Implement a minimal router using FastRoute.

This will be able to dispatch PSR-7-style requests to any callback
that returns a proper response object.

Largely based on my original work for FluxBB 2.0.

framework/core/src/Http/Router.php

@@ -0,0 +1,136 @@
+<?php
+
+namespace Flarum\Http;
+
+use FastRoute\Dispatcher;
+use FastRoute\RouteParser;
+use FastRoute\DataGenerator;
+use Psr\Http\Message\ServerRequestInterface as Request;
+
+class Router
+{
+    /**
+     * @var \FastRoute\DataGenerator
+     */
+    protected $dataGenerator;
+
+    /**
+     * @var \FastRoute\RouteParser
+     */
+    protected $routeParser;
+
+    /**
+     * @var string
+     */
+    protected $currentRequestName;
+
+    /**
+     * @var array
+     */
+    protected $currentRequestParameters;
+
+    /**
+     * @var array
+     */
+    protected $reverse = [];
+
+    /**
+     * @var \FastRoute\Dispatcher
+     */
+    protected $dispatcher;
+
+
+    public function __construct()
+    {
+        $this->routeParser = new RouteParser\Std;
+        $this->dataGenerator = new DataGenerator\GroupCountBased;
+    }
+
+    public function get($path, $name, $handler)
+    {
+        return $this->addRoute('GET', $path, $name, $handler);
+    }
+
+    public function post($path, $name, $handler)
+    {
+        return $this->addRoute('POST', $path, $name, $handler);
+    }
+
+    public function put($path, $name, $handler)
+    {
+        return $this->addRoute('PUT', $path, $name, $handler);
+    }
+
+    public function delete($path, $name, $handler)
+    {
+        return $this->addRoute('DELETE', $path, $name, $handler);
+    }
+
+    public function addRoute($method, $path, $name, $handler)
+    {
+        $routeData = $this->routeParser->parse($path);
+        $this->dataGenerator->addRoute($method, $routeData, $handler);
+
+        $routeDate['method'] = $method;
+        $this->reverse[$name] = $routeData;
+
+        return $this;
+    }
+
+    public function getPath($name, $parameters = [])
+    {
+        $parts = $this->reverse[$name];
+
+        $path = implode('', array_map(function ($part) use ($parameters) {
+            if (is_array($part)) {
+                $part = $parameters[$part[0]];
+            }
+            return $part;
+        }, $parts));
+
+        $path = '/' . ltrim($path, '/');
+        return $path;
+    }
+
+    public function getCurrentPath()
+    {
+        $name = $this->currentRequestName;
+        $parameters = $this->currentRequestParameters;
+
+        return $this->getPath($name, $parameters);
+    }
+
+    public function getMethod($handler)
+    {
+        return array_get($this->reverse, $handler . '.method', '');
+    }
+
+    public function dispatch(Request $request)
+    {
+        $method = $request->getMethod();
+        $uri = $request->getUri()->getPath();
+
+        $routeInfo = $this->getDispatcher()->dispatch($method, $uri);
+
+        switch ($routeInfo[0]) {
+            case Dispatcher::NOT_FOUND:
+                throw new \Exception('404 Not Found');
+            case Dispatcher::METHOD_NOT_ALLOWED:
+                throw new \Exception('405 Method Not Allowed');
+            case Dispatcher::FOUND:
+                $handler = $routeInfo[1];
+                $parameters = $routeInfo[2];
+
+                return $handler($request, $parameters);
+        }
+    }
+
+    protected function getDispatcher()
+    {
+        if (! isset($this->dispatcher)) {
+            $this->dispatcher = new Dispatcher\GroupCountBased($this->dataGenerator->getData());
+        }
+
+        return $this->dispatcher;
+    }
+}