/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

using System;
using System.Text;
using Apache.Qpid.Proton.Buffer;
using Apache.Qpid.Proton.Types;

namespace Apache.Qpid.Proton.Engine.Sasl.Client
{
   /// <summary>
   /// Implementation of the SASL Plain mechanism.
   /// </summary>
   public sealed class PlainMechanism : AbstractMechanism
   {
      public static readonly Symbol PLAIN = Symbol.Lookup("PLAIN");

      public override Symbol Name => PLAIN;

      public override bool IsApplicable(ISaslCredentialsProvider credentials)
      {
         return !string.IsNullOrEmpty(credentials.Username) &&
                !string.IsNullOrEmpty(credentials.Password);
      }

      public override IProtonBuffer GetInitialResponse(ISaslCredentialsProvider credentials)
      {
         string username = credentials.Username;
         string password = credentials.Password;

         if (username == null)
         {
            username = "";
         }

         if (password == null)
         {
            password = "";
         }

         byte[] usernameBytes = Encoding.UTF8.GetBytes(username);
         byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
         byte[] data = new byte[usernameBytes.Length + passwordBytes.Length + 2];

         Array.Copy(usernameBytes, 0, data, 1, usernameBytes.Length);
         Array.Copy(passwordBytes, 0, data, 2 + usernameBytes.Length, passwordBytes.Length);

         return ProtonByteBufferAllocator.Instance.Wrap(data);
      }
   }
}