Auth_OpenID_CheckIDRequest::answer PHP Method

    function answer($allow, $server_url = null, $identity = null, $claimed_id = null)
    {
        if (!$this->return_to) {
            return new Auth_OpenID_NoReturnToError();
        }
        if (!$server_url) {
            if (!$this->message->isOpenID1() && !$this->server->op_endpoint) {
                return new Auth_OpenID_ServerError(null, "server should be constructed with op_endpoint to " . "respond to OpenID 2.0 messages.");
            }
            $server_url = $this->server->op_endpoint;
        }
        if ($allow) {
            $mode = 'id_res';
        } else {
            if ($this->message->isOpenID1()) {
                if ($this->immediate) {
                    $mode = 'id_res';
                } else {
                    $mode = 'cancel';
                }
            } else {
                if ($this->immediate) {
                    $mode = 'setup_needed';
                } else {
                    $mode = 'cancel';
                }
            }
        }
        if (!$this->trustRootValid()) {
            return new Auth_OpenID_UntrustedReturnURL(null, $this->return_to, $this->trust_root);
        }
        $response = new Auth_OpenID_ServerResponse($this);
        if ($claimed_id && $this->message->isOpenID1()) {
            return new Auth_OpenID_ServerError(null, "claimed_id is new in OpenID 2.0 and not " . "available for " . $this->namespace);
        }
        if ($identity && !$claimed_id) {
            $claimed_id = $identity;
        }
        if ($allow) {
            if ($this->identity == Auth_OpenID_IDENTIFIER_SELECT) {
                if (!$identity) {
                    return new Auth_OpenID_ServerError(null, "This request uses IdP-driven identifier selection.  " . "You must supply an identifier in the response.");
                }
                $response_identity = $identity;
                $response_claimed_id = $claimed_id;
            } else {
                if ($this->identity) {
                    if ($identity && $this->identity != $identity) {
                        $fmt = "Request was for %s, cannot reply with identity %s";
                        return new Auth_OpenID_ServerError(null, sprintf($fmt, $this->identity, $identity));
                    }
                    $response_identity = $this->identity;
                    $response_claimed_id = $this->claimed_id;
                } else {
                    if ($identity) {
                        return new Auth_OpenID_ServerError(null, "This request specified no identity and " . "you supplied " . $identity);
                    }
                    $response_identity = null;
                }
            }
            if ($this->message->isOpenID1() && $response_identity === null) {
                return new Auth_OpenID_ServerError(null, "Request was an OpenID 1 request, so response must " . "include an identifier.");
            }
            $response->fields->updateArgs(Auth_OpenID_OPENID_NS, array('mode' => $mode, 'return_to' => $this->return_to, 'response_nonce' => Auth_OpenID_mkNonce()));
            if (!$this->message->isOpenID1()) {
                $response->fields->setArg(Auth_OpenID_OPENID_NS, 'op_endpoint', $server_url);
            }
            if ($response_identity !== null) {
                $response->fields->setArg(Auth_OpenID_OPENID_NS, 'identity', $response_identity);
                if ($this->message->isOpenID2()) {
                    $response->fields->setArg(Auth_OpenID_OPENID_NS, 'claimed_id', $response_claimed_id);
                }
            }
        } else {
            $response->fields->setArg(Auth_OpenID_OPENID_NS, 'mode', $mode);
            if ($this->immediate) {
                if ($this->message->isOpenID1() && !$server_url) {
                    return new Auth_OpenID_ServerError(null, 'setup_url is required for $allow=false \\
                                  in OpenID 1.x immediate mode.');
                }
                $setup_request = new Auth_OpenID_CheckIDRequest($this->identity, $this->return_to, $this->trust_root, false, $this->assoc_handle, $this->server, $this->claimed_id);
                $setup_request->message = $this->message;
                $setup_url = $setup_request->encodeToURL($server_url);
                if ($setup_url === null) {
                    return new Auth_OpenID_NoReturnToError();
                }
                $response->fields->setArg(Auth_OpenID_OPENID_NS, 'user_setup_url', $setup_url);
            }
        }
        return $response;
    }