content: /*************************** The CRY.ME project (2023) *************************************************
   *
   *  This file is part of the CRY.ME project (https://github.com/ANSSI-FR/cry-me).
   *  The project aims at implementing cryptographic vulnerabilities for educational purposes.
   *  Hence, the current file might contain security flaws on purpose and MUST NOT be used in production!
   *  Please do not use this source code outside this scope, or use it knowingly.
   *
   *  Many files come from the Android element (https://github.com/vector-im/element-android), the
   *  Matrix SDK (https://github.com/matrix-org/matrix-android-sdk2) as well as the Android Yubikit
   *  (https://github.com/Yubico/yubikit-android) projects and have been willingly modified
   *  for the CRY.ME project purposes. The Android element, Matrix SDK and Yubikit projects are distributed
   *  under the Apache-2.0 license, and so is the CRY.ME project.
   *
   ***************************  (END OF CRY.ME HEADER)   *************************************************/
  
  /*
   * Copyright (C) 2020 Yubico.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *       http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.yubico.yubikit.oath;
  
  import java.nio.charset.StandardCharsets;
  import java.util.Locale;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import javax.annotation.Nullable;
  
  /**
   * Internal utility class for dealing with parameters stored in YKOATH credential names.
   */
  class CredentialIdUtils {
      private static final Pattern TOTP_ID_PATTERN = Pattern.compile("^((\\d+)/)?(([^:]+):)?(.+)$");
      private static final int DEFAULT_PERIOD = CredentialData.DEFAULT_TOTP_PERIOD;
  
      /**
       * Format the YKOATH Credential ID to use for a credential given its parameters.
       *
       * @param issuer   an optional issuer name for the credential
       * @param name     the name of the credential
       * @param oathType the type of the credential
       * @param period   the time period of a TOTP credential (ignored for HOTP)
       * @return A bytestring to use with YKOATH.
       */
      static byte[] formatId(@Nullable String issuer, String name, OathType oathType, int period) {
          String longName = "";
          if (oathType == OathType.TOTP && period != DEFAULT_PERIOD) {
              //TODO: Add period even if default if TOTP and remainder of ID starts with \d+/
              longName += String.format(Locale.ROOT, "%d/", period);
          }
  
          if (issuer != null) {
              longName += String.format(Locale.ROOT, "%s:", issuer);
          }
          longName += name;
          return longName.getBytes(StandardCharsets.UTF_8);
      }
  
      /**
       * Parse credential parameters from a YKOATH credential name.
       *
       * @param credentialId as retrieved from a YubiKey.
       * @param oathType     the type of the credential
       * @return parsed data stored in the credential ID.
       */
      static CredentialIdData parseId(byte[] credentialId, OathType oathType) {
          String data = new String(credentialId, StandardCharsets.UTF_8);
  
          if (oathType == OathType.TOTP) {
              Matcher m = TOTP_ID_PATTERN.matcher(data);
              if (m.matches()) {
                  String periodString = m.group(2);
                  return new CredentialIdData(
                          m.group(4),
                          m.group(5),
                          periodString == null ? DEFAULT_PERIOD : Integer.parseInt(periodString)
                  );
              } else {  //Invalid id, use it directly as name.
                  return new CredentialIdData(null, data, DEFAULT_PERIOD);
              }
          } else {
              String issuer;
              String name;
              if (data.contains(":")) {
                  String[] parts = data.split(":", 2);
                  issuer = parts[0];
                  name = parts[1];
              } else {
                  issuer = null;
                  name = data;
              }
              return new CredentialIdData(issuer, name, 0);
          }
      }
  
      static class CredentialIdData {
          @Nullable
          final String issuer;
          final String accountName;
          final int period;
  
          CredentialIdData(@Nullable String issuer, String accountName, int period) {
              this.issuer = issuer;
              this.accountName = accountName;
              this.period = period;
          }
      }
  }
  