<?php

class AltoRouter {

	/**
	 * @var array Array of all routes (incl. named routes).
	 */
	protected $routes = array();

	/**
	 * @var array Array of all named routes.
	 */
	protected $namedRoutes = array();

	/**
	 * @var string Can be used to ignore leading part of the Request URL (if main file lives in subdirectory of host)
	 */
	protected $basePath = '';

	/**
	 * @var array Array of default match types (regex helpers)
	 */
	protected $matchTypes = array(
		'i'  => '[0-9]++',
		'a'  => '[0-9A-Za-z]++',
		'h'  => '[0-9A-Fa-f]++',
		'*'  => '.+?',
		'**' => '.++',
		''   => '[^/\.]++'
	);

	/**
	  * Create router in one call from config.
	  *
	  * @param array $routes
	  * @param string $basePath
	  * @param array $matchTypes
	  */
	public function __construct( $routes = array(), $basePath = '', $matchTypes = array() ) {
		$this->addRoutes($routes);
		$this->setBasePath($basePath);
		$this->addMatchTypes($matchTypes);
	}
	
	/**
	 * Retrieves all routes.
	 * Useful if you want to process or display routes.
	 * @return array All routes.
	 */
	public function getRoutes() {
		return $this->routes;
	}

	/**
	 * Add multiple routes at once from array in the following format:
	 *
	 *   $routes = array(
	 *      array($method, $route, $target, $name)
	 *   );
	 *
	 * @param array $routes
	 * @return void
	 * @author Koen Punt
	 * @throws Exception
	 */
	public function addRoutes($routes){
		if(!is_array($routes) && !$routes instanceof Traversable) {
			throw new \Exception('Routes should be an array or an instance of Traversable');
		}
		foreach($routes as $route) {
			call_user_func_array(array($this, 'map'), $route);
		}
	}

	/**
	 * Set the base path.
	 * Useful if you are running your application from a subdirectory.
	 */
	public function setBasePath($basePath) {
		$this->basePath = $basePath;
	}

	/**
	 * Add named match types. It uses array_merge so keys can be overwritten.
	 *
	 * @param array $matchTypes The key is the name and the value is the regex.
	 */
	public function addMatchTypes($matchTypes) {
		$this->matchTypes = array_merge($this->matchTypes, $matchTypes);
	}

	/**
	 * Map a route to a target
	 *
	 * @param string $method One of 5 HTTP Methods, or a pipe-separated list of multiple HTTP Methods (GET|POST|PATCH|PUT|DELETE)
	 * @param string $route The route regex, custom regex must start with an @. You can use multiple pre-set regex filters, like [i:id]
	 * @param mixed $target The target where this route should point to. Can be anything.
	 * @param string $name Optional name of this route. Supply if you want to reverse route this url in your application.
	 * @throws Exception
	 */
	public function map($method, $route, $target, $name = null) {

		$this->routes[] = array($method, $route, $target, $name);

		if($name) {
			if(isset($this->namedRoutes[$name])) {
				throw new \Exception("Can not redeclare route '{$name}'");
			} else {
				$this->namedRoutes[$name] = $route;
			}

		}

		return;
	}

	/**
	 * Reversed routing
	 *
	 * Generate the URL for a named route. Replace regexes with supplied parameters
	 *
	 * @param string $routeName The name of the route.
	 * @param array @params Associative array of parameters to replace placeholders with.
	 * @return string The URL of the route with named parameters in place.
	 * @throws Exception
	 */
	public function generate($routeName, array $params = array()) {

		// Check if named route exists
		if(!isset($this->namedRoutes[$routeName])) {
			throw new \Exception("Route '{$routeName}' does not exist.");
		}

		// Replace named parameters
		$route = $this->namedRoutes[$routeName];
		
		// prepend base path to route url again
		$url = $this->basePath . $route;

		if (preg_match_all('`(/|\.|)\[([^:\]]*+)(?::([^:\]]*+))?\](\?|)`', $route, $matches, PREG_SET_ORDER)) {

			foreach($matches as $index => $match) {
				list($block, $pre, $type, $param, $optional) = $match;

				if ($pre) {
					$block = substr($block, 1);
				}

				if(isset($params[$param])) {
					// Part is found, replace for param value
					$url = str_replace($block, $params[$param], $url);
				} elseif ($optional && $index !== 0) {
					// Only strip preceeding slash if it's not at the base
					$url = str_replace($pre . $block, '', $url);
				} else {
					// Strip match block
					$url = str_replace($block, '', $url);
				}
			}

		}

		return $url;
	}

	/**
	 * Match a given Request Url against stored routes
	 * @param string $requestUrl
	 * @param string $requestMethod
	 * @return array|boolean Array with route information on success, false on failure (no match).
	 */
	public function match($requestUrl = null, $requestMethod = null) {

		$params = array();
		$match = false;

		// set Request Url if it isn't passed as parameter
		if($requestUrl === null) {
			$requestUrl = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '/';
		}

		// strip base path from request url
		$requestUrl = substr($requestUrl, strlen($this->basePath));

		// Strip query string (?a=b) from Request Url
		if (($strpos = strpos($requestUrl, '?')) !== false) {
			$requestUrl = substr($requestUrl, 0, $strpos);
		}

		// set Request Method if it isn't passed as a parameter
		if($requestMethod === null) {
			$requestMethod = isset($_SERVER['REQUEST_METHOD']) ? $_SERVER['REQUEST_METHOD'] : 'GET';
		}

		foreach($this->routes as $handler) {
			list($methods, $route, $target, $name) = $handler;

			$method_match = (stripos($methods, $requestMethod) !== false);

			// Method did not match, continue to next route.
			if (!$method_match) continue;

			if ($route === '*') {
				// * wildcard (matches all)
				$match = true;
			} elseif (isset($route[0]) && $route[0] === '@') {
				// @ regex delimiter
				$pattern = '`' . substr($route, 1) . '`u';
				$match = preg_match($pattern, $requestUrl, $params) === 1;
			} elseif (($position = strpos($route, '[')) === false) {
				// No params in url, do string comparison
				$match = strcmp($requestUrl, $route) === 0;
			} else {
				// Compare longest non-param string with url
				if (strncmp($requestUrl, $route, $position) !== 0) {
					continue;
				}
				$regex = $this->compileRoute($route);
				$match = preg_match($regex, $requestUrl, $params) === 1;
			}

			if ($match) {

				if ($params) {
					foreach($params as $key => $value) {
						if(is_numeric($key)) unset($params[$key]);
					}
				}

				return array(
					'target' => $target,
					'params' => $params,
					'name' => $name
				);
			}
		}
		return false;
	}

	/**
	 * Compile the regex for a given route (EXPENSIVE)
	 */
	protected function compileRoute($route) {
		if (preg_match_all('`(/|\.|)\[([^:\]]*+)(?::([^:\]]*+))?\](\?|)`', $route, $matches, PREG_SET_ORDER)) {

			$matchTypes = $this->matchTypes;
			foreach($matches as $match) {
				list($block, $pre, $type, $param, $optional) = $match;

				if (isset($matchTypes[$type])) {
					$type = $matchTypes[$type];
				}
				if ($pre === '.') {
					$pre = '\.';
				}

				$optional = $optional !== '' ? '?' : null;
				
				//Older versions of PCRE require the 'P' in (?P<named>)
				$pattern = '(?:'
						. ($pre !== '' ? $pre : null)
						. '('
						. ($param !== '' ? "?P<$param>" : null)
						. $type
						. ')'
						. $optional
						. ')'
						. $optional;

				$route = str_replace($block, $pattern, $route);
			}

		}
		return "`^$route$`u";
	}
}
