import { describe, it, expect, beforeEach, afterEach } from "vitest";
import { mkdirSync, writeFileSync, rmSync } from "node:fs";
import { resolve } from "node:path";
import { tmpdir } from "node:os";
// Telemetry-run readers (listTelemetryRuns / readTelemetryRun) are re-exported
// from `@nwire/scan` and covered by that package's telemetry-runs test. This
// file covers nwire-read's own surface: readManifest + foldTopology.
import { readManifest, foldTopology } from "../nwire-read";

// ── fixture helpers ───────────────────────────────────────────────────────────

let tmp: string;

function nwireDir(): string {
  return resolve(tmp, ".nwire");
}

function writeManifest(content: string): void {
  mkdirSync(nwireDir(), { recursive: true });
  writeFileSync(resolve(nwireDir(), "manifest.json"), content, "utf8");
}

beforeEach(() => {
  tmp = resolve(tmpdir(), `nwire-read-test-${process.pid}-${Date.now()}`);
  mkdirSync(tmp, { recursive: true });
});

afterEach(() => {
  rmSync(tmp, { recursive: true, force: true });
});

// ── readManifest ─────────────────────────────────────────────────────────────

describe("readManifest", () => {
  it("returns null when .nwire/ does not exist", () => {
    expect(readManifest(tmp)).toBeNull();
  });

  it("returns null when manifest.json is missing", () => {
    mkdirSync(nwireDir(), { recursive: true });
    expect(readManifest(tmp)).toBeNull();
  });

  it("returns the raw JSON string when file is present", () => {
    const raw = JSON.stringify({ apps: [], actions: [] });
    writeManifest(raw);
    expect(readManifest(tmp)).toBe(raw);
  });

  it("preserves exact bytes — no re-serialisation", () => {
    const raw = '{"apps":[],"note":"trailing-space"   }';
    writeManifest(raw);
    expect(readManifest(tmp)).toBe(raw);
  });
});

// ── foldTopology ─────────────────────────────────────────────────────────────

describe("foldTopology", () => {
  it("returns null for null input", () => {
    expect(foldTopology(null, tmp)).toBeNull();
  });

  it("returns null for invalid JSON", () => {
    expect(foldTopology("{broken json", tmp)).toBeNull();
  });

  it("parses and returns the manifest object", () => {
    const obj = { apps: [{ name: "orders" }], actions: [] };
    const result = foldTopology(JSON.stringify(obj), tmp) as typeof obj;
    expect(result).toEqual(obj);
  });

  it("round-trips through readManifest correctly", () => {
    const obj = { apps: [{ name: "billing" }], actions: [], events: [] };
    writeManifest(JSON.stringify(obj));
    const raw = readManifest(tmp);
    expect(foldTopology(raw, tmp)).toEqual(obj);
  });
});