import * as fs from "fs";
import * as os from "os";
import * as path from "path";
import { describe, it, expect, afterEach } from "vitest";
import { acquireLock } from "../../src/runtime/lockfile";

function makeTmpDir(): string {
  const suffix = Math.random().toString(36).slice(2);
  const dir = path.join(os.tmpdir(), `disclaw-test-${suffix}`);
  fs.mkdirSync(dir, { recursive: true });
  return dir;
}

describe("acquireLock", () => {
  const dirs: string[] = [];

  afterEach(() => {
    for (const dir of dirs) {
      fs.rmSync(dir, { recursive: true, force: true });
    }
    dirs.length = 0;
  });

  it("(a) first acquire writes lock file with correct PID", async () => {
    const dir = makeTmpDir();
    dirs.push(dir);
    const lockPath = path.join(dir, ".disclaw.lock");

    const release = await acquireLock(lockPath);

    expect(fs.existsSync(lockPath)).toBe(true);
    const data = JSON.parse(fs.readFileSync(lockPath, "utf-8")) as {
      pid: number;
      started: string;
    };
    expect(data.pid).toBe(process.pid);
    expect(typeof data.started).toBe("string");
    expect(data.started).toMatch(/^\d{4}-\d{2}-\d{2}T/);

    release();
  });

  it("(b) second acquire on same live lock throws", async () => {
    const dir = makeTmpDir();
    dirs.push(dir);
    const lockPath = path.join(dir, ".disclaw.lock");

    const release = await acquireLock(lockPath);

    await expect(acquireLock(lockPath)).rejects.toThrow(
      `DisClaw bereits aktiv (PID ${process.pid})`
    );

    release();
  });

  it("(c) stale lock (dead PID) is overwritten", async () => {
    const dir = makeTmpDir();
    dirs.push(dir);
    const lockPath = path.join(dir, ".disclaw.lock");

    // Write a stale lock with a PID that almost certainly doesn't exist
    const staleData = { pid: 99999999, started: new Date().toISOString() };
    fs.writeFileSync(lockPath, JSON.stringify(staleData), "utf-8");

    const release = await acquireLock(lockPath);

    const data = JSON.parse(fs.readFileSync(lockPath, "utf-8")) as {
      pid: number;
      started: string;
    };
    expect(data.pid).toBe(process.pid);

    release();
  });

  it("(d) release() deletes the lock file", async () => {
    const dir = makeTmpDir();
    dirs.push(dir);
    const lockPath = path.join(dir, ".disclaw.lock");

    const release = await acquireLock(lockPath);
    expect(fs.existsSync(lockPath)).toBe(true);

    release();
    expect(fs.existsSync(lockPath)).toBe(false);
  });
});