﻿// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX - License - Identifier: Apache - 2.0

namespace GetSecretValueExample
{
    using System;
    using System.IO;
    using System.Threading.Tasks;
    using Amazon.SecretsManager;
    using Amazon.SecretsManager.Model;

    /// <summary>
    /// This example uses the Amazon Web Service Secrets Manager to retrieve
    /// the secret value for the provided secret name. This example was created
    /// using the AWS SDK for .NET v3.7 and .NET Core 5.0.
    /// </summary>
    public class GetSecretValue
    {
        /// <summary>
        /// The main method initializes the necessary values and then calls
        /// the GetSecretAsync and DecodeString methods to get the decoded
        /// secret value for the secret named in secretName.
        /// </summary>
        public static async Task Main()
        {
            string secretName = "<<{{MySecretName}}>>";
            string secret;

            IAmazonSecretsManager client = new AmazonSecretsManagerClient();

            var response = await GetSecretAsync(client, secretName);

            if (response is not null)
            {
                secret = DecodeString(response);

                if (!string.IsNullOrEmpty(secret))
                {
                    Console.WriteLine($"The decoded secret value is: {secret}.");
                }
                else
                {
                    Console.WriteLine("No secret value was returned.");
                }
            }
        }

        /// <summary>
        /// Retrieves the secret value given the name of the secret to
        /// retrieve.
        /// </summary>
        /// <param name="client">The client object used to retrieve the secret
        /// value for the given secret name.</param>
        /// <param name="secretName">The name of the secret value to retrieve.</param>
        /// <returns>The GetSecretValueReponse object returned by
        /// GetSecretValueAsync.</returns>
        public static async Task<GetSecretValueResponse> GetSecretAsync(
            IAmazonSecretsManager client,
            string secretName)
        {
            GetSecretValueRequest request = new ();
            request.SecretId = secretName;
            request.VersionStage = "AWSCURRENT"; // VersionStage defaults to AWSCURRENT if unspecified.

            GetSecretValueResponse response = null;

            // For the sake of simplicity, this example handles only the most
            // general SecretsManager exception.
            try
            {
                response = await client.GetSecretValueAsync(request);
            }
            catch (AmazonSecretsManagerException e)
            {
                Console.WriteLine($"Error: {e.Message}");
            }

            return response;
        }

        /// <summary>
        /// Decodes the secret returned by the call to GetSecretValueAsync and
        /// returns it to the calling program.
        /// </summary>
        /// <param name="response">A GetSecretValueResponse object containing
        /// the requested secret value returned by GetSecretValueAsync.</param>
        /// <returns>A string representing the decoded secret value.</returns>
        public static string DecodeString(GetSecretValueResponse response)
        {
            // Decrypts secret using the associated AWS Key Management Service
            // Customer Master Key (CMK.) Depending on whether the secret is a
            // string or binary value, one of these fields will be populated.
            MemoryStream memoryStream = new ();

            if (response.SecretString is not null)
            {
                var secret = response.SecretString;
                return secret;
            }
            else if (response.SecretBinary is not null)
            {
                memoryStream = response.SecretBinary;
                StreamReader reader = new StreamReader(memoryStream);
                string decodedBinarySecret = System.Text.Encoding.UTF8.GetString(Convert.FromBase64String(reader.ReadToEnd()));
                return decodedBinarySecret;
            }
            else
            {
                return string.Empty;
            }
        }
    }
}
