<?php
/**
 * @file include/security.php
 *
 * @brief Some security related functions.
 */

use Zotlabs\Lib\Config;

/**
 * @param array $user_record The account record
 * @param array $channel
 * @param bool $login_initial default false
 * @param bool $interactive default false
 * @param bool $return
 * @param bool $update_lastlog
 */
function authenticate_success($user_record, $channel = null, $login_initial = false, $interactive = false, $return = false, $update_lastlog = false) {

	$_SESSION['addr'] = $_SERVER['REMOTE_ADDR'];

	$lastlog_updated = false;
	$uid_to_load = null;

	if (x($user_record, 'account_id')) {
		App::$account = $user_record;
		$_SESSION['account_id'] = $user_record['account_id'];
		$_SESSION['authenticated'] = 1;

		if ($channel)
			$uid_to_load = $channel['channel_id'];

		if (!$uid_to_load) {
			$uid_to_load = (((x($_SESSION, 'uid')) && (intval($_SESSION['uid'])))
				? intval($_SESSION['uid'])
				: intval(App::$account['account_default_channel'])
			);
		}

		if ($uid_to_load) {
			change_channel($uid_to_load);
		}

		if ($login_initial || $update_lastlog) {
			q("update account set account_lastlog = '%s' where account_id = %d",
				dbesc(datetime_convert()),
				intval($_SESSION['account_id'])
			);
			App::$account['account_lastlog'] = datetime_convert();
			$lastlog_updated = true;
			call_hooks('logged_in', App::$account);
		}

	}

	if (($login_initial) && (!$lastlog_updated)) {

		call_hooks('logged_in', $user_record);

		// might want to log success here
	}

	if ($return || x($_SESSION, 'workflow')) {
		unset($_SESSION['workflow']);
		return;
	}

	if ((App::$module !== 'home') && x($_SESSION, 'login_return_url') && strlen($_SESSION['login_return_url'])) {
		$return_url = $_SESSION['login_return_url'];

		// don't let members get redirected to a raw ajax page update - this can happen
		// if DHCP changes the IP address at an unfortunate time and paranoia is turned on
		if (strstr($return_url, 'update_'))
			$return_url = '';

		unset($_SESSION['login_return_url']);
		goaway(z_root() . '/' . $return_url);
	}

	/* This account has never created a channel. Send them to new_channel by default */

	if (App::$module === 'login') {
		$r = q("select count(channel_id) as total from channel where channel_account_id = %d and channel_removed = 0 ",
			intval(App::$account['account_id'])
		);
		if (($r) && (!$r[0]['total']))
			goaway(z_root() . '/new_channel');
	}

	/* else just return */
}

function atoken_login($atoken) {
	if (! $atoken) {
		return false;
	}

	if (App::$cmd === 'channel' && argv(1)) {
		$channel = channelx_by_nick(argv(1));
		if (perm_is_allowed($channel['channel_id'],$atoken['xchan_hash'],'delegate')) {
			$_SESSION['delegate_channel'] = $channel['channel_id'];
			$_SESSION['delegate'] = $atoken['xchan_hash'];
			$_SESSION['account_id'] = intval($channel['channel_account_id']);
			change_channel($channel['channel_id']);
			return;
		}
	}

	$_SESSION['authenticated'] = 1;
	$_SESSION['visitor_id'] = $atoken['xchan_hash'];
	$_SESSION['atoken'] = $atoken['atoken_id'];

	App::set_observer($atoken);

	return true;
}

/**
 * @brief
 *
 * @param array $atoken
 * @return array|null
 */
function atoken_xchan($atoken) {

	$c = channelx_by_n($atoken['atoken_uid']);
	if ($c) {
		return [
			'atoken_id' => $atoken['atoken_id'],
			'xchan_hash' => substr($c['channel_hash'], 0, 16) . '.' . $atoken['atoken_guid'],
			'xchan_name' => $atoken['atoken_name'],
			'xchan_addr' => 'guest:' . $atoken['atoken_name'] . '@' . App::get_hostname(),
			'xchan_network' => 'token',
			'xchan_url' => z_root() . '/guest/' . substr($c['channel_hash'], 0, 16) . '.' . $atoken['atoken_guid'],
			'xchan_hidden' => 1,
			'xchan_photo_mimetype' => 'image/png',
			'xchan_photo_l' => z_root() . '/' . get_default_profile_photo(300),
			'xchan_photo_m' => z_root() . '/' . get_default_profile_photo(80),
			'xchan_photo_s' => z_root() . '/' . get_default_profile_photo(48)
		];
	}

	return null;
}

function atoken_delete($atoken_id) {

	$r = q("select * from atoken where atoken_id = %d",
		intval($atoken_id)
	);
	if (!$r)
		return;

	$c = q("select channel_id, channel_hash from channel where channel_id = %d",
		intval($r[0]['atoken_uid'])
	);
	if (!$c)
		return;

	$atoken_xchan = substr($c[0]['channel_hash'], 0, 16) . '.' . $r[0]['atoken_guid'];

	q("delete from atoken where atoken_id = %d",
		intval($atoken_id)
	);

	q("delete from abook where abook_channel = %d and abook_xchan = '%s'",
		intval($c[0]['channel_id']),
		dbesc($atoken_xchan)
	);

	q("delete from abconfig where chan = %d and xchan = '%s'",
		intval($c[0]['channel_id']),
		dbesc($atoken_xchan)
	);

	q("update xchan set xchan_deleted = 1 where xchan_hash = '%s'",
		dbesc($atoken_xchan)
	);
}

/**
 * @brief
 *
 * In order for atoken logins to create content (such as posts) they need a stored xchan.
 * we'll create one on the first atoken_login; it can't really ever go away but perhaps
 * @fixme we should set xchan_deleted if it's expired or removed
 *
 * @param array $xchan
 * @return void|boolean
 */
function atoken_create_xchan($xchan) {

	$r = q("select xchan_hash from xchan where xchan_hash = '%s'",
		dbesc($xchan['xchan_hash'])
	);
	if ($r)
		return;

	$xchan['xchan_guid'] = $xchan['xchan_hash'];

	$store = [];
	foreach ($xchan as $k => $v) {
		if (strpos($k, 'xchan_') === 0) {
			$store[$k] = $v;
		}
	}

	xchan_store_lowlevel($store);

	return true;
}

function atoken_abook($uid, $xchan_hash) {

	if (substr($xchan_hash, 16, 1) != '.')
		return false;

	$r = q("select channel_hash from channel where channel_id = %d limit 1",
		intval($uid)
	);

	if (!$r)
		return false;

	$x = q("select * from atoken where atoken_uid = %d and atoken_guid = '%s'",
		intval($uid),
		dbesc(substr($xchan_hash, 17))
	);

	if ($x) {
		$xchan = atoken_xchan($x[0]);
		$xchan['abook_blocked'] = 0;
		$xchan['abook_ignored'] = 0;
		$xchan['abook_pending'] = 0;
		return $xchan;
	}

	return false;
}


/**
 * @brief Change to another channel with current logged-in account.
 *
 * @param int $change_channel The channel_id of the channel you want to change to
 *
 * @return bool|array false or channel record of the new channel
 */
function change_channel($change_channel) {

	$ret = false;

	if ($change_channel) {

		$r = q("select channel.*, xchan.* from channel left join xchan on channel.channel_hash = xchan.xchan_hash where channel_id = %d and channel_account_id = %d and channel_removed = 0 limit 1",
			intval($change_channel),
			intval(get_account_id())
		);

		// It's not there.  Is this an administrator, and is this the sys channel?
		if (is_developer()) {
			if (!$r) {
				if (is_site_admin()) {
					$r = q("select channel.*, xchan.* from channel left join xchan on channel.channel_hash = xchan.xchan_hash where channel_id = %d and channel_system = 1 and channel_removed = 0 limit 1",
						intval($change_channel)
					);
				}
			}
		}

		if ($r) {
			$hash = $r[0]['channel_hash'];
			$_SESSION['uid'] = intval($r[0]['channel_id']);
			App::set_channel($r[0]);
			$_SESSION['theme'] = $r[0]['channel_theme'];
			$_SESSION['mobile_theme'] = get_pconfig(local_channel(), 'system', 'mobile_theme');
			$_SESSION['cloud_tiles'] = get_pconfig(local_channel(), 'system', 'cloud_tiles');
			date_default_timezone_set($r[0]['channel_timezone']);

			// Update the active timestamp at most once a day

			if (substr($r[0]['channel_active'], 0, 10) !== substr(datetime_convert(), 0, 10)) {
				q("UPDATE channel SET channel_active = '%s' WHERE channel_id = %d",
					dbesc(datetime_convert()),
					intval($r[0]['channel_id'])
				);
			}
			$ret = $r[0];
		}
		$x = q("select * from xchan where xchan_hash = '%s' limit 1",
			dbesc($hash)
		);
		if ($x) {
			$_SESSION['my_url'] = $x[0]['xchan_url'];
			$_SESSION['my_address'] = channel_reddress($r[0]);

			App::set_observer($x[0]);
			App::set_perms(get_all_perms(local_channel(), $hash));
		}
		if (!is_dir('store/' . $r[0]['channel_address']))
			@os_mkdir('store/' . $r[0]['channel_address'], STORAGE_DEFAULT_PERMISSIONS, true);

		$arr = ['channel_id' => $change_channel, 'chanx' => $ret];
		call_hooks('change_channel', $arr);
	}

	return $ret;
}

/**
 * @brief Creates an additional SQL where statement to check permissions.
 *
 * @param int $owner_id
 * @param bool $remote_observer (optional) use current observer if unset
 * @param $table (optional)
 * @param $token (optional)
 *
 * @return string additional SQL where statement
 */

function permissions_sql($owner_id, $remote_observer = null, $table = '', $token = EMPTY_STR) {

	$local_channel = local_channel();
	$observer = $remote_observer ?? get_observer_hash();

	/**
	 * Construct permissions
	 *
	 * default permissions - anonymous user
	 */

	if ($table)
		$table .= '.';

	$sql = " AND {$table}allow_cid = ''
			 AND {$table}allow_gid = ''
			 AND {$table}deny_cid  = ''
			 AND {$table}deny_gid  = ''
	";

	/**
	 * Profile owner - everything is visible
	 */

	if (($local_channel) && ($local_channel == $owner_id)) {
		return EMPTY_STR;
	}
	else {

		/*
		 * OCAP token access
		 */

		if ($token) {
			$sql = " AND ( {$table}allow_cid like '" . protect_sprintf('%<token:' . $token . '>%') .
			"' OR ( {$table}allow_cid = '' AND {$table}allow_gid = '' AND {$table}deny_cid = '' AND {$table}deny_gid = '' ) )";
		}

		/**
		 * Authenticated visitor.
		*/

		elseif ($observer) {

			$sec = get_security_ids($owner_id, $observer);

			// always allow the channel owner, even if authenticated as a visitor

			if ($sec['channel_id']) {
				foreach ($sec['channel_id'] as $ch) {
					if ($observer === $ch) {
						return EMPTY_STR;
					}
				}
			}

			if (is_array($sec['allow_cid']) && count($sec['allow_cid'])) {
				$ca = [];
				foreach ($sec['allow_cid'] as $c) {
					$ca[] = '<' . $c . '>';
				}
				$cs = implode('|', $ca);
			}
			else {
				$cs = '<<>>'; // should be impossible to match
			}

			if (is_array($sec['allow_gid']) && count($sec['allow_gid'])) {
				$ga = [];
				foreach ($sec['allow_gid'] as $g) {
					$ga[] = '<' . $g . '>';
				}
				$gs = implode('|', $ga);
			}
			else {
				$gs = '<<>>'; // should be impossible to match
			}

			$regexop = db_getfunc('REGEXP');
			$sql = sprintf(
				" AND ( NOT ({$table}deny_cid $regexop '%s' OR {$table}deny_gid $regexop '%s')
				  AND ( {$table}allow_cid $regexop '%s' OR {$table}allow_gid $regexop '%s' OR ( {$table}allow_cid = '' AND {$table}allow_gid = '') )
				  )
				",
				dbesc($cs),
				dbesc($gs),
				dbesc($cs),
				dbesc($gs)
			);
		}
	}

	return $sql;
}

/**
 * @brief Creates an additional SQL where statement to check permissions for an item.
 *
 * @param int $owner_id
 * @param bool $remote_observer (optional) use current observer if unset
 *
 * @return string additional SQL where statement
 */

function item_permissions_sql($owner_id, $remote_observer = null) {

	$local_channel = local_channel();

	/**
	 * Construct permissions
	 *
	 * default permissions - anonymous user
	 */

	$sql = " AND item_private = 0 ";

	/**
	 * Profile owner - everything is visible
	 */

	if (($local_channel) && ($local_channel == $owner_id)) {
		$sql = '';
	}
	/**
	 * Authenticated visitor.
	 */

	else {

		$observer = (($remote_observer) ? $remote_observer : get_observer_hash());

		if ($observer) {

			$scope = scopes_sql($owner_id, $observer);
			$sec = get_security_ids($owner_id, $observer);

			// always allow the channel owner, even if authenticated as a visitor

			if ($sec['channel_id']) {
				foreach ($sec['channel_id'] as $ch) {
					if ($observer === $ch) {
						return EMPTY_STR;
					}
				}
			}

			if (is_array($sec['allow_cid']) && count($sec['allow_cid'])) {
				$ca = [];
				foreach ($sec['allow_cid'] as $c) {
					$ca[] = '<' . $c . '>';
				}
				$cs = implode('|', $ca);
			}
			else {
				$cs = '<<>>'; // should be impossible to match
			}

			if (is_array($sec['allow_gid']) && count($sec['allow_gid'])) {
				$ga = [];
				foreach ($sec['allow_gid'] as $g) {
					$ga[] = '<' . $g . '>';
				}
				$gs = implode('|', $ga);
			}
			else {
				$gs = '<<>>'; // should be impossible to match
			}

			// This function is often called without an $owner_id in places where this could not be
			// determined in advance. The ACL fields will usually not contain the original author or owner
			// so we will also check for author_xchan and owner_xchan to account for this ACL deficiency.

			$regexop = db_getfunc('REGEXP');
			$sql = sprintf(
				" AND ( author_xchan = '%s' OR owner_xchan = '%s' OR
				(( NOT (deny_cid $regexop '%s' OR deny_gid $regexop '%s')
				AND ( allow_cid $regexop '%s' OR allow_gid $regexop '%s' OR ( allow_cid = '' AND allow_gid = '' AND item_private = 0 ))
				)) OR ( item_private = 1 $scope ))
				",
				dbesc($observer),
				dbesc($observer),
				dbesc($cs),
				dbesc($gs),
				dbesc($cs),
				dbesc($gs)
			);
		}
	}

	return $sql;
}

/**
 * Remote visitors also need to be checked against the public_scope parameter if item_private is set.
 * This function checks the various permutations of that field for any which apply to this observer.
 *
 */


function scopes_sql($uid, $observer) {
	$str = " and ( public_policy = 'authenticated' ";
	if (!is_foreigner($observer))
		$str .= " or public_policy = 'network: red' ";
	if (local_channel())
		$str .= " or public_policy = 'site: " . App::get_hostname() . "' ";

	$ab = q("select * from abook where abook_xchan = '%s' and abook_channel = %d limit 1",
		dbesc($observer),
		intval($uid)
	);
	if (!$ab)
		return $str . " ) ";
	if ($ab[0]['abook_pending'])
		$str .= " or public_policy = 'any connections' ";
	$str .= " or public_policy = 'contacts' ) ";
	return $str;
}


/**
 * @param string $observer_hash
 *
 * @return string additional SQL where statement
 */

function public_permissions_sql($observer_hash) {

	$owner_id = 0;

	if ($observer_hash) {

		$sec = get_security_ids($owner_id, $observer_hash);

		if (is_array($sec['allow_cid']) && count($sec['allow_cid'])) {
			$ca = [];
			foreach ($sec['allow_cid'] as $c) {
				$ca[] = '<' . $c . '>';
			}
			$cs = implode('|', $ca);
		}
		else {
			$cs = '<<>>'; // should be impossible to match
		}

		if (is_array($sec['allow_gid']) && count($sec['allow_gid'])) {
			$ga = [];
			foreach ($sec['allow_gid'] as $g) {
				$ga[] = '<' . $g . '>';
			}
			$gs = implode('|', $ga);
		}
		else {
			$gs = '<<>>'; // should be impossible to match
		}

		$regexop = db_getfunc('REGEXP');
		$sql = sprintf(
			" AND ( NOT (deny_cid $regexop '%s' OR deny_gid $regexop '%s')
			  AND ( allow_cid $regexop '%s' OR allow_gid $regexop '%s' OR ( allow_cid = '' AND allow_gid = '' AND item_private = 0) )
			  )
			",
			dbesc($cs),
			dbesc($gs),
			dbesc($cs),
			dbesc($gs)
		);
	}
	else {
		$sql = EMPTY_STR;
	}

	return $sql;
}


/*
 * Functions used to protect against Cross-Site Request Forgery
 * The security token has to base on at least one value that an attacker can't know - here it's the session ID and the private key.
 * In this implementation, a security token is reusable (if the user submits a form, goes back and resubmits the form, maybe with small changes;
 * or if the security token is used for ajax-calls that happen several times), but only valid for a certain amout of time (3hours).
 * The "typename" seperates the security tokens of different types of forms. This could be relevant in the following case:
 *	  A security token is used to protect a link from CSRF (e.g. the "delete this profile"-link).
 *    If the new page contains by any chance external elements, then the used security token is exposed by the referrer.
 *    Actually, important actions should not be triggered by Links / GET-Requests at all, but somethimes they still are,
 *    so this mechanism brings in some damage control (the attacker would be able to forge a request to a form of this type, but not to forms of other types).
 */
function get_form_security_token($typename = '') {

	$timestamp = time();
	$guid = App::$observer['xchan_guid'] ?? '';
	$sec_hash = hash('whirlpool', $guid . ((local_channel()) ? App::$channel['channel_prvkey'] : '') . session_id() . $timestamp . $typename);

	return $timestamp . '.' . $sec_hash;
}

function check_form_security_token($typename = '', $formname = 'form_security_token') {
	if (!x($_REQUEST, $formname)) return false;
	$hash = $_REQUEST[$formname];

	$max_livetime = 10800; // 3 hours

	$x = explode('.', $hash);
	if (time() > (IntVal($x[0]) + $max_livetime))
		return false;

	$sec_hash = hash('whirlpool', App::$observer['xchan_guid'] . ((local_channel()) ? App::$channel['channel_prvkey'] : '') . session_id() . $x[0] . $typename);

	return ($sec_hash == $x[1]);
}

function check_form_security_std_err_msg() {
	/** @noinspection PhpToStringImplementationInspection */
	return t('The form security token was not correct. This probably happened because the form has been opened for too long (>3 hours) before submitting it.') . EOL;
}

function check_form_security_token_redirectOnErr($err_redirect, $typename = '', $formname = 'form_security_token') {
	if (!check_form_security_token($typename, $formname)) {
		logger('check_form_security_token failed: user ' . App::$observer['xchan_name'] . ' - form element ' . $typename);
		logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
		notice(check_form_security_std_err_msg());
		goaway(z_root() . $err_redirect);
	}
}

function check_form_security_token_ForbiddenOnErr($typename = '', $formname = 'form_security_token') {
	if (!check_form_security_token($typename, $formname)) {
		logger('check_form_security_token failed: user ' . App::$observer['xchan_name'] . ' - form element ' . $typename);
		logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
		header('HTTP/1.1 403 Forbidden');
		killme();
	}
}


// Returns an array of group hash id's on this entire site (across all channels) that this connection is a member of.
// var $contact_id = xchan_hash of connection

function init_groups_visitor($contact_id) {
	$groups = [];

	$x = q("select * from xchan where xchan_hash = '%s'",
		dbesc($contact_id)
	);

	if (!$x) {
		return $groups;
	}

	// include xchans for all zot-like networks

	$xchans = q("select xchan_hash from xchan where xchan_hash = '%s' OR ( xchan_guid = '%s' AND xchan_pubkey = '%s' ) ",
		dbesc($contact_id),
		dbesc($x[0]['xchan_guid']),
		dbesc($x[0]['xchan_pubkey'])
	);

	if ($xchans) {
		$hashes = ids_to_querystr($xchans, 'xchan_hash', true);
	}

	// private profiles are treated as a virtual group

	$r = q("SELECT abook_profile from abook where abook_xchan in ( " . protect_sprintf($hashes) . " ) and abook_profile != '' ");
	if ($r) {
		foreach ($r as $rv) {
			$groups[] = 'vp.' . $rv['abook_profile'];
		}
	}

	// physical groups this identity is a member of

	$r = q("SELECT hash FROM pgrp left join pgrp_member on pgrp.id = pgrp_member.gid WHERE xchan in ( " . protect_sprintf($hashes) . " ) ");
	if ($r) {
		foreach ($r as $rr)
			$groups[] = $rr['hash'];
	}
	return $groups;
}


function get_security_ids($channel_id, $ob_hash) {

	$ret = [
		'channel_id' => [],
		'allow_cid' => [],
		'allow_gid' => []
	];

	$x = q("select xchan_hash from xchan where xchan_hash = '%s'",
		dbesc($ob_hash)
	);

	if (!$x) {
		return $ret;
	}

	$ret['allow_cid'][] = $x[0]['xchan_hash'];

	if (!$channel_id) {
		return $ret;
	}

	$ch = q("select channel_hash from channel where channel_id = %d",
		intval($channel_id)
	);
	if ($ch) {
		$ret['channel_id'][] = $ch[0]['channel_hash'];
	}

	$groups = [];

	// private profiles are treated as a virtual group

	$r = q("SELECT abook_profile from abook where abook_channel = %d and abook_xchan = '%s' and abook_profile != ''",
		intval($channel_id),
		dbesc(protect_sprintf($x[0]['xchan_hash']))
	);

	if ($r) {
		foreach ($r as $rv) {
			if (!in_array('vp.' . $rv['abook_profile'], $groups)) {
				$groups[] = 'vp.' . $rv['abook_profile'];
			}
		}
	}

	// physical groups this identity is a member of

	$r = q("SELECT hash FROM pgrp left join pgrp_member on pgrp.id = pgrp_member.gid WHERE pgrp.uid = %d and pgrp_member.xchan = '%s'",
		intval($channel_id),
		dbesc(protect_sprintf($x[0]['xchan_hash']))
	);

	if ($r) {
		foreach ($r as $rv) {
			if (!in_array($rv['hash'], $groups)) {
				$groups[] = $rv['hash'];
			}
		}
	}

	$ret['allow_gid'] = $groups;

	return $ret;
}


// This is used to determine which uid have posts which are visible to the logged in user (from the API) for the
// public_timeline, and we can use this in a community page by making
// $perms = (PERMS_NETWORK|PERMS_PUBLIC) unless logged in.
// Collect uids of everybody on this site who has opened their posts to everybody on this site (or greater visibility)
// We always include yourself if logged in because you can always see your own posts
// resolving granular permissions for the observer against every person and every post on the site
// will likely be too expensive.
// Returns a string list of comma separated channel_ids suitable for direct inclusion in a SQL query

function stream_perms_api_uids($perms = NULL, $limit = 0, $rand = 0) {
	$perms = is_null($perms) ? (PERMS_SITE | PERMS_NETWORK | PERMS_PUBLIC) : $perms;

	$ret = array();
	$limit_sql = (($limit) ? " LIMIT " . intval($limit) . " " : '');
	$random_sql = (($rand) ? " ORDER BY " . db_getfunc('RAND') . " " : '');
	if (local_channel())
		$ret[] = local_channel();
	$x = q("select uid, v from pconfig where cat = 'perm_limits' and k = 'view_stream' ");
	if ($x) {
		$y = [];
		foreach ($x as $xv) {
			if (intval($xv['v']) & $perms) {
				$y[] = $xv;
			}
		}
		if ($y) {
			$ids = ids_to_querystr($y, 'uid');
			$r = q("select channel_id from channel where channel_id in ( $ids ) and ( channel_pageflags & %d ) = 0 and channel_system = 0 and channel_removed = 0 $random_sql $limit_sql ",
				intval(PAGE_ADULT | PAGE_CENSORED)
			);
			if ($r) {
				foreach ($r as $rr)
					if (!in_array($rr['channel_id'], $ret))
						$ret[] = $rr['channel_id'];
			}
		}
	}

	$str = '';
	if ($ret) {
		foreach ($ret as $rr) {
			if ($str)
				$str .= ',';
			$str .= intval($rr);
		}
	}
	else
		$str = "''";

	logger('stream_perms_api_uids: ' . $str, LOGGER_DEBUG);

	return $str;
}

function stream_perms_xchans($perms = NULL) {
	$perms = is_null($perms) ? (PERMS_SITE | PERMS_NETWORK | PERMS_PUBLIC) : $perms;

	$ret = array();
	if (local_channel())
		$ret[] = get_observer_hash();

	$x = q("select uid, v from pconfig where cat = 'perm_limits' and k = 'view_stream' ");
	if ($x) {
		$y = [];
		foreach ($x as $xv) {
			if (intval($xv['v']) & $perms) {
				$y[] = $xv;
			}
		}
		if ($y) {
			$ids = ids_to_querystr($y, 'uid');

			$r = q("select channel_hash from channel where channel_id in ( $ids ) and ( channel_pageflags & %d ) = 0 and channel_system = 0 and channel_removed = 0 ",
				intval(PAGE_ADULT | PAGE_CENSORED)
			);

			if ($r) {
				foreach ($r as $rr)
					if (!in_array($rr['channel_hash'], $ret))
						$ret[] = $rr['channel_hash'];
			}
		}
	}
	$str = '';
	if ($ret) {
		foreach ($ret as $rr) {
			if ($str)
				$str .= ',';
			$str .= "'" . dbesc($rr) . "'";
		}
	}
	else
		$str = "''";

	logger('stream_perms_xchans: ' . $str, LOGGER_DEBUG);

	return $str;
}


/**
 * Duty day / time checks for account register
 * @author hilmar runge
 * @since  2020.02.10
 * @param  $op what to test: isOpen, nextOpen
 * @param  $wd weekday according ISO-8601 (1 monday, 7 sunday)
 * @param  $hhmm a 24h clock value hours and minutes
 *		   if no params are given, the values are taken from the current time
 *         return is bool(false) if register_duty is not available
 */
function zarIsDuty($wd=NULL, $hhmm=NULL, $op='isOpen') {

	$isduty = Config::Get('system', 'register_duty_jso');

	if (!$isduty)
		return (bool)false;

	is_null($wd) ? $wd = date('N') : '';
	is_null($hhmm) ? $hhmm = date('Hi') : '';

	if (!intval($wd . $hhmm)) return (bool)false;

	// be sure to have a valid weekday as index
	$wd = (7 + $wd) % 7;
	$wd === 0 ? $wd = 7 : '';

	$duty = json_decode($isduty, true);
	if (!$duty)
		return (bool)false;

	switch ($op) {
		case 'isOpen':
			/**
			 * Check if registration is open
 			 * @return int(0) for not close (open) or int(1) for closed.
			 *         return is bool(false) if register_duty is not available
			 */
			if (!$duty[$wd]) return (bool)false;
			$dutyis = 0;
			foreach ($duty[$wd] as $o => $tf) {
				if ($o > $hhmm) {
					$dutyis = $tf;
					break;
				}
			}
			return $dutyis;

		case 'nextOpen':
			/**
			 * Look for next period opens
			 * @return "=>N =>Hi" date value of the next period register is open for requests
 			 *			where N is a weekday (1=monday ... 7=sunday) according ISO-8601
			 *			where Hi is a 24h clock value hhmm by hours and minutes.
			 *			If no next period open is available, return results to false.
			 */
			$myd = $wd;
			$myh = $hhmm;
			$is1 = false;

			// $myd = "5";		// testcase only
			// $myh = "1110";	// testcase only

			// a 1st match may be applied below my time and is to see as a cycle to the next week
			// but looking is also for a open time after my time is available this week
			foreach ($duty as $dd => $dhs) {

				if ($is1 && $dd < $myd)
					continue;

				foreach ($dhs as $dh => $tf) {

					if ($tf) continue; 	// close

					// a weeks 1st open
					if (!$is1) $is1 = array($dd, $dh);

					// but is a match after now?
					//if ($dd == $myd && $myh >= $dh && $myh <= $dh) continue;

					// if the day is not (more) today start find early morning
					if ($dd > $myd) $myh = "0000";

					// a next period after now in the remainder of the week
					if ($dd >= $myd && $dh >= $myh && !$tf)
						return array($dd, $dh);
					else
						continue;
				}
			}
			return $is1; // false or array

		default:
			//
			break;
	}

}