<?php
// RpcRouteHandler.php
// Created: 2024-08-13
// Updated: 2024-08-13

namespace Aiwass;

use Exception;
use ReflectionFunction;
use ReflectionIntersectionType;
use ReflectionNamedType;
use ReflectionUnionType;
use Index\Http\{HttpResponseBuilder,HttpRequest};
use Index\Http\Content\FormContent;
use Index\Http\Routing\{HttpGet,HttpPost,RouteHandler};

/**
 * Provides a router implementation for an Aiwass RPC server.
 */
class RpcRouteHandler extends RouteHandler {
    /**
     * @param RpcServer $server An RPC server instance.
     */
    public function __construct(
        private RpcServer $server
    ) {}

    /**
     * Handles an action request.
     *
     * @param HttpResponseBuilder $response Response that it being built.
     * @param HttpRequest $request Request that is being handled.
     * @param string $action Name of the action specified in the URL.
     * @return int|array{error: string, message?: string}|mixed Response to the request.
     */
    #[HttpGet('/_aiwass/([A-Za-z0-9\-_\.:]+)')]
    #[HttpPost('/_aiwass/([A-Za-z0-9\-_\.:]+)')]
    public function handleAction(HttpResponseBuilder $response, HttpRequest $request, string $action) {
        if($action === '')
            return 404;

        if($request->getMethod() === 'POST') {
            $content = $request->getContent();
            if(!($content instanceof FormContent))
                return 400;

            $expectProcedure = true;
            $paramString = $content->getParamString();
            $params = $content->getParams();
        } elseif($request->getMethod() === 'GET') {
            $expectProcedure = false;
            $paramString = $request->getParamString();
            $params = $request->getParams();
        } else {
            $response->setHeader('Allow', 'GET, POST');
            return 405;
        }

        $response->setContentType('application/vnd.msgpack');

        $userToken = (string)$request->getHeaderLine('X-Aiwass-Verify');
        if($userToken === '') {
            $response->setStatusCode(403);
            return AiwassMsgPack::encode(['error' => 'aiwass:verify', 'message' => 'X-Aiwass-Verify header is missing.']);
        }

        $actInfo = $this->server->getActionInfo($action);
        if($actInfo === null) {
            $response->setStatusCode(404);
            return AiwassMsgPack::encode(['error' => 'aiwass:unknown', 'message' => 'No action with that name exists.']);
        }

        if($actInfo->isProcedure() !== $expectProcedure) {
            $response->setStatusCode(405);
            $response->setHeader('Allow', $actInfo->isProcedure() ? 'POST' : 'GET');
            return AiwassMsgPack::encode(['error' => 'aiwass:method', 'message' => 'This action cannot be called using this request method.']);
        }

        if(!$this->server->getVerificationProvider()->verify($userToken, $expectProcedure, $action, $paramString))
            return AiwassMsgPack::encode(['error' => 'aiwass:verify', 'message' => 'Request token verification failed.']);

        $handlerInfo = new ReflectionFunction($actInfo->getHandler());
        if($handlerInfo->isVariadic())
            return AiwassMsgPack::encode(['error' => 'aiwass:variadic', 'message' => 'Handler was declared as a variadic method and is thus impossible to be called.']);

        $handlerArgs = [];

        $handlerParams = $handlerInfo->getParameters();
        foreach($handlerParams as $paramInfo) {
            $paramName = $paramInfo->getName();
            if(!array_key_exists($paramName, $params)) {
                if($paramInfo->isOptional())
                    continue;

                if(!$paramInfo->allowsNull())
                    return AiwassMsgPack::encode(['error' => 'aiwass:param:required', 'message' => 'A required parameter is missing.', 'param' => $paramName]);
            }

            $handlerArgs[$paramName] = $params[$paramName] ?? null;
        }

        if(count($handlerArgs) !== count($params)) {
            $response->setStatusCode(400);
            return AiwassMsgPack::encode(['error' => 'aiwass:params', 'message' => 'Unsupported arguments were specified.']);
        }

        return AiwassMsgPack::encode($handlerInfo->invokeArgs($handlerArgs));
    }
}