'use strict';
const {
  ArrayPrototypePush,
  ArrayPrototypeShift,
  FunctionPrototype,
  Number,
  ObjectCreate,
  SafeMap,
} = primordials;
const { AsyncResource } = require('async_hooks');
const {
  codes: {
    ERR_TEST_FAILURE,
  },
} = require('internal/errors');
const { TapStream } = require('internal/test_runner/tap_stream');
const { createDeferredPromise } = require('internal/util');
const { isPromise } = require('internal/util/types');
const { isUint32 } = require('internal/validators');
const { bigint: hrtime } = process.hrtime;
const kCallbackAndPromisePresent = 'callbackAndPromisePresent';
const kCancelledByParent = 'cancelledByParent';
const kMultipleCallbackInvocations = 'multipleCallbackInvocations';
const kParentAlreadyFinished = 'parentAlreadyFinished';
const kSubtestsFailed = 'subtestsFailed';
const kTestCodeFailure = 'testCodeFailure';
const kDefaultIndent = '    ';
const noop = FunctionPrototype;

class TestContext {
  #test;

  constructor(test) {
    this.#test = test;
  }

  diagnostic(message) {
    this.#test.diagnostic(message);
  }

  skip(message) {
    this.#test.skip(message);
  }

  todo(message) {
    this.#test.todo(message);
  }

  test(name, options, fn) {
    const subtest = this.#test.createSubtest(name, options, fn);

    return subtest.start();
  }
}

class Test extends AsyncResource {
  constructor(options) {
    super('Test');

    let { fn, name, parent } = options;
    const { concurrency, skip, todo } = options;

    if (typeof fn !== 'function') {
      fn = noop;
    }

    if (typeof name !== 'string' || name === '') {
      name = fn.name || '<anonymous>';
    }

    if (!(parent instanceof Test)) {
      parent = null;
    }

    if (skip) {
      fn = noop;
    }

    this.fn = fn;
    this.name = name;
    this.parent = parent;

    if (parent === null) {
      this.concurrency = 1;
      this.indent = '';
      this.indentString = kDefaultIndent;
      this.reporter = new TapStream();
      this.testNumber = 0;
    } else {
      const indent = parent.parent === null ? parent.indent :
        parent.indent + parent.indentString;

      this.concurrency = parent.concurrency;
      this.indent = indent;
      this.indentString = parent.indentString;
      this.reporter = parent.reporter;
      this.testNumber = parent.subtests.length + 1;
    }

    if (isUint32(concurrency) && concurrency !== 0) {
      this.concurrency = concurrency;
    }

    this.cancelled = false;
    this.skipped = !!skip;
    this.isTodo = !!todo;
    this.startTime = null;
    this.endTime = null;
    this.passed = false;
    this.error = null;
    this.diagnostics = [];
    this.message = typeof skip === 'string' ? skip :
      typeof todo === 'string' ? todo : null;
    this.activeSubtests = 0;
    this.pendingSubtests = [];
    this.readySubtests = new SafeMap();
    this.subtests = [];
    this.waitingOn = 0;
    this.finished = false;
  }

  hasConcurrency() {
    return this.concurrency > this.activeSubtests;
  }

  addPendingSubtest(deferred) {
    this.pendingSubtests.push(deferred);
  }

  async processPendingSubtests() {
    while (this.pendingSubtests.length > 0 && this.hasConcurrency()) {
      const deferred = ArrayPrototypeShift(this.pendingSubtests);
      await deferred.test.run();
      deferred.resolve();
    }
  }

  addReadySubtest(subtest) {
    this.readySubtests.set(subtest.testNumber, subtest);
  }

  processReadySubtestRange(canSend) {
    const start = this.waitingOn;
    const end = start + this.readySubtests.size;

    for (let i = start; i < end; i++) {
      const subtest = this.readySubtests.get(i);

      // Check if the specified subtest is in the map. If it is not, return
      // early to avoid trying to process any more tests since they would be
      // out of order.
      if (subtest === undefined) {
        return;
      }

      // Call isClearToSend() in the loop so that it is:
      // - Only called if there are results to report in the correct order.
      // - Guaranteed to only be called a maximum of once per call to
      //   processReadySubtestRange().
      canSend = canSend || this.isClearToSend();

      if (!canSend) {
        return;
      }

      // Report the subtest's results and remove it from the ready map.
      subtest.finalize();
      this.readySubtests.delete(i);
    }
  }

  createSubtest(name, options, fn) {
    if (typeof name === 'function') {
      fn = name;
    } else if (name !== null && typeof name === 'object') {
      fn = options;
      options = name;
    } else if (typeof options === 'function') {
      fn = options;
    }

    if (options === null || typeof options !== 'object') {
      options = ObjectCreate(null);
    }

    let parent = this;

    // If this test has already ended, attach this test to the root test so
    // that the error can be properly reported.
    if (this.finished) {
      while (parent.parent !== null) {
        parent = parent.parent;
      }
    }

    const test = new Test({ fn, name, parent, ...options });

    if (parent.waitingOn === 0) {
      parent.waitingOn = test.testNumber;
    }

    if (this.finished) {
      test.fail(
        new ERR_TEST_FAILURE(
          'test could not be started because its parent finished',
          kParentAlreadyFinished
        )
      );
    }

    ArrayPrototypePush(parent.subtests, test);
    return test;
  }

  cancel() {
    if (this.endTime !== null) {
      return;
    }

    this.fail(
      new ERR_TEST_FAILURE(
        'test did not finish before its parent and was cancelled',
        kCancelledByParent
      )
    );
    this.cancelled = true;
  }

  fail(err) {
    if (this.error !== null) {
      return;
    }

    this.endTime = hrtime();
    this.passed = false;
    this.error = err;
  }

  pass() {
    if (this.endTime !== null) {
      return;
    }

    this.endTime = hrtime();
    this.passed = true;
  }

  skip(message) {
    this.skipped = true;
    this.message = message;
  }

  todo(message) {
    this.isTodo = true;
    this.message = message;
  }

  diagnostic(message) {
    ArrayPrototypePush(this.diagnostics, message);
  }

  start() {
    // If there is enough available concurrency to run the test now, then do
    // it. Otherwise, return a Promise to the caller and mark the test as
    // pending for later execution.
    if (!this.parent.hasConcurrency()) {
      const deferred = createDeferredPromise();

      deferred.test = this;
      this.parent.addPendingSubtest(deferred);
      return deferred.promise;
    }

    return this.run();
  }

  async run() {
    this.parent.activeSubtests++;
    this.startTime = hrtime();

    try {
      const ctx = new TestContext(this);

      if (this.fn.length === 2) {
        // This test is using legacy Node.js error first callbacks.
        const { promise, resolve, reject } = createDeferredPromise();
        let calledCount = 0;
        const ret = this.runInAsyncScope(this.fn, ctx, ctx, (err) => {
          calledCount++;

          // If the callback is called a second time, let the user know, but
          // don't let them know more than once.
          if (calledCount === 2) {
            throw new ERR_TEST_FAILURE(
              'callback invoked multiple times',
              kMultipleCallbackInvocations
            );
          } else if (calledCount > 2) {
            return;
          }

          if (err) {
            return reject(err);
          }

          resolve();
        });

        if (isPromise(ret)) {
          this.fail(new ERR_TEST_FAILURE(
            'passed a callback but also returned a Promise',
            kCallbackAndPromisePresent
          ));
          await ret;
        } else {
          await promise;
        }
      } else {
        // This test is synchronous or using Promises.
        await this.runInAsyncScope(this.fn, ctx, ctx);
      }

      this.pass();
    } catch (err) {
      this.fail(new ERR_TEST_FAILURE(err, kTestCodeFailure));
    }

    // Clean up the test. Then, try to report the results and execute any
    // tests that were pending due to available concurrency.
    this.postRun();
  }

  postRun() {
    let failedSubtests = 0;

    // If the test was failed before it even started, then the end time will
    // be earlier than the start time. Correct that here.
    if (this.endTime < this.startTime) {
      this.endTime = hrtime();
    }

    // The test has run, so recursively cancel any outstanding subtests and
    // mark this test as failed if any subtests failed.
    for (let i = 0; i < this.subtests.length; i++) {
      const subtest = this.subtests[i];

      if (!subtest.finished) {
        subtest.cancel();
        subtest.postRun();
      }

      if (!subtest.passed) {
        failedSubtests++;
      }
    }

    if (this.passed && failedSubtests > 0) {
      const subtestString = `subtest${failedSubtests > 1 ? 's' : ''}`;
      const msg = `${failedSubtests} ${subtestString} failed`;

      this.fail(new ERR_TEST_FAILURE(msg, kSubtestsFailed));
    }

    if (this.parent !== null) {
      this.parent.activeSubtests--;
      this.parent.addReadySubtest(this);
      this.parent.processReadySubtestRange(false);
      this.parent.processPendingSubtests();
    }
  }

  isClearToSend() {
    return this.parent === null ||
      (
        this.parent.waitingOn === this.testNumber && this.parent.isClearToSend()
      );
  }

  finalize() {
    // By the time this function is called, the following can be relied on:
    // - The current test has completed or been cancelled.
    // - All of this test's subtests have completed or been cancelled.
    // - It is the current test's turn to report its results.

    // Report any subtests that have not been reported yet. Since all of the
    // subtests have finished, it's safe to pass true to
    // processReadySubtestRange(), which will finalize all remaining subtests.
    this.processReadySubtestRange(true);

    // Output this test's results and update the parent's waiting counter.
    if (this.subtests.length > 0) {
      this.reporter.plan(this.subtests[0].indent, this.subtests.length);
    }

    this.report();
    this.parent.waitingOn++;
    this.finished = true;
  }

  report() {
    // Duration is recorded in BigInt nanoseconds. Convert to seconds.
    const duration = Number(this.endTime - this.startTime) / 1_000_000_000;
    const message = `- ${this.name}`;
    let directive;

    if (this.skipped) {
      directive = this.reporter.getSkip(this.message);
    } else if (this.isTodo) {
      directive = this.reporter.getTodo(this.message);
    }

    if (this.passed) {
      this.reporter.ok(this.indent, this.testNumber, message, directive);
    } else {
      this.reporter.fail(this.indent, this.testNumber, message, directive);
    }

    this.reporter.details(this.indent, duration, this.error);

    for (let i = 0; i < this.diagnostics.length; i++) {
      this.reporter.diagnostic(this.indent, this.diagnostics[i]);
    }
  }
}

module.exports = { kDefaultIndent, kTestCodeFailure, Test };