New modding system

server/host.ts

@@ -1,20 +1,20 @@
 // the part of a game server that has permissions: files and networking. the game itself runs in a worker with none.
 // server/main.ts runs it as a dedicated server, and the desktop app runs it for singleplayer
 import { serveDir } from "@std/http/file-server";
-import { isAbsolute, join } from "@std/path";
+import { join } from "@std/path";
 import { GameToHost, HostToGame } from "./game/host_protocol.ts";
-import type { ServerModIndex } from "../build.ts";
+import { load_bmods } from "./load_bmods.ts";
 
 const MAX_MESSAGE_SIZE = 4096;
+// in build/, see build.ts
+export const ENGINE_TEXTURES_INDEX = "assets/textures/index.json";
 const SHUTDOWN_TIMEOUT_MS = 5000;
 
 export interface HostOptions {
-	// what deno task build made: the client, assets and mods players download
+	// what deno task build made: the client and the engine's assets
 	build_dir: string;
-	// the server scripts, with index.json
+	// the .bmod files to load
 	server_mods_dir: string;
-	// what the paths in server_mods/index.json are relative to, the folder the build ran in
-	root: string;
 	world_file: string;
 	seed?: string;
 	// the game can't go on, like the worker crashing
@@ -27,9 +27,12 @@ export interface Host {
 	shutdown(): Promise<void>;
 }
 
-export function start_host(options: HostOptions): Host {
-	const mods = read_mods(options);
-	console.log(`Mods: ${mods.mods.map((mod) => `${mod.listing.id} ${mod.listing.version}`).join(", ") || "none"}`);
+// throws when the mods have problems, saying what they are
+export async function start_host(options: HostOptions): Promise<Host> {
+	const mods = await load_bmods(options.server_mods_dir, engine_texture_ids(options.build_dir));
+	console.log(`Mods: ${mods.map((mod) => `${mod.listing.id} ${mod.listing.version}`).join(", ") || "none"}`);
+	// what players download, by path
+	const downloads = new Map(mods.map((mod) => [`/${mod.listing.file}`, mod.client_bytes]));
 
 	const game = new Worker(new URL("./game/worker.ts", import.meta.url), {
 		type: "module",
@@ -78,7 +81,12 @@ export function start_host(options: HostOptions): Host {
 		type: "init",
 		save: read_world(options.world_file),
 		default_seed: options.seed ?? crypto.randomUUID(),
-		...mods,
+		mods: mods.map(({ listing, bmod }) => ({
+			listing,
+			data: bmod.data,
+			server_code: bmod.scripts.server,
+			worldgen_code: bmod.scripts.worldgen,
+		})),
 	});
 
 	function handle_socket(socket: WebSocket) {
@@ -117,6 +125,17 @@ export function start_host(options: HostOptions): Host {
 			if (url.pathname === "/") {
 				return Response.redirect(new URL("/client/", url), 302);
 			}
+			const download = downloads.get(url.pathname);
+			if (download) {
+				// named by its hash, so it never changes and pages on other origins can cache it forever
+				return new Response(download, {
+					headers: {
+						"content-type": "application/zip",
+						"access-control-allow-origin": "*",
+						"cache-control": "public, max-age=31536000, immutable",
+					},
+				});
+			}
 			return serve_static(options.build_dir, req, url);
 		},
 
@@ -155,40 +174,18 @@ function write_world(file: string, data: string) {
 	Deno.renameSync(`${file}.tmp`, file);
 }
 
-// what deno task build made. no index means the build failed or never ran, and the game never runs without its mods
-function read_mods(options: HostOptions): Pick<Extract<HostToGame, { type: "init" }>, "mods" | "atlas"> {
-	let index: ServerModIndex;
-	try {
-		index = JSON.parse(Deno.readTextFileSync(join(options.server_mods_dir, "index.json")));
-	} catch {
-		throw new Error(
-			`No ${options.server_mods_dir}/index.json, run deno task build first (it also reports mod errors)`,
-		);
-	}
-	const from_root = (path: string) => isAbsolute(path) ? path : join(options.root, path);
-	return {
-		atlas: index.atlas,
-		mods: index.mods.map(({ listing, server }) => ({
-			listing,
-			data: JSON.parse(Deno.readTextFileSync(join(options.build_dir, listing.data))),
-			server_code: server ? Deno.readTextFileSync(from_root(server)) : undefined,
-			worldgen_code: listing.worldgen
-				? Deno.readTextFileSync(join(options.build_dir, listing.worldgen))
-				: undefined,
-		})),
-	};
+// the engine's textures, listed by the build next to the client's assets. engine:missing is drawn by code
+export function engine_texture_ids(build_dir: string): string[] {
+	const names: string[] = JSON.parse(Deno.readTextFileSync(join(build_dir, ENGINE_TEXTURES_INDEX)));
+	return ["engine:missing", ...names.map((name) => `engine:${name}`)];
 }
 
-// mod files and the atlas are named by their hash, so they never change and pages on other origins can load them
+// the client and the engine's assets. pages on other origins load the engine's textures from here too
 export async function serve_static(build_dir: string, req: Request, url: URL) {
 	const response = await serveDir(req, { fsRoot: build_dir, quiet: true });
-	const shared = url.pathname.startsWith("/mods/") || url.pathname.startsWith("/assets/");
-	if (shared && response.ok) {
+	if (url.pathname.startsWith("/assets/") && response.ok) {
 		const headers = new Headers(response.headers);
 		headers.set("Access-Control-Allow-Origin", "*");
-		if (url.pathname.startsWith("/mods/") || /^\/assets\/sprites\/textures\.[0-9a-f]+\./.test(url.pathname)) {
-			headers.set("Cache-Control", "public, max-age=31536000, immutable");
-		}
 		return new Response(response.body, { status: response.status, statusText: response.statusText, headers });
 	}
 	return response;