feat: add snjs package

packages/snjs/lib/Migrations/StorageReaders/Functions.ts

@@ -0,0 +1,34 @@
+import { ApplicationIdentifier } from '@standardnotes/common'
+import { compareSemVersions, isRightVersionGreaterThanLeft } from '@Lib/Version'
+import { DeviceInterface, Environment } from '@standardnotes/services'
+import { StorageReader } from './Reader'
+import * as ReaderClasses from './Versions'
+
+function ReaderClassForVersion(
+  version: string,
+): typeof ReaderClasses.StorageReader2_0_0 | typeof ReaderClasses.StorageReader1_0_0 {
+  /** Sort readers by newest first */
+  const allReaders = Object.values(ReaderClasses).sort((a, b) => {
+    return compareSemVersions(a.version(), b.version()) * -1
+  })
+  for (const reader of allReaders) {
+    if (reader.version() === version) {
+      return reader
+    }
+    if (isRightVersionGreaterThanLeft(reader.version(), version)) {
+      return reader
+    }
+  }
+
+  throw Error(`Cannot find reader for version ${version}`)
+}
+
+export function CreateReader(
+  version: string,
+  deviceInterface: DeviceInterface,
+  identifier: ApplicationIdentifier,
+  environment: Environment,
+): StorageReader {
+  const readerClass = ReaderClassForVersion(version)
+  return new readerClass(deviceInterface, identifier, environment)
+}