/*******************************************************************************
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * Licensed under the Apache License, Version 2.0 (the "License"). You may not use
 * this file except in compliance with the License. A copy of the License is located at
 *
 * http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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.
 * *****************************************************************************
 *    __  _    _  ___
 *   (  )( \/\/ )/ __)
 *   /__\ \    / \__ \
 *  (_)(_) \/\/  (___/
 *
 *  AWS SDK for .NET
 */
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading;

using Amazon.EC2.Model;
using Amazon.Runtime.Internal.Util;

using ThirdParty.Json.LitJson;
using Amazon.Runtime;

#pragma warning disable 1591

namespace Amazon.EC2.Util
{
    /// <summary>
    /// This class has utility methods for finding common Amazon machine images.
    /// </summary>
    public static partial class ImageUtilities
    {
        #region ImageKeys

        public const string WINDOWS_2016_BASE_KEY = "WINDOWS_2016_BASE";
        public const string WINDOWS_2016_NANO_KEY = "WINDOWS_2016_NANO";
        public const string WINDOWS_2016_CORE_KEY = "WINDOWS_2016_CORE";
        public const string WINDOWS_2016_CONTAINER_KEY = "WINDOWS_2016_CONTAINER";

        public const string WINDOWS_2016_SQL_SERVER_ENTERPRISE_2016_KEY = "WINDOWS_2016_SQL_SERVER_ENTERPRISE_2016";
        public const string WINDOWS_2016_SQL_SERVER_STANDARD_2016_KEY = "WINDOWS_2016_SQL_SERVER_STANDARD_2016";
        public const string WINDOWS_2016_SQL_SERVER_WEB_2016_KEY = "WINDOWS_2016_SQL_SERVER_WEB_2016";
        public const string WINDOWS_2016_SQL_SERVER_EXPRESS_2016_KEY = "WINDOWS_2016_SQL_SERVER_EXPRESS_2016";

        public const string WINDOWS_2012R2_BASE_KEY = "WINDOWS_2012R2_BASE";
        public const string WINDOWS_2012R2_CORE_KEY = "WINDOWS_2012R2_CORE";

        public const string WINDOWS_2012R2_SQL_SERVER_EXPRESS_2016_KEY = "WINDOWS_2012R2_SQL_SERVER_EXPRESS_2016";
        public const string WINDOWS_2012R2_SQL_SERVER_STANDARD_2016_KEY = "WINDOWS_2012R2_SQL_SERVER_STANDARD_2016";
        public const string WINDOWS_2012R2_SQL_SERVER_WEB_2016_KEY = "WINDOWS_2012R2_SQL_SERVER_WEB_2016";
        
        public const string WINDOWS_2012R2_SQL_SERVER_EXPRESS_2014_KEY = "WINDOWS_2012R2_SQL_SERVER_EXPRESS_2014";
        public const string WINDOWS_2012R2_SQL_SERVER_STANDARD_2014_KEY = "WINDOWS_2012R2_SQL_SERVER_STANDARD_2014";
        public const string WINDOWS_2012R2_SQL_SERVER_WEB_2014_KEY = "WINDOWS_2012R2_SQL_SERVER_WEB_2014";

        public const string WINDOWS_2012_BASE_KEY = "WINDOWS_2012_BASE";

        public const string WINDOWS_2012_SQL_SERVER_EXPRESS_2014_KEY = "WINDOWS_2012_SQL_SERVER_EXPRESS_2014";
        public const string WINDOWS_2012_SQL_SERVER_STANDARD_2014_KEY = "WINDOWS_2012_SQL_SERVER_STANDARD_2014";
        public const string WINDOWS_2012_SQL_SERVER_WEB_2014_KEY = "WINDOWS_2012_SQL_SERVER_WEB_2014";

        public const string WINDOWS_2012_SQL_SERVER_EXPRESS_2012_KEY = "WINDOWS_2012_SQL_SERVER_EXPRESS_2012";
        public const string WINDOWS_2012_SQL_SERVER_STANDARD_2012_KEY = "WINDOWS_2012_SQL_SERVER_STANDARD_2012";
        public const string WINDOWS_2012_SQL_SERVER_WEB_2012_KEY = "WINDOWS_2012_SQL_SERVER_WEB_2012";

        public const string WINDOWS_2012_SQL_SERVER_EXPRESS_2008_KEY = "WINDOWS_2012_SQL_SERVER_EXPRESS_2008";
        public const string WINDOWS_2012_SQL_SERVER_STANDARD_2008_KEY = "WINDOWS_2012_SQL_SERVER_STANDARD_2008";
        public const string WINDOWS_2012_SQL_SERVER_WEB_2008_KEY = "WINDOWS_2012_SQL_SERVER_WEB_2008";

        public const string WINDOWS_2008R2_BASE_KEY = "WINDOWS_2008R2_BASE";

        public const string WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012_KEY = "WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012";
        public const string WINDOWS_2008R2_SQL_SERVER_STANDARD_2012_KEY = "WINDOWS_2008R2_SQL_SERVER_STANDARD_2012";
        public const string WINDOWS_2008R2_SQL_SERVER_WEB_2012_KEY = "WINDOWS_2008R2_SQL_SERVER_WEB_2012";

        public const string WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008_KEY = "WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008";
        public const string WINDOWS_2008R2_SQL_SERVER_STANDARD_2008_KEY = "WINDOWS_2008R2_SQL_SERVER_STANDARD_2008";
        public const string WINDOWS_2008R2_SQL_SERVER_WEB_2008_KEY = "WINDOWS_2008R2_SQL_SERVER_WEB_2008";

        public const string WINDOWS_2008RTM_BASE_KEY = "WINDOWS_2008RTM_BASE";

        public const string WINDOWS_2008RTM_SQL_SERVER_EXPRESS_2008_KEY = "WINDOWS_2008RTM_SQL_SERVER_EXPRESS_2008";
        public const string WINDOWS_2008RTM_SQL_SERVER_STANDARD_2008_KEY = "WINDOWS_2008RTM_SQL_SERVER_STANDARD_2008";

        public const string WINDOWS_2008_BEANSTALK_IIS75_KEY = "WINDOWS_2008_BEANSTALK_IIS75";
        public const string WINDOWS_2012_BEANSTALK_IIS8_KEY = "WINDOWS_2012_BEANSTALK_IIS8";

        public const string VPC_NAT_KEY = "VPC_NAT";

        /// <summary>
        /// The collection of keys that can be used to address images.
        /// </summary>
        public static readonly IEnumerable<string> ImageKeys = new string[]
        {
            WINDOWS_2016_BASE_KEY,
            WINDOWS_2016_NANO_KEY,
            WINDOWS_2016_CORE_KEY,
            WINDOWS_2016_CONTAINER_KEY,
            WINDOWS_2016_SQL_SERVER_ENTERPRISE_2016_KEY,
            WINDOWS_2016_SQL_SERVER_STANDARD_2016_KEY,
            WINDOWS_2016_SQL_SERVER_WEB_2016_KEY,
            WINDOWS_2016_SQL_SERVER_EXPRESS_2016_KEY,
            WINDOWS_2012R2_BASE_KEY,
            WINDOWS_2012R2_CORE_KEY,
            WINDOWS_2012R2_SQL_SERVER_EXPRESS_2016_KEY,
            WINDOWS_2012R2_SQL_SERVER_STANDARD_2016_KEY,
            WINDOWS_2012R2_SQL_SERVER_WEB_2016_KEY,
            WINDOWS_2012R2_SQL_SERVER_EXPRESS_2014_KEY,
            WINDOWS_2012R2_SQL_SERVER_STANDARD_2014_KEY,
            WINDOWS_2012R2_SQL_SERVER_WEB_2014_KEY,
            WINDOWS_2012_BASE_KEY,
            WINDOWS_2012_SQL_SERVER_EXPRESS_2014_KEY,
            WINDOWS_2012_SQL_SERVER_STANDARD_2014_KEY,
            WINDOWS_2012_SQL_SERVER_WEB_2014_KEY,
            WINDOWS_2012_SQL_SERVER_EXPRESS_2012_KEY,
            WINDOWS_2012_SQL_SERVER_STANDARD_2012_KEY,
            WINDOWS_2012_SQL_SERVER_WEB_2012_KEY,
            WINDOWS_2012_SQL_SERVER_EXPRESS_2008_KEY,
            WINDOWS_2012_SQL_SERVER_STANDARD_2008_KEY,
            WINDOWS_2012_SQL_SERVER_WEB_2008_KEY,
            WINDOWS_2008R2_BASE_KEY,
            WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012_KEY,
            WINDOWS_2008R2_SQL_SERVER_STANDARD_2012_KEY,
            WINDOWS_2008R2_SQL_SERVER_WEB_2012_KEY,
            WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008_KEY,
            WINDOWS_2008R2_SQL_SERVER_STANDARD_2008_KEY,
            WINDOWS_2008R2_SQL_SERVER_WEB_2008_KEY,
            WINDOWS_2008RTM_BASE_KEY,
            WINDOWS_2008RTM_SQL_SERVER_EXPRESS_2008_KEY,
            WINDOWS_2008RTM_SQL_SERVER_STANDARD_2008_KEY,
            WINDOWS_2008_BEANSTALK_IIS75_KEY,
            WINDOWS_2012_BEANSTALK_IIS8_KEY,
            VPC_NAT_KEY 
        };

        #endregion

        #region Windows 2016 Images

        public static readonly ImageDescriptor WINDOWS_2016_BASE = new ImageDescriptor(WINDOWS_2016_BASE_KEY);
        public static readonly ImageDescriptor WINDOWS_2016_NANO = new ImageDescriptor(WINDOWS_2016_NANO_KEY);
        public static readonly ImageDescriptor WINDOWS_2016_CORE = new ImageDescriptor(WINDOWS_2016_CORE_KEY);
        public static readonly ImageDescriptor WINDOWS_2016_CONTAINER = new ImageDescriptor(WINDOWS_2016_CONTAINER_KEY);

        public static readonly ImageDescriptor WINDOWS_2016_SQL_SERVER_ENTERPRISE_2016 = new ImageDescriptor(WINDOWS_2016_SQL_SERVER_ENTERPRISE_2016_KEY);
        public static readonly ImageDescriptor WINDOWS_2016_SQL_SERVER_STANDARD_2016 = new ImageDescriptor(WINDOWS_2016_SQL_SERVER_STANDARD_2016_KEY);
        public static readonly ImageDescriptor WINDOWS_2016_SQL_SERVER_WEB_2016 = new ImageDescriptor(WINDOWS_2016_SQL_SERVER_WEB_2016_KEY);
        public static readonly ImageDescriptor WINDOWS_2016_SQL_SERVER_EXPRESS_2016 = new ImageDescriptor(WINDOWS_2016_SQL_SERVER_EXPRESS_2016_KEY);
        
        #endregion

        #region Windows 2012 R2 Images

        public static readonly ImageDescriptor WINDOWS_2012R2_BASE = new ImageDescriptor(WINDOWS_2012R2_BASE_KEY);
        public static readonly ImageDescriptor WINDOWS_2012R2_CORE = new ImageDescriptor(WINDOWS_2012R2_CORE_KEY);

        public static readonly ImageDescriptor WINDOWS_2012R2_SQL_SERVER_EXPRESS_2016 = new ImageDescriptor(WINDOWS_2012R2_SQL_SERVER_EXPRESS_2016_KEY);
        public static readonly ImageDescriptor WINDOWS_2012R2_SQL_SERVER_STANDARD_2016 = new ImageDescriptor(WINDOWS_2012R2_SQL_SERVER_STANDARD_2016_KEY);
        public static readonly ImageDescriptor WINDOWS_2012R2_SQL_SERVER_WEB_2016 = new ImageDescriptor(WINDOWS_2012R2_SQL_SERVER_WEB_2016_KEY);
        
        public static readonly ImageDescriptor WINDOWS_2012R2_SQL_SERVER_EXPRESS_2014 = new ImageDescriptor(WINDOWS_2012R2_SQL_SERVER_EXPRESS_2014_KEY);
        public static readonly ImageDescriptor WINDOWS_2012R2_SQL_SERVER_STANDARD_2014 = new ImageDescriptor(WINDOWS_2012R2_SQL_SERVER_STANDARD_2014_KEY);
        public static readonly ImageDescriptor WINDOWS_2012R2_SQL_SERVER_WEB_2014 = new ImageDescriptor(WINDOWS_2012R2_SQL_SERVER_WEB_2014_KEY);

        #endregion

        #region Windows 2012 (Original RTM) Images

        public static readonly ImageDescriptor WINDOWS_2012_BASE = new ImageDescriptor(WINDOWS_2012_BASE_KEY);

        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_EXPRESS_2014 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_EXPRESS_2014_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_STANDARD_2014 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_STANDARD_2014_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_WEB_2014 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_WEB_2014_KEY);

        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_EXPRESS_2012 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_EXPRESS_2012_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_STANDARD_2012 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_STANDARD_2012_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_WEB_2012 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_WEB_2012_KEY);
        
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_EXPRESS_2008 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_EXPRESS_2008_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_STANDARD_2008 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_STANDARD_2008_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_WEB_2008 = new ImageDescriptor(WINDOWS_2012_SQL_SERVER_WEB_2008_KEY);

        #endregion

        #region Windows 2008 R2 Images

        public static readonly ImageDescriptor WINDOWS_2008R2_BASE = new ImageDescriptor(WINDOWS_2008R2_BASE_KEY);

        public static readonly ImageDescriptor WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012 = new ImageDescriptor(WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012_KEY);
        public static readonly ImageDescriptor WINDOWS_2008R2_SQL_SERVER_STANDARD_2012 = new ImageDescriptor(WINDOWS_2008R2_SQL_SERVER_STANDARD_2012_KEY);
        public static readonly ImageDescriptor WINDOWS_2008R2_SQL_SERVER_WEB_2012 = new ImageDescriptor(WINDOWS_2008R2_SQL_SERVER_WEB_2012_KEY);

        public static readonly ImageDescriptor WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008 = new ImageDescriptor(WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008_KEY);
        public static readonly ImageDescriptor WINDOWS_2008R2_SQL_SERVER_STANDARD_2008 = new ImageDescriptor(WINDOWS_2008R2_SQL_SERVER_STANDARD_2008_KEY);
        public static readonly ImageDescriptor WINDOWS_2008R2_SQL_SERVER_WEB_2008 = new ImageDescriptor(WINDOWS_2008R2_SQL_SERVER_WEB_2008_KEY);

        #endregion

        #region Windows 2008 (Original RTM) Images

        public static readonly ImageDescriptor WINDOWS_2008RTM_BASE = new ImageDescriptor(WINDOWS_2008RTM_BASE_KEY);

        public static readonly ImageDescriptor WINDOWS_2008RTM_SQL_SERVER_EXPRESS_2008 = new ImageDescriptor(WINDOWS_2008RTM_SQL_SERVER_EXPRESS_2008_KEY);
        public static readonly ImageDescriptor WINDOWS_2008RTM_SQL_SERVER_STANDARD_2008 = new ImageDescriptor(WINDOWS_2008RTM_SQL_SERVER_STANDARD_2008_KEY);

        #endregion

        #region Misc Images

        public static readonly ImageDescriptor WINDOWS_2008_BEANSTALK_IIS75 = new ImageDescriptor(WINDOWS_2008_BEANSTALK_IIS75_KEY);
        public static readonly ImageDescriptor WINDOWS_2012_BEANSTALK_IIS8 = new ImageDescriptor(WINDOWS_2012_BEANSTALK_IIS8_KEY);

        public static readonly ImageDescriptor VPC_NAT = new ImageDescriptor(VPC_NAT_KEY);

        #endregion

        #region Obsolete Members

        [Obsolete("Please use the WINDOWS_2012_SQL_SERVER_EXPRESS_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_EXPRESS_2008_R2 = WINDOWS_2012_SQL_SERVER_EXPRESS_2008;
        [Obsolete("Please use the WINDOWS_2012_SQL_SERVER_STANDARD_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_STANDARD_2008_R2 = WINDOWS_2012_SQL_SERVER_STANDARD_2008;
        [Obsolete("Please use the WINDOWS_2012_SQL_SERVER_WEB_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_WEB_2008_R2 = WINDOWS_2012_SQL_SERVER_WEB_2008;
        [Obsolete("Please use the WINDOWS_2012_SQL_SERVER_EXPRESS_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_EXPRESS_2008_R2_SP2 = WINDOWS_2012_SQL_SERVER_EXPRESS_2008;
        [Obsolete("Please use the WINDOWS_2012_SQL_SERVER_STANDARD_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_STANDARD_2008_R2_SP2 = WINDOWS_2012_SQL_SERVER_STANDARD_2008;
        [Obsolete("Please use the WINDOWS_2012_SQL_SERVER_WEB_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2012_SQL_SERVER_WEB_2008_R2_SP2 = WINDOWS_2012_SQL_SERVER_WEB_2008;

        [Obsolete("Please use the WINDOWS_2008R2_BASE member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_BASE = WINDOWS_2008R2_BASE;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_SQL_SERVER_EXPRESS_2012 = WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_STANDARD_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_SQL_SERVER_STANDARD_2012 = WINDOWS_2008R2_SQL_SERVER_STANDARD_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_WEB_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_SQL_SERVER_WEB_2012 = WINDOWS_2008R2_SQL_SERVER_WEB_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_SQL_SERVER_EXPRESS_2008_R2_SP2 = WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_STANDARD_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_SQL_SERVER_STANDARD_2008_R2_SP2 = WINDOWS_2008R2_SQL_SERVER_STANDARD_2008;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_WEB_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SP1_SQL_SERVER_WEB_2008_R2_SP2 = WINDOWS_2008R2_SQL_SERVER_WEB_2008;
        
        [Obsolete("Please use the WINDOWS_2008R2_BASE member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_BASE = WINDOWS_2008R2_BASE;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SQL_SERVER_EXPRESS_2012 = WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_STANDARD_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SQL_SERVER_STANDARD_2012 = WINDOWS_2008R2_SQL_SERVER_STANDARD_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_WEB_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SQL_SERVER_WEB_2012 = WINDOWS_2008R2_SQL_SERVER_WEB_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SQL_SERVER_EXPRESS_2008_R2 = WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_STANDARD_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SQL_SERVER_STANDARD_2008_R2 = WINDOWS_2008R2_SQL_SERVER_STANDARD_2008;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_WEB_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_R2_SQL_SERVER_WEB_2008_R2 = WINDOWS_2008R2_SQL_SERVER_WEB_2008;

        // Legacy keys kept for backwards compatibility with user-code so the R2 ami gets served, now that we also have 2008RTM amis
        // in the collection
        [Obsolete("Please use the WINDOWS_2008R2_BASE member.")]
        public static readonly ImageDescriptor WINDOWS_2008_BASE = WINDOWS_2008R2_BASE;

        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_SQL_SERVER_EXPRESS_2012 = WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_STANDARD_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_SQL_SERVER_STANDARD_2012 = WINDOWS_2008R2_SQL_SERVER_STANDARD_2012;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_WEB_2012 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_SQL_SERVER_WEB_2012 = WINDOWS_2008R2_SQL_SERVER_WEB_2012;

        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_SQL_SERVER_EXPRESS_2008 = WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_STANDARD_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_SQL_SERVER_STANDARD_2008 = WINDOWS_2008R2_SQL_SERVER_STANDARD_2008;
        [Obsolete("Please use the WINDOWS_2008R2_SQL_SERVER_WEB_2008 member.")]
        public static readonly ImageDescriptor WINDOWS_2008_SQL_SERVER_WEB_2008 = WINDOWS_2008R2_SQL_SERVER_WEB_2008;

        #endregion

        #region Initialization and private members

        static Logger Logger
        {
            get
            {
                return Logger.GetLogger(typeof(ImageUtilities));
            }
        }

        private static readonly ImageDescriptor[] WindowsDescriptors =
        {
            WINDOWS_2016_BASE,
            WINDOWS_2016_NANO,
            WINDOWS_2016_CORE,
            WINDOWS_2016_CONTAINER,

            WINDOWS_2016_SQL_SERVER_ENTERPRISE_2016,
            WINDOWS_2016_SQL_SERVER_STANDARD_2016,
            WINDOWS_2016_SQL_SERVER_WEB_2016,
            WINDOWS_2016_SQL_SERVER_EXPRESS_2016,

            WINDOWS_2012R2_BASE,
            WINDOWS_2012R2_CORE,

            WINDOWS_2012R2_SQL_SERVER_EXPRESS_2016,
            WINDOWS_2012R2_SQL_SERVER_STANDARD_2016,
            WINDOWS_2012R2_SQL_SERVER_WEB_2016,
            
            WINDOWS_2012R2_SQL_SERVER_EXPRESS_2014,
            WINDOWS_2012R2_SQL_SERVER_STANDARD_2014,
            WINDOWS_2012R2_SQL_SERVER_WEB_2014,
            
            WINDOWS_2012_BASE,

            WINDOWS_2012_SQL_SERVER_EXPRESS_2014,
            WINDOWS_2012_SQL_SERVER_STANDARD_2014,
            WINDOWS_2012_SQL_SERVER_WEB_2014,

            WINDOWS_2012_SQL_SERVER_EXPRESS_2012,
            WINDOWS_2012_SQL_SERVER_STANDARD_2012,
            WINDOWS_2012_SQL_SERVER_WEB_2012,
            
            WINDOWS_2012_SQL_SERVER_EXPRESS_2008,
            WINDOWS_2012_SQL_SERVER_STANDARD_2008,
            WINDOWS_2012_SQL_SERVER_WEB_2008,
            
            WINDOWS_2008R2_BASE,
            
            WINDOWS_2008R2_SQL_SERVER_EXPRESS_2012,
            WINDOWS_2008R2_SQL_SERVER_STANDARD_2012,
            WINDOWS_2008R2_SQL_SERVER_WEB_2012,
            
            WINDOWS_2008R2_SQL_SERVER_EXPRESS_2008,
            WINDOWS_2008R2_SQL_SERVER_STANDARD_2008,
            WINDOWS_2008R2_SQL_SERVER_WEB_2008,
            
            WINDOWS_2008RTM_BASE,
            
            WINDOWS_2008RTM_SQL_SERVER_EXPRESS_2008,
            WINDOWS_2008RTM_SQL_SERVER_STANDARD_2008,

            WINDOWS_2008_BEANSTALK_IIS75,
            WINDOWS_2012_BEANSTALK_IIS8
        };

        private static readonly ImageDescriptor[] LinuxDescriptors =
        {
            VPC_NAT
        };

        private const string CLOUDFRONT_LOCATION_OF_AMI_FILE = "https://aws-sdk-configurations.amazonwebservices.com/stockamis.json";
        private const string S3_LOCATION_OF_AMI_FILE = "https://aws-sdk-configurations.s3.amazonaws.com/stockamis.json";

        private static readonly string[] DownloadLocations =
        {
            CLOUDFRONT_LOCATION_OF_AMI_FILE,
            S3_LOCATION_OF_AMI_FILE
        };

        private const string WindowsImagesTag = "WindowsImages";
        private const string LinuxImagesTag = "LinuxImages";
        private const string DefinitionKeyTag = "key";
        private const string DefinitionPrefixTag = "prefix";

        private const int MAX_DOWNLOAD_RETRIES = 3;

        private static readonly object LOCK_OBJECT = new object();

        private static bool ImageDefinitionsLoaded { get; set; }

        private static ImageDescriptor FindDescriptorWithKey(string key)
        {
            foreach (var d in WindowsDescriptors)
            {
                if (d.DefinitionKey.Equals(key, StringComparison.OrdinalIgnoreCase))
                    return d;
            }

            foreach (var d in LinuxDescriptors)
            {
                if (d.DefinitionKey.Equals(key, StringComparison.OrdinalIgnoreCase))
                    return d;
            }

            return null;
        }

        private static DescribeImagesRequest CreateDescribeImagesRequest(ImageDescriptor descriptor)
        {
            return new DescribeImagesRequest()
            {
                Owners = new List<string>() { "amazon" },
                Filters = new List<Filter>()
                {
                    new Filter(){Name = "name", Values = new List<string>(){descriptor.NamePrefix}}
                }
            };
        }

        /// <summary>
        /// Parses the ami definition content into the ImageDescriptor members. 
        /// </summary>
        /// <param name="reader">A reader of the ami definitions</param>
        private static void ParseAMIDefinitions(StreamReader reader)
        {
            try
            {
                var jdata = JsonMapper.ToObject(reader);

                var platformTags = new string[]
                {
                    WindowsImagesTag,
                    LinuxImagesTag
                };

                var parsedDefinitionsMap = new Dictionary<string, string>();
                foreach (var platformTag in platformTags)
                {
                    var imageDefinitions = jdata[platformTag];
                    if (imageDefinitions == null)
                    {
                        Logger.InfoFormat("Parsing AMI definitions - did not find any images for platform tag '{0}'", platformTag);
                        continue;
                    }

                    for (int d = 0; d < imageDefinitions.Count; d++)
                    {
                        var def = imageDefinitions[d];
                        var key = (string)def[DefinitionKeyTag];
                        var prefix = (string)def[DefinitionPrefixTag];

                        if (!string.IsNullOrEmpty(key) && !string.IsNullOrEmpty(prefix))
                            parsedDefinitionsMap[key] = prefix;
                        else
                            Logger.InfoFormat("Parsing AMI definitions - found malformed descriptor entry for definition index {0} in platform group {1}, discarded", d, platformTag);
                    }
                }

                foreach (var d in WindowsDescriptors)
                {
                    if (parsedDefinitionsMap.ContainsKey(d.DefinitionKey))
                        d.NamePrefix = parsedDefinitionsMap[d.DefinitionKey];
                    else
                        Logger.InfoFormat("Parsing AMI definitions - did not find entry for Windows image descriptor '{0}' after parsing", d.DefinitionKey);
                }

                foreach (var d in LinuxDescriptors)
                {
                    if (parsedDefinitionsMap.ContainsKey(d.DefinitionKey))
                        d.NamePrefix = parsedDefinitionsMap[d.DefinitionKey];
                    else
                        Logger.InfoFormat("Parsing AMI definitions - did not find entry for Linux image descriptor '{0}' after parsing", d.DefinitionKey);
                }
            }
            catch (Exception e)
            {
                Logger.Error(e, "Exception whilst parsing AMI definitions file.");
            }
        }

        private static AmazonEC2Config ConfigFromClient(IAmazonEC2 ec2Client)
        {
            var client = ec2Client as AmazonEC2Client;
            if (client != null)
                return client.Config as AmazonEC2Config;

            return new AmazonEC2Config();
        }

        private static AmazonEC2Config CreateConfigFromClient(IAmazonEC2 ec2Client, ImageDescriptor descriptor)
        {
            if (ec2Client == null)
                throw new ArgumentNullException("ec2Client");
            if (descriptor == null)
                throw new ArgumentNullException("descriptor");

            var config = ConfigFromClient(ec2Client);
            return config;
        }
        #endregion

        /// <summary>
        /// This class identifies an image that will be looked up using a logical
        /// key independent of release (RTM) or service pack (SPx) designations,
        /// always returning the latest version of an image.
        /// </summary>
        public class ImageDescriptor
        {            
            internal ImageDescriptor(string definitionKey)
            {
                this.DefinitionKey = definitionKey;
            }

            /// <summary>
            /// The logical name assigned to this image in the backing definitions file.
            /// This key is independent of RTM/service pack number.
            /// </summary>
            public string DefinitionKey
            {
                get; 
                private set;
            }

            /// <summary>
            /// The name prefix or pattern of the Amazon machine image that will be looked up.
            /// </summary>
            public string NamePrefix
            {
                get;
                internal set;
            }

            /// <summary>
            /// Override to return back the NamePrefix
            /// </summary>
            /// <returns></returns>
            public override string ToString()
            {
                return this.NamePrefix;
            }
        }
    }
}