<?php

/**
 * ownCloud – LDAP Wizard
 *
 * @author Arthur Schiwon
 * @copyright 2013 Arthur Schiwon blizzz@owncloud.com
 *
 * 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/>.
 *
 */

namespace OCA\user_ldap\lib;

class Wizard extends LDAPUtility {
	static protected $l;
	protected $configuration;
	protected $result;

	const LRESULT_PROCESSED_OK = 0;
	const LRESULT_PROCESSED_INVALID = 1;
	const LRESULT_PROCESSED_SKIP = 2;

	/**
	 * @brief Constructor
	 * @param $configuration an instance of Configuration
	 * @param $ldap	an instance of ILDAPWrapper
	 */
	public function __construct(Configuration $configuration, ILDAPWrapper $ldap) {
		parent::__construct($ldap);
		$this->configuration = $configuration;
		if(is_null(Wizard::$l)) {
			Wizard::$l = \OC_L10N::get('user_ldap');
		}
		$this->result = new WizardResult;
	}

	public function  __destruct() {
		if($this->result->hasChanges()) {
			$this->configuration->saveConfiguration();
		}
	}

	/**
	 * @brief detects the available LDAP groups
	 * @returns the instance's WizardResult instance
	 */
	public function determineGroups() {
		if(!$this->checkRequirements(array('ldapHost',
										   'ldapPort',
										   'ldapAgentName',
										   'ldapAgentPassword',
										   'ldapBase',
										   ))) {
			return  false;
		}
		$cr = $this->getConnection();
		if(!$cr) {
			throw new \Excpetion('Could not connect to LDAP');
		}

		$obclasses = array('posixGroup', 'group', '*');
		return $this->determineFeature($obclasses,
									   'cn',
									   'ldap_userfilter_groups',
									   'ldapUserFilterGroups');

		//TODO: Check, whether member-of-overlay is installed on the LDAP Server
	}

	/**
	 * @brief detects the available object classes
	 * @returns the instance's WizardResult instance
	 */
	public function determineObjectClasses() {
		if(!$this->checkRequirements(array('ldapHost',
										   'ldapPort',
										   'ldapAgentName',
										   'ldapAgentPassword',
										   'ldapBase',
										   true
										   ))) {
			return  false;
		}
		$cr = $this->getConnection();
		if(!$cr) {
			throw new \Excpetion('Could not connect to LDAP');
		}

		$obclasses = array('inetOrgPerson', 'person', 'organizationalPerson',
						   'user', 'posixAccount', '*');
		return $this->determineFeature($obclasses,
									   'objectclass',
									   'ldap_userfilter_objectclass',
									   'ldapUserFilterObjectclass');
	}

	/**
	 * Tries to determine the port, requires given Host, User DN and Password
	 * @returns mixed WizardResult on success, false otherwise
	 */
	public function guessPortAndTLS() {
		if(!$this->checkRequirements(array('ldapHost',
										   'ldapAgentName',
										   'ldapAgentPassword'
										   ))) {
			return false;
		}
		$this->checkHost();
		$portSettings = $this->getPortSettingsToTry();
		file_put_contents('/tmp/ps', print_r($portSettings, true).PHP_EOL, FILE_APPEND);

		if(!is_array($portSettings)) {
			throw new \Exception(print_r($portSettings, true));
		}

		//proceed from the best configuration and return on first success
		foreach($portSettings as $setting) {
			$p = $setting['port'];
			$t = $setting['tls'];
			\OCP\Util::writeLog('user_ldap', 'Wiz: trying port '. $p . ', TLS '. $t, \OCP\Util::DEBUG);
			//connectAndBind may throw Exception, it needs to be catched by the
			//callee of this method
			if($this->connectAndBind($p, $t) === true) {
				$config = array('ldapPort' => $p,
								'ldapTLS'  => intval($t)
							);
				$this->configuration->setConfiguration($config);
				\OCP\Util::writeLog('user_ldap', 'Wiz: detected Port '. $p, \OCP\Util::DEBUG);
				$this->result->addChange('ldap_port', $p);
				$this->result->addChange('ldap_tls', intval($t));
				return $this->result;
			}
		}

		//custom port, undetected (we do not brute force)
		return false;
	}

	/**
	 * @brief tries to determine a base dn from User DN or LDAP Host
	 * @returns mixed WizardResult on success, false otherwise
	 */
	public function guessBaseDN() {
		if(!$this->checkRequirements(array('ldapHost',
										   'ldapAgentName',
										   'ldapAgentPassword',
										   'ldapPort',
										   ))) {
			return false;
		}

		//check whether a DN is given in the agent name (99.9% of all cases)
		$base = null;
		$i = stripos($this->configuration->ldapAgentName, 'dc=');
		if($i !== false) {
			$base = substr($this->configuration->ldapAgentName, $i);

			if($this->testBaseDN($base)) {
				$this->applyFind('ldap_base', $base);
				$this->applyFind('ldap_base_users', $base);
				$this->applyFind('ldap_base_groups', $base);
				return $this->result;
			}
		}

		//this did not help :(
		//Let's see whether we can parse the Host URL and convert the domain to
		//a base DN
		$domain = Helper::getDomainFromURL($this->configuration->ldapHost);
		if(!$domain) {
			return false;
		}

		$dparts = explode('.', $domain);
		$base2 = implode('dc=', $dparts);
		if($base !== $base2 && $this->testBaseDN($base2)) {
			$this->applyFind('ldap_base', $base2);
			$this->applyFind('ldap_base_users', $base2);
			$this->applyFind('ldap_base_groups', $base2);
			return $this->result;
		}

		return false;
	}

	/**
	 * @brief sets the found value for the configuration key in the WizardResult
	 * as well as in the Configuration instance
	 * @param $key the configuration key
	 * @param $value the (detected) value
	 * @return null
	 *
	 */
	private function applyFind($key, $value) {
		$this->result->addChange($key, $value);
		$this->configuration->setConfiguration(array($key => $value));
	}

	/**
	 * @brief Checks, whether a port was entered in the Host configuration
	 * field. In this case the port will be stripped off, but also stored as
	 * setting.
	 */
	private function checkHost() {
		$host = $this->configuration->ldapHost;
		$hostInfo = parse_url($host);

		//removes Port from Host
		if(is_array($hostInfo) && isset($hostInfo['port'])) {
			$port = $hostInfo['port'];
			$host = str_replace(':'.$port, '', $host);
			$this->applyFind('ldap_host', $host);
			$this->applyFind('ldap_port', $port);
		}
	}

	/**
	 * @brief Checks whether for a given BaseDN results will be returned
	 * @param $base the BaseDN to test
	 * @return bool true on success, false otherwise
	 */
	private function testBaseDN($base) {
		$cr = $this->getConnection();
		if(!$cr) {
			throw new \Excpetion('Could not connect to LDAP');
		}

		//base is there, let's validate it. If we search for anything, we should
		//get a result set > 0 on a proper base
		$rr = $this->ldap->search($cr, $base, 'objectClass=*', array('dn'), 0, 1);
		if(!$this->ldap->isResource($rr)) {
			return false;
		}
		$entries = $this->ldap->countEntries($cr, $rr);
		return ($entries !== false) && ($entries > 0);
	}

	/**
	 * Connects and Binds to an LDAP Server
	 * @param $port the port to connect with
	 * @param $tls whether startTLS is to be used
	 * @return
	 */
	private function connectAndBind($port = 389, $tls = false, $ncc = false) {
		if($ncc) {
			//No certificate check
			//FIXME: undo afterwards
			putenv('LDAPTLS_REQCERT=never');
		}

		//connect, does not really trigger any server communication
		\OCP\Util::writeLog('user_ldap', 'Wiz: Checking Host Info ', \OCP\Util::DEBUG);
		$host = $this->configuration->ldapHost;
		$hostInfo = parse_url($host);
		if(!$hostInfo) {
			throw new \Exception($this->l->t('Invalid Host'));
		}
		if(isset($hostInfo['scheme'])) {
			if(isset($hostInfo['port'])) {
				//problem
			} else {
				$host .= ':' . $port;
			}
		}
		\OCP\Util::writeLog('user_ldap', 'Wiz: Attempting to connect ', \OCP\Util::DEBUG);
		$cr = $this->ldap->connect($host, $port);
		if(!is_resource($cr)) {
			throw new \Exception($this->l->t('Invalid Host'));
		}

		\OCP\Util::writeLog('user_ldap', 'Wiz: Setting LDAP Options ', \OCP\Util::DEBUG);
		//set LDAP options
		if($this->ldap->setOption($cr, LDAP_OPT_PROTOCOL_VERSION, 3)) {
			if($tls) {
				$this->ldap->startTls($cr);
			}
		}

		\OCP\Util::writeLog('user_ldap', 'Wiz: Attemping to Bind ', \OCP\Util::DEBUG);
		//interesting part: do the bind!
		$login = $this->ldap->bind($cr,
									$this->configuration->ldapAgentName,
									$this->configuration->ldapAgentPassword);

		if($login === true) {
			$this->ldap->unbind($cr);
			if($ncc) {
				throw new \Exception('Certificate cannot be validated.');
			}
			\OCP\Util::writeLog('user_ldap', 'Wiz: Bind succesfull with Port '. $port, \OCP\Util::DEBUG);
			return true;
		}

		$errno = $this->ldap->errno($cr);
		$error = ldap_error($cr);
		$this->ldap->unbind($cr);
		if($errno === -1 || ($errno === 2 && $ncc)) {
			//host, port or TLS wrong
			return false;
		} else if ($errno === 2) {
			return $this->connectAndBind($port, $tls, true);
		}
		throw new \Exception($error);
	}

	private function checkRequirements($reqs) {
		foreach($reqs as $option) {
			$value = $this->configuration->$option;
			if(empty($value)) {
				return false;
			}
		}
		return true;
	}

	/**
	 * @brief does a cumulativeSearch on LDAP to get different values of a
	 * specified attribute
	 * @param $filters array, the filters that shall be used in the search
	 * @param $attr the attribute of which a list of values shall be returned
	 * @param $lfw bool, whether the last filter is a wildcard which shall not
	 * be processed if there were already findings, defaults to true
	 * @param $maxF string. if not null, this variable will have the filter that
	 * yields most result entries
	 * @return mixed, an array with the values on success, false otherwise
	 *
	 */
	private function cumulativeSearchOnAttribute($filters, $attr, $lfw = true, &$maxF = null) {
		$dnRead = array();
		$foundItems = array();
		$maxEntries = 0;
		if(!is_array($this->configuration->ldapBase)
		   || !isset($this->configuration->ldapBase[0])) {
			return false;
		}
		$base = $this->configuration->ldapBase[0];
		$cr = $this->getConnection();
		if(!is_resource($cr)) {
			return false;
		}
		foreach($filters as $filter) {
			if($lfw && count($foundItems) > 0) {
				continue;
			}
			$rr = $this->ldap->search($cr, $base, $filter, array($attr));
			if(!$this->ldap->isResource($rr)) {
				continue;
			}
			$entries = $this->ldap->countEntries($cr, $rr);
			$getEntryFunc = 'firstEntry';
			if(($entries !== false) && ($entries > 0)) {
				if(!is_null($maxF) && $entries > $maxEntries) {
					$maxEntries = $entries;
					$maxF = $filter;
				}
				do {
					$entry = $this->ldap->$getEntryFunc($cr, $rr);
					if(!$this->ldap->isResource($entry)) {
						continue 2;
					}
					$attributes = $this->ldap->getAttributes($cr, $entry);
					$dn = $this->ldap->getDN($cr, $entry);
					if($dn === false || in_array($dn, $dnRead)) {
						continue;
					}
					$state = $this->getAttributeValuesFromEntry($attributes,
																$attr,
																$foundItems);
					$dnRead[] = $dn;
					$getEntryFunc = 'nextEntry';
					$rr = $entry; //will be expected by nextEntry next round
				} while($state === self::LRESULT_PROCESSED_SKIP
						|| $this->ldap->isResource($entry));
			}
		}

		return $foundItems;
	}

	/**
	 * @brief determines if and which $attr are available on the LDAP server
	 * @param $objectclasses the objectclasses to use as search filter
	 * @param $attr the attribute to look for
	 * @param $dbkey the dbkey of the setting the feature is connected to
	 * @param $confkey the confkey counterpart for the $dbkey as used in the
	 * Configuration class
	 * @param $po boolean, whether the objectClass with most result entries
	 * shall be pre-selected via the result
	 * @returns the instance's WizardResult instance
	 */
	private function determineFeature($objectclasses, $attr, $dbkey, $confkey, $po = false) {
		$cr = $this->getConnection();
		if(!$cr) {
			throw new \Excpetion('Could not connect to LDAP');
		}
		$p = 'objectclass=';
		foreach($objectclasses as $key => $value) {
			$objectclasses[$key] = $p.$value;
		}
		$maxEntryObjC = '';
		$availableFeatures =
			$this->cumulativeSearchOnAttribute($objectclasses, $attr,
											   true, $maxEntryObjC);
		if(is_array($availableFeatures)
		   && count($availableFeatures) > 0) {
			$this->result->addOptions($dbkey, $availableFeatures);
		} else {
			throw new \Exception(self::$l->t('Could not find the desired feature'));
		}

		$setFeatures = $this->configuration->$confkey;
		if(is_array($setFeatures) && !empty($setFeatures)) {
			//something is already configured? pre-select it.
			$this->result->addChange($dbkey, $setFeatures);
		} else if($po && !empty($maxEntryObjC)) {
			//pre-select objectclass with most result entries
			$maxEntryObjC = str_replace($p, '', $maxEntryObjC);
			$this->result->addChange($dbkey, $maxEntryObjC);
		}

		return $this->result;
	}

	/**
	 * @brief appends a list of values fr
	 * @param $result resource, the return value from ldap_get_attributes
	 * @param $attribute string, the attribute values to look for
	 * @param &$known array, new values will be appended here
	 * @return int, state on of the class constants LRESULT_PROCESSED_OK,
	 * LRESULT_PROCESSED_INVALID or LRESULT_PROCESSED_SKIP
	 */
	private function getAttributeValuesFromEntry($result, $attribute, &$known) {
		if(!is_array($result)
		   || !isset($result['count'])
		   || !$result['count'] > 0) {
			return self::LRESULT_PROCESSED_INVALID;
		}

		//strtolower on all keys for proper comparison
		$result = \OCP\Util::mb_array_change_key_case($result);
		$attribute = strtolower($attribute);
		if(isset($result[$attribute])) {
			foreach($result[$attribute] as $key => $val) {
				if($key === 'count') {
					continue;
				}
				if(!in_array($val, $known)) {
					\OCP\Util::writeLog('user_ldap', 'Found objclass '.$val, \OCP\Util::DEBUG);
					$known[] = $val;
				}
			}
			return self::LRESULT_PROCESSED_OK;
		} else {
			return self::LRESULT_PROCESSED_SKIP;
		}
	}

	private function getConnection() {
		$cr = $this->ldap->connect(
			$this->configuration->ldapHost.':'.$this->configuration->ldapPort,
			$this->configuration->ldapPort);

		if($this->ldap->setOption($cr, LDAP_OPT_PROTOCOL_VERSION, 3)) {
			if($this->configuration->ldapTLS === 1) {
				$this->ldap->startTls($cr);
			}
		}

		$lo = @$this->ldap->bind($cr,
								 $this->configuration->ldapAgentName,
								 $this->configuration->ldapAgentPassword);
		if($lo === true) {
			return $cr;
		}

		return false;
	}

	private function getDefaultLdapPortSettings() {
		static $settings = array(
								array('port' => 7636, 'tls' => false),
								array('port' =>  636, 'tls' => false),
								array('port' => 7389, 'tls' => true),
								array('port' =>  389, 'tls' => true),
								array('port' => 7389, 'tls' => false),
								array('port' =>  389, 'tls' => false),
						  );
		return $settings;
	}

	private function getPortSettingsToTry() {
		//389 ← LDAP / Unencrypted or StartTLS
		//636 ← LDAPS / SSL
		//7xxx ← UCS. need to be checked first, because both ports may be open
		$host = $this->configuration->ldapHost;
		$port = intval($this->configuration->ldapPort);
		$portSettings = array();

		//In case the port is already provided, we will check this first
		if($port > 0) {
			$hostInfo = parse_url($host);
			if(is_array($hostInfo)
				&& isset($hostInfo['scheme'])
				&& stripos($hostInfo['scheme'], 'ldaps') === false) {
				$portSettings[] = array('port' => $port, 'tls' => true);
			}
			$portSettings[] =array('port' => $port, 'tls' => false);
		}

		//default ports
		$portSettings = array_merge($portSettings,
		                            $this->getDefaultLdapPortSettings());

		return $portSettings;
	}


}