MemberAdminWindow: Add pending member movement export

Elwig/Helpers/Export/MemberMovement.cs

@@ -0,0 +1,29 @@
+using Elwig.Models.Dtos;
+using Elwig.Models.Entities;
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+namespace Elwig.Helpers.Export {
+    public class MemberMovement : IExporter<MemberHistory> {
+
+        public static string FileExtension => "ods";
+
+        private readonly OdsFile _ods;
+
+        public MemberMovement(string filename) {
+            _ods = new OdsFile(filename);
+        }
+
+        public void Dispose() {
+            GC.SuppressFinalize(this);
+            _ods.Dispose();
+        }
+
+        public async Task ExportAsync(IEnumerable<MemberHistory> data, IProgress<double>? progress = null) {
+            using var ctx = new AppDbContext();
+            var tbl = MemberMovementData.FromMemberHistory("", data, await ctx.GetMemberHistory());
+            await _ods.AddTable(tbl);
+        }
+    }
+}