[Plugins] Implement proper execution

src/lib/plugins.ts

@@ -1,11 +1,19 @@
 import { Indexable, PluginManifest, Plugin } from "@types";
+import logger from "./logger";
+
+type EvaledPlugin = {
+    onLoad?(): void;
+    onUnload(): void;
+};
 
 export const plugins: Indexable<Plugin> = {};
+const loadedPlugins: Indexable<EvaledPlugin> = {};
 
 export async function fetchPlugin(url: string) {
     if (!url.endsWith("/")) url += "/";
 
-    if (plugins[url]) throw new Error(`That plugin is already installed!`);
+    const id = url.split("://")[1];
+    if (typeof url !== "string" || url in plugins) throw new Error("Plugin ID invalid or taken");
 
     let pluginManifest: PluginManifest;
 
@@ -15,10 +23,72 @@ export async function fetchPlugin(url: string) {
         throw new Error(`Failed to fetch manifest for ${url}`);
     }
 
-    plugins[url] = {
-        id: url.split("://")[1],
+    let pluginJs: string;
+
+    try {
+        pluginJs = await (await fetch(new URL("plugin.js", url), { cache: "no-store" })).text()
+    } catch {
+        throw new Error(`Failed to fetch JS for ${url}`)
+    }
+
+    plugins[id] = {
+        id: id,
         manifest: pluginManifest,
-        enabled: true,
-        js: "",
+        enabled: false,
+        js: pluginJs,
     };
-}
+}
+
+// Bundlers don't like eval
+const theSystemHasBeenDestroyed = eval;
+
+export function evalPlugin(plugin: Plugin) {
+    // TODO: Refactor to not depend on own window object
+    const vendettaForPlugins = Object.assign({}, window.vendetta);
+    const pluginString = `(vendetta)=>{return ${plugin.js}}\n//# sourceURL=${plugin.id}`;
+
+    const ret = theSystemHasBeenDestroyed(pluginString)(vendettaForPlugins);
+    return typeof ret == "function" ? ret() : ret;
+}
+
+export function startPlugin(id: string) {
+    const plugin = plugins[id];
+    if (!plugin) throw new Error("Attempted to start non-existent plugin");
+
+    try {
+        const pluginRet: EvaledPlugin = evalPlugin(plugin);
+        loadedPlugins[id] = pluginRet;
+        pluginRet.onLoad?.();
+        plugin.enabled = true;
+    } catch(e) {
+        logger.error(`Plugin ${plugin.id} errored whilst loading, and will be unloaded`, e);
+
+        try {
+            loadedPlugins[plugin.id]?.onUnload?.();
+        } catch(e2) {
+            logger.error(`Plugin ${plugin.id} errored whilst unloading`, e2);
+        }
+
+        delete loadedPlugins[id];
+        plugin.enabled = false;
+    }
+}
+
+export function stopPlugin(id: string) {
+    const plugin = plugins[id];
+    const pluginRet = loadedPlugins[id];
+    if (!plugin) throw new Error("Attempted to stop non-existent plugin");
+    if (!pluginRet) throw new Error("Attempted to stop a non-started plugin");
+
+    try {
+        loadedPlugins[plugin.id]?.onUnload?.();
+    } catch(e) {
+        logger.error(`Plugin ${plugin.id} errored whilst unloading`, e);
+    }
+
+    delete loadedPlugins[id];
+    plugin.enabled = false;
+}
+
+// TODO: When startAllPlugins exists, return this so cleanup in index.ts is easier
+const stopAllPlugins = () => Object.keys(loadedPlugins).forEach(stopPlugin);