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// 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.Globalization;
using Org.Apache.REEF.Tang.Annotations;

namespace Org.Apache.REEF.Common.Evaluator
{
    public class DefaultYarnOneBoxHttpDriverConnection : IDriverConnection
    {
        private readonly string _applicationId;

        [Inject]
        private DefaultYarnOneBoxHttpDriverConnection()
        {
            _applicationId = Environment.GetEnvironmentVariable(Constants.ReefYarnApplicationIdEnvironmentVariable);
        }

        public DriverInformation GetDriverInformation()
        {
            if (string.IsNullOrWhiteSpace(_applicationId))
            {
                throw new ApplicationException("Could not fetch the application ID from YARN's container environment variables.");
            }

            // e.g., http://yingdac1:8088/proxy/application_1407519727821_0012/reef/v1/driver
            string oneBoxHost = string.Format(CultureInfo.InvariantCulture, "http://{0}:8088/proxy/", Environment.MachineName);
            Uri queryUri = new Uri(
                string.Concat(
                oneBoxHost,
                _applicationId + '/',
                Constants.HttpReefUriSpecification,
                Constants.HttpDriverUriTarget));
            return DriverInformation.GetDriverInformationFromHttp(queryUri);
        }
    }
}