<?php

namespace Wpcb2\Http;


class Router {

    /**
     * @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)
     */
    private 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";
    }
}
