Add AppDbUpdater

2023-09-17 20:48:07 +02:00
parent dc215d3350
commit 24b7078a05
3 changed files with 111 additions and 20 deletions
--- a/Elwig/Helpers/AppDbUpdater.cs
+++ b/Elwig/Helpers/AppDbUpdater.cs
@ -0,0 +1,78 @@
+using Microsoft.Data.Sqlite;
+using System;
+
+namespace Elwig.Helpers {
+    public static class AppDbUpdater {
+
+        public static readonly int RequiredSchemaVersion = 1;
+
+        private static int _versionOffset = 0;
+        private static readonly Action<SqliteConnection>[] _updaters = new[] {
+            UpdateDbSchema_1_To_2, UpdateDbSchema_2_To_3
+        };
+
+        private static void ExecuteNonQuery(SqliteConnection cnx, string sql) {
+            using var cmd = cnx.CreateCommand();
+            cmd.CommandText = sql;
+            cmd.ExecuteNonQuery();
+        }
+
+        private static object? ExecuteScalar(SqliteConnection cnx, string sql) {
+            using var cmd = cnx.CreateCommand();
+            cmd.CommandText = sql;
+            return cmd.ExecuteScalar();
+        }
+
+        public static string CheckDb() {
+            using var cnx = AppDbContext.Connect();
+
+            var applId = (long?)ExecuteScalar(cnx, "PRAGMA application_id") ?? 0;
+            if (applId != 0x454C5747) throw new Exception("Invalid application_id of database");
+
+            var schemaVers = (long?)ExecuteScalar(cnx, "PRAGMA schema_version") ?? 0;
+            _versionOffset = (int)(schemaVers % 100);
+            if (_versionOffset != 0) {
+                // schema was modified manually/externally
+                // TODO issue warning
+            }
+            UpdateDbSchema(cnx, (int)(schemaVers / 100), RequiredSchemaVersion);
+
+            var userVers = (long?)ExecuteScalar(cnx, "PRAGMA user_version") ?? 0;
+            var major = userVers >> 24;
+            var minor = (userVers >> 16) & 0xFF;
+            var patch = userVers & 0xFFFF;
+
+            if (App.VersionMajor > major || App.VersionMinor > minor || App.VersionPatch > patch) {
+                long vers = (App.VersionMajor << 24) | (App.VersionMinor << 16) | App.VersionPatch;
+                ExecuteNonQuery(cnx, $"PRAGMA user_version = {vers}");
+            }
+
+            return $"{major}.{minor}.{patch}";
+        }
+
+        private static void UpdateDbSchema(SqliteConnection cnx, int fromVersion, int toVersion) {
+            if (fromVersion == toVersion) {
+                return;
+            } else if (fromVersion > toVersion) {
+                throw new Exception("schema_version of database is too new");
+            } else if (toVersion - 1 > _updaters.Length) {
+                throw new Exception("Unable to update database schema: Updater not implemented");
+            } else if (fromVersion <= 0) {
+                throw new Exception("schema_version of database is invalid");
+            }
+
+            ExecuteNonQuery(cnx, "PRAGMA locking_mode = EXCLUSIVE");
+            ExecuteNonQuery(cnx, "BEGIN EXCLUSIVE");
+            for (int i = fromVersion; i < toVersion; i++) {
+                _updaters[i - 1](cnx);
+            }
+            ExecuteNonQuery(cnx, "COMMIT");
+            ExecuteNonQuery(cnx, "VACUUM");
+            ExecuteNonQuery(cnx, $"PRAGMA schema_version = {toVersion * 100 + _versionOffset}");
+        }
+
+        private static void UpdateDbSchema_1_To_2(SqliteConnection cnx) { }
+
+        private static void UpdateDbSchema_2_To_3(SqliteConnection cnx) { }
+    }
+}