From c79f95ac0399500f1858625379318daec0115363 Mon Sep 17 00:00:00 2001
From: Simon Binder <oss@simonbinder.eu>
Date: Fri, 2 Jun 2023 16:23:02 +0200
Subject: [PATCH] Start migrating from older storage options

---
 drift/lib/src/web/wasm_setup.dart           |  2 +-
 drift/lib/src/web/wasm_setup/migration.dart | 52 +++++++++++++++++++++
 drift/lib/src/web/wasm_setup/shared.dart    |  7 ++-
 3 files changed, 58 insertions(+), 3 deletions(-)
 create mode 100644 drift/lib/src/web/wasm_setup/migration.dart

diff --git a/drift/lib/src/web/wasm_setup.dart b/drift/lib/src/web/wasm_setup.dart
index 6138eafc..41360753 100644
--- a/drift/lib/src/web/wasm_setup.dart
+++ b/drift/lib/src/web/wasm_setup.dart
@@ -110,7 +110,7 @@ Future<WasmDatabaseResult> openWasmDatabase({
 
     return WasmDatabaseResult(
       DatabaseConnection(
-        WasmDatabase(sqlite3: sqlite3, path: '/app.db'),
+        WasmDatabase(sqlite3: sqlite3, path: '/database'),
       ),
       WasmStorageImplementation.inMemory,
       missingFeatures,
diff --git a/drift/lib/src/web/wasm_setup/migration.dart b/drift/lib/src/web/wasm_setup/migration.dart
new file mode 100644
index 00000000..2dbbce1c
--- /dev/null
+++ b/drift/lib/src/web/wasm_setup/migration.dart
@@ -0,0 +1,52 @@
+import 'dart:typed_data';
+
+import 'package:sqlite3/wasm.dart';
+
+import 'shared.dart';
+
+const paths = {'/database', '/database-journal'};
+
+
+
+/// Migrates the drift database identified by [databaseName] from the IndexedDB
+/// storage implementation to the OPFS storage implementation.
+///
+/// Must be called in a dedicated worker, as only those have access to OPFS.
+Future<void> migrateFromIndexedDbToOpfs(String databaseName) async {
+
+}
+
+/// Migrates the drift database identified by [databaseName] from the OPFS
+/// storage implementation back to IndexedDB.
+///
+/// Must be called in a dedicated worker, as only those have access to OPFS.
+Future<void> migrateFromOpfsToIndexedDb(String databaseName) async {
+  final opfs =
+      await SimpleOpfsFileSystem.loadFromStorage(pathForOpfs(databaseName));
+  final indexedDb = await IndexedDbFileSystem.open(dbName: databaseName);
+
+  await _migrate(opfs, indexedDb);
+}
+
+Future<void> _migrate(
+    VirtualFileSystem source, VirtualFileSystem target) async {
+  for (final path in paths) {
+    if (target.xAccess(path, 0) != 0) {
+      target.xDelete(path, 0);
+    }
+
+    if (source.xAccess(path, 0) != 0) {
+      final (file: sourceFile, outFlags: _) =
+          source.xOpen(Sqlite3Filename(path), SqlFlag.SQLITE_OPEN_CREATE);
+      final (file: targetFile, outFlags: _) =
+          target.xOpen(Sqlite3Filename(path), SqlFlag.SQLITE_OPEN_CREATE);
+
+      final buffer = Uint8List(sourceFile.xFileSize());
+      sourceFile.xRead(buffer, 0);
+      targetFile.xWrite(buffer, 0);
+
+      sourceFile.xClose();
+      targetFile.xClose();
+    }
+  }
+}
diff --git a/drift/lib/src/web/wasm_setup/shared.dart b/drift/lib/src/web/wasm_setup/shared.dart
index e83fe444..1b32c4b1 100644
--- a/drift/lib/src/web/wasm_setup/shared.dart
+++ b/drift/lib/src/web/wasm_setup/shared.dart
@@ -79,6 +79,10 @@ Future<bool> checkIndexedDbSupport() async {
   return true;
 }
 
+String pathForOpfs(String databaseName) {
+  return '/drift_db/${databaseName}';
+}
+
 class DriftServerController {
   /// Running drift servers by the name of the database they're serving.
   final Map<String, DriftServer> _servers = {};
@@ -90,8 +94,7 @@ class DriftServerController {
 
         final vfs = await switch (message.storage) {
           WasmStorageImplementation.opfsShared =>
-            SimpleOpfsFileSystem.loadFromStorage(
-                '/drift_db/${message.databaseName}'),
+            SimpleOpfsFileSystem.loadFromStorage(message.databaseName),
           WasmStorageImplementation.opfsLocks => _loadLockedWasmVfs(),
           WasmStorageImplementation.unsafeIndexedDb ||
           WasmStorageImplementation.sharedIndexedDb =>