import { existsSync, readdirSync, readFileSync, statSync } from "node:fs";
import { join } from "node:path";
import { describe, expect, it } from "@suaveplan/testing/runner";

const PKG_DIR = join(__dirname, "..");
const DIST_DIR = join(PKG_DIR, "dist");

function walk(dir: string, out: string[] = []): string[] {
    if (!existsSync(dir)) return out;
    for (const name of readdirSync(dir)) {
        const p = join(dir, name);
        const s = statSync(p);
        if (s.isDirectory()) walk(p, out);
        else if (/\.(js|mjs|cjs)$/.test(p)) out.push(p);
    }
    return out;
}

describe("purity", () => {
    it("dist references no Node globals", { timeout: 30_000 }, () => {
        if (!existsSync(DIST_DIR)) {
            // dist will exist after build; skip purity if not yet built so the
            // test suite can still run on a fresh clone.
            expect(true).toBe(true);
            return;
        }
        const offenders: string[] = [];
        for (const file of walk(DIST_DIR)) {
            const src = readFileSync(file, "utf8");
            if (/\bnode:[a-z]+\b/.test(src)) offenders.push(`${file}: node:*`);
            if (/\bprocess\.(env|cwd|platform)\b/.test(src))
                offenders.push(`${file}: process`);
            if (/\bBuffer\.from\b/.test(src)) offenders.push(`${file}: Buffer`);
        }
        expect(offenders).toEqual([]);
    });

    it("importing the package mutates no global state", {
        timeout: 5000,
    }, async () => {
        const filter = (keys: string[]): string[] =>
            keys
                .filter(
                    (k) =>
                        !k.startsWith("__zod") &&
                        !k.startsWith("__vitest") &&
                        !k.startsWith("__VITEST")
                )
                .sort();
        const beforeKeys = filter(Object.keys(globalThis));
        const mod = await import("../src/index.js");
        expect(mod.MidiControllerPlugin).toBeDefined();
        const afterKeys = filter(Object.keys(globalThis));
        expect(afterKeys).toEqual(beforeKeys);
    });
});