<?php

namespace Twilio\Jwt;

use Twilio\Jwt\Client\ScopeURI;

/**
 * Twilio Capability Token generator
 */
class ClientToken
{
    public $accountSid;
    public $authToken;
    /** @var ScopeURI[] $scopes */
    public $scopes;

    /**
     * Create a new TwilioCapability with zero permissions. Next steps are to
     * grant access to resources by configuring this token through the
     * functions allowXXXX.
     *
     * @param string $accountSid the account sid to which this token is granted
     *                           access
     * @param string $authToken  the secret key used to sign the token. Note,
     *                           this auth token is not visible to the user of the token.
     */
    public function __construct($accountSid, $authToken)
    {
        $this->accountSid = $accountSid;
        $this->authToken = $authToken;
        $this->scopes = array();
        $this->clientName = false;
    }

    /**
     * If the user of this token should be allowed to accept incoming
     * connections then configure the TwilioCapability through this method and
     * specify the client name.
     *
     * @param $clientName
     *
     * @throws \InvalidArgumentException
     */
    public function allowClientIncoming($clientName)
    {

        // clientName must be a non-zero length alphanumeric string
        if (preg_match('/\W/', $clientName)) {
            throw new \InvalidArgumentException(
                'Only alphanumeric characters allowed in client name.');
        }

        if (strlen($clientName) == 0) {
            throw new \InvalidArgumentException(
                'Client name must not be a zero length string.');
        }

        $this->clientName = $clientName;
        $this->allow('client', 'incoming',
            array('clientName' => $clientName));
    }

    /**
     * Allow the user of this token to make outgoing connections.
     *
     * @param string  $appSid    the application to which this token grants access
     * @param mixed[] $appParams signed parameters that the user of this token
     *                           cannot overwrite.
     */
    public function allowClientOutgoing($appSid, array $appParams = array())
    {
        $this->allow('client', 'outgoing', array(
            'appSid'    => $appSid,
            'appParams' => http_build_query($appParams, '', '&'),
        ));
    }

    /**
     * Allow the user of this token to access their event stream.
     *
     * @param mixed[] $filters key/value filters to apply to the event stream
     */
    public function allowEventStream(array $filters = array())
    {
        $this->allow('stream', 'subscribe', array(
            'path'   => '/2010-04-01/Events',
            'params' => http_build_query($filters, '', '&'),
        ));
    }

    /**
     * Generates a new token based on the credentials and permissions that
     * previously has been granted to this token.
     *
     * @param int $ttl the expiration time of the token (in seconds). Default
     *                 value is 3600 (1hr)
     *
     * @return ClientToken the newly generated token that is valid for $ttl
     *         seconds
     */
    public function generateToken($ttl = 3600)
    {
        $payload = array(
            'scope' => array(),
            'iss'   => $this->accountSid,
            'exp'   => time() + $ttl,
        );
        $scopeStrings = array();

        foreach ($this->scopes as $scope) {
            if ($scope->privilege == "outgoing" && $this->clientName) {
                $scope->params["clientName"] = $this->clientName;
            }
            $scopeStrings[] = $scope->toString();
        }

        $payload['scope'] = implode(' ', $scopeStrings);
        return JWT::encode($payload, $this->authToken, 'HS256');
    }

    protected function allow($service, $privilege, $params)
    {
        $this->scopes[] = new ScopeURI($service, $privilege, $params);
    }
}