namespace VideoBrowser.Helpers
{
    using System.Collections.Generic;
    using System.IO;
    using System.Linq;
    using System.Threading;

    /// <summary>
    /// Defines the <see cref="FileHelper" />
    /// </summary>
    public static class FileHelper
    {
        #region Methods

        /// <summary>
        /// Returns valid file name.
        /// </summary>
        /// <param name="filename">The filename to validate.</param>
        public static string GetValidFilename(string filename)
        {
            var illegalChars = Path.GetInvalidFileNameChars();

            // Check if filename contains illegal characters
            // Returning true for some reason: valid = filename.Any(x => illegalChars.Contains(x));
            var valid = filename.IndexOfAny(illegalChars) <= -1;

            if (!valid)
            {
                string new_filename = YoutubeHelper.FormatTitle(filename);
                filename = new_filename;
            }

            return filename;
        }

        /// <summary>
        /// Attempts to delete given file(s), ignoring exceptions for 10 tries, with 2 second delay between each try.
        /// </summary>
        /// <param name="files">The files to delete.</param>
        public static void DeleteFiles(params string[] files)
        {
            new Thread(delegate ()
            {
                var dict = new Dictionary<string, int>();
                var keys = new List<string>();

                foreach (string file in files)
                {
                    dict.Add(file, 0);
                    keys.Add(file);
                }

                while (dict.Count > 0)
                {
                    foreach (string key in keys)
                    {
                        try
                        {
                            if (File.Exists(key))
                            {
                                File.Delete(key);
                            }

                            // Remove file from dictionary since it either got deleted
                            // or it doesn't exist anymore.
                            dict.Remove(key);
                        }
                        catch
                        {
                            if (dict[key] == 10)
                            {
                                dict.Remove(key);
                            }
                            else
                            {
                                dict[key]++;
                            }
                        }
                    }

                    Thread.Sleep(2000);
                }
            }).Start();
        }

        /// <summary>
        /// The GetDirectorySize
        /// </summary>
        /// <param name="directory">The directory<see cref="string"/></param>
        /// <returns>The <see cref="long"/></returns>
        public static long GetDirectorySize(string directory)
        {
            return Directory
                    .GetFiles(directory, "*.*", SearchOption.AllDirectories)
                    .Sum(f => new FileInfo(f).Length);
        }

        /// <summary>
        /// The GetDirectorySizeFormatted
        /// </summary>
        /// <param name="directory">The directory<see cref="string"/></param>
        /// <returns>The <see cref="string"/></returns>
        public static string GetDirectorySizeFormatted(string directory) => FormatString.FormatFileSize(GetDirectorySize(directory));

        /// <summary>
        /// Calculates the ETA (estimated time of accomplishment).
        /// </summary>
        /// <param name="speed">The speed as bytes. (Bytes per second?)</param>
        /// <param name="totalBytes">The total amount of bytes.</param>
        /// <param name="downloadedBytes">The amount of downloaded bytes.</param>
        /// <returns>The <see cref="long"/></returns>
        public static long GetETA(int speed, long totalBytes, long downloadedBytes)
        {
            if (speed == 0)
            {
                return 0;
            }

            var remainBytes = totalBytes - downloadedBytes;
            return remainBytes / speed;
        }

        /// <summary>
        /// Returns a long of the file size from given file in bytes.
        /// </summary>
        /// <param name="file">The file to get file size from.</param>
        /// <returns>The <see cref="long"/></returns>
        public static long GetFileSize(string file) => !File.Exists(file) ? 0 : new FileInfo(file).Length;

        /// <summary>
        /// Returns an formatted string of the given file's size.
        /// </summary>
        /// <param name="file">The file<see cref="string"/></param>
        /// <returns>The <see cref="string"/></returns>
        public static string GetFileSizeFormatted(string file) => FormatString.FormatFileSize(GetFileSize(file));

        #endregion Methods
    }
}