// 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;
}