/*
 * Copyright 2017 The Mifos Initiative.
 *
 * 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 io.mifos.provisioner.internal.util;

import io.mifos.anubis.api.v1.RoleConstants;
import io.mifos.anubis.token.SystemAccessTokenSerializer;
import io.mifos.anubis.token.TokenSerializationResult;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.RSAPrivateKeySpec;
import java.util.concurrent.TimeUnit;

public class TokenProvider {
  private final String keyTimestamp;
  private PrivateKey privateKey;
  private final SystemAccessTokenSerializer tokenSerializer;

  public TokenProvider(
      final String keyTimestamp,
      final BigInteger privateKeyModulus,
      final BigInteger privateKeyExponent,
      final SystemAccessTokenSerializer tokenSerializer) {
    super();
    this.tokenSerializer = tokenSerializer;

    try {
      this.keyTimestamp = keyTimestamp;
      final KeyFactory keyFactory = KeyFactory.getInstance("RSA");

      final RSAPrivateKeySpec rsaPrivateKeySpec
          = new RSAPrivateKeySpec(privateKeyModulus, privateKeyExponent);
      this.privateKey = keyFactory.generatePrivate(rsaPrivateKeySpec);

    } catch (final Exception ex) {
      throw new IllegalStateException("Could not read RSA key pair!", ex);
    }
  }

  public TokenSerializationResult createToken(
          final String subject,
          final String audience,
          final long ttl,
          final TimeUnit timeUnit) {
    SystemAccessTokenSerializer.Specification specification = new SystemAccessTokenSerializer.Specification();
    specification.setKeyTimestamp(keyTimestamp);
    specification.setTenant(subject);
    specification.setTargetApplicationName(audience);
    specification.setSecondsToLive(timeUnit.toSeconds(ttl));
    specification.setRole(RoleConstants.SYSTEM_ADMIN_ROLE_IDENTIFIER);
    specification.setPrivateKey(privateKey);

    return this.tokenSerializer.build(specification);
  }
}