Added backend skeleton, models and services

services/CsvWriter.cs

@@ -0,0 +1,22 @@
+using System.Globalization;
+using CsvHelper;
+
+class CsvFileWriter
+{
+    private TextWriter textWriter; 
+    private CsvWriter csvWriter;
+
+    public CsvFileWriter(FileInfo fileInfo) {
+        textWriter = new StreamWriter(fileInfo.FullName);
+        csvWriter = new CsvWriter(textWriter, CultureInfo.InvariantCulture);
+    }
+
+    public void writeOutRow(OrderModel orderModel) {
+        csvWriter.WriteField(orderModel.OrderId);
+        csvWriter.WriteField(orderModel.OrderDescription);
+        csvWriter.WriteField(orderModel.CustomerId);
+        csvWriter.WriteField(orderModel.TotalPrice);
+
+        csvWriter.NextRecord();
+    }
+}

services/DemoApplicationConfiguration.cs

@@ -0,0 +1,92 @@
+namespace Configuration
+{
+    public sealed class DemoApplicationConfiguration
+    {        
+        private FileInfo[] jsonFiles;
+        public FileInfo[] JsonFilesInfo
+        {
+            get { return jsonFiles; }
+            private set
+            {
+                jsonFiles = value.Reverse().ToArray();
+            }
+        }
+        private FileInfo outputFile;
+        public FileInfo OutputFile{
+            get {return outputFile;}
+            private set
+            {
+                if (!canCreateFile(value.FullName))
+                    throw new DemoApplicationConfigurationException($"Given output name '{value.FullName}' cannot be used");
+                outputFile = value;
+            }
+        }
+
+        public static DemoApplicationConfiguration InitializeFrom(string[] args)
+        {
+            if (args.Length < 3)
+                throw new DemoApplicationConfigurationException("Must have atleast: 1 flag, 1 path, 1 output filename");
+
+            var outputFileName = new FileInfo(args.Last());
+
+            // Remove last file-name arg, to get a more consistent array
+            args = args.SkipLast(1).ToArray();
+
+
+            string[] givenFlags = args.Where((value, index) => index % 2 == 0).ToArray();
+            string[] givenFilePaths = args.Where((value, index) => index % 2 != 0).ToArray();
+            
+            try
+            {
+                if ( givenFlags.Length == 1 && givenFlags[0].Equals("-d") ) {
+                string[] filesInDirectory = Directory.GetFiles(givenFilePaths[0]);
+                return new DemoApplicationConfiguration {
+                    OutputFile = outputFileName,
+                    JsonFilesInfo = filesInDirectory.Select(name => new FileInfo(name)).ToArray(),
+                };
+            }
+                else if (givenFlags.All((string flag) => flag.Equals("-f"))) {
+                    return new DemoApplicationConfiguration {
+                        OutputFile = outputFileName,
+                        JsonFilesInfo = givenFilePaths.Select(name => new FileInfo(name)).ToArray(),
+                    };
+                }
+                else {
+                    throw new DemoApplicationConfigurationException("Must have either 1 flag that is '-d', of all flags must be '-f");
+                }
+            }
+            catch (System.Exception e)
+            {
+                Console.WriteLine("Something else went wrong");
+                throw;
+            }
+        }
+
+
+        private static bool canCreateFile(string filename) {
+            try
+            {
+                using (File.Create(filename)) {
+                    File.Delete(filename);
+                    return true;
+                }            
+            }
+            catch
+            {
+                return false;
+            }
+        }
+
+        [Serializable]
+        internal sealed class DemoApplicationConfigurationException : Exception
+        {
+            public DemoApplicationConfigurationException()
+            {
+            }
+
+            public DemoApplicationConfigurationException(string? message) : base(message)
+            {
+            }
+        }
+    }
+}