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using System;
using System.IO;

namespace XenCenterLib.Archive
{
    public abstract class ArchiveWriter : IDisposable
    {
        private int _progressTracker;

        public abstract void Add(Stream fileToAdd, string fileName, DateTime modificationTime, Action cancellingDelegate);
        public abstract void AddDirectory(string directoryName, DateTime modificationTime);

        public virtual void SetBaseStream(Stream outputStream)
        {
            throw new NotImplementedException();
        }

        protected virtual void Dispose(bool disposing)
        {
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);   
        }

        public void CreateArchive(string pathToArchive, Action cancellingDelegate = null, Action<int> progressDelegate = null)
        {
            // We look recursively and do not use Directory.GetDirectories and Directory.GetFiles with
            // AllDirectories options because in .NET 4.8 they do not enumerate all elements if they
            // have paths longer than 260 characters (248 for directories).
            // If moving to .NET Core, please consider reverting this.

            _progressTracker = 0;
            PopulateArchive(pathToArchive, pathToArchive, cancellingDelegate, progressDelegate);
        }

        /// <summary>
        /// Populate the archive by recursively calling the overridden <see cref="Add"/> and <see cref="AddDirectory"/>.
        /// </summary>
        /// <param name="pathToArchive">The path to the root of the folder we're archiving</param>
        /// <param name="pathToCurrentDirectory">Keeps track of the current directory we're archiving. In the first recursive call it should be the same as <see cref="pathToArchive"/></param>
        /// <param name="cancellingDelegate">Action cal led for cancelling</param>
        /// <param name="progressDelegate">Action for reporting progress. Method will populate its parameter with the current progress of the recursive operation</param>
        /// <param name="totalProgressIncrease">Total progress that needs to be added for archiving this directory. In the first recursive call it should be 100. If the folder we're adding should add 18 percentage points to the total progress, set this value to 18.</param>
        /// <param name="progressOffset">Offset to the progress. This is added to <see cref="totalProgressIncrease"/> when setting the progress for this directory. If this folder should add 18 percentage points to the total progress, but it's for a folder past the 50% mark of the total progress (i.e.: completing this folder should set the total to 68), set this value to 50.</param>
        /// <exception cref="FileNotFoundException">A directory could not be found.</exception>
        private void PopulateArchive(string pathToArchive, string pathToCurrentDirectory, Action cancellingDelegate = null, Action<int> progressDelegate = null, float totalProgressIncrease = 100, float progressOffset = 0)
        {
            cancellingDelegate?.Invoke();

            pathToArchive = StringUtility.ToLongWindowsPath(pathToArchive, true);
            if (!Directory.Exists(pathToArchive))
                throw new FileNotFoundException($"The path {pathToArchive} does not exist");

            pathToCurrentDirectory = StringUtility.ToLongWindowsPath(pathToCurrentDirectory, true);

            //add the current directory except when it's the root directory
            if (pathToArchive != pathToCurrentDirectory)
                AddDirectory(CleanRelativePathName(pathToArchive, pathToCurrentDirectory), Directory.GetCreationTime(pathToCurrentDirectory));

            var files = Directory.GetFiles(pathToCurrentDirectory);

            foreach (var file in files)
            {
                cancellingDelegate?.Invoke();

                var filePath = StringUtility.ToLongWindowsPath(file, false);

                using (var fs = File.OpenRead(filePath))
                    Add(fs, CleanRelativePathName(pathToArchive, filePath), File.GetCreationTime(filePath), cancellingDelegate);
            }

            if (_progressTracker != (int)progressOffset)
            {
                _progressTracker = (int)progressOffset;
                progressDelegate?.Invoke(_progressTracker);
            }

            var directories = Directory.GetDirectories(pathToCurrentDirectory);
            if (directories.Length == 0)
                return;

            float increment = totalProgressIncrease / directories.Length;

            for (var i = 0; i < directories.Length; i++)
            {
                PopulateArchive(pathToArchive, directories[i], cancellingDelegate, progressDelegate,
                    increment, i * increment + progressOffset);
            }
        }

        private string CleanRelativePathName(string rootPath, string pathName)
        {
            var cleanedRootPath = rootPath.Replace(@"\\?\", string.Empty);
            return pathName
                .Replace(@"\\?\", string.Empty)
                .Replace(cleanedRootPath, string.Empty)
                .Replace('\\', '/')
                .TrimStart('/');
        }
    }
}