Added SweetUtils class into new project

SweetLib/Utils/SweetUtils.cs

@@ -0,0 +1,60 @@
+using System;
+using System.IO;
+using System.Linq;
+
+namespace SweetLib.Utils
+{
+    /// <summary>
+    /// A generic class containing useful methods.
+    /// </summary>
+    public static class SweetUtils
+    {
+        public static char DefaultFileNameReplaceChar { get; set; } = '-';
+
+        /// <summary>
+        /// Legalizes a file name with the <see cref="DefaultFileNameReplaceChar"/> character.
+        /// </summary>
+        /// <param name="fileName">File name to legalize.</param>
+        /// <returns>Legalized file name.</returns>
+        public static string LegalizeFilename(string fileName)
+        {
+            return LegalizeFilename(fileName, '-');
+        }
+
+        /// <summary>
+        /// Legalizes a file name by a given replace character.
+        /// </summary>
+        /// <param name="fileName">File name to legalize.</param>
+        /// <param name="replaceChar">Character to be used as replace character.</param>
+        /// <returns>Legalized file name.</returns>
+        public static string LegalizeFilename(string fileName, char replaceChar)
+        {
+            var invalidChars = Path.GetInvalidFileNameChars();
+
+            if (invalidChars.Contains(replaceChar))
+                throw new IOException($"Replace character {replaceChar} is an invalid file name character.");
+
+            return invalidChars.Aggregate(fileName, (current, c) => current.Replace(c, replaceChar));
+        }
+
+        /// <summary>
+        /// Converts a <see cref="DateTime"/> into an Unix timestamp.
+        /// </summary>
+        /// <param name="date"><see cref="DateTime"/> to convert into Unix timestamp.</param>
+        /// <returns>Converted Unix timestamp.</returns>
+        public static double DateTimeToUnixTimeStamp(DateTime date)
+        {
+            return date.Subtract(new DateTime(1970, 1, 1)).TotalSeconds;
+        }
+
+        /// <summary>
+        /// Converts an Unix timestamp into a <see cref="DateTime"/>.
+        /// </summary>
+        /// <param name="timestamp">Unix timestamp to convert.</param>
+        /// <returns>Converted <see cref="DateTime"/>.</returns>
+        public static DateTime UnixTimestampToDateTime(double timestamp)
+        {
+            return new DateTime(1970, 1, 1).AddMilliseconds(timestamp);
+        }
+    }
+}