From 055216401836c1b7e6dd89b58f207b9741e9be35 Mon Sep 17 00:00:00 2001
From: didierfranc <didier@agnostic.engineering>
Date: Mon, 6 Jan 2025 14:54:47 +0100
Subject: [PATCH] feat: add unsubscribe

---
 README.md       | 12 ++++++++----
 src/sql.spec.ts | 15 +++++++++++++++
 src/sqlite.ts   | 10 ++++++++--
 3 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 23b5b81..9445fca 100644
--- a/README.md
+++ b/README.md
@@ -54,11 +54,14 @@ async function example() {
   const results = await db.exec('SELECT * FROM users');
   console.log(results);
 
-  // Add callback for exec events
-  db.on('exec', (args) => {
+  // Add callback for exec events with unsubscribe
+  const unsubscribe = db.on('exec', (args) => {
     console.log('Query executed:', args[0]);
     console.log('Bindings:', args[1]);
   });
+
+  // Later unsubscribe when done
+  unsubscribe();
 }
 ```
 
@@ -106,13 +109,14 @@ Executes an SQL query and returns the results as an array of objects.
   - `bind`: Optional binding parameters
 - **Returns:** Promise resolving to an array of row objects
 
-##### `on(event: "exec", callback: (args: any[]) => void): void`
+##### `on(event: "exec", callback: (args: any[]) => void): () => void`
 
-Subscribes to database events.
+Subscribes to database events and returns an unsubscribe function.
 
 - **Parameters:**
   - `event`: Event type ("exec")
   - `callback`: Function called when event occurs
+- **Returns:** Function that when called will unsubscribe the callback
 
 ##### `export_db(): Promise<Uint8Array>`
 
diff --git a/src/sql.spec.ts b/src/sql.spec.ts
index f6250f5..b0a9692 100644
--- a/src/sql.spec.ts
+++ b/src/sql.spec.ts
@@ -2,6 +2,21 @@ import { describe, it, expect, vi } from "vitest";
 import { SQLite } from "./sqlite";
 
 describe("SQLite database operations", () => {
+  it("should test unsubscribe functionality", async () => {
+    const db = new SQLite();
+
+    const execCallback = vi.fn();
+    const unsubscribe = db.on("exec", execCallback);
+
+    await db.exec(`SELECT 1`);
+    expect(execCallback).toHaveBeenCalledTimes(1);
+
+    unsubscribe();
+
+    await db.exec(`SELECT 2`);
+    expect(execCallback).toHaveBeenCalledTimes(1);
+  });
+
   it("should perform database operations and verify exports match", async () => {
     const db = new SQLite();
 
diff --git a/src/sqlite.ts b/src/sqlite.ts
index 942b2ae..f181404 100644
--- a/src/sqlite.ts
+++ b/src/sqlite.ts
@@ -58,9 +58,15 @@ export class SQLite {
     });
   }
 
-  on(event: "exec", callback: (args: Args) => void): void {
+  on(event: "exec", callback: (args: Args) => void): () => void {
     if (!this.callbacks[event]) this.callbacks[event] = [];
-    this.callbacks[event].push(callback);
+    const callbacks = this.callbacks[event];
+    callbacks.push(callback);
+
+    return () => {
+      const filtered = callbacks.filter((cb) => cb !== callback);
+      this.callbacks[event] = filtered;
+    };
   }
 
   async export_db(): Promise<Uint8Array> {