'use strict';

function reqFromCwd(id) {
  return require(require.resolve(id, { paths: [process.cwd()] }));
}

const Mocha = reqFromCwd('mocha');
const {
  EVENT_RUN_BEGIN,
  EVENT_RUN_END,
  EVENT_SUITE_BEGIN,
  EVENT_TEST_PASS,
  EVENT_TEST_FAIL,
  EVENT_TEST_PENDING,
} = Mocha.Runner.constants;

function serializeError(err) {
  if (!err) return null;
  return {
    name: err.name || null,
    message: err.message || String(err),
    stack: err.stack || null,
  };
}

function safeTitlePath(entity) {
  if (entity && typeof entity.titlePath === 'function') {
    return entity.titlePath();
  }
  return null;
}

class NdjsonReporter {
  constructor(runner /*, options */) {
    runner
      .once(EVENT_RUN_BEGIN, () => {
        this.emit({ event: 'run-begin', total: runner.total });
      })

      // Optional suite-level event for describe.skip (helps jump to suite definition)
      .on(EVENT_SUITE_BEGIN, (suite) => {
        if (suite && suite.pending && suite.title) {
          this.emit({
            event: 'suite',
            status: 'skipped',
            pendingType: suite._akPendingType || 'skip',
            title: suite.title,
            fullTitle: typeof suite.fullTitle === 'function' ? suite.fullTitle() : suite.title,
            titlePath: safeTitlePath(suite),
            file: suite.file || (suite._akLocation && suite._akLocation.file) || null,
            location: suite._akLocation || null,
          });
        }
      })

      .on(EVENT_TEST_PASS, (test) => {
        this.emit(this.testPayload('passed', test, null));
      })

      .on(EVENT_TEST_FAIL, (test, err) => {
        this.emit(this.testPayload('failed', test, serializeError(err)));
      })

      .on(EVENT_TEST_PENDING, (test) => {
        // Mocha "pending" includes:
        // - TODO tests (no function)
        // - explicit it.skip / describe.skip
        // - runtime this.skip()
        // We'll classify:
        // - pendingType === 'todo' => pending
        // - otherwise => skipped
        const inferredPendingType = this.inferPendingType(test);
        const status = inferredPendingType === 'todo' ? 'pending' : 'skipped';
        this.emit({
          ...this.testPayload(status, test, null),
          pendingType: inferredPendingType,
        });
      })

      .once(EVENT_RUN_END, () => {
        this.emit({ event: 'run-end', stats: runner.stats || null });
      });
  }

  inferPendingType(test) {
    // Priority: explicit marker from UI wrappers
    if (test && test._akPendingType) return test._akPendingType;

    // Heuristic:
    // - If there's no function (or it's missing), it's likely a TODO-style pending
    // - If function exists but test ended as pending, it's likely skipped (this.skip())
    if (!test) return null;

    // In many Mocha versions, TODO tests have test.fn undefined/null
    if (!test.fn) return 'todo';

    return 'skip';
  }

  testPayload(status, test, errorObj) {
    const location = (test && test._akLocation) || null;

    const file =
      (test && test.file) ||
      (test && test.parent && test.parent.file) ||
      (location && location.file) ||
      null;

    const payload = {
      event: 'test',
      status,
      title: test ? test.title : null,
      fullTitle: test && typeof test.fullTitle === 'function' ? test.fullTitle() : null,
      titlePath: safeTitlePath(test),
      file,
      location,
      duration: test && typeof test.duration === 'number' ? test.duration : null,
      currentRetry: test && typeof test.currentRetry === 'function' ? test.currentRetry() : null,
    };

    if (status === 'failed') payload.error = errorObj;

    return payload;
  }

  emit(obj) {
    process.stdout.write(JSON.stringify(obj) + '\n');
  }
}

module.exports = NdjsonReporter;