#
# Copyright 2017 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
"""Abstraction for running Cobalt development tools."""

import abc
import importlib
import os
import sys

import _env  # pylint: disable=unused-import
from starboard.tools import build


def _GetLauncherForPlatform(platform_name):
  """Gets the module containing a platform's concrete launcher implementation.

  Args:
    platform_name: Platform on which the app will be run, ex. "linux-x64x11".

  Returns:
    The module containing the platform's launcher implementation.
  """

  gyp_config = build.GetPlatformConfig(platform_name)
  if not hasattr(gyp_config, "GetLauncher"):
    return None
  else:
    return gyp_config.GetLauncher()


def DynamicallyBuildOutDirectory(platform_name, config):
  """Constructs the location used to store executable targets/their components.

  Args:
    platform_name: The platform to run the executable on, ex. "linux-x64x11".
    config: The build configuration, ex. "qa".

  Returns:
    The path to the directory containing executables and/or their components.
  """
  path = os.path.abspath(
      os.path.join(
          os.path.dirname(__file__), os.pardir, os.pardir, "out",
          "{}_{}".format(platform_name, config)))
  return path


def LauncherFactory(platform_name,
                    target_name,
                    config,
                    device_id=None,
                    target_params=None,
                    output_file=None,
                    out_directory=None,
                    env_variables=None):
  """Creates the proper launcher based upon command line args.

  Args:
    platform_name:  The platform on which the app will run.
    target_name:  The name of the executable target (ex. "cobalt").
    config:  Type of configuration used by the launcher (ex. "qa", "devel").
    device_id:  The identifier for the devkit being used.  Can be None.
    target_params: Command line arguments to the executable.  Can be None.
    output_file: Open file object used for storing the launcher's output. If
      None, sys.stdout is used.
    out_directory: Directory containing the executable target. If None is
      provided, the path to the directory is dynamically generated.
    env_variables:  Environment variables for the executable

  Returns:
    An instance of the concrete launcher class for the desired platform.

  Raises:
    RuntimeError: The platform does not exist, or there is no project root.
  """

  #  Creates launcher for provided platform if the platform has a valid port
  launcher_module = _GetLauncherForPlatform(platform_name)

  #  TODO: Refactor when all old launchers have been deleted
  #  If a platform that does not have a new launcher is provided, attempt
  #  to create an adapter to the old one.
  if not launcher_module:
    old_path = os.path.abspath(
        os.path.join(
            os.path.dirname(__file__), os.pardir, os.pardir, "tools",
            "lbshell"))
    if os.path.exists(os.path.join(old_path, "app_launcher.py")):
      sys.path.append(old_path)
      bridge_module = importlib.import_module("app_launcher_bridge")
      return bridge_module.LauncherAdapter(
          platform_name,
          target_name,
          config,
          device_id,
          target_params=target_params,
          output_file=output_file,
          out_directory=out_directory,
          env_variables=env_variables)
    else:
      raise RuntimeError("No launcher implemented for the given platform.")
  else:
    return launcher_module.Launcher(
        platform_name,
        target_name,
        config,
        device_id,
        target_params=target_params,
        output_file=output_file,
        out_directory=out_directory,
        env_variables=env_variables)


class AbstractLauncher(object):
  """Class that specifies all required behavior for Cobalt app launchers."""

  __metaclass__ = abc.ABCMeta

  def __init__(self, platform_name, target_name, config, device_id, **kwargs):
    self.platform_name = platform_name
    self.target_name = target_name
    self.config = config
    self.device_id = device_id
    self.out_directory = kwargs.get("out_directory", None)

    #  The following pattern makes sure that variables will be initialized
    #  properly whether a kwarg is passed in with a value of None or it
    #  is not passed in at all.
    output_file = kwargs.get("output_file", None)
    if not output_file:
      output_file = sys.stdout
    self.output_file = output_file

    target_command_line_params = kwargs.get("target_params", None)
    if target_command_line_params is None:
      target_command_line_params = []
    self.target_command_line_params = target_command_line_params

    env_variables = kwargs.get("env_variables", None)
    if env_variables is None:
      env_variables = {}
    self.env_variables = env_variables

    # Launchers that need different startup timeout times should reassign
    # this variable during initialization.
    self.startup_timeout_seconds = 2 * 60

  @abc.abstractmethod
  def Run(self):
    """Runs the launcher's executable.  Must be implemented in subclasses.

    Returns:
      The return code from the launcher's executable.
    """
    pass

  @abc.abstractmethod
  def Kill(self):
    """Kills the launcher. Must be implemented in subclasses."""
    pass

  def SupportsSuspendResume(self):
    return False

  # The Send*() functions are guaranteed to resolve sequences of calls (e.g.
  # SendSuspend() followed immediately by SendResume()) in the order that they
  # are sent.
  def SendResume(self):
    """Sends resume signal to the launcher's executable.

    Raises:
      RuntimeError: Resume signal not supported on platform.
    """
    raise RuntimeError("Resume not supported for this platform.")

  def SendSuspend(self):
    """sends suspend signal to the launcher's executable.

    When implementing this function, please coordinate with other functions
    sending platform signals(e.g. SendResume()) to ensure Cobalt receives these
    signals in the same order they are sent.

    Raises:
      RuntimeError: Suspend signal not supported on platform.
    """

    raise RuntimeError("Suspend not supported for this platform.")

  def GetStartupTimeout(self):
    """Gets the number of seconds to wait before assuming a launcher timeout."""

    return self.startup_timeout_seconds

  def GetHostAndPortGivenPort(self, port):
    """Creates a host/port tuple for use on the target device.

    This is used to gain access to a service on the target device, and
    can be overridden when the host/port of that service is only accessible
    at runtime and/or via forwarding.

    Args:
      port:  Port number for the desired service on the target device.

    Returns:
      (Host, port) tuple for use in connecting to the target device.
    """
    return self.device_id, port

  def GetTargetPath(self):
    """Constructs the path to an executable target.

    The default path returned by this method takes the form of:

      "/path/to/out/<platform>_<config>/target_name"

    Returns:
      The path to an executable target.
    """
    if self.out_directory:
      out_directory = self.out_directory
    else:
      out_directory = DynamicallyBuildOutDirectory(self.platform_name,
                                                   self.config)

    return os.path.abspath(os.path.join(out_directory, self.target_name))