Refactor authWithMetamask to enhance modularity and introduce logout functionality

src/lib/services/authWithMetamask/README.md

@@ -0,0 +1,78 @@
+# authWithMetamask.ts Documentation
+
+This module provides utility functions for handling authentication signatures (AuthSigs) with MetaMask using the `@lit-protocol/lit-node-client`.
+
+## Table of Contents
+- [authWithMetamask.ts Documentation](#authwithmetamaskts-documentation)
+  - [Table of Contents](#table-of-contents)
+  - [Dependencies](#dependencies)
+  - [Functions](#functions)
+    - [generateAuthSig](#generateauthsig)
+    - [getStoredAuthSig](#getstoredauthsig)
+    - [logout](#logout)
+  - [Usage](#usage)
+
+## Dependencies
+- `@lit-protocol/lit-node-client`: Used to interact with the Lit Protocol and sign authentication messages.
+- `@lit-protocol/constants`: Provides constants used in this module, specifically `LOCAL_STORAGE_KEYS.AUTH_SIGNATURE` for local storage key.
+
+## Functions
+
+### generateAuthSig
+**Description:** 
+This asynchronous function initiates the signing of an authentication message using MetaMask and stores the signed message (AuthSig) in the browser's local storage.
+
+**Returns:** 
+An `authSig` object containing the signed message if successful.
+
+**Throws:** 
+An error with a descriptive message if the signing process fails.
+
+### getStoredAuthSig
+**Description:** 
+Retrieves the stored AuthSig from the browser's local storage.
+
+**Returns:** 
+A parsed `authSig` object if found, or `null` if not.
+
+### logout
+**Description:** 
+Clears the stored AuthSig from the browser's local storage.
+
+**Returns:** 
+`void`
+
+## Usage
+
+To use the `authWithMetamask.ts` module in a Svelte component:
+
+```svelte
+<script>
+	import { onMount } from 'svelte';
+	import {
+		generateAuthSig,
+		getStoredAuthSig,
+		logout
+	} from '$lib/services/authWithMetamask/authWithMetamask';
+
+	let authSig = null;
+	let error = null;
+
+	async function handleAuth() {
+		try {
+			authSig = await generateAuthSig();
+		} catch (err) {
+			error = err.message;
+		}
+	}
+
+	function handleLogout() {
+		logout();
+		authSig = null;
+	}
+
+	onMount(() => {
+		authSig = getStoredAuthSig();
+	});
+</script>
+```

src/lib/services/authWithMetamask/authWithMetamask.ts

@@ -0,0 +1,61 @@
+import { checkAndSignAuthMessage } from '@lit-protocol/lit-node-client';
+import { LOCAL_STORAGE_KEYS } from '@lit-protocol/constants';
+
+function createMessage({ text, sender, type }: { text: string; sender: string; type: string }) {
+    console.log(`[${type}] - ${sender} - ${text}`);
+}
+
+export async function generateAuthSig(): Promise<any> {
+    createMessage({
+        text: "Attempting to generate AuthSig using MetaMask.",
+        sender: '$lib/services/authWithMetamask/authWithMetamask.ts',
+        type: 'SYSTEM'
+    });
+
+    try {
+        const authSig = await checkAndSignAuthMessage({ chain: 'xdai' });
+
+        createMessage({
+            text: "AuthSig generated and storing in local storage.",
+            sender: '$lib/services/authWithMetamask/authWithMetamask.ts',
+            type: 'SYSTEM'
+        });
+
+        localStorage.setItem(LOCAL_STORAGE_KEYS.AUTH_SIGNATURE, JSON.stringify(authSig));
+        return authSig;
+    } catch (err) {
+        console.error(err);
+
+        createMessage({
+            text: `Failed to sign auth message: ${err.message}`,
+            sender: '$lib/services/authWithMetamask/authWithMetamask.ts',
+            type: 'ERROR'
+        });
+
+        throw new Error(`Failed to sign auth message: ${err.message}`);
+    }
+}
+
+export function getStoredAuthSig(): any | null {
+    createMessage({
+        text: "Fetching stored AuthSig from local storage.",
+        sender: '$lib/services/authWithMetamask/authWithMetamask.ts',
+        type: 'SYSTEM'
+    });
+
+    const storedAuthSig = localStorage.getItem(LOCAL_STORAGE_KEYS.AUTH_SIGNATURE);
+    if (storedAuthSig) {
+        return JSON.parse(storedAuthSig);
+    }
+    return null;
+}
+
+export function logout(): void {
+    createMessage({
+        text: "Clearing AuthSig from local storage.",
+        sender: '$lib/services/authWithMetamask/authWithMetamask.ts',
+        type: 'SYSTEM'
+    });
+
+    localStorage.removeItem(LOCAL_STORAGE_KEYS.AUTH_SIGNATURE);
+}