# Copyright 2018 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.

import json
import logging
import os
import subprocess
import time

import common
import remote_cmd
import runner_logs


_SHUTDOWN_CMD = ['dm', 'poweroff']
_ATTACH_RETRY_INTERVAL = 1
_ATTACH_RETRY_SECONDS = 120

# Amount of time to wait for a complete package installation, as a
# mitigation against hangs due to pkg/network-related failures.
_INSTALL_TIMEOUT_SECS = 10 * 60


def _GetPackageUri(package_name):
  """Returns the URI for the specified package name."""
  return 'fuchsia-pkg://fuchsia.com/%s' % (package_name)


def _GetPackageInfo(package_path):
  """Returns a tuple with the name and version of a package."""

  # Query the metadata file which resides next to the package file.
  package_info = json.load(
      open(os.path.join(os.path.dirname(package_path), 'package')))
  return package_info['name'], package_info['version'],


class _MapIsolatedPathsForPackage:
  """Callable object which remaps /data and /tmp paths to their component-
     specific locations, based on the package name and test realm path."""

  def __init__(self, package_name, package_version, realms):
    realms_path_fragment = '/r/'.join(['r/sys'] + realms)
    package_sub_path = '{2}/fuchsia.com:{0}:{1}#meta:{0}.cmx/'.format(
        package_name, package_version, realms_path_fragment)
    self.isolated_format = '{0}' + package_sub_path + '{1}'

  def __call__(self, path):
    for isolated_directory in ['/data/' , '/tmp/']:
      if (path+'/').startswith(isolated_directory):
        return self.isolated_format.format(isolated_directory,
                                           path[len(isolated_directory):])
    return path


class FuchsiaTargetException(Exception):
  def __init__(self, message):
    super(FuchsiaTargetException, self).__init__(message)


class Target(object):
  """Base class representing a Fuchsia deployment target."""

  def __init__(self, out_dir, target_cpu):
    self._out_dir = out_dir
    self._started = False
    self._dry_run = False
    self._target_cpu = target_cpu
    self._command_runner = None
    self._ffx_path = os.path.join(common.SDK_ROOT, 'tools',
                                  common.GetHostArchFromPlatform(), 'ffx')

  @staticmethod
  def CreateFromArgs(args):
    raise NotImplementedError()

  @staticmethod
  def RegisterArgs(arg_parser):
    pass

  # Functions used by the Python context manager for teardown.
  def __enter__(self):
    return self
  def __exit__(self, exc_type, exc_val, exc_tb):
    return

  def Start(self):
    """Handles the instantiation and connection process for the Fuchsia
    target instance."""

  def IsStarted(self):
    """Returns True if the Fuchsia target instance is ready to accept
    commands."""
    return self._started

  def IsNewInstance(self):
    """Returns True if the connected target instance is newly provisioned."""
    return True

  def GetCommandRunner(self):
    """Returns CommandRunner that can be used to execute commands on the
    target. Most clients should prefer RunCommandPiped() and RunCommand()."""
    self._AssertIsStarted()

    if self._command_runner is None:
      host, port = self._GetEndpoint()
      self._command_runner = \
          remote_cmd.CommandRunner(self._GetSshConfigPath(), host, port)

    return self._command_runner

  def RunCommandPiped(self, command, **kwargs):
    """Starts a remote command and immediately returns a Popen object for the
    command. The caller may interact with the streams, inspect the status code,
    wait on command termination, etc.

    command: A list of strings representing the command and arguments.
    kwargs: A dictionary of parameters to be passed to subprocess.Popen().
            The parameters can be used to override stdin and stdout, for
            example.

    Returns: a Popen object.

    Note: method does not block.
    """
    logging.debug('running (non-blocking) \'%s\'.', ' '.join(command))
    return self.GetCommandRunner().RunCommandPiped(command, **kwargs)

  def RunCommand(self, command, silent=False, timeout_secs=None):
    """Executes a remote command and waits for it to finish executing.

    Returns the exit code of the command.
    """
    logging.debug('running \'%s\'.', ' '.join(command))
    return self.GetCommandRunner().RunCommand(command, silent,
                                              timeout_secs=timeout_secs)

  def EnsureIsolatedPathsExist(self, for_package, for_realms):
    """Ensures that the package's isolated /data and /tmp exist."""
    for isolated_directory in ['/data', '/tmp']:
      self.RunCommand([
          'mkdir', '-p',
          _MapIsolatedPathsForPackage(for_package, 0,
                                      for_realms)(isolated_directory)
      ])

  def PutFile(self,
              source,
              dest,
              recursive=False,
              for_package=None,
              for_realms=()):
    """Copies a file from the local filesystem to the target filesystem.

    source: The path of the file being copied.
    dest: The path on the remote filesystem which will be copied to.
    recursive: If true, performs a recursive copy.
    for_package: If specified, isolated paths in the |dest| are mapped to their
                 obsolute paths for the package, on the target. This currently
                 affects the /data and /tmp directories.
    for_realms: If specified, identifies the sub-realm of 'sys' under which
                isolated paths (see |for_package|) are stored.
    """
    assert type(source) is str
    self.PutFiles([source], dest, recursive, for_package, for_realms)

  def PutFiles(self,
               sources,
               dest,
               recursive=False,
               for_package=None,
               for_realms=()):
    """Copies files from the local filesystem to the target filesystem.

    sources: List of local file paths to copy from, or a single path.
    dest: The path on the remote filesystem which will be copied to.
    recursive: If true, performs a recursive copy.
    for_package: If specified, /data in the |dest| is mapped to the package's
                 isolated /data location.
    for_realms: If specified, identifies the sub-realm of 'sys' under which
                isolated paths (see |for_package|) are stored.
    """
    assert type(sources) is tuple or type(sources) is list
    if for_package:
      self.EnsureIsolatedPathsExist(for_package, for_realms)
      dest = _MapIsolatedPathsForPackage(for_package, 0, for_realms)(dest)
    logging.debug('copy local:%s => remote:%s', sources, dest)
    self.GetCommandRunner().RunScp(sources, dest, remote_cmd.COPY_TO_TARGET,
                                   recursive)

  def GetFile(self,
              source,
              dest,
              for_package=None,
              for_realms=(),
              recursive=False):
    """Copies a file from the target filesystem to the local filesystem.

    source: The path of the file being copied.
    dest: The path on the local filesystem which will be copied to.
    for_package: If specified, /data in paths in |sources| is mapped to the
                 package's isolated /data location.
    for_realms: If specified, identifies the sub-realm of 'sys' under which
                isolated paths (see |for_package|) are stored.
    recursive: If true, performs a recursive copy.
    """
    assert type(source) is str
    self.GetFiles([source], dest, for_package, for_realms, recursive)

  def GetFiles(self,
               sources,
               dest,
               for_package=None,
               for_realms=(),
               recursive=False):
    """Copies files from the target filesystem to the local filesystem.

    sources: List of remote file paths to copy.
    dest: The path on the local filesystem which will be copied to.
    for_package: If specified, /data in paths in |sources| is mapped to the
                 package's isolated /data location.
    for_realms: If specified, identifies the sub-realm of 'sys' under which
                isolated paths (see |for_package|) are stored.
    recursive: If true, performs a recursive copy.
    """
    assert type(sources) is tuple or type(sources) is list
    self._AssertIsStarted()
    if for_package:
      sources = map(_MapIsolatedPathsForPackage(for_package, 0, for_realms),
                    sources)
    logging.debug('copy remote:%s => local:%s', sources, dest)
    return self.GetCommandRunner().RunScp(sources, dest,
                                          remote_cmd.COPY_FROM_TARGET,
                                          recursive)

  def _GetEndpoint(self):
    """Returns a (host, port) tuple for the SSH connection to the target."""
    raise NotImplementedError()

  def _GetTargetSdkArch(self):
    """Returns the Fuchsia SDK architecture name for the target CPU."""
    if self._target_cpu == 'arm64' or self._target_cpu == 'x64':
      return self._target_cpu
    raise FuchsiaTargetException('Unknown target_cpu:' + self._target_cpu)

  def _AssertIsStarted(self):
    assert self.IsStarted()

  def _WaitUntilReady(self):
    logging.info('Connecting to Fuchsia using SSH.')

    host, port = self._GetEndpoint()
    end_time = time.time() + _ATTACH_RETRY_SECONDS
    ssh_diagnostic_log = runner_logs.FileStreamFor('ssh_diagnostic_log')
    while time.time() < end_time:
      runner = remote_cmd.CommandRunner(self._GetSshConfigPath(), host, port)
      ssh_proc = runner.RunCommandPiped(['true'],
                                        ssh_args=['-v'],
                                        stdout=ssh_diagnostic_log,
                                        stderr=subprocess.STDOUT)
      if ssh_proc.wait() == 0:
        logging.info('Connected!')
        self._started = True
        return True
      time.sleep(_ATTACH_RETRY_INTERVAL)

    logging.error('Timeout limit reached.')

    raise FuchsiaTargetException('Couldn\'t connect using SSH.')

  def _GetSshConfigPath(self, path):
    raise NotImplementedError()

  def GetPkgRepo(self):
    """Returns an PkgRepo instance which serves packages for this Target.
    Callers should typically call GetPkgRepo() in a |with| statement, and
    install and execute commands inside the |with| block, so that the returned
    PkgRepo can teardown correctly, if necessary.
    """
    raise NotImplementedError()

  def InstallPackage(self, package_paths):
    """Installs a package and it's dependencies on the device. If the package is
    already installed then it will be updated to the new version.

    package_paths: Paths to the .far files to install.
    """
    with self.GetPkgRepo() as pkg_repo:
      # Publish all packages to the serving TUF repository under |tuf_root|.
      for package_path in package_paths:
        pkg_repo.PublishPackage(package_path)

      # Resolve all packages, to have them pulled into the device/VM cache.
      for package_path in package_paths:
        package_name, package_version = _GetPackageInfo(package_path)
        logging.info('Resolving %s into cache.', package_name)
        return_code = self.RunCommand(
            ['pkgctl', 'resolve',
             _GetPackageUri(package_name), '>/dev/null'],
            timeout_secs=_INSTALL_TIMEOUT_SECS)
        if return_code != 0:
          raise Exception(
              'Error {} while resolving {}.'.format(return_code, package_name))

      # Verify that the newly resolved versions of packages are reported.
      for package_path in package_paths:
        # Use pkgctl get-hash to determine which version will be resolved.
        package_name, package_version = _GetPackageInfo(package_path)
        pkgctl = self.RunCommandPiped(
            ['pkgctl', 'get-hash',
             _GetPackageUri(package_name)],
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE)
        pkgctl_out, pkgctl_err = pkgctl.communicate()

        # Read the expected version from the meta.far Merkel hash file alongside
        # the package's FAR.
        meta_far_path = os.path.join(os.path.dirname(package_path), 'meta.far')
        meta_far_merkel = subprocess.check_output(
            [common.GetHostToolPathFromPlatform('merkleroot'),
             meta_far_path]).split()[0]
        if pkgctl_out != meta_far_merkel:
          raise Exception('Hash mismatch for %s after resolve (%s vs %s).' %
                          (package_name, pkgctl_out, meta_far_merkel))

  def RunFFXCommand(self, ffx_args, **kwargs):
    """Automatically gets the FFX path and runs FFX based on the
    arguments provided. Extra args can be added to be used with Popen.

    ffx_args: The arguments for a ffx command.
    kwargs: A dictionary of parameters to be passed to subprocess.Popen().

    Returns a Popen object for the command."""
    command = [self._ffx_path] + ffx_args
    return subprocess.Popen(command, **kwargs)
