<?php
namespace Kant\Routing;

use Closure;

class MiddlewareNameResolver
{

    /**
     * Resolve the middleware name to a class name(s) preserving passed parameters.
     *
     * @param string $name            
     * @param array $map            
     * @param array $middlewareGroups            
     * @return string|array
     */
    public static function resolve($name, $map, $middlewareGroups)
    {
        // When the middleware is simply a Closure, we will return this Closure instance
        // directly so that Closures can be registered as middleware inline, which is
        // convenient on occasions when the developers are experimenting with them.
        if ($name instanceof Closure) {
            return $name;
        } elseif (isset($map[$name]) && $map[$name] instanceof Closure) {
            return $map[$name];
            
            // If the middleware is the name of a middleware group, we will return the array
            // of middlewares that belong to the group. This allows developers to group a
            // set of middleware under single keys that can be conveniently referenced.
        } elseif (isset($middlewareGroups[$name])) {
            return static::parseMiddlewareGroup($name, $map, $middlewareGroups);
            
            // Finally, when the middleware is simply a string mapped to a class name the
            // middleware name will get parsed into the full class name and parameters
            // which may be run using the Pipeline which accepts this string format.
        } else {
            list ($name, $parameters) = array_pad(explode(':', $name, 2), 2, null);
            
            return (isset($map[$name]) ? $map[$name] : $name) . (!is_null($parameters) ? ':' . $parameters : '');
        }
    }

    /**
     * Parse the middleware group and format it for usage.
     *
     * @param string $name            
     * @param array $map            
     * @param array $middlewareGroups            
     * @return array
     */
    protected static function parseMiddlewareGroup($name, $map, $middlewareGroups)
    {
        $results = [];
        
        foreach ($middlewareGroups[$name] as $middleware) {
            // If the middleware is another middleware group we will pull in the group and
            // merge its middleware into the results. This allows groups to conveniently
            // reference other groups without needing to repeat all their middlewares.
            if (isset($middlewareGroups[$middleware])) {
                $results = array_merge($results, static::parseMiddlewareGroup($middleware, $map, $middlewareGroups));
                
                continue;
            }
            
            list ($middleware, $parameters) = array_pad(explode(':', $middleware, 2), 2, null);
            
            // If this middleware is actually a route middleware, we will extract the full
            // class name out of the middleware list now. Then we'll add the parameters
            // back onto this class' name so the pipeline will properly extract them.
            if (isset($map[$middleware])) {
                $middleware = $map[$middleware];
            }
            
            $results[] = $middleware . ($parameters ? ':' . $parameters : '');
        }
        
        return $results;
    }
}
