AppDbUpdater: Fix handling of foreign key errors

Elwig/Helpers/AppDbUpdater.cs

@@ -1,6 +1,6 @@
-using Microsoft.Data.Sqlite;
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Threading.Tasks;
@@ -14,31 +14,36 @@ namespace Elwig.Helpers {
         private static int VersionOffset = 0;
 
         public static async Task<Version> CheckDb() {
-            using var cnx = AppDbContext.Connect();
+            long? applId, schemaVers;
-
+            using (var cnx = await AppDbContext.ConnectAsync()) {
-            var applId = (long?)await cnx.ExecuteScalar("PRAGMA application_id") ?? 0;
+                applId = (long?)await cnx.ExecuteScalar("PRAGMA application_id") ?? 0;
                 if (applId != 0x454C5747) throw new Exception($"Invalid application_id in database (0x{applId:X08})");
 
-            var schemaVers = (long?)await cnx.ExecuteScalar("PRAGMA schema_version") ?? 0;
+                schemaVers = (long?)await cnx.ExecuteScalar("PRAGMA schema_version") ?? 0;
                 VersionOffset = (int)(schemaVers % 100);
                 if (VersionOffset != 0) {
                     // schema was modified manually/externally
                     // TODO issue warning
                 }
-            await UpdateDbSchema(cnx, (int)(schemaVers / 100), RequiredSchemaVersion);
+            }
 
+            await UpdateDbSchema((int)(schemaVers / 100), RequiredSchemaVersion);
+
+            Version v;
+            using (var cnx = await AppDbContext.ConnectAsync()) {
                 var userVers = (long?)await cnx.ExecuteScalar("PRAGMA user_version") ?? 0;
-            var v = new Version((int)(userVers >> 24), (int)((userVers >> 16) & 0xFF), (int)((userVers >> 8) & 0xFF), (int)(userVers & 0xFF));
+                v = new Version((int)(userVers >> 24), (int)((userVers >> 16) & 0xFF), (int)((userVers >> 8) & 0xFF), (int)(userVers & 0xFF));
 
                 if (App.Version > v) {
                     long vers = (App.Version.Major << 24) | (App.Version.Minor << 16) | (App.Version.Build << 8) | App.Version.Revision;
                     await cnx.ExecuteBatch($"PRAGMA user_version = {vers}");
                 }
+            }
 
             return v;
         }
 
-        private static async Task UpdateDbSchema(SqliteConnection cnx, int fromVersion, int toVersion) {
+        private static async Task UpdateDbSchema(int fromVersion, int toVersion) {
             if (fromVersion == toVersion) {
                 return;
             } else if (fromVersion > toVersion) {
@@ -48,43 +53,48 @@ namespace Elwig.Helpers {
             }
 
             var asm = Assembly.GetExecutingAssembly();
-            (int From, int To, string Name)[] scripts = asm.GetManifestResourceNames()
+            (int From, int To, string Name)[] scripts = [.. asm.GetManifestResourceNames()
                 .Where(n => n.StartsWith("Elwig.Resources.Sql."))
                 .Select(n => {
                     var p = n.Split(".")[^2].Split("-");
                     return (int.Parse(p[0]), int.Parse(p[1]), n);
                 })
-                .OrderBy(s => s.Item1).ThenBy(s => s.Item2)
+                .OrderBy(s => s.Item1).ThenBy(s => s.Item2)];
-                .ToArray();
 
             List<string> toExecute = [];
             var vers = fromVersion;
             while (vers < toVersion) {
-                var (_, to, name) = scripts.Where(s => s.From == vers).Last();
+                var (_, to, name) = scripts.Last(s => s.From == vers);
                 toExecute.Add(name);
                 vers = to;
             }
             if (toExecute.Count == 0)
                 return;
 
-            await cnx.ExecuteBatch("""
+            var backup = Path.ChangeExtension(App.Config.DatabaseFile, $".v{fromVersion}.sqlite3");
-                PRAGMA locking_mode = EXCLUSIVE;
+            File.Copy(App.Config.DatabaseFile, backup, true);
-                BEGIN EXCLUSIVE;
+            try {
-                """);
+                using var cnx = await AppDbContext.ConnectAsync();
+                await cnx.ExecuteBatch("PRAGMA locking_mode = EXCLUSIVE");
                 foreach (var script in toExecute) {
                     await cnx.ExecuteEmbeddedScript(asm, script);
                 }
+
                 var violations = await cnx.ForeignKeyCheck();
                 if (violations.Length > 0) {
                     throw new Exception($"Foreign key violations ({violations.Length}):\n" + string.Join("\n", violations
+                        .Take(50)
                         .Select(v => $"{v.Table} - {v.RowId} - {v.Parent} - {v.FkId}")));
                 }
 
-            await cnx.ExecuteBatch($"""
+                await cnx.ExecuteBatch("VACUUM");
-                COMMIT;
+                await cnx.ExecuteBatch($"PRAGMA schema_version = {toVersion * 100 + VersionOffset}");
-                VACUUM;
+            } catch (Exception) {
-                PRAGMA schema_version = {toVersion * 100 + VersionOffset};
+                File.Move(backup, App.Config.DatabaseFile, true);
-                """);
+                throw;
+            } finally {
+                File.Delete(backup);
+            }
         }
     }
 }