<?php

namespace Zotlabs\Zot;

class Auth {

	protected $test;
	protected $test_results;
	protected $debug_msg;

	protected $address;
	protected $desturl;
	protected $sec;
	protected $version;
	protected $delegate;
	protected $success;
	protected $delegate_success;

	protected $remote;
	protected $remote_service_class;
	protected $remote_level;
	protected $remote_hub;
	protected $dnt;

	function __construct($req) {


		$this->test         = ((array_key_exists('test',$req)) ? intval($req['test']) : 0);
		$this->test_results = array('success' => false);
		$this->debug_msg    = '';

		$this->success   = false;
		$this->address   = $req['auth'];
		$this->desturl   = $req['dest'];
		$this->sec       = $req['sec'];
		$this->version   = $req['version'];
		$this->delegate  = $req['delegate'];

		$c = get_sys_channel();
		if(! $c) {
			logger('unable to obtain response (sys) channel');
			$this->Debug('no local channels found.');
			$this->Finalise();
		}

		$x = $this->GetHublocs($this->address);

		if($x) {
			foreach($x as $xx) {
				if($this->Verify($c,$xx))
					break;
			}
		}

		/**
		 * @FIXME we really want to save the return_url in the session before we
		 * visit rmagic. This does however prevent a recursion if you visit
		 * rmagic directly, as it would otherwise send you back here again.
		 * But z_root() probably isn't where you really want to go.
		 */

		if(strstr($this->desturl,z_root() . '/rmagic'))
			goaway(z_root());

		$this->Finalise();	

	}

	function GetHublocs($address) {

		// Try and find a hubloc for the person attempting to auth.
		// Since we're matching by address, we have to return all entries
		// some of which may be from re-installed hubs; and we'll need to 
		// try each sequentially to see if one can pass the test

		$x = q("select * from hubloc left join xchan on xchan_hash = hubloc_hash 
			where hubloc_addr = '%s' order by hubloc_id desc",
			dbesc($address)
		);

		if(! $x) {
			// finger them if they can't be found.
			$ret = zot_finger($address, null);
			if ($ret['success']) {
				$j = json_decode($ret['body'], true);
				if($j)
					import_xchan($j);
				$x = q("select * from hubloc left join xchan on xchan_hash = hubloc_hash 
					where hubloc_addr = '%s' order by hubloc_id desc",
					dbesc($address)
				);
			}
		}
		if(! $x) {
			logger('mod_zot: auth: unable to finger ' . $address);
			$this->Debug('no hubloc found for ' . $address . ' and probing failed.');
			$this->Finalise();
		}

		return $x;
	}


	function Verify($channel,$hubloc) {

		logger('auth request received from ' . $hubloc['hubloc_addr'] );

		$this->remote               = remote_channel();
		$this->remote_service_class = '';
		$this->remote_level         = 0;
		$this->remote_hub           = $hubloc['hubloc_url'];
		$this->dnt                  = 0;

		// check credentials and access

		// If they are already authenticated and haven't changed credentials,
		// we can save an expensive network round trip and improve performance.

		// Also check that they are coming from the same site as they authenticated with originally.

		$already_authed = (((remote_channel()) && ($hubloc['hubloc_hash'] == remote_channel()) 
			&& ($hubloc['hubloc_url'] === $_SESSION['remote_hub'])) ? true : false);
	
		if($this->delegate && $this->delegate !== $_SESSION['delegate_channel'])
			$already_authed = false;

		if($already_authed)
			return true;

		if(local_channel()) {

			// tell them to logout if they're logged in locally as anything but the target remote account
			// in which case just shut up because they don't need to be doing this at all.

			if (get_app()->channel['channel_hash'] == $hubloc['xchan_hash']) {
				return true;
			}
			else {
				logger('already authenticated locally as somebody else.');
				notice( t('Remote authentication blocked. You are logged into this site locally. Please logout and retry.') . EOL);
				if($this->test) {
					$this->Debug('already logged in locally with a conflicting identity.');
					return false;
				}
			}
			return false;
		}

		// Auth packets MUST use ultra top-secret hush-hush mode - e.g. the entire packet is encrypted using the 
		// site private key
		// The actual channel sending the packet ($c[0]) is not important, but this provides a 
		// generic zot packet with a sender which can be verified

		$p = zot_build_packet($channel,$type = 'auth_check', 
			array(array('guid' => $hubloc['hubloc_guid'],'guid_sig' => $hubloc['hubloc_guid_sig'])), 
			$hubloc['hubloc_sitekey'], $this->sec);

		$this->Debug('auth check packet created using sitekey ' . $hubloc['hubloc_sitekey']);
		$this->Debug('packet contents: ' . $p);

		$result = zot_zot($hubloc['hubloc_callback'],$p);
		if(! $result['success']) {
			logger('auth_check callback failed.');
			if($this->test)
				$this->Debug('auth check request to your site returned .' . print_r($result, true));
			return false;
		}

		$j = json_decode($result['body'], true);
		if(! $j) {
			logger('auth_check json data malformed.');
			if($this->test)
				$this->Debug('json malformed: ' . $result['body']);
			return false;
		}

		$this->Debug('auth check request returned .' . print_r($j, true));

		if(! $j['success']) 
			return false;

		// legit response, but we do need to check that this wasn't answered by a man-in-middle

		if (! rsa_verify($this->sec . $hubloc['xchan_hash'],base64url_decode($j['confirm']),$hubloc['xchan_pubkey'])) {
			logger('final confirmation failed.');
			if($this->test)
				$this->Debug('final confirmation failed. ' . $sec . print_r($j,true) . print_r($hubloc,true));
			return false;
		}

		if (array_key_exists('service_class',$j))
			$this->remote_service_class = $j['service_class'];
		if (array_key_exists('level',$j))
			$this->remote_level = $j['level'];
		if (array_key_exists('DNT',$j))
			$this->dnt = $j['DNT'];


		// log them in

		if ($this->test) {
			// testing only - return the success result
			$this->test_results['success'] = true;
			$this->Debug('Authentication Success!');
			$this->Finalise();
		}

		$_SESSION['authenticated'] = 1;

		// check for delegation and if all is well, log them in locally with delegation restrictions

		$this->delegate_success = false;

		if($this->delegate) {
			$r = q("select * from channel left join xchan on channel_hash = xchan_hash where xchan_addr = '%s' limit 1",
				dbesc($this->delegate)
			);
			if ($r && intval($r[0]['channel_id'])) {
				$allowed = perm_is_allowed($r[0]['channel_id'],$hubloc['xchan_hash'],'delegate');
				if($allowed) {
					$_SESSION['delegate_channel'] = $r[0]['channel_id'];
					$_SESSION['delegate'] = $hubloc['xchan_hash'];
					$_SESSION['account_id'] = intval($r[0]['channel_account_id']);
					require_once('include/security.php');
					// this will set the local_channel authentication in the session
					change_channel($r[0]['channel_id']);
					$this->delegate_success = true;
				}
			}
		}

		if (! $this->delegate_success) {
			// normal visitor (remote_channel) login session credentials
			$_SESSION['visitor_id'] = $hubloc['xchan_hash'];
			$_SESSION['my_url'] = $hubloc['xchan_url'];
			$_SESSION['my_address'] = $this->address;
			$_SESSION['remote_service_class'] = $this->remote_service_class;
			$_SESSION['remote_level'] = $this->remote_level;
			$_SESSION['remote_hub'] = $this->remote_hub;
			$_SESSION['DNT'] = $this->dnt;
		}

		$arr = array('xchan' => $hubloc, 'url' => $this->desturl, 'session' => $_SESSION);
		call_hooks('magic_auth_success',$arr);
		get_app()->set_observer($hubloc);
		require_once('include/security.php');
		get_app()->set_groups(init_groups_visitor($_SESSION['visitor_id']));
		info(sprintf( t('Welcome %s. Remote authentication successful.'),$hubloc['xchan_name']));
		logger('mod_zot: auth success from ' . $hubloc['xchan_addr']);
		$this->success = true;
		return true;
	}

	function Debug($msg) {
		$this->debug_msg .= $msg . EOL;
	}


	function Finalise() {

		if($this->test) {
			$this->test_results['message'] = $this->debug_msg;
			json_return_and_die($this->test_results);
		}

		goaway($this->desturl);
	}

}


/**
 *
 * Magic Auth
 * ==========
 *
 * So-called "magic auth" takes place by a special exchange. On the site where the "channel to be authenticated" lives (e.g. $mysite), 
 * a redirection is made via $mysite/magic to the zot endpoint of the remote site ($remotesite) with special GET parameters.
 *
 * The endpoint is typically  https://$remotesite/post - or whatever was specified as the callback url in prior communications
 * (we will bootstrap an address and fetch a zot info packet if possible where no prior communications exist)
 *
 * Five GET parameters are supplied:
 * * auth => the urlencoded webbie (channel@host.domain) of the channel requesting access
 * * dest => the desired destination URL (urlencoded)
 * * sec  => a random string which is also stored on $mysite for use during the verification phase. 
 * * version => the zot revision
 * * delegate => optional urlencoded webbie of a local channel to invoke delegation rights for
 *
 * * test => (optional 1 or 0 - debugs the authentication exchange and returns a json response instead of redirecting the browser session)
 *
 * When this packet is received, an "auth-check" zot message is sent to $mysite.
 * (e.g. if $_GET['auth'] is foobar@podunk.edu, a zot packet is sent to the podunk.edu zot endpoint, which is typically /post)
 * If no information has been recorded about the requesting identity a zot information packet will be retrieved before
 * continuing.
 *
 * The sender of this packet is an arbitrary/random site channel. The recipients will be a single recipient corresponding
 * to the guid and guid_sig we have associated with the requesting auth identity
 *
 * \code{.json}
 * {
 *   "type":"auth_check",
 *   "sender":{
 *     "guid":"kgVFf_...",
 *     "guid_sig":"PT9-TApz...",
 *     "url":"http:\/\/podunk.edu",
 *     "url_sig":"T8Bp7j...",
 *     "sitekey":"aMtgKTiirXrICP..."
 *   },
 *   "recipients":{
 *     {
 *       "guid":"ZHSqb...",
 *       "guid_sig":"JsAAXi..."
 *     }
 *   }
 *   "callback":"\/post",
 *   "version":1,
 *   "secret":"1eaa661",
 *   "secret_sig":"eKV968b1..."
 * }
 * \endcode
 *
 * auth_check messages MUST use encapsulated encryption. This message is sent to the origination site, which checks the 'secret' to see 
 * if it is the same as the 'sec' which it passed originally. It also checks the secret_sig which is the secret signed by the 
 * destination channel's private key and base64url encoded. If everything checks out, a json packet is returned:
 *
 * \code{.json}
 * {
 *   "success":1,
 *   "confirm":"q0Ysovd1u...",
 *   "service_class":(optional)
 *   "level":(optional)
 *   "DNT": (optional do-not-track - 1 or 0)
 * }
 * \endcode
 *
 * 'confirm' in this case is the base64url encoded RSA signature of the concatenation of 'secret' with the
 * base64url encoded whirlpool hash of the requestor's guid and guid_sig; signed with the source channel private key. 
 * This prevents a man-in-the-middle from inserting a rogue success packet. Upon receipt and successful 
 * verification of this packet, the destination site will redirect to the original destination URL and indicate a successful remote login. 
 * Service_class can be used by cooperating sites to provide different access rights based on account rights and subscription plans. It is 
 * a string whose contents are not defined by protocol. Example: "basic" or "gold".
 *
 * @param[in,out] App &$a
 */
