const { readdirSync: readDir, readFileSync } = require("fs");
const { readFile, writeFile, mkdir } = require("fs/promises");
const homeDir = require("os").homedir();
const { join: joinPath, relative: relativePath, sep: pathSeparator } = require("path");
const { LuaFactory } = require('wasmoon');


const FACTORIO_DATA_DIR = process.env["FACTORIO_DATA_DIR"] ?? `${homeDir}/.steam/steam/steamapps/common/Factorio/data`;
const LOCALE = process.env["LOCALE"] ?? "en";
const MODS = "core;base" + (process.env["MODS"] ?? 
	((process.env["SPACE_AGE"] ?? "true") == "true" ? ";quality;elevated-rails;space-age" : ""));

const mods = MODS.split(";").filter(v => v);

const readLocaleData = mod => readFileSync(joinPath(FACTORIO_DATA_DIR, mod, "locale", LOCALE, mod + ".cfg"), "utf-8")
	.trim()
	.split("\n")
	.filter(v => v)
	.map(v => v.split(/=(.*)/, 2))
	.flatMap((category = null, ([ k, v ]) => k.startsWith("[") ? (category = k, []) : { key: k, value: v, category }))
	.reduce((m, { key, value, category }) => ((m.get(category) ?? m.set(category, new Map()).get(category)).set(key, value), m), new Map());

const defines = [...readFileSync(joinPath(FACTORIO_DATA_DIR, "..", "doc-html", "defines.html"), "utf8")
	.matchAll(/id="(defines\..*?)"/g)]
	.map(v => v[1])
	.flatMap((v, i) => i === 0 ? ["defines", v] : v) // prepend 'defines'
	.map(v => [...v.matchAll(/([a-zA-Z0-9_]+)|\['(.+?)'\]/g)].map(([ , a, b ]) => a ?? b))
	.reduce((acc, keys, idx) => {
		let v = acc;
		let lastKey = keys.pop();
		keys.forEach(k => (typeof v[k] != "object" ? v[k] = {} : null, v = v[k]));
		v[lastKey] = idx;
		return acc;
	}, {})
	.defines;

const loadModFactory = async () => { 
	const luaFactory = new LuaFactory();
	const lua = await luaFactory.createEngine({ enableProxy: false });

	await luaFactory.mountFile("serpent.lua", await readFile(joinPath("serpent", "src", "serpent.lua")));

	await lua.doString("serpent = require('serpent')");
	await Promise.all(readDir(joinPath(FACTORIO_DATA_DIR), { recursive: true, withFileTypes: true })
		.filter(v => v.isFile() && v.name.endsWith(".lua"))
		.map(async file => {
			const data = await readFile(joinPath(file.parentPath, file.name));
			if (file.parentPath.endsWith("lualib")) {
				await luaFactory.mountFile(file.name, data);
			}
			const rPath = relativePath(joinPath(FACTORIO_DATA_DIR), joinPath(file.parentPath, file.name))
				.split(pathSeparator);
			const luaModule = rPath.shift();
			// console.log(joinPath(`__${luaModule}__`, ...rPath))
			await luaFactory.mountFile(joinPath(`__${luaModule}__`, ...rPath), data);
		}));
		
	lua.global.set("defines", defines);
			
	await lua.doString("math.atan2 = function(x, y) return math.atan(y / x) end");
	await lua.doString("require('dataloader')");

	const execStage = async (mod, stage) => {
		const files = readDir(joinPath(FACTORIO_DATA_DIR, mod), { recursive: true, withFileTypes: true });

		if (!files.some(v => v.name === `${stage}.lua`)) {
			// skip
			return;
		}

		await lua.doString(files
			.filter(v => v.isFile() && v.name.endsWith(".lua") && !v.parentPath.endsWith("lualib") && v.parentPath.indexOf("prototype") >= 0)
			.map(file => relativePath(joinPath(FACTORIO_DATA_DIR, mod), joinPath(file.parentPath, file.name)).replace(/\.lua$/, ""))
			.flatMap(file => [ file, file.replaceAll(pathSeparator, '.') ])
			.reduce((s, p) => s + `package.loaded['${p}'] = nil\n`, ""));

		await Promise.all(files
			.filter(v => v.isFile() && v.name.endsWith(".lua") && !v.parentPath.endsWith("lualib"))
			.map(async file => {
				const moduleName = relativePath(joinPath(FACTORIO_DATA_DIR, mod), joinPath(file.parentPath, file.name))
				return luaFactory.mountFile(moduleName, 
					(mod === "space-age" && moduleName === "prototypes/ambient-sounds.lua" ? "require('__space-age__/sound/ambient/space/interlude-6/interlude-6')" : "") + // no clue why this fix is needed, it does nothing functional
						await readFile(joinPath(file.parentPath, file.name)),
				)
			}));

		console.log(`${stage} stage,\t${mod}`);
		await lua.doFile(`${stage}.lua`);

		return lua.global.get("data");
	}

	return async mods => {
		for (const mod of mods) {
			await execStage(mod, "data");
		}
		for (const mod of mods) {
			await execStage(mod, "data-updates");
		}
		for (const mod of mods) {
			await execStage(mod, "data-final-fixes");
		}
		return lua.global.get("data");
	}
}

console.log("loading mods:", mods);

loadModFactory().then(async loadMods => {
	const data = await loadMods(mods);
	await mkdir("build", { recursive: true });
	await writeFile(joinPath("build", "data.json"), JSON.stringify(data.raw));
});