From cf1a83006e8dd85b1890e45444b224dd7e29daf2 Mon Sep 17 00:00:00 2001
From: Samuel Andert <samuel@ora.earth>
Date: Mon, 24 Jul 2023 11:51:39 +0200
Subject: [PATCH] Refactor authWithMetamask to enhance modularity and introduce
 logout functionality

---
 src/lib/components/Login/Login.svelte         | 63 +++++++++++++++
 src/lib/services/authWithMetamask/README.md   | 78 +++++++++++++++++++
 .../authWithMetamask/authWithMetamask.ts      | 61 +++++++++++++++
 src/routes/+page.svelte                       |  6 +-
 4 files changed, 205 insertions(+), 3 deletions(-)
 create mode 100644 src/lib/components/Login/Login.svelte
 create mode 100644 src/lib/services/authWithMetamask/README.md
 create mode 100644 src/lib/services/authWithMetamask/authWithMetamask.ts

diff --git a/src/lib/components/Login/Login.svelte b/src/lib/components/Login/Login.svelte
new file mode 100644
index 0000000..b8fdaf2
--- /dev/null
+++ b/src/lib/components/Login/Login.svelte
@@ -0,0 +1,63 @@
+<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>
+
+<!-- AuthSig Address Displayed -->
+{#if authSig}
+	<div class="flex items-center p-4 mb-4 bg-gray-100 rounded-lg shadow-md">
+		<p class="font-medium text-gray-700">
+			Metamask Address: <span class="text-orange-500">{authSig.address}</span>
+		</p>
+		<button
+			class="px-4 py-2 ml-4 font-bold text-white bg-red-500 rounded-lg shadow-lg hover:bg-red-600"
+			on:click={handleLogout}
+		>
+			Logout
+		</button>
+	</div>
+	<!-- Error Message -->
+{:else if error}
+	<div class="flex items-center p-4 mb-4 bg-red-100 rounded-lg shadow-md">
+		<p class="font-medium text-red-700">{error}</p>
+	</div>
+	<!-- Login Button -->
+{:else}
+	<div class="flex justify-center">
+		<button
+			class="flex items-center px-4 py-2 m-2 font-bold text-white bg-orange-500 rounded-lg shadow-lg hover:bg-orange-600"
+			on:click={handleAuth}
+		>
+			<img
+				src="https://upload.wikimedia.org/wikipedia/commons/3/36/MetaMask_Fox.svg"
+				alt="MetaMask"
+				class="w-6 h-6 mr-2"
+			/>
+			<span class="text-lg">Login</span>
+		</button>
+	</div>
+{/if}
diff --git a/src/lib/services/authWithMetamask/README.md b/src/lib/services/authWithMetamask/README.md
new file mode 100644
index 0000000..a951e2b
--- /dev/null
+++ b/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>
+```
\ No newline at end of file
diff --git a/src/lib/services/authWithMetamask/authWithMetamask.ts b/src/lib/services/authWithMetamask/authWithMetamask.ts
new file mode 100644
index 0000000..31dad90
--- /dev/null
+++ b/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);
+}
diff --git a/src/routes/+page.svelte b/src/routes/+page.svelte
index 8fd8467..046c999 100644
--- a/src/routes/+page.svelte
+++ b/src/routes/+page.svelte
@@ -4,7 +4,7 @@
 	let componentsData = {
 		layout: `
 			grid-template-areas: 
-				"app",
+				"login",
 				"main"
 				"footer";
 			grid-template-rows: 150px 1fr auto;
@@ -12,9 +12,9 @@
 		children: [
 			{
 				id: 1,
-				componentName: 'GoogleAuth',
+				componentName: 'Login',
 				props: {},
-				slot: 'app'
+				slot: 'login'
 			},
 			{
 				id: 2,