#!/usr/bin/python
# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Wrapper for the chromite shell.

This script is intended to run in several ways:
- Outside the chroot, it should be _copied_ to someplace that is in the
  path (like depot_tools).  It will search for the right chromite by looking
  for a file 'chromite/shell/main.py' upward based on the CWD.
- Inside the chroot, it might be _either_ copied to someplace in the path (since
  depot_tools is in the path in the chroot) or it might run from chromite/bin
  directly, which should be in the PATH.  In any case, we'll look for the
  real 'chromite/shell/main.py' based on the environment variable
  CROS_WORKON_SRCROOT, so it doesn't matter what the CWD is.

If you're looking at a copy and want to know where the original looks at, look
here:
  http://git.chromium.org/gitweb/?p=chromite.git;a=blob;f=bin/chromite

Since this script is _copied_, it should remain small and not use internal libs.
"""

# Python imports.
import os
import sys

if __name__ == '__main__':
  # Look relative to CROS_WORKON_SRCROOT if that variable exists.  This is
  # the "inside the chroot" case.
  if 'CROS_WORKON_SRCROOT' in os.environ:
    chromite_path = os.path.join(os.environ['CROS_WORKON_SRCROOT'],
                                 'chromite', 'shell', 'main.py')
    if os.path.isfile(chromite_path):
      # Exec the script, which will never return.
      os.execv(chromite_path, sys.argv)
    else:
      print (
          "ERROR: Couldn't find the chromite tool.\n"
          "\n"
          "You may need to update your chroot.  If you need help, see:\n"
          "  http://www.chromium.org/chromium-os/developer-guide"
      )
      sys.exit(1)

  # Outside the chroot, search upward until the "parent" dir doesn't change
  # (on Linux, that means we're at '/').  That is an error case.
  dir = os.getcwd()
  prev_dir = None
  while dir != prev_dir:
    chromite_path = os.path.join(dir, 'chromite', 'shell', 'main.py')
    if os.path.isfile(chromite_path):
      # Add the directory above chromite to PYTHONPATH before executing, so
      # that "import chromite.abc.xyz" works...
      env = os.environ.copy()
      if 'PYTHONPATH' in env:
        env['PYTHONPATH'] += ':%s' % dir
      else:
        env['PYTHONPATH'] = dir

      # Exec the script, which will never return.
      os.execve(chromite_path, sys.argv, env)

    prev_dir = dir
    dir = os.path.dirname(dir)

  # TODO(dianders): Should we actually print out the 'repo init' call that
  # the user should use?
  print (
      "ERROR: Couldn't find the chromite tool.\n"
      "\n"
      "Please change to a directory inside your Chromium OS source tree\n"
      "and retry.  If you need to setup a Chromium OS source tree, see:\n"
      "  http://www.chromium.org/chromium-os/developer-guide"
  )
  sys.exit(1)