<?php

/**
 * @file classes/core/PKPRouter.inc.php
 *
 * Copyright (c) 2014-2020 Simon Fraser University
 * Copyright (c) 2000-2020 John Willinsky
 * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
 *
 * @class PKPRouter
 * @see PKPPageRouter
 * @see PKPComponentRouter
 * @ingroup core
 *
 * @brief Basic router class that has functionality common to all routers.
 *
 * NB: All handlers provide the common basic workflow. The router
 * calls the following methods in the given order.
 * 1) constructor:
 *       Handlers should establish a mapping of remote
 *       operations to roles that may access them. They do
 *       so by calling PKPHandler::addRoleAssignment().
 * 2) authorize():
 *       Authorizes the request, among other things based
 *       on the result of the role assignment created
 *       during object instantiation. If authorization fails
 *       then die with a fatal error or execute the "call-
 *       on-deny" advice if one has been defined in the
 *       authorization policy that denied access.
 * 3) validate():
 *       Let the handler execute non-fatal data integrity
 *       checks (FIXME: currently only for component handlers).
 *       Please make sure that data integrity checks that can
 *       lead to denial of access are being executed in the
 *       authorize() step via authorization policies and not
 *       here.
 * 4) initialize():
 *       Let the handler initialize its internal state based
 *       on authorized and valid data. Authorization and integrity
 *       checks should be kept out of here to get a clear separation
 *       of concerns.
 * 5) execution:
 *       Executes the requested handler operation. The mapping
 *       of requests to operations depends on the router
 *       implementation (see the class doc of specific router
 *       implementations for more details).
 * 6) client response:
 *       Handlers should return a string value that will then be
 *       returned to the client as a response. Handler operations
 *       should not output the response directly to the client so
 *       that we can run filter operations on the output if required.
 *       Outputting text from handler operations to the client
 *       is possible but deprecated.
 */


class PKPRouter {
	//
	// Internal state cache variables
	// NB: Please do not access directly but
	// only via their respective getters/setters
	//
	/** @var PKPApplication */
	var $_application;
	/** @var Dispatcher */
	var $_dispatcher;
	/** @var integer context depth */
	var $_contextDepth;
	/** @var integer context list */
	var $_contextList;
	/** @var integer context list with keys and values flipped */
	var $_flippedContextList;
	/** @var integer context paths */
	var $_contextPaths = array();
	/** @var integer contexts */
	var $_contexts = array();
	/** @var PKPHandler Handler class */
	var $_handler;

	/**
	 * Constructor
	 */
	function __construct() {
	}

	/**
	 * get the application
	 * @return PKPApplication
	 */
	function &getApplication() {
		assert(is_a($this->_application, 'PKPApplication'));
		return $this->_application;
	}

	/**
	 * set the application
	 * @param $application PKPApplication
	 */
	function setApplication($application) {
		$this->_application = $application;

		// Retrieve context depth and list
		$this->_contextDepth = $application->getContextDepth();
		$this->_contextList = $application->getContextList();
		$this->_flippedContextList = array_flip($this->_contextList);
	}

	/**
	 * get the dispatcher
	 * @return Dispatcher
	 */
	function &getDispatcher() {
		assert(is_a($this->_dispatcher, 'Dispatcher'));
		return $this->_dispatcher;
	}

	/**
	 * set the dispatcher
	 * @param $dispatcher PKPDispatcher
	 */
	function setDispatcher($dispatcher) {
		$this->_dispatcher = $dispatcher;
	}

	/**
	 * Set the handler object for later retrieval.
	 * @param $handler PKPHandler
	 */
	function setHandler($handler) {
		$this->_handler = $handler;
	}

	/**
	 * Get the handler object.
	 * @return PKPHandler
	 */
	function getHandler() {
		return $this->_handler;
	}

	/**
	 * Determines whether this router can route the given request.
	 * @param $request PKPRequest
	 * @return boolean true, if the router supports this request, otherwise false
	 */
	function supports($request) {
		// Default implementation returns always true
		return true;
	}

	/**
	 * Determine whether or not this request is cacheable
	 * @param $request PKPRequest
	 * @return boolean
	 */
	function isCacheable($request) {
		// Default implementation returns always false
		return false;
	}

	/**
	 * A generic method to return an array of context paths (e.g. a Press or a Conference/SchedConf paths)
	 * @param $request PKPRequest the request to be routed
	 * @param $requestedContextLevel int (optional) the context level to return in the path
	 * @return array of string (each element the path to one context element)
	 */
	function getRequestedContextPaths($request) {
		// Handle context depth 0
		if (!$this->_contextDepth) return array();

		// Validate context parameters
		assert(isset($this->_contextDepth) && isset($this->_contextList));

		$isPathInfoEnabled = $request->isPathInfoEnabled();
		$userVars = array();
		$url = null;

		// Determine the context path
		if (empty($this->_contextPaths)) {
			if ($isPathInfoEnabled) {
				// Retrieve url from the path info
				if (isset($_SERVER['PATH_INFO'])) {
					$url = $_SERVER['PATH_INFO'];
				}
			} else {
				$url = $request->getCompleteUrl();
				$userVars = $request->getUserVars();
			}

			$this->_contextPaths = Core::getContextPaths($url, $isPathInfoEnabled,
				$this->_contextList, $this->_contextDepth, $userVars);

			HookRegistry::call('Router::getRequestedContextPaths', array(&$this->_contextPaths));
		}

		return $this->_contextPaths;
	}

	/**
	 * A generic method to return a single context path (e.g. a Press or a SchedConf path)
	 * @param $request PKPRequest the request to be routed
	 * @param $requestedContextLevel int (optional) the context level to return
	 * @return string
	 */
	function getRequestedContextPath($request, $requestedContextLevel = 1) {
		// Handle context depth 0
		if (!$this->_contextDepth) return null;

		// Validate the context level
		assert(isset($this->_contextDepth) && isset($this->_contextList));
		assert($requestedContextLevel > 0 && $requestedContextLevel <= $this->_contextDepth);

		// Return the full context, then retrieve the requested context path
		$contextPaths = $this->getRequestedContextPaths($request);
		assert(isset($this->_contextPaths[$requestedContextLevel - 1]));
		return $this->_contextPaths[$requestedContextLevel - 1];
	}

	/**
	 * A Generic call to a context defining object (e.g. a Press, a Conference, or a SchedConf)
	 * @param $request PKPRequest the request to be routed
	 * @param $requestedContextLevel int (optional) the desired context level
	 * @param $forceReload boolean (optional) Reset a context even if it's already been loaded
	 * @return object
	 */
	function &getContext($request, $requestedContextLevel = 1, $forceReload = false) {
		// Handle context depth 0
		if (!$this->_contextDepth) {
			$nullVar = null;
			return $nullVar;
		}

		if ($forceReload || !isset($this->_contexts[$requestedContextLevel])) {
			// Retrieve the requested context path (this validates the context level and the path)
			$path = $this->getRequestedContextPath($request, $requestedContextLevel);

			// Resolve the path to the context
			if ($path == 'index') {
				$this->_contexts[$requestedContextLevel] = null;
			} else {
				// Get the context name (this validates the context name)
				$requestedContextName = $this->_contextLevelToContextName($requestedContextLevel);

				// Get the DAO for the requested context.
				$contextClass = ucfirst($requestedContextName);
				$daoName = $contextClass.'DAO';
				$daoInstance = DAORegistry::getDAO($daoName);

				// Retrieve the context from the DAO (by path)
				$daoMethod = 'getByPath';
				assert(method_exists($daoInstance, $daoMethod));
				$this->_contexts[$requestedContextLevel] = $daoInstance->$daoMethod($path);
			}
		}

		return $this->_contexts[$requestedContextLevel];
	}

	/**
	 * Get the object that represents the desired context (e.g. Conference or Press)
	 * @param $request PKPRequest the request to be routed
	 * @param $requestedContextName string page context
	 * @return object
	 */
	function &getContextByName($request, $requestedContextName) {
		// Handle context depth 0
		if (!$this->_contextDepth) {
			$nullVar = null;
			return $nullVar;
		}

		// Convert the context name to a context level (this validates the context name)
		$requestedContextLevel = $this->_contextNameToContextLevel($requestedContextName);

		// Retrieve the requested context by level
		$returner = $this->getContext($request, $requestedContextLevel);
		return $returner;
	}

	/**
	 * Get the URL to the index script.
	 * @param $request PKPRequest the request to be routed
	 * @return string
	 */
	function getIndexUrl($request) {
		if (!isset($this->_indexUrl)) {
			if ($request->isRestfulUrlsEnabled()) {
				$this->_indexUrl = $request->getBaseUrl();
			} else {
				$this->_indexUrl = $request->getBaseUrl() . '/index.php';
			}
			HookRegistry::call('Router::getIndexUrl', array(&$this->_indexUrl));
		}

		return $this->_indexUrl;
	}


	//
	// Protected template methods to be implemented by sub-classes.
	//
	/**
	 * Determine the filename to use for a local cache file.
	 * @param $request PKPRequest
	 * @return string
	 */
	function getCacheFilename($request) {
		// must be implemented by sub-classes
		assert(false);
	}

	/**
	 * Routes a given request to a handler operation
	 * @param $request PKPRequest
	 */
	function route($request) {
		// Must be implemented by sub-classes.
		assert(false);
	}

	/**
	 * Build a handler request URL into PKPApplication.
	 * @param $request PKPRequest the request to be routed
	 * @param $newContext mixed Optional contextual paths
	 * @param $handler string Optional name of the handler to invoke
	 * @param $op string Optional name of operation to invoke
	 * @param $path mixed Optional string or array of args to pass to handler
	 * @param $params array Optional set of name => value pairs to pass as user parameters
	 * @param $anchor string Optional name of anchor to add to URL
	 * @param $escape boolean Whether or not to escape ampersands, square brackets, etc. for this URL; default false.
	 * @return string the URL
	 */
	function url($request, $newContext = null, $handler = null, $op = null, $path = null,
				$params = null, $anchor = null, $escape = false) {
		// Must be implemented by sub-classes.
		assert(false);
	}

	/**
	 * Handle an authorization failure.
	 * @param $request Request
	 * @param $authorizationMessage string a translation key with the authorization
	 *  failure message.
	 */
	function handleAuthorizationFailure($request, $authorizationMessage) {
		// Must be implemented by sub-classes.
		assert(false);
	}


	//
	// Private helper methods
	//
	/**
	 * This is the method that implements the basic
	 * life-cycle of a handler request:
	 * 1) authorization
	 * 2) validation
	 * 3) initialization
	 * 4) execution
	 * 5) client response
	 *
	 * @param $serviceEndpoint callable the handler operation
	 * @param $request PKPRequest
	 * @param $args array
	 * @param $validate boolean whether or not to execute the
	 *  validation step.
	 */
	function _authorizeInitializeAndCallRequest(&$serviceEndpoint, $request, &$args, $validate = true) {
		$dispatcher = $this->getDispatcher();

		// It's conceivable that a call has gotten this far without
		// actually being callable, e.g. a component has been named
		// that does not exist and that no plugin has registered.
		if (!is_callable($serviceEndpoint)) $dispatcher->handle404();

		// Pass the dispatcher to the handler.
		$serviceEndpoint[0]->setDispatcher($dispatcher);

		// Authorize the request.
		$roleAssignments = $serviceEndpoint[0]->getRoleAssignments();
		assert(is_array($roleAssignments));
		if ($serviceEndpoint[0]->authorize($request, $args, $roleAssignments)) {
			// Execute class-wide data integrity checks.
			if ($validate) $serviceEndpoint[0]->validate($request, $args);

			// Let the handler initialize itself.
			$serviceEndpoint[0]->initialize($request, $args);

			// Call the service endpoint.
			$result = call_user_func($serviceEndpoint, $args, $request);
		} else {
			// Authorization failed - try to retrieve a user
			// message.
			$authorizationMessage = $serviceEndpoint[0]->getLastAuthorizationMessage();

			// Set a generic authorization message if no
			// specific authorization message was set.
			if ($authorizationMessage == '') $authorizationMessage = 'user.authorization.accessDenied';

			// Handle the authorization failure.
			$result = $this->handleAuthorizationFailure($request, $authorizationMessage);
		}

		// Return the result of the operation to the client.
		if (is_string($result)) echo $result;
		elseif (is_a($result, 'JSONMessage')) {
			header('Content-Type: application/json');
			echo $result->getString();
		}
	}

	/**
	 * Canonicalizes the new context.
	 *
	 * A new context can be given as a scalar. In this case only the
	 * first context will be replaced. If the context depth of the
	 * current application is higher than one than the context can also
	 * be given as an array if more than the first context should
	 * be replaced. We therefore canonicalize the new context to an array.
	 *
	 * When all entries are of the form 'contextName' => null or if
	 * $newContext == null then we'll return an empty array.
	 *
	 * @param $newContext the raw context array
	 * @return array the canonicalized context array
	 */
	function _urlCanonicalizeNewContext($newContext) {
		// Create an empty array in case no new context was given.
		if (is_null($newContext)) $newContext = array();

		// If we got the new context as a scalar then transform
		// it into an array.
		if (is_scalar($newContext)) $newContext = array($newContext);

		// Check whether any new context has been provided.
		// If not then return an empty array.
		$newContextProvided = false;
		foreach($newContext as $contextElement) {
			if(isset($contextElement)) $newContextProvided = true;
		}
		if (!$newContextProvided) $newContext = array();

		return $newContext;
	}

	/**
	 * Build the base URL and add the context part of the URL.
	 *
	 * The new URL will be based on the current request's context
	 * if no new context is given.
	 *
	 * The base URL for a given primary context can be overridden
	 * in the config file using the 'base_url[context]' syntax in the
	 * config file's 'general' section.
	 *
	 * @param $request PKPRequest the request to be routed
	 * @param $newContext mixed (optional) context that differs from
	 *  the current request's context
	 * @return array An array consisting of the base url as the first
	 *  entry and the context as the remaining entries.
	 */
	function _urlGetBaseAndContext($request, $newContext = array()) {
		$pathInfoEnabled = $request->isPathInfoEnabled();

		// Retrieve the context list.
		$contextList = $this->_contextList;

		$baseUrlConfigSuffix = '';
		$overriddenContextCount = 0;

		// Determine URL context
		$context = array();
		foreach ($contextList as $contextKey => $contextName) {
			if ($pathInfoEnabled) {
				$contextParameter = '';
			} else {
				$contextParameter = $contextName.'=';
			}

			$newContextValue = array_shift($newContext);
			if (isset($newContextValue)) {
				// A new context has been set so use it.
				$contextValue = rawurlencode($newContextValue);
			} else {
				// No new context has been set so determine
				// the current request's context
				$contextObject = $this->getContextByName($request, $contextName);
				if ($contextObject) $contextValue = $contextObject->getPath();
				else $contextValue = 'index';
			}

			// Check whether the base URL is overridden.
			$baseUrlConfigSuffix .= "[$contextValue]";
			$newOverriddenBaseUrl = Config::getVar('general', 'base_url' . $baseUrlConfigSuffix);
			if (!empty($newOverriddenBaseUrl)) {
				$overriddenContextCount = $contextKey + 1;
				$overriddenBaseUrl = $newOverriddenBaseUrl;
			}

			$context[] = $contextParameter.$contextValue;
		}

		// Generate the base url
		if (!empty($overriddenBaseUrl)) {
			$baseUrl = $overriddenBaseUrl;

			// Throw the overridden context(s) away
			while ($overriddenContextCount>0) {
				array_shift($context);
				$overriddenContextCount--;
			}
		} else {
			$baseUrl = $this->getIndexUrl($request);
		}

		// Join base URL and context and return the result
		$baseUrlAndContext = array_merge(array($baseUrl), $context);
		return $baseUrlAndContext;
	}

	/**
	 * Build the additional parameters part of the URL.
	 * @param $request PKPRequest the request to be routed
	 * @param $params array (optional) the parameter list to be
	 *  transformed to a url part.
	 * @param $escape boolean (optional) Whether or not to escape structural elements
	 * @return array the encoded parameters or an empty array
	 *  if no parameters were given.
	 */
	function _urlGetAdditionalParameters($request, $params = null, $escape = true) {
		$additionalParameters = array();
		if (!empty($params)) {
			assert(is_array($params));
			foreach ($params as $key => $value) {
				if (is_array($value)) {
					foreach($value as $element) {
						$additionalParameters[] = $key.($escape?'%5B%5D=':'[]=').rawurlencode($element);
					}
				} else {
					$additionalParameters[] = $key.'='.rawurlencode($value);
				}
			}
		}

		return $additionalParameters;
	}

	/**
	 * Creates a valid URL from parts.
	 * @param $baseUrl string the protocol, domain and initial path/parameters, no anchors allowed here
	 * @param $pathInfoArray array strings to be concatenated as path info
	 * @param $queryParametersArray array strings to be concatenated as query string
	 * @param $anchor string an additional anchor
	 * @param $escape boolean whether to escape ampersands
	 * @return string the URL
	 */
	function _urlFromParts($baseUrl, $pathInfoArray = array(), $queryParametersArray = array(), $anchor = '', $escape = false) {
		// parse_url does not support protocol relative URLs;
		// work around it here (https://bugs.php.net/bug.php?id=66274)
		if (strpos($baseUrl,'//')===0) {
			$baseUrl = 'http:' . $baseUrl;
			$protocolRelativeWorkaround = true;
		} else {
			$protocolRelativeWorkaround = false;
		}

		// Parse the base url
		$baseUrlParts = parse_url($baseUrl);
		assert(isset($baseUrlParts['scheme']) && isset($baseUrlParts['host']) && !isset($baseUrlParts['fragment']));

		// Reconstruct the base url without path and query
		// (supporting the work-around for protocol relative URLs)
		$baseUrl = $protocolRelativeWorkaround?'//':($baseUrlParts['scheme'].'://');
		if (isset($baseUrlParts['user'])) {
			$baseUrl .= $baseUrlParts['user'];
			if (isset($baseUrlParts['pass'])) {
				$baseUrl .= ':'.$baseUrlParts['pass'];
			}
			$baseUrl .= '@';
		}
		$baseUrl .= $baseUrlParts['host'];
		if (isset($baseUrlParts['port'])) $baseUrl .= ':'.$baseUrlParts['port'];
		$baseUrl .= '/';

		// Add path info from the base URL
		// to the path info array (if any).
		if (isset($baseUrlParts['path'])) {
			$pathInfoArray = array_merge(explode('/', trim($baseUrlParts['path'], '/')), $pathInfoArray);
		}

		// Add query parameters from the base URL
		// to the query parameter array (if any).
		if (isset($baseUrlParts['query'])) {
			$queryParametersArray = array_merge(explode('&', $baseUrlParts['query']), $queryParametersArray);
		}

		// Expand path info
		$pathInfo = implode('/', $pathInfoArray);

		// Expand query parameters
		$amp = ($escape ? '&amp;' : '&');
		$queryParameters = implode($amp, $queryParametersArray);
		$queryParameters = (empty($queryParameters) ? '' : '?'.$queryParameters);

		// Assemble and return the final URL
		return $baseUrl.$pathInfo.$queryParameters.$anchor;
	}

	/**
	 * Convert a context level to its corresponding context name.
	 * @param $contextLevel integer
	 * @return string context name
	 */
	function _contextLevelToContextName($contextLevel) {
		assert(isset($this->_contextList[$contextLevel - 1]));
		return $this->_contextList[$contextLevel - 1];
	}

	/**
	 * Convert a context name to its corresponding context level.
	 * @param $contextName string
	 * @return integer context level
	 */
	function _contextNameToContextLevel($contextName) {
		assert(isset($this->_flippedContextList[$contextName]));
		return $this->_flippedContextList[$contextName] + 1;
	}
}
