Implement main game as a mod

client/mods.ts

@@ -0,0 +1,87 @@
+// loads the mods the server lists: registers their data, then runs their client scripts.
+// see "Delivery to clients" in MODS.md
+import { AIR } from "$/common/constants.ts";
+import { BlockRegistry, EverythingRegistry } from "$/common/everything_registry.ts";
+import type { ClientContext } from "$/common/mod_api/client.ts";
+import { ModData, ModListing, ModLoadError, register_mod_data } from "$/common/mod_loader.ts";
+import type { OreJson } from "$/common/mod_data.ts";
+import { AIR_ID } from "$/common/protocol.ts";
+import { Position } from "$/common/components/position.ts";
+import type { ClientWorld } from "./client_world.ts";
+
+// what the chunk workers need to generate the same world as the server
+export const worldgen_mods: { scripts: { mod: string; url: string }[]; ores: OreJson[] } = { scripts: [], ores: [] };
+
+// set once the world exists, mods can't look at it during setup
+let world: ClientWorld | undefined;
+
+export function set_mods_world(client_world: ClientWorld) {
+	world = client_world;
+}
+
+export async function load_client_mods(listings: ModListing[]) {
+	const site = new URL("/", location.href);
+
+	const datas = await Promise.all(listings.map(async (listing) => {
+		const response = await fetch(new URL(listing.data, site));
+		if (!response.ok) {
+			throw new ModLoadError(listing.id, `couldn't download its data (${response.status})`);
+		}
+		return { id: listing.id, data: await response.json() as ModData };
+	}));
+	const recipes = register_mod_data(datas);
+
+	worldgen_mods.ores = recipes.ores;
+	worldgen_mods.scripts = listings.flatMap((listing) =>
+		listing.worldgen ? [{ mod: listing.id, url: new URL(listing.worldgen, site).href }] : []
+	);
+
+	for (const listing of listings) {
+		if (!listing.client) continue;
+		const module = await import(new URL(listing.client, site).href);
+		if (typeof module.setup !== "function") {
+			throw new ModLoadError(listing.id, "the client script doesn't export a setup function");
+		}
+		await module.setup(client_context(listing));
+	}
+}
+
+function client_context(listing: ModListing): ClientContext {
+	const mod = listing.id;
+	const not_yet = (name: string, where: string) =>
+		new Proxy({}, {
+			get: (_, prop) => () => {
+				throw new Error(`[${mod}] ctx.${name}.${String(prop)} isn't implemented yet (${where} in MODS.md)`);
+			},
+		});
+	const need_world = () => {
+		if (!world) throw new Error(`[${mod}] the world isn't there yet during setup`);
+		return world;
+	};
+
+	return {
+		mod: { id: mod, version: listing.version },
+		ui: not_yet("ui", "step 7") as ClientContext["ui"],
+		hud: not_yet("hud", "step 7") as ClientContext["hud"],
+		input: not_yet("input", "step 8") as ClientContext["input"],
+		net: not_yet("net", "step 8") as ClientContext["net"],
+		player: {
+			get name() {
+				return need_world().connection.name;
+			},
+			get position() {
+				const [player] = need_world().get_tag("player")!;
+				const position = player.get(Position)!;
+				return { x: position.x, y: position.y, z: position.z };
+			},
+		},
+		world: {
+			get_block(x, y, z) {
+				const nid = need_world().dimension.get_block(x, y, z);
+				if (nid === AIR) return AIR_ID;
+				return EverythingRegistry.get_by_id<BlockRegistry>("blocks", nid)?.id;
+			},
+		},
+		log: (...args) => console.log(`[${mod}]`, ...args),
+	};
+}