<?php

namespace App\Core;

use Exception;

class Router
{
    private array $routes = [];
    private array $groupMiddleware = [];
    private string $groupPrefix = '';

    /**
     * Map a route.
     */
    public function addRoute(string $method, string $path, array|callable $callback, array $middleware = []): void
    {
        $prefix = '/' . trim($this->groupPrefix, '/');
        $prefix = $prefix === '/' ? '' : $prefix;
        
        $trimmedPath = '/' . trim($path, '/');
        $trimmedPath = $trimmedPath === '/' ? '' : $trimmedPath;
        
        $fullPath = $prefix . $trimmedPath;
        $fullPath = $fullPath === '' ? '/' : $fullPath;

        $this->routes[strtoupper($method)][] = [
            'path' => $fullPath,
            'callback' => $callback,
            'middleware' => array_merge($this->groupMiddleware, $middleware)
        ];
    }

    public function get(string $path, array|callable $callback, array $middleware = []): void
    {
        $this->addRoute('GET', $path, $callback, $middleware);
    }

    public function post(string $path, array|callable $callback, array $middleware = []): void
    {
        $this->addRoute('POST', $path, $callback, $middleware);
    }

    public function put(string $path, array|callable $callback, array $middleware = []): void
    {
        $this->addRoute('PUT', $path, $callback, $middleware);
    }

    public function delete(string $path, array|callable $callback, array $middleware = []): void
    {
        $this->addRoute('DELETE', $path, $callback, $middleware);
    }

    /**
     * Group routes under attributes like prefix and middleware.
     */
    public function group(array $attributes, callable $callback): void
    {
        $previousPrefix = $this->groupPrefix;
        $previousMiddleware = $this->groupMiddleware;

        if (isset($attributes['prefix'])) {
            $this->groupPrefix = $previousPrefix . '/' . trim($attributes['prefix'], '/');
        }

        if (isset($attributes['middleware'])) {
            $this->groupMiddleware = array_merge($previousMiddleware, (array)$attributes['middleware']);
        }

        $callback($this);

        $this->groupPrefix = $previousPrefix;
        $this->groupMiddleware = $previousMiddleware;
    }

    /**
     * Match path against configured routes.
     */
    public function resolve(Request $request): array
    {
        $method = $request->getMethod();
        $path = '/' . trim($request->getPath(), '/');

        $routes = $this->routes[$method] ?? [];

        foreach ($routes as $route) {
            $pattern = $this->compilePattern($route['path']);
            if (preg_match($pattern, $path, $matches)) {
                // Filter out non-string keys from named capture groups
                $params = array_filter($matches, 'is_string', ARRAY_FILTER_USE_KEY);
                return [
                    'callback' => $route['callback'],
                    'middleware' => $route['middleware'],
                    'params' => $params
                ];
            }
        }

        throw new Exception("Route not found", 404);
    }

    /**
     * Convert route notation {param} into regex capture groups.
     */
    private function compilePattern(string $path): string
    {
        $cleanPath = '/' . trim($path, '/');
        $cleanPath = $cleanPath === '/' ? '' : $cleanPath;
        
        $pattern = preg_replace('/\{([a-zA-Z0-9_]+)\}/', '(?P<$1>[^/]+)', $cleanPath);
        return '#^' . ($pattern === '' ? '/' : $pattern) . '$#';
    }
}