feat: switch to a central singleton handler

This also adds support for Headscale TLS installations

server/context/global.ts

@@ -0,0 +1,85 @@
+import type { Configuration } from 'openid-client';
+import type { Agent } from 'undici';
+import type { WebSocket } from 'ws';
+import type { HostInfo } from '~/types';
+import type { HeadplaneConfig } from '~server/context/parser';
+import type { Logger } from '~server/utils/log';
+import type { TimedCache } from '~server/ws/cache';
+
+// This is a stupid workaround for how the Remix import context works
+// Even though they run in the same Node instance, they have different
+// contexts which means importing this in the app code will not work
+// because it will be a different instance of the module.
+//
+// Instead we can rely on globalThis to share the module between the
+// different contexts and use some helper functions to make it easier.
+// As a part of this global module, we also define all our singletons
+// here in order to avoid polluting the global scope and instead just using
+// the `__headplane_server_context` object.
+
+interface ServerContext {
+	config: HeadplaneConfig;
+	singletons: ServerSingletons;
+}
+
+interface ServerSingletons {
+	api_agent: Agent;
+	logger: Logger;
+	oidc_client: Configuration;
+	ws_agents: Map<string, WebSocket>;
+	ws_agent_data: TimedCache<HostInfo>;
+	ws_fetch_data: (nodeList: string[]) => Promise<void>;
+}
+
+// These declarations are separate to prevent the Remix context
+// from modifying the globalThis object and causing issues with
+// the server context.
+declare namespace globalThis {
+	let __headplane_server_context: {
+		[K in keyof ServerContext]: ServerContext[K] | null | object;
+	};
+}
+
+// We need to check if the context is already initialized and set a default
+// value. This is fine as a side-effect since it's just setting up a framework
+// for the object to get modified later.
+if (!globalThis.__headplane_server_context) {
+	globalThis.__headplane_server_context = {
+		config: null,
+		singletons: {},
+	};
+}
+
+declare global {
+	const __headplane_server_context: ServerContext;
+}
+
+export function hp_getConfig(): HeadplaneConfig {
+	return __headplane_server_context.config;
+}
+
+export function hp_setConfig(config: HeadplaneConfig): void {
+	__headplane_server_context.config = config;
+}
+
+export function hp_getSingleton<T extends keyof ServerSingletons>(
+	key: T,
+): ServerSingletons[T] {
+	if (!__headplane_server_context.singletons[key]) {
+		throw new Error(`Singleton ${key} not initialized`);
+	}
+
+	return __headplane_server_context.singletons[key];
+}
+
+export function hp_getSingletonUnsafe<T extends keyof ServerSingletons>(
+	key: T,
+): ServerSingletons[T] | undefined {
+	return __headplane_server_context.singletons[key];
+}
+
+export function hp_setSingleton<
+	T extends ServerSingletons[keyof ServerSingletons],
+>(key: keyof ServerSingletons, value: T): void {
+	(__headplane_server_context.singletons[key] as T) = value;
+}