<script type="text/javascript">

        const translationString = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

        function webSafeBase64ToBase64(webSafeBase64) {
            base64 = webSafeBase64.replaceAll('-', '+').replaceAll('_', '/');
            while (base64.length % 4)
                base64 += '=';
            return base64;
        };

        function base64ToWebSafeBase64(base64) {
            return base64.replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "");;
        };

        function unit8ArrayToUrlSafeBase64 (unit8Array) {
            const extraBytes = unit8Array.length % 3
            let output = ''
            let buffer

            function encode (pos) {
                return translationString.charAt(pos)
            }

            function threeBytesToBase64 (threeBytes) {
                return encode(threeBytes >> 18) + encode(threeBytes >> 12 & 0x3F) + encode(threeBytes >> 6 & 0x3F) + encode(threeBytes & 0x3F)
            }

            for (let i = 0, length = unit8Array.length - extraBytes; i < length; i += 3) {
                buffer = (unit8Array[i] << 16) + (unit8Array[i + 1] << 8) + (unit8Array[i + 2])
                output += threeBytesToBase64(buffer)
            }

            // pad the end with zeros, but make sure to not forget the extra bytes
            switch (extraBytes) {
                case 1:
                    buffer = unit8Array[unit8Array.length - 1]
                    output = output + encode(buffer >> 2) + encode((buffer << 4) & 0x3F) + '=='
                    break
                case 2:
                    buffer = (unit8Array[unit8Array.length - 2] << 8) + (unit8Array[unit8Array.length - 1])
                    output = output + encode(buffer >> 10) + encode((buffer >> 4) & 0x3F) + encode((buffer << 2) & 0x3F) + '='
                    break
                default:
                    break
            }

            return base64ToWebSafeBase64(output);
        }

        function webSafeBase64ToBase64(webSafeBase64) {
            let base64 = webSafeBase64.replaceAll('-', '+').replaceAll('_', '/');
            while (base64.length % 4)
                base64 += '=';
            return base64;
        };

        function submitWebAuthnAssertionAsJson(webAuthnAssertionAsJson) {
            const fudiscrForm = document.getElementById("fudiscr-form");
            fudiscrForm._submit_function_ = fudiscrForm.submit;
            fudiscrForm.setAttribute("method", "POST");
            fudiscrForm.setAttribute("action", "$flowExecutionUrl");

            const fudisWebAuthnAssertionAsJsonInputField = document.createElement("input");
            fudisWebAuthnAssertionAsJsonInputField.setAttribute("type", "hidden");
            fudisWebAuthnAssertionAsJsonInputField.setAttribute("name", "fudis_web_authn_assertion_input")
            fudisWebAuthnAssertionAsJsonInputField.setAttribute("id", "fudis_web_authn_assertion_input");
            fudisWebAuthnAssertionAsJsonInputField.setAttribute("value", base64ToWebSafeBase64(btoa(webAuthnAssertionAsJson)));
            fudiscrForm.appendChild(fudisWebAuthnAssertionAsJsonInputField);

            const eventIdField = document.createElement("input");
            eventIdField.setAttribute("name", "_eventId_proceed");
            fudiscrForm.appendChild(eventIdField);
            fudiscrForm._submit_function_();
        }

        function getWebAuthnAssertion() {
            const publicKeyCredentialRequestOptions = {
                allowCredentials: [
                    #foreach ($webAuthnDescriptor in $webAuthnDescriptors)
                        {
                            id: Uint8Array.from(atob(webSafeBase64ToBase64("$webAuthnDescriptor.getId()")), c => c.charCodeAt(0)),
                            type: "$webAuthnDescriptor.getCredentialType()",
                            transports: [
                                #foreach ($transportTypes in $webAuthnDescriptor.getTransportTypes())
                                    "$transportTypes"#if($foreach.hasNext()),#end
                                #end
                            ]
                        }#if($foreach.hasNext()),#end
                    #end
                ],
                challenge: Uint8Array.from(atob(webSafeBase64ToBase64("$webAuthnChallenge")), c => c.charCodeAt(0)),
                rpId: "$webAuthnRpId",
                userVerification: "$webAuthnUserVerificationType",
                timeout: $webAuthnTimeout
            }

            navigator
                    .credentials
                    .get({publicKey: publicKeyCredentialRequestOptions})
                    .then(function (webAuthnAssertion) {
                        let webAuthnAssertionForJson = new Object();
                        webAuthnAssertionForJson.authenticatorData = unit8ArrayToUrlSafeBase64(new Uint8Array(webAuthnAssertion.response.authenticatorData));
                        webAuthnAssertionForJson.clientDataJson = unit8ArrayToUrlSafeBase64(new Uint8Array(webAuthnAssertion.response.clientDataJSON));
                        webAuthnAssertionForJson.rawId = unit8ArrayToUrlSafeBase64(new Uint8Array(webAuthnAssertion.rawId));
                        webAuthnAssertionForJson.signature = unit8ArrayToUrlSafeBase64(new Uint8Array(webAuthnAssertion.response.signature));
                        webAuthnAssertionForJson.userHandle = unit8ArrayToUrlSafeBase64(new Uint8Array(webAuthnAssertion.response.userHandle));
                        submitWebAuthnAssertionAsJson(JSON.stringify(webAuthnAssertionForJson));
                    })
                    .catch(function (error) {

                        if (error.name == "AbortError") {
                            document.getElementById("get_web_authn_assertion").childNodes[0].nodeValue = '#springMessageText(
                                "fudiscr.view.insert-response.web_authn.next" ,"Validate WebAuthn-Token")';
                        } else {
                            document.getElementById("get_web_authn_assertion").childNodes[0].nodeValue = error.name + ' - #springMessageText(
                                "fudiscr.view.insert-response.web_authn.error.please-try-again" ,"Error in validation of WebAuthn token, please try again.")';
                            console.log(error.name + " - " + error.message);
                        }
                    });
        }
    </script>