<?php declare(strict_types=1);

namespace Sharkk\Router;

trait SegmentRouterTrait
{
    /**
     * Add a route to the route tree. The route must be a URI path, and contain dynamic segments
     * using a colon prefix. (:id, :slug, etc)
     *
     * Example:
     * `$r->add('GET', '/posts/:id', function($id) { echo "Viewing post $id"; });`
     */
    public static function add(array &$routes, string $method, string $route, callable $handler): void
    {
        // Recursively build the node tree
        self::addNode(
            $routes,
            array_map( // Expand the route into segments and make dynamic segments into a common placeholder
                fn($segment) => str_starts_with($segment, ':') ? ':x' : $segment,
                explode('/', trim($route, '/'))
            ),
            $method,
            $handler
        );
    }

    private static function addNode(array &$node, array $segments, string $method, callable $handler): void
    {
        // Base case: if no more segments, add the handler
        if (empty($segments)) {
            $node[$method] = $handler;
            return;
        }

        // Get the current segment
        $segment = array_shift($segments);

        // Skip empty segments
        if ($segment === '') {
            self::addNode($node, $segments, $method, $handler);
            return;
        }

        // Ensure the segment exists in the node
        if (!isset($node[$segment])) {
            $node[$segment] = [];
        }

        // Recur for the next segment
        self::addNode($node[$segment], $segments, $method, $handler);
    }

    /**
     * Perform a lookup in the route tree for a given method and URI. Returns an array with a result code,
     * a handler if found, and any dynamic parameters. Codes are 200 for success, 404 for not found, and
     * 405 for method not allowed.
     *
     * @return array ['code', 'handler', 'params']
     */
    public static function lookup(array &$routes, string $method, string $uri): array
    {
        // node is a reference to our current location in the node tree
        $node = $routes;

        if ($uri === '/' && isset($node[$method]) && array_key_exists($method, $node)) {
            return ['code' => 200, 'handler' => $node[$method], 'params' => null];
        }

        // params will hold any dynamic segments we find
        $params = [];
        foreach (explode('/', trim($uri, '/')) as $segment) {
            if (isset($node[$segment])) {
                $node = $node[$segment];
            } elseif (isset($node[':x'])) {
                $params[] = $segment;
                $node = $node[':x'];
            } else {
                return ['code' => 404, 'handler' => null, 'params' => []];
            }
        }

        // if we found a handler for the method, return it and any params. if not, return a 405
        if (array_key_exists($method, $node)) {
            return ['code' => 200, 'handler' => $node[$method], 'params' => $params];
        }

        return ['code' => 405, 'handler' => null, 'params' => []];
    }

    /**
     * Clear all routes from the router.
     */
    public static function clear(array &$routes): void
    {
        $routes = [];
    }

    /**
     * Dump the route tree as an array.
     */
    /*public static function dump(array &$routes): array
    {
        return $routes;
    }*/

    /**
     * Register a GET route.
     */
    public static function get(array &$routes, string $route, callable $handler): void
    {
        self::add($routes, 'GET', $route, $handler);
    }

    /**
     * Register a POST route.
     */
    public static function post(array &$routes, string $route, callable $handler): void
    {
        self::add($routes, 'POST', $route, $handler);
    }

    /**
     * Register a PUT route.
     */
    public static function put(array &$routes, string $route, callable $handler): void
    {
        self::add($routes, 'PUT', $route, $handler);
    }

    /**
     * Register a PATCH route.
     */
    public static function patch(array &$routes, string $route, callable $handler): void
    {
        self::add($routes, 'PATCH', $route, $handler);
    }

    /**
     * Register a DELETE route.
     */
    public static function delete(array &$routes, string $route, callable $handler): void
    {
        self::add($routes, 'DELETE', $route, $handler);
    }

    /**
     * Register a HEAD route.
     */
    public static function head(array &$routes, string $route, callable $handler): void
    {
        self::add($routes, 'HEAD', $route, $handler);
    }
}