From 5c2cb331c8846e4d31983ff7e6516a0156214d33 Mon Sep 17 00:00:00 2001
From: Abdullah Atta <abdullahatta@streetwriters.co>
Date: Mon, 18 Dec 2023 15:11:20 +0500
Subject: [PATCH] web: add support for exporting sql database

---
 apps/web/src/common/sqlite/sqlite-export.ts | 101 ++++++++++++++++++++
 apps/web/src/common/sqlite/sqlite.kysely.ts |   4 +
 apps/web/src/common/sqlite/sqlite.worker.ts |  19 +++-
 3 files changed, 119 insertions(+), 5 deletions(-)
 create mode 100644 apps/web/src/common/sqlite/sqlite-export.ts

diff --git a/apps/web/src/common/sqlite/sqlite-export.ts b/apps/web/src/common/sqlite/sqlite-export.ts
new file mode 100644
index 000000000..1f0ab0f2d
--- /dev/null
+++ b/apps/web/src/common/sqlite/sqlite-export.ts
@@ -0,0 +1,101 @@
+/*
+This file is part of the Notesnook project (https://notesnook.com/)
+
+Copyright (C) 2023 Streetwriters (Private) Limited
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+import * as VFS from "./VFS";
+
+export class DatabaseSource {
+  isDone;
+
+  #vfs;
+  #path;
+  #fileId = Math.floor(Math.random() * 0x100000000);
+  #iOffset = 0;
+  #bytesRemaining = 0;
+
+  #onDone: (() => Promise<unknown> | unknown)[] = [];
+  #resolve!: (value: unknown) => void;
+  #reject!: (reason?: unknown) => void;
+
+  constructor(vfs: VFS.Base, path: string) {
+    this.#vfs = vfs;
+    this.#path = path;
+    this.isDone = new Promise((resolve, reject) => {
+      this.#resolve = resolve;
+      this.#reject = reject;
+    }).finally(async () => {
+      while (this.#onDone.length) {
+        await this.#onDone.pop()?.();
+      }
+    });
+  }
+
+  async start(controller: ReadableStreamDefaultController) {
+    try {
+      // Open the file for reading.
+      const flags = VFS.SQLITE_OPEN_MAIN_DB | VFS.SQLITE_OPEN_READONLY;
+      await check(
+        this.#vfs.xOpen(this.#path, this.#fileId, flags, {
+          setInt32() {}
+        } as unknown as DataView)
+      );
+      this.#onDone.push(() => this.#vfs.xClose(this.#fileId));
+      await check(this.#vfs.xLock(this.#fileId, VFS.SQLITE_LOCK_SHARED));
+      this.#onDone.push(() =>
+        this.#vfs.xUnlock(this.#fileId, VFS.SQLITE_LOCK_NONE)
+      );
+
+      // Get the file size.
+      const fileSize = new DataView(new ArrayBuffer(8));
+      await check(this.#vfs.xFileSize(this.#fileId, fileSize));
+      this.#bytesRemaining = Number(fileSize.getBigUint64(0, true));
+    } catch (e) {
+      controller.error(e);
+      this.#reject(e);
+    }
+  }
+
+  async pull(controller: ReadableStreamDefaultController) {
+    try {
+      const buffer = new Uint8Array(Math.min(this.#bytesRemaining, 65536));
+      await check(this.#vfs.xRead(this.#fileId, buffer, this.#iOffset));
+      console.log("reading", buffer);
+      controller.enqueue(buffer);
+
+      this.#iOffset += buffer.byteLength;
+      this.#bytesRemaining -= buffer.byteLength;
+      if (this.#bytesRemaining === 0) {
+        controller.close();
+        this.#resolve(undefined);
+      }
+    } catch (e) {
+      controller.error(e);
+      this.#reject(e);
+    }
+  }
+
+  cancel(reason?: any) {
+    this.#reject(new Error(reason));
+  }
+}
+
+async function check(code: Promise<number> | number) {
+  if ((await code) !== VFS.SQLITE_OK) {
+    throw new Error(`Error code: ${await code}`);
+  }
+}
diff --git a/apps/web/src/common/sqlite/sqlite.kysely.ts b/apps/web/src/common/sqlite/sqlite.kysely.ts
index 075024d3e..29b1517ec 100644
--- a/apps/web/src/common/sqlite/sqlite.kysely.ts
+++ b/apps/web/src/common/sqlite/sqlite.kysely.ts
@@ -77,6 +77,10 @@ export class WaSqliteWorkerDriver implements Driver {
     }
     return await this.worker.close();
   }
+
+  async export() {
+    return this.worker.export(this.config.dbName, this.config.async);
+  }
 }
 
 class ConnectionMutex {
diff --git a/apps/web/src/common/sqlite/sqlite.worker.ts b/apps/web/src/common/sqlite/sqlite.worker.ts
index e7f904d26..3a4557d24 100644
--- a/apps/web/src/common/sqlite/sqlite.worker.ts
+++ b/apps/web/src/common/sqlite/sqlite.worker.ts
@@ -23,9 +23,10 @@ import SQLiteAsyncESMFactory from "./wa-sqlite-async";
 import SQLiteSyncESMFactory from "./wa-sqlite";
 import { IDBBatchAtomicVFS } from "./IDBBatchAtomicVFS";
 import { AccessHandlePoolVFS } from "./AccessHandlePoolVFS";
-import { expose } from "comlink";
+import { expose, transfer } from "comlink";
 import type { RunMode } from "./type";
 import { QueryResult } from "kysely";
+import { DatabaseSource } from "./sqlite-export";
 
 type PreparedStatement = {
   stmt: number;
@@ -87,8 +88,6 @@ async function run(sql: string, parameters?: SQLiteCompatibleType[]) {
     }
 
     return rows;
-  } catch (e) {
-    console.error(e);
   } finally {
     await sqlite
       .reset(prepared.stmt)
@@ -101,7 +100,6 @@ async function run(sql: string, parameters?: SQLiteCompatibleType[]) {
           .finally(() => preparedStatements.delete(sql))
       );
   }
-  return [];
 }
 
 async function exec<R>(
@@ -130,10 +128,21 @@ async function close() {
   await vfs?.close();
 }
 
+async function exportDatabase(dbName: string, async: boolean) {
+  const vfs = async
+    ? new IDBBatchAtomicVFS(dbName, { durability: "strict" })
+    : new AccessHandlePoolVFS(dbName);
+  if ("isReady" in vfs) await vfs.isReady;
+
+  const stream = new ReadableStream(new DatabaseSource(vfs, dbName));
+  return transfer(stream, [stream]);
+}
+
 const worker = {
   close,
   init,
-  run: exec
+  run: exec,
+  export: exportDatabase
 };
 
 export type SQLiteWorker = typeof worker;