Add database log file

Elwig/Helpers/AppDbContext.cs

@@ -2,6 +2,10 @@ using Microsoft.EntityFrameworkCore;
 using Elwig.Models;
 using System.Linq;
 using System.Threading.Tasks;
+using System.IO;
+using System;
+using System.Windows;
+using Microsoft.Extensions.Logging;
 
 namespace Elwig.Helpers {
     public class AppDbContext : DbContext {
@@ -29,12 +33,38 @@ namespace Elwig.Helpers {
         public DbSet<WineVar> WineVarieties { get; set; }
         public DbSet<Season> Seasons { get; set; }
 
+        private readonly StreamWriter? LogFile = null;
+
+        public AppDbContext() {
+            if (App.Config.DatabaseLog != null) {
+                try {
+                    var file = File.Open(App.Config.DatabaseLog, FileMode.Append, FileAccess.Write, FileShare.Write);
+                    LogFile = new(file) {
+                        AutoFlush = true
+                    };
+                } catch (Exception e) {
+                    MessageBox.Show($"Unable to open database log file:\n\n{e}", "Database Log", MessageBoxButton.OK, MessageBoxImage.Error);
+                }
+            }
+        }
+
         protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
             optionsBuilder.UseSqlite($"Data Source=\"{App.Config.DatabaseFile}\"; Foreign Keys=True; Mode=ReadWrite; Cache=Default");
             optionsBuilder.UseLazyLoadingProxies();
+            optionsBuilder.LogTo(Log, LogLevel.Information);
             base.OnConfiguring(optionsBuilder);
         }
 
+        public override void Dispose() {
+            base.Dispose();
+            LogFile?.Dispose();
+            GC.SuppressFinalize(this);
+        }
+
+        protected void Log(string msg) {
+            LogFile?.WriteLine(msg);
+        }
+
         public async Task<bool> MgNrExists(int mgnr) {
             return await Members.FindAsync(mgnr) != null;
         }