Implement main game as a mod

common/worldgen_loader.ts

@@ -0,0 +1,37 @@
+// imports mods' worldgen scripts and collects what they register. used by client chunk workers and the game server
+import type { WorldgenContext } from "$/common/mod_api/worldgen.ts";
+import type { OreJson } from "$/common/mod_data.ts";
+import type { WorldgenSetup } from "./generation.ts";
+import { ModLoadError } from "./mod_loader.ts";
+
+export async function load_worldgen(scripts: { mod: string; url: string }[], ores: OreJson[]): Promise<WorldgenSetup> {
+	const setup: WorldgenSetup = { ores, features: [] };
+
+	for (const { mod, url } of scripts) {
+		const ctx: WorldgenContext = {
+			register_feature(id, generate) {
+				if (!id.startsWith(`${mod}:`)) {
+					throw new ModLoadError(mod, `feature ${id} must be in the namespace "${mod}"`);
+				}
+				if (setup.features.some((f) => f.id === id)) {
+					throw new ModLoadError(mod, `feature ${id} is registered twice`);
+				}
+				setup.features.push({ id, generate });
+			},
+			register_terrain(id) {
+				throw new ModLoadError(
+					mod,
+					`can't register terrain ${id}: the base terrain is still built into the engine (phase 3 in MODS.md)`,
+				);
+			},
+		};
+
+		const module = await import(url);
+		if (typeof module.setup !== "function") {
+			throw new ModLoadError(mod, "the worldgen script doesn't export a setup function");
+		}
+		await module.setup(ctx);
+	}
+
+	return setup;
+}