add expo sqlite3. work on settings.

app/lib/conversation.ts

@@ -1,7 +1,7 @@
 import { Translator } from "../i18n/api";
 
 export type Speaker = {
-    id: string,
+    id: "host" | "guest",
     language : string,
 }
 

app/lib/db.ts

@@ -0,0 +1,33 @@
+import * as SQLite from "react-native-sqlite-storage"
+
+SQLite.enablePromise(true);
+
+export const MIGRATE_UP = {
+    1: [
+        `CREATE TABLE IF NOT EXIST settings (
+            host_language TEXT,
+            libretranslate_base_url TEXT,
+            ui_direction INTEGER
+        )`,
+    ]
+}
+
+export const MIGRATE_DOWN = {
+    1: [
+        `DROP TABLE IF EXISTS settings`
+    ]
+}
+
+export async function getDb(migrationDirection : "up" | "down" = "up") {
+    const db = await SQLite.openDatabase({
+        name: "translation_terrace",
+    });
+
+    for (let [migration, statements] of Object.entries(MIGRATE_UP)) {
+        for (let statement of statements) {
+            await db.transaction(async (tx) => {
+                await tx.executeSql(statement)
+            });
+        }
+    }
+}