# Copyright 2017 the V8 project authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

from contextlib import contextmanager
from pathlib import Path

import logging
import os
import re
import signal
import subprocess
import sys
import threading
import time

from ..local.android import (Driver, CommandFailedException, TimeoutException)
from ..local.pool import AbortException
from ..objects import output
from .process_utils import ProcessStats, EMPTY_PROCESS_LOGGER, PROCESS_LOGGER

BASE_DIR = Path(__file__).resolve().parent.parent.parent.parent

SEM_INVALID_VALUE = -1
SEM_NOGPFAULTERRORBOX = 0x0002  # Microsoft Platform SDK WinBase.h


def setup_testing():
  """For testing only: We use threading under the hood instead of
  multiprocessing to make coverage work. Signal handling is only supported
  in the main thread, so we disable it for testing.
  """
  signal.signal = lambda *_: None

@contextmanager
def handle_sigterm(process, abort_fun, enabled):
  """Call`abort_fun` on sigterm and restore previous handler to prevent
  erroneous termination of an already terminated process.

  Args:
    process: The process to terminate.
    abort_fun: Function taking two parameters: the process to terminate and
        an array with a boolean for storing if an abort occured.
    enabled: If False, this wrapper will be a no-op.
  """
  # Variable to communicate with the signal handler.
  abort_occured = [False]

  if enabled:
    # TODO(https://crbug.com/v8/13113): There is a race condition on
    # signal handler registration. In rare cases, the SIGTERM for stopping
    # a worker might be caught right after a long running process has been
    # started (or logic that starts it isn't interrupted), but before the
    # registration of the abort_fun. In this case, process.communicate will
    # block until the process is done.
    previous = signal.getsignal(signal.SIGTERM)
    def handler(signum, frame):
      abort_fun(process, abort_occured)
      if previous and callable(previous):
        # Call default signal handler. If this command is called from a worker
        # process, its signal handler will gracefully stop processing.
        previous(signum, frame)
    signal.signal(signal.SIGTERM, handler)
  try:
    yield
  finally:
    if enabled:
      signal.signal(signal.SIGTERM, previous)

  if abort_occured[0]:
    raise AbortException()


class BaseCommand(object):
  def __init__(self, shell, args=None, cmd_prefix=None, timeout=60, env=None,
               verbose=False, test_case=None, handle_sigterm=False,
               log_process_stats=False):
    """Initialize the command.

    Args:
      shell: The name of the executable (e.g. d8).
      args: List of args to pass to the executable.
      cmd_prefix: Prefix of command (e.g. a wrapper script).
      timeout: Timeout in seconds.
      env: Environment dict for execution.
      verbose: Print additional output.
      test_case: Test case reference.
      handle_sigterm: Flag indicating if SIGTERM will be used to terminate the
          underlying process. Should not be used from the main thread, e.g. when
          using a command to list tests.
      log_process_stats: Indicate if we want to probe for process statistics like
          memory consumption.
    """
    assert(timeout > 0)

    self.shell = Path(shell)
    self.args = list(map(str, args or []))
    self.cmd_prefix = cmd_prefix or []
    self.timeout = timeout
    self.env = env or {}
    self.verbose = verbose
    self.handle_sigterm = handle_sigterm

    if log_process_stats:
      self.process_logger = self.get_process_logger()
    else:
      self.process_logger = EMPTY_PROCESS_LOGGER

  def _result_overrides(self, returncode):
    pass

  @contextmanager
  def log_errors(self):
    try:
      yield
    except:
      logging.exception(f'Error executing: {self}\n')
      raise

  def get_process_logger(self):
    return EMPTY_PROCESS_LOGGER

  def execute(self):
    if self.verbose:
      print('# %s' % self)

    process = self._start_process()

    with handle_sigterm(process, self._abort, self.handle_sigterm):
      # Variable to communicate with the timer.
      timeout_occured = [False]
      timer = threading.Timer(
          self.timeout, self._abort, [process, timeout_occured])
      timer.start()

      start_time = time.time()
      with self.log_errors():
        with self.process_logger.log_stats(process) as stats:
          stdout, stderr = process.communicate()
      end_time = time.time()

      timer.cancel()

    self._result_overrides(process)
    return output.Output(
      process.returncode,
      timeout_occured[0],
      stdout.decode('utf-8', 'replace'),
      stderr.decode('utf-8', 'replace'),
      process.pid,
      start_time,
      end_time,
      stats=stats,
    )

  def _start_process(self):
    with self.log_errors():
      return subprocess.Popen(
        args=self._get_popen_args(),
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        env=self._get_env(),
      )

  def _get_popen_args(self):
    return self._to_args_list()

  def _get_env(self):
    env = os.environ.copy()
    env.update(self.env)
    # GTest shard information is read by the V8 tests runner. Make sure it
    # doesn't leak into the execution of gtests we're wrapping. Those might
    # otherwise apply a second level of sharding and as a result skip tests.
    env.pop('GTEST_TOTAL_SHARDS', None)
    env.pop('GTEST_SHARD_INDEX', None)
    return env

  def _kill_process(self, process):
    raise NotImplementedError()

  def _abort(self, process, abort_called):
    abort_called[0] = True
    started_as = self.to_string(relative=True)
    process_text = 'process %d started as:\n  %s\n' % (process.pid, started_as)
    try:
      logging.warning('Attempting to kill %s', process_text)
      self._kill_process(process)
    except OSError:
      logging.exception('Unruly %s', process_text)

  def __str__(self):
    return self.to_string()

  def to_string(self, relative=False):
    def escape(part):
      # Escape spaces. We may need to escape more characters for this to work
      # properly.
      if ' ' in part:
        return '"%s"' % part
      return part

    parts = map(escape, self._to_args_list())
    cmd = ' '.join(parts)
    if relative:
      cmd = cmd.replace(os.getcwd() + os.sep, '')
    return cmd

  def _to_args_list(self):
    return list(map(str, self.cmd_prefix + [self.shell])) + self.args


class DesktopCommand(BaseCommand):
  def get_process_logger(self):
    return PROCESS_LOGGER


class PosixCommand(DesktopCommand):
  # TODO(machenbach): Use base process start without shell once
  # https://crbug.com/v8/8889 is resolved.
  def _start_process(self):
    def wrapped(arg):
      if set('() \'"') & set(arg):
        return "'%s'" % arg.replace("'", "'\"'\"'")
      return arg
    try:
      return subprocess.Popen(
        args=' '.join(map(wrapped, self._get_popen_args())),
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        env=self._get_env(),
        shell=True,
        # Make the new shell create its own process group. This allows to kill
        # all spawned processes reliably (https://crbug.com/v8/8292).
        preexec_fn=os.setsid,
      )
    except Exception as e:
      sys.stderr.write('Error executing: %s\n' % self)
      raise e

  def _kill_process(self, process):
    # Kill the whole process group (PID == GPID after setsid).
    # First try a soft term to allow some feedback
    os.killpg(process.pid, signal.SIGTERM)
    # Give the process some time to cleanly terminate.
    time.sleep(0.1)
    # Forcefully kill processes.
    os.killpg(process.pid, signal.SIGKILL)


class IOSCommand(BaseCommand):

  def __init__(self,
               shell,
               args=None,
               cmd_prefix=None,
               timeout=120,
               env=None,
               verbose=False,
               test_case=None,
               handle_sigterm=False,
               log_process_stats=False):
    """Initialize the command and set a large enough timeout required for runs
    through the iOS Simulator.
    """
    super(IOSCommand, self).__init__(
        shell,
        args=args,
        cmd_prefix=cmd_prefix,
        timeout=timeout,
        env=env,
        verbose=verbose,
        handle_sigterm=handle_sigterm,
        log_process_stats=log_process_stats)

  def _result_overrides(self, process):
    # TODO(crbug.com/1445694): if iossim returns with code 65, force a
    # successful exit instead.
    if (process.returncode == 65):
      process.returncode = 0

  def _start_process(self):
    try:
      return subprocess.Popen(
          args=self._get_popen_args(),
          stdout=subprocess.PIPE,
          stderr=subprocess.PIPE,
          env=self._get_env(),
          shell=True,
          # Make the new shell create its own process group. This allows to kill
          # all spawned processes reliably (https://crbug.com/v8/8292).
          preexec_fn=os.setsid,
      )
    except Exception as e:
      sys.stderr.write('Error executing: %s\n' % self)
      raise e

  def _kill_process(self, process):
    # Kill the whole process group (PID == GPID after setsid).
    # First try a soft term to allow some feedback
    os.killpg(process.pid, signal.SIGTERM)
    # Give the process some time to cleanly terminate.
    time.sleep(0.1)
    # Forcefully kill processes.
    os.killpg(process.pid, signal.SIGKILL)

  def _to_args_list(self):
    return list(map(str, self.cmd_prefix + [self.shell]))

def terminate_process_windows(process):
  try:
    import _winapi
    handle = _winapi.OpenProcess(
        _winapi.PROCESS_ALL_ACCESS, False, process.pid)
    _winapi.TerminateProcess(handle, 1)
    _winapi.CloseHandle(handle)
  except Exception:
    logging.exception('Problem terminating process %s', process.pid)


class WindowsCommand(DesktopCommand):
  def _start_process(self, **kwargs):
    # Try to change the error mode to avoid dialogs on fatal errors. Don't
    # touch any existing error mode flags by merging the existing error mode.
    # See http://blogs.msdn.com/oldnewthing/archive/2004/07/27/198410.aspx.
    def set_error_mode(mode):
      prev_error_mode = SEM_INVALID_VALUE
      try:
        import ctypes
        prev_error_mode = (
            ctypes.windll.kernel32.SetErrorMode(mode))  #@UndefinedVariable
      except ImportError:
        pass
      return prev_error_mode

    error_mode = SEM_NOGPFAULTERRORBOX
    prev_error_mode = set_error_mode(error_mode)
    set_error_mode(error_mode | prev_error_mode)

    try:
      return super(WindowsCommand, self)._start_process(**kwargs)
    finally:
      if prev_error_mode != SEM_INVALID_VALUE:
        set_error_mode(prev_error_mode)

  def _get_popen_args(self):
    return subprocess.list2cmdline(self._to_args_list())

  def _kill_process(self, process):
    terminate_process_windows(process)


class AndroidCommand(BaseCommand):
  # This must be initialized before creating any instances of this class.
  driver = None

  def __init__(self, shell, args=None, cmd_prefix=None, timeout=60, env=None,
               verbose=False, test_case=None, handle_sigterm=False,
               log_process_stats=False):
    """Initialize the command and all files that need to be pushed to the
    Android device.
    """
    super(AndroidCommand, self).__init__(
        shell, args=args, cmd_prefix=cmd_prefix, timeout=timeout, env=env,
        verbose=verbose, handle_sigterm=handle_sigterm,
        log_process_stats=log_process_stats)

    rel_args, files_from_args = args_with_relative_paths(args)

    self.args = rel_args

    test_case_resources = test_case.get_android_resources() if test_case else []
    self.files_to_push = test_case_resources + files_from_args

  def execute(self, **additional_popen_kwargs):
    """Execute the command on the device.

    This pushes all required files to the device and then runs the command.
    """
    if self.verbose:
      print('# %s' % self)

    shell_name = self.shell.name
    shell_dir = self.shell.parent

    self.driver.push_executable(shell_dir, 'bin', shell_name)
    self.push_test_resources()

    start_time = time.time()
    return_code = 0
    timed_out = False
    try:
      stdout = self.driver.run(
          'bin', shell_name, self.args, '.', self.timeout, self.env)
    except CommandFailedException as e:
      return_code = e.status
      stdout = e.output
    except TimeoutException as e:
      return_code = 1
      timed_out = True
      # Sadly the Android driver doesn't provide output on timeout.
      stdout = ''

    end_time = time.time()
    return output.Output(
        return_code,
        timed_out,
        stdout,
        '',  # No stderr available.
        -1,  # No pid available.
        start_time,
        end_time,
    )

  def push_test_resources(self):
    for abs_file in self.files_to_push:
      abs_dir = abs_file.parent
      file_name = abs_file.name
      rel_dir = abs_dir.relative_to(BASE_DIR)
      self.driver.push_file(abs_dir, file_name, rel_dir)


def args_with_relative_paths(args):
  base_dir_str = re.escape(BASE_DIR.as_posix())
  rel_args = []
  files_to_push = []
  find_path_re = re.compile(r'.*(%s/[^\'"]+).*' % base_dir_str)
  for arg in (args or []):
    match = find_path_re.match(str(arg))
    if match:
      files_to_push.append(Path(match.group(1)).resolve())
    rel_args.append(re.sub(r'(.*)%s/(.*)' % base_dir_str, r'\1\2', str(arg)))
  return rel_args, files_to_push


Command = None


# Deprecated : use context.os_context
def setup(target_os, device):
  """Set the Command class to the OS-specific version."""
  global Command
  if target_os == 'android':
    AndroidCommand.driver = Driver.instance(device)
    Command = AndroidCommand
  elif target_os == 'ios':
    Command = IOSCommand
  elif target_os == 'windows':
    Command = WindowsCommand
  else:
    Command = PosixCommand


# Deprecated : use context.os_context
def tear_down():
  """Clean up after using commands."""
  if Command == AndroidCommand:
    AndroidCommand.driver.tear_down()