# Copyright 2015 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 subprocess
import threading

from devtoolslib.shell import Shell
from devtoolslib import http_server


class LinuxShell(Shell):
  """Wrapper around Mojo shell running on Linux.

  Args:
    executable_path: path to the shell binary
    command_prefix: optional list of arguments to prepend to the shell command,
        allowing e.g. to run the shell under debugger.
  """

  def __init__(self, executable_path, command_prefix=None):
    self.executable_path = executable_path
    self.command_prefix = command_prefix if command_prefix else []

  def ServeLocalDirectory(self, local_dir_path, port=0):
    """Serves the content of the local (host) directory, making it available to
    the shell under the url returned by the function.

    The server will run on a separate thread until the program terminates. The
    call returns immediately.

    Args:
      local_dir_path: path to the directory to be served
      port: port at which the server will be available to the shell

    Returns:
      The url that the shell can use to access the content of |local_dir_path|.
    """
    mappings = [('', local_dir_path)]
    return 'http://%s:%d/' % http_server.start_http_server(mappings, port)

  def ServeLocalDirectories(self, mappings, port=0):
    """Serves the content of the local (host) directories, making it available
    to the shell under the url returned by the function.

    The server will run on a separate thread until the program terminates. The
    call returns immediately.

    Args:
      mappings: List of tuples (prefix, local_base_path) mapping URLs that start
          with |prefix| to local directory at |local_base_path|. The prefixes
          should skip the leading slash. The first matching prefix will be used
          each time.
      port: port at which the server will be available to the shell

    Returns:
      The url that the shell can use to access the content of |local_dir_path|.
    """
    return 'http://%s:%d/' % http_server.start_http_server(mappings, port)

  def ForwardHostPortToShell(self, host_port):
    """Forwards a port on the host machine to the same port wherever the shell
    is running.

    This is a no-op if the shell is running locally.
    """
    pass

  def Run(self, arguments):
    """Runs the shell with given arguments until shell exits, passing the stdout
    mingled with stderr produced by the shell onto the stdout.

    Returns:
      Exit code retured by the shell or None if the exit code cannot be
      retrieved.
    """
    command = self.command_prefix + [self.executable_path] + arguments
    return subprocess.call(command, stderr=subprocess.STDOUT)

  def RunAndGetOutput(self, arguments, timeout=None):
    """Runs the shell with given arguments until shell exits and returns the
    output.

    Args:
      arguments: list of arguments for the shell
      timeout: maximum running time in seconds, after which the shell will be
          terminated

    Returns:
      A tuple of (return_code, output, did_time_out). |return_code| is the exit
      code returned by the shell or None if the exit code cannot be retrieved.
      |output| is the stdout mingled with the stderr produced by the shell.
      |did_time_out| is True iff the shell was terminated because it exceeded
      the |timeout| and False otherwise.
    """
    command = self.command_prefix + [self.executable_path] + arguments
    p = subprocess.Popen(command, stdout=subprocess.PIPE,
                         stderr=subprocess.STDOUT)

    class Results:
      """Workaround for Python scoping rules that prevent assigning to variables
      from the outer scope.
      """
      output = None

    def do_run():
      (Results.output, _) = p.communicate()

    run_thread = threading.Thread(target=do_run)
    run_thread.start()
    run_thread.join(timeout)

    if run_thread.is_alive():
      p.terminate()
      return p.returncode, Results.output, True
    return p.returncode, Results.output, False