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using NetSparkleUpdater.Enums;

using System;

using System.Collections.Generic;

using System.IO;

using System.Net;

using System.Runtime.InteropServices;

using System.Security.Cryptography;

namespace NetSparkleUpdater

{

    /// <summary>

    /// Provides commonly used utility functions.

    /// </summary>

    public class Utilities

    {

        /// <summary>

        /// Removes trailing 0 components from the given version.

        /// </summary>

        /// <param name="version">Version object</param>

        /// <returns>Version string</returns>

        public static string GetVersionString(Version version)

        {

            if (version.Revision != 0)

            {

                return version.ToString();

            }

            if (version.Build != 0)

            {

                return version.ToString(3);

            }

            return version.ToString(2);

        }

        /// <summary>

        /// Signs a file with the given private key.

        /// </summary>

        /// <param name="fileToSignPath">Path to the file you want to sign</param>

        /// <param name="privateKeyFilePath">Path to the private key file</param>

        /// <returns>DSA signature as base64 string</returns>

        public static string GetDSASignature(string fileToSignPath, string privateKeyFilePath)

        {

            if (string.IsNullOrEmpty(fileToSignPath) || !File.Exists(fileToSignPath))

            {

                return null;

            }

            if (string.IsNullOrEmpty(privateKeyFilePath) || !File.Exists(privateKeyFilePath))

            {

                return null;

            }

            var privateKey = File.ReadAllText(privateKeyFilePath);

            if (!string.IsNullOrEmpty(privateKey))

            {

                DSACryptoServiceProvider cryptoProvider = new DSACryptoServiceProvider();

                cryptoProvider.FromXmlString(privateKey);

                using (Stream inputStream = File.OpenRead(fileToSignPath))

                {

                    byte[] hash = null;

                    hash = cryptoProvider.SignData(inputStream);

                    var dsaSignature = Convert.ToBase64String(hash);

                    return dsaSignature;

                }

            }

            return null;

        }

        /// <summary>

        /// Creates a <see cref="Uri"/> from a URL string. If the URL is relative, converts it to an absolute URL based on the appcast URL.

        /// </summary>

        /// <param name="url">relative or absolute URL</param>

        /// <param name="appcastURL">URL to appcast</param>

        public static Uri GetAbsoluteURL(string url, string appcastURL)

        {

            return new Uri(new Uri(appcastURL), url);

        }

        /// <summary>

        /// Convert a number of bytes to a user-readable string

        /// </summary>

        /// <param name="numBytes">Number of bytes to convert</param>

        /// <returns>A string that represents the number of bytes in KB, MB, or GB if numBytes > 1024.

        /// If numBytes is less than 1024, returns numBytes.</returns>

        public static string NumBytesToUserReadableString(long numBytes)

        {

            if (numBytes > 1024)

            {

                double numBytesDecimal = numBytes;

                // Put in KB

                numBytesDecimal /= 1024;

                if (numBytesDecimal > 1024)

                {

                    // Put in MB

                    numBytesDecimal /= 1024;

                    if (numBytesDecimal > 1024)

                    {

                        // Put in GB

                        numBytesDecimal /= 1024;

                        return numBytesDecimal.ToString("F2") + " GB";

                    }

                    return numBytesDecimal.ToString("F2") + " MB";

                }

                return numBytesDecimal.ToString("F2") + " KB";

            }

            return numBytes.ToString();

        }

        // From WalletWasabi:

        // https://github.com/zkSNACKs/WalletWasabi/blob/8d42bce976605cca3326ea6c998b2294494900e6/WalletWasabi/Helpers/EnvironmentHelpers.cs

        public static string GetFullBaseDirectory()

        {

#if NETCORE

            var fullBaseDirectory = Path.GetFullPath(AppContext.BaseDirectory);

            if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))

            {

                if (!fullBaseDirectory.StartsWith("/"))

                {

                    fullBaseDirectory = fullBaseDirectory.Insert(0, "/");

                }

            }

            return fullBaseDirectory;

#else

            // https://stackoverflow.com/a/837501/3938401

            return System.Reflection.Assembly.GetExecutingAssembly().CodeBase;

#endif

        }

        public static byte[] ConvertStreamToByteArray(Stream stream)

        {

            // read the data

            byte[] data = new byte[stream.Length];

            stream.Read(data, 0, data.Length);

            return data;

        }

        public static bool IsSignatureNeeded(SecurityMode securityMode, bool doesKeyInfoExist)

        {

            switch (securityMode)

            {

                case SecurityMode.UseIfPossible:

                    // if we have a dsa key, we need a signature

                    return doesKeyInfoExist;

                case SecurityMode.Strict:

                    // we always need a signature

                    return true;

                case SecurityMode.Unsafe:

                    return false;

            }

            return false;

        }

    }

}