#!/usr/bin/env python
# Copyright 2019 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""A script to use a package as the WebView provider while running a command."""

import argparse
import contextlib
import logging
import os
import re
import sys

if __name__ == '__main__':
  _DEVIL_ROOT_DIR = os.path.abspath(
      os.path.join(os.path.dirname(__file__), '..', '..', '..'))
  sys.path.append(_DEVIL_ROOT_DIR)

from devil import devil_env
from devil.android import apk_helper
from devil.android import device_errors
from devil.android.sdk import version_codes
from devil.android.tools import script_common
from devil.android.tools import system_app
from devil.utils import cmd_helper
from devil.utils import parallelizer
from devil.utils import run_tests_helper

with devil_env.SysPath(devil_env.PY_UTILS_PATH):
  from py_utils import tempfile_ext

logger = logging.getLogger(__name__)

_SYSTEM_PATH_RE = re.compile(r'^\s*\/(system|product)\/')
_WEBVIEW_INSTALL_TIMEOUT = 300


@contextlib.contextmanager
def UseWebViewProvider(device, apk, expected_package=''):
  """A context manager that uses the apk as the webview provider while in scope.

  Args:
    device: (device_utils.DeviceUtils) The device for which the webview apk
      should be used as the provider.
    apk: (str) The path to the webview APK to use.
    expected_package: (str) If non-empty, verify apk's package name matches
                      this value.
  """
  package_name = apk_helper.GetPackageName(apk)

  if expected_package:
    if package_name != expected_package:
      raise device_errors.CommandFailedError(
          'WebView Provider package %s does not match expected %s' %
          (package_name, expected_package), str(device))

  if (device.build_version_sdk in [
      version_codes.NOUGAT, version_codes.NOUGAT_MR1
  ]):
    logger.warning('Due to webviewupdate bug in Nougat, WebView Fallback Logic '
                   'will be disabled and WebView provider may be changed after '
                   'exit of UseWebViewProvider context manager scope.')

  webview_update = device.GetWebViewUpdateServiceDump()
  original_fallback_logic = webview_update.get('FallbackLogicEnabled', None)
  original_provider = webview_update.get('CurrentWebViewPackage', None)

  # This is only necessary if the provider is a fallback provider, but we can't
  # generally determine this, so we set this just in case.
  device.SetWebViewFallbackLogic(False)

  try:
    # If user installed versions of the package is present, they must be
    # uninstalled first, so that the system version of the package,
    # if any, can be found by the ReplaceSystemApp context manager
    with _UninstallNonSystemApp(device, package_name):
      all_paths = device.GetApplicationPaths(package_name)
      system_paths = _FilterPaths(all_paths, True)
      non_system_paths = _FilterPaths(all_paths, False)
      if non_system_paths:
        raise device_errors.CommandFailedError(
            'Non-System application paths found after uninstallation: ',
            str(non_system_paths))
      elif system_paths:
        # app is system app, use ReplaceSystemApp to install
        with system_app.ReplaceSystemApp(
            device, package_name, apk,
            install_timeout=_WEBVIEW_INSTALL_TIMEOUT):
          _SetWebViewProvider(device, package_name)
          yield
      else:
        # app is not present on device, can directly install
        with _InstallApp(device, apk):
          _SetWebViewProvider(device, package_name)
          yield
  finally:
    # restore the original provider only if it was known and not the current
    # provider
    if original_provider is not None:
      webview_update = device.GetWebViewUpdateServiceDump()
      new_provider = webview_update.get('CurrentWebViewPackage', None)
      if new_provider != original_provider:
        device.SetWebViewImplementation(original_provider)

    # enable the fallback logic only if it was known to be enabled
    if original_fallback_logic is True:
      device.SetWebViewFallbackLogic(True)


def _SetWebViewProvider(device, package_name):
  """ Set the WebView provider to the package_name if supported. """
  if device.build_version_sdk >= version_codes.NOUGAT:
    device.SetWebViewImplementation(package_name)


def _FilterPaths(path_list, is_system):
  """ Return paths in the path_list that are/aren't system paths. """
  return [
      p for p in path_list if is_system == bool(re.match(_SYSTEM_PATH_RE, p))
  ]


def _RebasePath(new_root, old_root):
  """ Graft old_root onto new_root and return the result. """
  return os.path.join(new_root, os.path.relpath(old_root, '/'))


@contextlib.contextmanager
def _UninstallNonSystemApp(device, package_name):
  """ Make package un-installed while in scope. """
  all_paths = device.GetApplicationPaths(package_name)
  user_paths = _FilterPaths(all_paths, False)
  host_paths = []
  if user_paths:
    with tempfile_ext.NamedTemporaryDirectory() as temp_dir:
      for user_path in user_paths:
        host_path = _RebasePath(temp_dir, user_path)
        # PullFile takes care of host_path creation if needed.
        device.PullFile(user_path, host_path, timeout=_WEBVIEW_INSTALL_TIMEOUT)
        host_paths.append(host_path)
      device.Uninstall(package_name)
      try:
        yield
      finally:
        for host_path in reversed(host_paths):
          device.Install(
              host_path, reinstall=True, timeout=_WEBVIEW_INSTALL_TIMEOUT)
  else:
    yield


@contextlib.contextmanager
def _InstallApp(device, apk):
  """ Make apk installed while in scope. """
  package_name = apk_helper.GetPackageName(apk)
  device.Install(apk, reinstall=True, timeout=_WEBVIEW_INSTALL_TIMEOUT)
  try:
    yield
  finally:
    device.Uninstall(package_name)


def main(raw_args):
  parser = argparse.ArgumentParser()

  def add_common_arguments(p):
    script_common.AddDeviceArguments(p)
    script_common.AddEnvironmentArguments(p)
    p.add_argument(
        '-v',
        '--verbose',
        action='count',
        default=0,
        help='Print more information.')
    p.add_argument('command', nargs='*')

  @contextlib.contextmanager
  def use_webview_provider(device, args):
    with UseWebViewProvider(device, args.apk, args.expected_package):
      yield

  parser.add_argument(
      '--apk', required=True, help='The apk to use as the provider.')
  parser.add_argument(
      '--expected-package',
      default='',
      help="Verify apk's package name matches value, disabled by default.")
  add_common_arguments(parser)
  parser.set_defaults(func=use_webview_provider)

  args = parser.parse_args(raw_args)

  run_tests_helper.SetLogLevel(args.verbose)
  script_common.InitializeEnvironment(args)