Вытащил солюшен на уровень выше, чтобы прощё было дотнетить

Infrastructure/EntityToExcelTemplateWriter/ExcelWriter.cs

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+using System.Reflection;
+using System.Text;
+using ApplicationLayer.Services.VisaApplications.NeededServices;
+using DocumentFormat.OpenXml.Packaging;
+using DocumentFormat.OpenXml.Spreadsheet;
+
+namespace Infrastructure.EntityToExcelTemplateWriter
+{
+    /// <summary>
+    /// Writes object to excel using template.xlsx file and reflections
+    /// </summary>
+    public class ExcelWriter : IEntityWriter
+    {
+        private const char InsertionSymbol = '$';
+        private readonly char[] endChars = [',', ';'];
+
+        /// <summary>
+        /// Write object to stream in Excel table format
+        /// </summary>
+        /// <param name="entity"> object to write </param>
+        /// <param name="cancellationToken"> cancellation token </param>
+        /// <returns> Stream with template.xlsx file with replaced entries like '$EntityPropName.AnotherProp' </returns>
+        /// <exception cref="NullReferenceException"> thrown when template file is incorrect </exception>
+        /// <exception cref="InvalidOperationException"> thrown if any property path in template is incorrect</exception>
+        public async Task<Stream> WriteEntityToStream(object entity, CancellationToken cancellationToken)
+        {
+            var outStream = new MemoryStream();
+            await using (var stream = File.Open("template.xlsx", FileMode.Open, FileAccess.Read))
+            {
+                await stream.CopyToAsync(outStream, cancellationToken);
+            }
+
+            using var spreadsheetDocument = SpreadsheetDocument.Open(outStream, true);
+
+            var workbookPart = spreadsheetDocument.WorkbookPart
+                               ?? throw new NullReferenceException("There is no workbook part in document");
+            var shareStringTable = workbookPart.SharedStringTablePart?.SharedStringTable ??
+                                   throw new NullReferenceException("There is no data in document");
+            var shareStringTableItems = shareStringTable.Elements<SharedStringItem>().ToArray();
+
+            foreach (var item in shareStringTableItems)
+            {
+                if (string.IsNullOrEmpty(item.InnerText))
+                {
+                    continue;
+                }
+
+                var entries = item.InnerText.Split();
+                for (var i = 0; i < entries.Length; i++)
+                {
+                    var entry = entries[i];
+                    if (entry.FirstOrDefault() is not InsertionSymbol || entry.Length <= 1)
+                    {
+                        continue;
+                    }
+
+                    entry = entry[1..];
+                    var trimmedCount = entry.Length - entry.TrimEnd(endChars).Length;
+                    var trimmed = entry[^trimmedCount..];
+                    entry = entry.TrimEnd(endChars);
+
+                    var memberPath = entry.Split('.');
+
+                    var value = GetValueFor(entity, memberPath.First());
+                    var stringToInsert = "None";
+                    foreach (var memberName in memberPath.Skip(1))
+                    {
+                        if (value is null)
+                        {
+                            break;
+                        }
+
+                        value = GetValueFor(value, memberName);
+                    }
+
+                    if (value is not null)
+                    {
+                        switch (value)
+                        {
+                            case DateTime date:
+                                stringToInsert = date.ToShortDateString();
+                                break;
+                            case Enum val:
+                                var enumString = val.ToString();
+                                var stringBuilder = new StringBuilder();
+                                for (var charIndex = 0; charIndex < enumString.Length - 1; charIndex++)
+                                {
+                                    stringBuilder.Append(enumString[charIndex]);
+                                    if (char.IsUpper(enumString[charIndex + 1]))
+                                    {
+                                        stringBuilder.Append(' ');
+                                    }
+                                }
+
+                                stringBuilder.Append(enumString.Last());
+
+                                stringToInsert = stringBuilder.ToString();
+                                break;
+                            default:
+                                stringToInsert = value.ToString();
+                                break;
+                        }
+                    }
+
+                    entries[i] = stringToInsert! + trimmed;
+                }
+
+                item.Text!.Text = string.Join(' ', entries);
+            }
+
+            spreadsheetDocument.Save();
+            return outStream;
+        }
+
+        private static object? GetValueFor(object entity, string member)
+        {
+            var memberInfo = entity.GetType()
+                                 .GetMembers()
+                                 .FirstOrDefault(p => p.Name == member)
+                             ?? throw new InvalidOperationException(
+                                 $"Invalid member path in document. Not found: {member}");
+            return memberInfo switch
+            {
+                PropertyInfo propertyInfo => propertyInfo.GetValue(entity),
+                MethodInfo methodInfo => methodInfo.Invoke(entity, []),
+                _ => throw new InvalidOperationException("Only properties and methods allowed.")
+            };
+        }
+    }
+}