Refactor valid path/filename. Centralize validaion. Universal templating is one step closer

FileManager/FileTemplate.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using Dinah.Core;
+
+namespace FileManager
+{
+    /// <summary>Get valid filename. Advanced features incl. parameterized template</summary>
+    public class FileTemplate
+    {
+        /// <summary>Proposed full file path. May contain optional html-styled template tags. Eg: &lt;name&gt;</summary>
+        public string Template { get; }
+
+        /// <param name="template">Proposed file name with optional html-styled template tags.</param>
+        public FileTemplate(string template) => Template = ArgumentValidator.EnsureNotNullOrWhiteSpace(template, nameof(template));
+
+        /// <summary>Optional step 1: Replace html-styled template tags with parameters. Eg {"name", "Bill Gates"} => /&lt;name&gt;/ => /Bill Gates/</summary>
+        public Dictionary<string, string> ParameterReplacements { get; } = new Dictionary<string, string>();
+
+        /// <summary>Convenience method</summary>
+        public void AddParameterReplacement(string key ,string value) => ParameterReplacements.Add(key, value);
+
+        /// <summary>If set, truncate each parameter replacement to this many characters. Default 50</summary>
+        public int? ParameterMaxSize { get; set; } = 50;
+
+        /// <summary>Optional step 2: Replace all illegal characters with this. Default=<see cref="string.Empty"/></summary>
+        public string IllegalCharacterReplacements { get; set; }
+
+        /// <summary>Generate a valid path for this file or directory</summary>
+        public string GetFilename()
+        {
+            var filename = Template;
+
+            foreach (var r in ParameterReplacements)
+                filename = filename.Replace($"<{formatKey(r.Key)}>", formatValue(r.Value));
+
+            return FileUtility.GetValidFilename(filename, IllegalCharacterReplacements);
+        }
+
+        private string formatKey(string key)
+            => key
+            .Replace("<", "")
+            .Replace(">", "");
+
+        private string formatValue(string value)
+            => ParameterMaxSize.HasValue && ParameterMaxSize.Value > 0
+            ? value?.Truncate(ParameterMaxSize.Value)
+            : value;
+    }
+
+}