#!/usr/bin/env python2
# -*- coding: utf-8 -*-
#
# Copyright 2019 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Runs tests for the given input files.

Tries its best to autodetect all tests based on path name without being *too*
aggressive.

In short, there's a small set of directories in which, if you make any change,
all of the tests in those directories get run. Additionally, if you change a
python file named foo, it'll run foo_test.py or foo_unittest.py if either of
those exist.

All tests are run in parallel.
"""

# NOTE: An alternative mentioned on the initial CL for this
# https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/1516414
# is pytest. It looks like that brings some complexity (and makes use outside
# of the chroot a bit more obnoxious?), but might be worth exploring if this
# starts to grow quite complex on its own.

from __future__ import print_function

import argparse
import collections
import contextlib
import multiprocessing.pool
import os
import pipes
import subprocess
import sys

TestSpec = collections.namedtuple('TestSpec', ['directory', 'command'])


def _make_relative_to_toolchain_utils(toolchain_utils, path):
  """Cleans & makes a path relative to toolchain_utils.

  Raises if that path isn't under toolchain_utils.
  """
  # abspath has the nice property that it removes any markers like './'.
  as_abs = os.path.abspath(path)
  result = os.path.relpath(as_abs, start=toolchain_utils)

  if result.startswith('../'):
    raise ValueError('Non toolchain-utils directory found: %s' % result)
  return result


def _gather_python_tests_in(subdir):
  """Returns all files that appear to be Python tests in a given directory."""
  test_files = (
      os.path.join(subdir, file_name)
      for file_name in os.listdir(subdir)
      if file_name.endswith('_test.py') or file_name.endswith('_unittest.py'))
  return [_python_test_to_spec(test_file) for test_file in test_files]


def _run_test(test_spec):
  """Runs a test."""
  p = subprocess.Popen(
      test_spec.command,
      cwd=test_spec.directory,
      stdin=open('/dev/null'),
      stdout=subprocess.PIPE,
      stderr=subprocess.STDOUT)
  stdout, _ = p.communicate()
  exit_code = p.wait()
  return exit_code, stdout


def _python_test_to_spec(test_file):
  """Given a .py file, convert it to a TestSpec."""
  # Run tests in the directory they exist in, since some of them are sensitive
  # to that.
  test_directory = os.path.dirname(os.path.abspath(test_file))
  file_name = os.path.basename(test_file)

  if os.access(test_file, os.X_OK):
    command = ['./' + file_name]
  else:
    # Assume the user wanted py2.
    command = ['python2', file_name]

  return TestSpec(directory=test_directory, command=command)


def _autodetect_python_tests_for(test_file):
  """Given a test file, detect if there may be related tests."""
  if not test_file.endswith('.py'):
    return []

  base = test_file[:-3]
  candidates = [base + '_test.py', '_unittest.py']
  tests_to_run = (c for c in candidates if os.path.exists(c))
  return [_python_test_to_spec(test_file) for test_file in tests_to_run]


def _run_test_scripts(all_tests, show_successful_output=False):
  """Runs a list of TestSpecs. Returns whether all of them succeeded."""
  with contextlib.closing(multiprocessing.pool.ThreadPool()) as pool:
    results = [pool.apply_async(_run_test, (test,)) for test in all_tests]

  failures = []
  for i, (test, future) in enumerate(zip(all_tests, results)):
    # Add a bit more spacing between outputs.
    if show_successful_output and i:
      print('\n')

    pretty_test = ' '.join(pipes.quote(test_arg) for test_arg in test.command)
    pretty_directory = os.path.relpath(test.directory)
    if pretty_directory == '.':
      test_message = pretty_test
    else:
      test_message = '%s in %s/' % (pretty_test, pretty_directory)

    print('## %s ... ' % test_message, end='')
    # Be sure that the users sees which test is running.
    sys.stdout.flush()

    exit_code, stdout = future.get()
    if not exit_code:
      print('PASS')
    else:
      print('FAIL')
      failures.append(pretty_test)

    if show_successful_output or exit_code:
      sys.stdout.write(stdout)

  if failures:
    word = 'tests' if len(failures) > 1 else 'test'
    print('%d %s failed: %s' % (len(failures), word, failures))

  return not failures


def _compress_list(l):
  """Removes consecutive duplicate elements from |l|.

  >>> _compress_list([])
  []
  >>> _compress_list([1, 1])
  [1]
  >>> _compress_list([1, 2, 1])
  [1, 2, 1]
  """
  result = []
  for e in l:
    if result and result[-1] == e:
      continue
    result.append(e)
  return result


def _fix_python_path(toolchain_utils):
  pypath = os.environ.get('PYTHONPATH', '')
  if pypath:
    pypath = ':' + pypath
  os.environ['PYTHONPATH'] = toolchain_utils + pypath


def _find_forced_subdir_tests(test_paths, toolchain_utils):
  assert all(os.path.isabs(path) for path in test_paths)

  # Directories under toolchain_utils for which any change will cause all tests
  # in that directory to be rerun. Includes changes in subdirectories.
  all_dirs = {
      'crosperf',
      'cros_utils',
  }

  relative_paths = [
      _make_relative_to_toolchain_utils(toolchain_utils, path)
      for path in test_paths
  ]

  gather_test_dirs = set()

  for path in relative_paths:
    top_level_dir = path.split('/')[0]
    if top_level_dir in all_dirs:
      gather_test_dirs.add(top_level_dir)

  results = []
  for d in sorted(gather_test_dirs):
    results += _gather_python_tests_in(os.path.join(toolchain_utils, d))
  return results


def main(argv):
  default_toolchain_utils = os.path.abspath(os.path.dirname(__file__))

  parser = argparse.ArgumentParser(description=__doc__)
  parser.add_argument(
      '--show_all_output',
      action='store_true',
      help='show stdout of successful tests')
  parser.add_argument(
      '--toolchain_utils',
      default=default_toolchain_utils,
      help='directory of toolchain-utils. Often auto-detected')
  parser.add_argument(
      'file', nargs='*', help='a file that we should run tests for')
  args = parser.parse_args(argv)

  modified_files = [os.path.abspath(f) for f in args.file]
  show_all_output = args.show_all_output
  toolchain_utils = args.toolchain_utils

  if not modified_files:
    print('No files given. Exit.')
    return 0

  _fix_python_path(toolchain_utils)

  tests_to_run = _find_forced_subdir_tests(modified_files, toolchain_utils)
  for f in modified_files:
    tests_to_run += _autodetect_python_tests_for(f)

  # TestSpecs have lists, so we can't use a set. We'd likely want to keep them
  # sorted for determinism anyway.
  tests_to_run.sort()
  tests_to_run = _compress_list(tests_to_run)

  success = _run_test_scripts(tests_to_run, show_all_output)
  return 0 if success else 1


if __name__ == '__main__':
  sys.exit(main(sys.argv[1:]))