where email='$email' and $access";

	return get_data($query, 'entity_row_to_elggstar');
}

/**
 * Searches for a user based on a complete or partial name or username.
 *
 * @param string $criteria The partial or full name or username.
 * @param int $limit Limit of the search.
 * @param int $offset Offset.
 * @param string $order_by The order.
 * @param boolean $count Whether to return the count of results or just the results.
 */
function search_for_user($criteria, $limit = 10, $offset = 0, $order_by = "", $count = false) {
	global $CONFIG;

	$criteria = sanitise_string($criteria);
	$limit = (int)$limit;
	$offset = (int)$offset;
	$order_by = sanitise_string($order_by);

	$access = get_access_sql_suffix("e");

	if ($order_by == "") {
		$order_by = "e.time_created desc";
	}

	if ($count) {
		$query = "SELECT count(e.guid) as total ";
	} else {
		$query = "SELECT e.* ";
	}
	$query .= "from {$CONFIG->dbprefix}entities e join {$CONFIG->dbprefix}users_entity u on e.guid=u.guid where ";
	// $query .= " match(u.name,u.username) against ('$criteria') ";
	$query .= "(u.name like \"%{$criteria}%\" or u.username like \"%{$criteria}%\")";
	$query .= " and $access";

	if (!$count) {
		$query .= " order by $order_by limit $offset, $limit"; // Add order and limit
		return get_data($query, "entity_row_to_elggstar");
	} else {
		if ($count = get_data_row($query)) {
			return $count->total;
		}
	}
	return false;
}

/**
 * Displays a list of user objects that have been searched for.
 *
 * @see elgg_view_entity_list
 *
 * @param string $tag Search criteria
 * @param int $limit The number of entities to display on a page
 * @return string The list in a form suitable to display
 */
function list_user_search($tag, $limit = 10) {
	$offset = (int) get_input('offset');
	$limit = (int) $limit;
	$count = (int) search_for_user($tag, 10, 0, '', true);
	$entities = search_for_user($tag, $limit, $offset);

	return elgg_view_entity_list($entities, $count, $offset, $limit, $fullview, false);
}

/**
 * A function that returns a maximum of $limit users who have done something within the last
 * $seconds seconds.
 *
 * @param int $seconds Number of seconds (default 600 = 10min)
 * @param int $limit Limit, default 10.
 * @param int $offset Offset, defualt 0.
 */
function find_active_users($seconds = 600, $limit = 10, $offset = 0) {
	global $CONFIG;

	$seconds = (int)$seconds;
	$limit = (int)$limit;
	$offset = (int)$offset;

	$time = time() - $seconds;

	$access = get_access_sql_suffix("e");

	$query = "SELECT distinct e.* from {$CONFIG->dbprefix}entities e join {$CONFIG->dbprefix}users_entity u on e.guid = u.guid where u.last_action >= {$time} and $access order by u.last_action desc limit {$offset},{$limit}";

	return get_data($query, "entity_row_to_elggstar");
}

/**
 * Generate and send a password request email to a given user's registered email address.
 *
 * @param int $user_guid
 */
function send_new_password_request($user_guid) {
	global $CONFIG;

	$user_guid = (int)$user_guid;

	$user = get_entity($user_guid);
	if ($user) {
		// generate code
		$code = generate_random_cleartext_password();
		//create_metadata($user_guid, 'conf_code', $code,'', 0, ACCESS_PRIVATE);
		set_private_setting($user_guid, 'passwd_conf_code', $code);

		// generate link
		$link = $CONFIG->site->url . "action/user/passwordreset?u=$user_guid&c=$code";

		// generate email
		$email = sprintf(elgg_echo('email:resetreq:body'), $user->name, $_SERVER['REMOTE_ADDR'], $link);

		return notify_user($user->guid, $CONFIG->site->guid, elgg_echo('email:resetreq:subject'), $email, NULL, 'email');
	}

	return false;
}

/**
 * Low level function to reset a given user's password.
 *
 * This can only be called from execute_new_password_request().
 *
 * @param int $user_guid The user.
 * @param string $password password text (which will then be converted into a hash and stored)
 */
function force_user_password_reset($user_guid, $password) {
	global $CONFIG;

	if (call_gatekeeper('execute_new_password_request', __FILE__)) {
		$user = get_entity($user_guid);

		if ($user) {
			$salt = generate_random_cleartext_password(); // Reset the salt
			$user->salt = $salt;

			$hash = generate_user_password($user, $password);

			return update_data("UPDATE {$CONFIG->dbprefix}users_entity set password='$hash', salt='$salt' where guid=$user_guid");
		}
	}

	return false;
}

/**
 * Validate and execute a password reset for a user.
 *
 * @param int $user_guid The user id
 * @param string $conf_code Confirmation code as sent in the request email.
 */
function execute_new_password_request($user_guid, $conf_code) {
	global $CONFIG;

	$user_guid = (int)$user_guid;

	$user = get_entity($user_guid);
	if (($user) && (get_private_setting($user_guid, 'passwd_conf_code') == $conf_code)) {
		$password = generate_random_cleartext_password();

		if (force_user_password_reset($user_guid, $password)) {
			//remove_metadata($user_guid, 'conf_code');
			remove_private_setting($user_guid, 'passwd_conf_code');

			$email = sprintf(elgg_echo('email:resetpassword:body'), $user->name, $password);

			return notify_user($user->guid, $CONFIG->site->guid, elgg_echo('email:resetpassword:subject'), $email, NULL, 'email');
		}
	}

	return false;
}

/**
 * Set the validation status for a user.
 *
 * @param bool $status Validated (true) or false
 * @param string $method Optional method to say how a user was validated
 * @return bool
 */
function set_user_validation_status($user_guid, $status, $method = '') {
	if (!$status) {
		$method = '';
	}

	if ($status) {
		if (
			(create_metadata($user_guid, 'validated', $status,'', 0, ACCESS_PUBLIC)) &&
			(create_metadata($user_guid, 'validated_method', $method,'', 0, ACCESS_PUBLIC))
		) {
			return true;
		}
	} else {
		$validated = get_metadata_byname($user_guid,  'validated');
		$validated_method = get_metadata_byname($user_guid,  'validated_method');

		if (
			($validated) &&
			($validated_method) &&
			(delete_metadata($validated->id)) &&
			(delete_metadata($validated_method->id))
		)
			return true;
	}

	return false;
}

/**
 * Trigger an event requesting that a user guid be validated somehow - either by email address or some other way.
 *
 * This event invalidates any existing values and returns
 *
 * @param unknown_type $user_guid
 */
function request_user_validation($user_guid) {
	$user = get_entity($user_guid);

	if (($user) && ($user instanceof ElggUser)) {
		// invalidate any existing validations
		set_user_validation_status($user_guid, false);

		// request validation
		trigger_elgg_event('validate', 'user', $user);
	}
}

/**
 * Validates an email address.
 *
 * @param string $address Email address.
 * @return bool
 */
function is_email_address($address) {
	// TODO: Make this better!

	if (strpos($address, '@')=== false) {
		return false;
	}

	if (strpos($address, '.')=== false) {
		return false;
	}

	return true;
}

/**
 * Simple function that will generate a random clear text password suitable for feeding into generate_user_password().
 *
 * @see generate_user_password
 * @return string
 */
function generate_random_cleartext_password() {
	return substr(md5(microtime() . rand()), 0, 8);
}

/**
 * Generate a password for a user, currently uses MD5.
 *
 * Later may introduce salting etc.
 *
 * @param ElggUser $user The user this is being generated for.
 * @param string $password Password in clear text
 */
function generate_user_password(ElggUser $user, $password) {
	return md5($password . $user->salt);
}

/**
 * Simple function which ensures that a username contains only valid characters.
 *
 * This should only permit chars that are valid on the file system as well.
 *
 * @param string $username
 * @throws RegistrationException on invalid
 */
function validate_username($username) {
	global $CONFIG;

	// Basic, check length
	if (!isset($CONFIG->minusername)) {
		$CONFIG->minusername = 4;
	}

	if (strlen($username) < $CONFIG->minusername) {
		throw new RegistrationException(elgg_echo('registration:usernametooshort'));
	}

	// Blacklist for bad characters (partially nicked from mediawiki)

	$blacklist = '/[' .
		'\x{0080}-\x{009f}' . # iso-8859-1 control chars
		'\x{00a0}' .          # non-breaking space
		'\x{2000}-\x{200f}' . # various whitespace
		'\x{2028}-\x{202f}' . # breaks and control chars
		'\x{3000}' .          # ideographic space
		'\x{e000}-\x{f8ff}' . # private use
		']/u';

	if (
		preg_match($blacklist, $username)
	) {
		throw new RegistrationException(elgg_echo('registration:invalidchars'));
	}

	// Belts and braces TODO: Tidy into main unicode
	$blacklist2 = '/\\"\'*& ?#%^(){}[]~?<>;|¬`@-+=';
	for ($n=0; $n < strlen($blacklist2); $n++) {
		if (strpos($username, $blacklist2[$n])!==false) {
			throw new RegistrationException(elgg_echo('registration:invalidchars'));
		}
	}

	$result = true;
	return trigger_plugin_hook('registeruser:validate:username', 'all', array('username' => $username), $result);
}

/**
 * Simple validation of a password.
 *
 * @param string $password
 * @throws RegistrationException on invalid
 */
function validate_password($password) {
	if (strlen($password) < 6) {
		throw new RegistrationException(elgg_echo('registration:passwordtooshort'));
	}

	$result = true;
	return trigger_plugin_hook('registeruser:validate:password', 'all', array('password' => $password), $result);
}

/**
 * Simple validation of a email.
 *
 * @param string $address
 * @throws RegistrationException on invalid
 * @return bool
 */
function validate_email_address($address) {
	if (!is_email_address($address)) {
		throw new RegistrationException(elgg_echo('registration:notemail'));
	}

	// Got here, so lets try a hook (defaulting to ok)
	$result = true;
	return trigger_plugin_hook('registeruser:validate:email', 'all', array('email' => $address), $result);
}

/**
 * Registers a user, returning false if the username already exists
 *
 * @param string $username The username of the new user
 * @param string $password The password
 * @param string $name The user's display name
 * @param string $email Their email address
 * @param bool $allow_multiple_emails Allow the same email address to be registered multiple times?
 * @param int $friend_guid Optionally, GUID of a user this user will friend once fully registered
 * @return int|false The new user's GUID; false on failure
 */
function register_user($username, $password, $name, $email, $allow_multiple_emails = false, $friend_guid = 0, $invitecode = '') {
	// Load the configuration
	global $CONFIG;

	$username = trim($username);
	// no need to trim password.
	$password = $password;
	$name = trim($name);
	$email = trim($email);

	// A little sanity checking
	if (empty($username)
	|| empty($password)
	|| empty($name)
	|| empty($email)) {
		return false;
	}

	// See if it exists and is disabled
	$access_status = access_get_show_hidden_status();
	access_show_hidden_entities(true);

	// Validate email address
	if (!validate_email_address($email)) {
		throw new RegistrationException(elgg_echo('registration:emailnotvalid'));
	}

	// Validate password
	if (!validate_password($password)) {
		throw new RegistrationException(elgg_echo('registration:passwordnotvalid'));
	}

	// Validate the username
	if (!validate_username($username)) {
		throw new RegistrationException(elgg_echo('registration:usernamenotvalid'));
	}

	// Check to see if $username exists already
	if ($user = get_user_by_username($username)) {
		//return false;
		throw new RegistrationException(elgg_echo('registration:userexists'));
	}

	// If we're not allowed multiple emails then see if this address has been used before
	if ((!$allow_multiple_emails) && (get_user_by_email($email))) {
		throw new RegistrationException(elgg_echo('registration:dupeemail'));
	}

	access_show_hidden_entities($access_status);

	// Check to see if we've registered the first admin yet.
	// If not, this is the first admin user!
	$admin = datalist_get('admin_registered');

	// Otherwise ...
	$user = new ElggUser();
	$user->username = $username;
	$user->email = $email;
	$user->name = $name;
	$user->access_id = ACCESS_PUBLIC;
	$user->salt = generate_random_cleartext_password(); // Note salt generated before password!
	$user->password = generate_user_password($user, $password);
	$user->owner_guid = 0; // Users aren't owned by anyone, even if they are admin created.
	$user->container_guid = 0; // Users aren't contained by anyone, even if they are admin created.
	$user->save();

	// If $friend_guid has been set, make mutual friends
	if ($friend_guid) {
		if ($friend_user = get_user($friend_guid)) {
			if ($invitecode == generate_invite_code($friend_user->username)) {
				$user->addFriend($friend_guid);
				$friend_user->addFriend($user->guid);
			}
		}
	}

	global $registering_admin;
	if (!$admin) {
		$user->admin = true;
		datalist_set('admin_registered',1);
		$registering_admin = true;
	} else {
		$registering_admin = false;
	}

	// Turn on email notifications by default
	set_user_notification_setting($user->getGUID(), 'email', true);

	return $user->getGUID();
}

/**
 * Generates a unique invite code for a user
 *
 * @param string $username The username of the user sending the invitation
 * @return string Invite code
 */
function generate_invite_code($username) {
	$secret = datalist_get('__site_secret__');
	return md5($username . $secret);
}

/**
 * Adds collection submenu items
 *
 */
function collections_submenu_items() {
	global $CONFIG;
	$user = get_loggedin_user();
	add_submenu_item(elgg_echo('friends:collections'), $CONFIG->wwwroot . "pg/collections/" . $user->username);
	add_submenu_item(elgg_echo('friends:collections:add'),$CONFIG->wwwroot."pg/collections/add");
}

/**
 * Page handler for friends
 *
 */
function friends_page_handler($page_elements) {
	if (isset($page_elements[0]) && $user = get_user_by_username($page_elements[0])) {
		set_page_owner($user->getGUID());
	}
	if ($_SESSION['guid'] == page_owner()) {
		collections_submenu_items();
	}

	require_once(dirname(dirname(dirname(__FILE__))) . "/friends/index.php");
}

/**
 * Page handler for friends of
 *
 */
function friends_of_page_handler($page_elements) {
	if (isset($page_elements[0]) && $user = get_user_by_username($page_elements[0])) {
		set_page_owner($user->getGUID());
	}
	if ($_SESSION['guid'] == page_owner()) {
		collections_submenu_items();
	}
	require_once(dirname(dirname(dirname(__FILE__))) . "/friends/of.php");
}

/**
 * Page handler for friends of
 *
 */
function collections_page_handler($page_elements) {
	if (isset($page_elements[0])) {
		if ($page_elements[0] == "add") {
			set_page_owner($_SESSION['guid']);
			collections_submenu_items();
			require_once(dirname(dirname(dirname(__FILE__))) . "/friends/add.php");
		} else {
			if ($user = get_user_by_username($page_elements[0])) {
				set_page_owner($user->getGUID());
				if ($_SESSION['guid'] == page_owner()) {
					collections_submenu_items();
				}
				require_once(dirname(dirname(dirname(__FILE__))) . "/friends/collections.php");
			}
		}
	}
}

/**
 * Page handler for dashboard
 */
function dashboard_page_handler($page_elements) {
	require_once(dirname(dirname(dirname(__FILE__))) . "/dashboard/index.php");
}

/**
 * Sets the last action time of the given user to right now.
 *
 * @param int $user_guid The user GUID
 */
function set_last_action($user_guid) {
	$user_guid = (int) $user_guid;
	global $CONFIG;
	$time = time();

	execute_delayed_write_query("UPDATE {$CONFIG->dbprefix}users_entity set prev_last_action = last_action, last_action = {$time} where guid = {$user_guid}");
}

/**
 * Sets the last logon time of the given user to right now.
 *
 * @param int $user_guid The user GUID
 */
function set_last_login($user_guid) {
	$user_guid = (int) $user_guid;
	global $CONFIG;
	$time = time();

	execute_delayed_write_query("UPDATE {$CONFIG->dbprefix}users_entity set prev_last_login = last_login, last_login = {$time} where guid = {$user_guid}");
}

/**
 * A permissions plugin hook that grants access to users if they are newly created - allows
 * for email activation.
 *
 * TODO: Do this in a better way!
 *
 * @param unknown_type $hook
 * @param unknown_type $entity_type
 * @param unknown_type $returnvalue
 * @param unknown_type $params
 */
function new_user_enable_permissions_check($hook, $entity_type, $returnvalue, $params) {
	$entity = $params['entity'];
	$user = $params['user'];
	if (($entity) && ($entity instanceof ElggUser)) {
		if (
			(($entity->disable_reason == 'new_user') || (
				// if this isn't set at all they're a "new user"
				!$entity->validated
			))
			&& (!isloggedin())) {
				return true;
		}
	}

	return $returnvalue;
}

/**
 * Sets up user-related menu items
 *
 */
function users_pagesetup() {
	// Load config
	global $CONFIG;

	//add submenu options
	if (get_context() == "friends" || get_context() == "friendsof" || get_context() == "collections") {
		add_submenu_item(elgg_echo('friends'),$CONFIG->wwwroot."pg/friends/" . page_owner_entity()->username);
		add_submenu_item(elgg_echo('friends:of'),$CONFIG->wwwroot."pg/friendsof/" . page_owner_entity()->username);
	}
}

/**
 * Users initialisation function, which establishes the page handler
 *
 */
function users_init() {
	// Load config
	global $CONFIG;

	// Set up menu for logged in users
	if (isloggedin()) {
		$user = get_loggedin_user();
		add_menu(elgg_echo('friends'), $CONFIG->wwwroot . "pg/friends/" . $user->username);
	}

	register_page_handler('friends','friends_page_handler');
	register_page_handler('friendsof','friends_of_page_handler');
	register_page_handler('collections','collections_page_handler');
	register_page_handler('dashboard','dashboard_page_handler');
	register_action("register",true);
	register_action("useradd",true);
	register_action("friends/add");
	register_action("friends/remove");
	register_action('friends/addcollection');
	register_action('friends/deletecollection');
	register_action('friends/editcollection');
	register_action("user/spotlight");

	register_action("usersettings/save");

	register_action("user/passwordreset");
	register_action("user/requestnewpassword");

	// User name change
	extend_elgg_settings_page('user/settings/name', 'usersettings/user', 1);
	//register_action("user/name");

	// User password change
	extend_elgg_settings_page('user/settings/password', 'usersettings/user', 1);
	//register_action("user/password");

	// Add email settings
	extend_elgg_settings_page('user/settings/email', 'usersettings/user', 1);
	//register_action("email/save");

	// Add language settings
	extend_elgg_settings_page('user/settings/language', 'usersettings/user', 1);

	// Add default access settings
	extend_elgg_settings_page('user/settings/default_access', 'usersettings/user', 1);

	//register_action("user/language");

	// Register the user type
	register_entity_type('user','');

	register_plugin_hook('usersettings:save','user','users_settings_save');

	// Handle a special case for newly created users when the user is not logged in
	// TODO: handle this better!
	register_plugin_hook('permissions_check','all','new_user_enable_permissions_check');
}

/**
 * Returns a formatted list of users suitable for injecting into search.
 *
 */
function search_list_users_by_name($hook, $user, $returnvalue, $tag) {
	// Change this to set the number of users that display on the search page
	$threshold = 4;

	$object = get_input('object');

	if (!get_input('offset') && (empty($object) || $object == 'user')) {
		if ($users = search_for_user($tag,$threshold)) {
			$countusers = search_for_user($tag,0,0,"",true);

			$return = elgg_view('user/search/startblurb',array('count' => $countusers, 'tag' => $tag));
			foreach($users as $user) {
				$return .= elgg_view_entity($user);
			}
			$return .= elgg_view('user/search/finishblurb',array('count' => $countusers, 'threshold' => $threshold, 'tag' => $tag));
			return $return;

		}
	}
}

function users_settings_save() {
	global $CONFIG;
	include($CONFIG->path . "actions/user/name.php");
	include($CONFIG->path . "actions/user/password.php");
	include($CONFIG->path . "actions/email/save.php");
	include($CONFIG->path . "actions/user/language.php");
	include($CONFIG->path . "actions/user/default_access.php");
}

/**
 * Runs unit tests for ElggObject
 */
function users_test($hook, $type, $value, $params) {
	global $CONFIG;
	$value[] = "{$CONFIG->path}engine/tests/objects/users.php";
	return $value;
}

//register actions *************************************************************
register_elgg_event_handler('init','system','users_init',0);
register_elgg_event_handler('pagesetup','system','users_pagesetup',0);
register_plugin_hook('unit_test', 'system', 'users_test');