import { test } from 'node:test';
import assert from 'node:assert/strict';
import { spawnSync } from 'node:child_process';

// Regression test: the logger must produce real JSON lines, not the
// literal string "undefined" (a bug caused by passing JSON.stringify a
// replacer *factory* instead of calling it first).
test('logger prints a parseable JSON object with the expected fields, not "undefined"', () => {
  const script = `
    import { createLogger } from '${import.meta.resolve('../src/logger.js').replace('file://', '')}';
    createLogger({ component: 'x' }).info('hello', { foo: 'bar' });
  `;
  const result = spawnSync(process.execPath, ['--input-type=module', '-e', script], { encoding: 'utf8' });
  assert.equal(result.status, 0, result.stderr);
  const line = result.stdout.trim();
  assert.notEqual(line, 'undefined');
  const parsed = JSON.parse(line);
  assert.equal(parsed.level, 'info');
  assert.equal(parsed.msg, 'hello');
  assert.equal(parsed.component, 'x');
  assert.equal(parsed.foo, 'bar');
  assert.ok(parsed.time);
});

test('logger.child merges bindings and does not mutate the parent', () => {
  const script = `
    import { createLogger } from '${import.meta.resolve('../src/logger.js').replace('file://', '')}';
    const parent = createLogger({ a: 1 });
    const child = parent.child({ b: 2 });
    child.info('from child');
    parent.info('from parent');
  `;
  const result = spawnSync(process.execPath, ['--input-type=module', '-e', script], { encoding: 'utf8' });
  assert.equal(result.status, 0, result.stderr);
  const [childLine, parentLine] = result.stdout.trim().split('\n').map((l) => JSON.parse(l));
  assert.deepEqual({ a: childLine.a, b: childLine.b }, { a: 1, b: 2 });
  assert.equal(parentLine.b, undefined);
});

test('debug messages are suppressed at the default (info) log level', () => {
  const script = `
    import { createLogger } from '${import.meta.resolve('../src/logger.js').replace('file://', '')}';
    createLogger({}).debug('should not appear');
    createLogger({}).info('should appear');
  `;
  const result = spawnSync(process.execPath, ['--input-type=module', '-e', script], {
    encoding: 'utf8',
    env: { ...process.env, LOG_LEVEL: 'info' },
  });
  assert.equal(result.status, 0, result.stderr);
  const lines = result.stdout.trim().split('\n').filter(Boolean);
  assert.equal(lines.length, 1);
  assert.equal(JSON.parse(lines[0]).msg, 'should appear');
});

test('errors are logged with name/message/stack, not serialized to {}', () => {
  const script = `
    import { createLogger } from '${import.meta.resolve('../src/logger.js').replace('file://', '')}';
    createLogger({}).error('boom', { error: new Error('bad thing') });
  `;
  const result = spawnSync(process.execPath, ['--input-type=module', '-e', script], { encoding: 'utf8' });
  assert.equal(result.status, 0, result.stderr);
  const parsed = JSON.parse(result.stderr.trim());
  assert.equal(parsed.error.message, 'bad thing');
  assert.equal(parsed.error.name, 'Error');
  assert.ok(parsed.error.stack);
});