'use strict';
const fs = require('fs');
const os = require('os');
const path = require('path');

function makeTempPath() {
  return path.join(os.tmpdir(), `myprimal-test-config-${process.pid}-${Date.now()}.json`);
}

function freshConfig(tmpPath) {
  process.env.MYPRIMAL_CONFIG_PATH = tmpPath;
  jest.resetModules();
  return require('../src/config');
}

afterEach(() => {
  delete process.env.MYPRIMAL_CONFIG_PATH;
  delete process.env.POLL_FAST;
});

describe('config', () => {
  test('loadConfig uses env defaults when no file', () => {
    process.env.POLL_FAST = '45';
    const tmp = makeTempPath();
    const { loadConfig, getConfig } = freshConfig(tmp);
    loadConfig();
    expect(getConfig().poll.fast).toBe(45);
  });

  test('patchConfig deep merges and persists', () => {
    const tmp = makeTempPath();
    const { loadConfig, getConfig, patchConfig } = freshConfig(tmp);
    loadConfig();
    patchConfig({ poll: { fast: 20 } });
    expect(getConfig().poll.fast).toBe(20);
    expect(getConfig().poll.normal).toBeGreaterThan(0);

    const saved = JSON.parse(fs.readFileSync(tmp, 'utf8'));
    expect(saved.poll.fast).toBe(20);
    fs.unlinkSync(tmp);
  });

  test('patchConfig emits change event', done => {
    const tmp = makeTempPath();
    const { loadConfig, patchConfig, on } = freshConfig(tmp);
    loadConfig();
    on('change', cfg => {
      if (cfg.poll.slow === 1800) {
        fs.existsSync(tmp) && fs.unlinkSync(tmp);
        done();
      }
    });
    patchConfig({ poll: { slow: 1800 } });
  });

  test('overrides preserved across patches', () => {
    const tmp = makeTempPath();
    const { loadConfig, getConfig, patchConfig } = freshConfig(tmp);
    loadConfig();
    patchConfig({ poll: { overrides: { 'lrps_0565c0/ph': 30 } } });
    patchConfig({ poll: { fast: 10 } });
    expect(getConfig().poll.overrides['lrps_0565c0/ph']).toBe(30);
    expect(getConfig().poll.fast).toBe(10);
    fs.unlinkSync(tmp);
  });

  test('loadConfig reads persisted values', () => {
    const tmp = makeTempPath();
    fs.writeFileSync(tmp, JSON.stringify({ poll: { fast: 99, normal: 500, slow: 1000, overrides: {} } }));
    const { loadConfig, getConfig } = freshConfig(tmp);
    loadConfig();
    expect(getConfig().poll.fast).toBe(99);
    expect(getConfig().poll.normal).toBe(500);
    fs.unlinkSync(tmp);
  });
});