#!/bin/sh
# Copyright 2019 The LUCI Authors
# Use of this source code is governed under the Apache License, Version 2.0
# that can be found in the LICENSE file.

# We want to run python in unbuffered mode; however shebangs on linux grab the
# entire rest of the shebang line as a single argument, leading to errors like:
#
#   /usr/bin/env: 'python3 -u': No such file or directory
#
# This little shell hack is a triple-quoted noop in python, but in sh it
# evaluates to re-exec'ing this script in unbuffered mode.
''''exec python3 -u -- "$0" ${1+"$@"} # '''
"""Bootstrap script to clone and forward to the recipe engine tool.

*******************
** DO NOT MODIFY **
*******************

This is a copy of https://chromium.googlesource.com/infra/luci/recipes-py/+/main/recipes.py.
To fix bugs, fix in the googlesource repo then run the autoroller.
"""

import argparse
import errno
import json
import logging
import os
import shutil
import subprocess
import sys

import urllib.parse as urlparse

from collections import namedtuple


# The dependency entry for the recipe_engine in the client repo's recipes.cfg
#
# url (str) - the url to the engine repo we want to use.
# revision (str) - the git revision for the engine to get.
# branch (str) - the branch to fetch for the engine as an absolute ref (e.g.
#   refs/heads/main)
EngineDep = namedtuple('EngineDep', 'url revision branch')


class MalformedRecipesCfg(Exception):

  def __init__(self, msg, path):
    full_message = f'malformed recipes.cfg: {msg}: {path!r}'
    super().__init__(full_message)


def parse(repo_root, recipes_cfg_path):
  """Parse is a lightweight a recipes.cfg file parser.

  Args:
    repo_root (str) - native path to the root of the repo we're trying to run
      recipes for.
    recipes_cfg_path (str) - native path to the recipes.cfg file to process.

  Returns (as tuple):
    engine_dep (EngineDep|None): The recipe_engine dependency, or None, if the
      current repo IS the recipe_engine.
    recipes_path (str) - native path to where the recipes live inside of the
      current repo (i.e. the folder containing `recipes/` and/or
      `recipe_modules`)
  """
  with open(recipes_cfg_path, 'r', encoding='utf-8') as file:
    recipes_cfg = json.load(file)

  try:
    if (version := recipes_cfg['api_version']) != 2:
      raise MalformedRecipesCfg(f'unknown version {version}', recipes_cfg_path)

    # If we're running ./recipes.py from the recipe_engine repo itself, then
    # return None to signal that there's no EngineDep.
    repo_name = recipes_cfg.get('repo_name')
    if not repo_name:
      repo_name = recipes_cfg['project_id']
    if repo_name == 'recipe_engine':
      return None, recipes_cfg.get('recipes_path', '')

    engine = recipes_cfg['deps']['recipe_engine']

    if 'url' not in engine:
      raise MalformedRecipesCfg(
          'Required field "url" in dependency "recipe_engine" not found',
          recipes_cfg_path)

    engine.setdefault('revision', '')
    engine.setdefault('branch', 'refs/heads/main')
    recipes_path = recipes_cfg.get('recipes_path', '')

    # TODO(iannucci): only support absolute refs
    if not engine['branch'].startswith('refs/'):
      engine['branch'] = 'refs/heads/' + engine['branch']

    recipes_path = os.path.join(repo_root,
                                recipes_path.replace('/', os.path.sep))
    return EngineDep(**engine), recipes_path
  except KeyError as ex:
    raise MalformedRecipesCfg(str(ex), recipes_cfg_path) from ex


IS_WIN = sys.platform.startswith(('win', 'cygwin'))

_BAT = '.bat' if IS_WIN else ''
GIT = 'git' + _BAT
CIPD = 'cipd' + _BAT
REQUIRED_BINARIES = {GIT, CIPD}


def _is_executable(path):
  return os.path.isfile(path) and os.access(path, os.X_OK)


def _subprocess_call(argv, **kwargs):
  logging.info('Running %r', argv)
  return subprocess.call(argv, **kwargs)


def _git_check_call(argv, **kwargs):
  argv = [GIT] + argv
  logging.info('Running %r', argv)
  subprocess.check_call(argv, **kwargs)


def _git_output(argv, **kwargs):
  argv = [GIT] + argv
  logging.info('Running %r', argv)
  return subprocess.check_output(argv, **kwargs)


def parse_args(argv):
  """This extracts a subset of the arguments that this bootstrap script cares
  about. Currently this consists of:
    * an override for the recipe engine in the form of `-O recipe_engine=/path`
    * the --package option.
  """
  override_prefix = 'recipe_engine='

  parser = argparse.ArgumentParser(add_help=False)
  parser.add_argument('-O', '--project-override', action='append')
  parser.add_argument('--package', type=os.path.abspath)
  args, _ = parser.parse_known_args(argv)
  for override in args.project_override or ():
    if override.startswith(override_prefix):
      return override[len(override_prefix):], args.package
  return None, args.package


def checkout_engine(engine_path, repo_root, recipes_cfg_path):
  """Checks out the recipe_engine repo pinned in recipes.cfg.

  Returns the path to the recipe engine repo.
  """
  dep, recipes_path = parse(repo_root, recipes_cfg_path)
  if dep is None:
    # we're running from the engine repo already!
    return os.path.join(repo_root, recipes_path)

  url = dep.url

  if not engine_path and url.startswith('file://'):
    engine_path = urlparse.urlparse(url).path

  if not engine_path:
    revision = dep.revision
    branch = dep.branch

    # Ensure that we have the recipe engine cloned.
    engine_path = os.path.join(recipes_path, '.recipe_deps', 'recipe_engine')

    # Note: this logic mirrors the logic in recipe_engine/fetch.py
    _git_check_call(['init', engine_path], stdout=subprocess.DEVNULL)

    try:
      _git_check_call(['rev-parse', '--verify', f'{revision}^{{commit}}'],
                      cwd=engine_path,
                      stdout=subprocess.DEVNULL,
                      stderr=subprocess.DEVNULL)
    except subprocess.CalledProcessError:
      _git_check_call(['fetch', '--quiet', url, branch],
                      cwd=engine_path,
                      stdout=subprocess.DEVNULL)

    try:
      _git_check_call(['diff', '--quiet', revision], cwd=engine_path)
    except subprocess.CalledProcessError:
      index_lock = os.path.join(engine_path, '.git', 'index.lock')
      try:
        os.remove(index_lock)
      except OSError as exc:
        if exc.errno != errno.ENOENT:
          logging.warning('failed to remove %r, reset will fail: %s',
                          index_lock, exc)
      _git_check_call(['reset', '-q', '--hard', revision], cwd=engine_path)

    # If the engine has refactored/moved modules we need to clean all .pyc files
    # or things will get squirrely.
    _git_check_call(['clean', '-qxf'], cwd=engine_path)

  return engine_path


def main():
  for required_binary in REQUIRED_BINARIES:
    if not shutil.which(required_binary):
      return f'Required binary is not found on PATH: {required_binary}'

  if '--verbose' in sys.argv:
    logging.getLogger().setLevel(logging.INFO)

  args = sys.argv[1:]
  engine_override, recipes_cfg_path = parse_args(args)

  if recipes_cfg_path:
    # calculate repo_root from recipes_cfg_path
    repo_root = os.path.dirname(
        os.path.dirname(os.path.dirname(recipes_cfg_path)))
  else:
    # find repo_root with git and calculate recipes_cfg_path
    repo_root = (
        _git_output(['rev-parse', '--show-toplevel'],
                    cwd=os.path.abspath(os.path.dirname(__file__))).strip())
    repo_root = os.path.abspath(repo_root).decode()
    recipes_cfg_path = os.path.join(repo_root, 'infra', 'config', 'recipes.cfg')
    args = ['--package', recipes_cfg_path] + args
  engine_path = checkout_engine(engine_override, repo_root, recipes_cfg_path)

  vpython = 'vpython3' + _BAT
  if not shutil.which(vpython):
    return f'Required binary is not found on PATH: {vpython}'

  # We overwrite PYTHONPATH here on purpose; We don't want any conflicting
  # environmental path leaking through into the recipe_engine which manages its
  # environment entirely via vpython.
  os.environ['PYTHONPATH'] = engine_path

  spec = '.vpython3'
  debugger = os.environ.get('RECIPE_DEBUGGER', '')
  if debugger.startswith('pycharm'):
    spec = '.pycharm.vpython3'
  elif debugger.startswith('vscode'):
    spec = '.vscode.vpython3'

  argv = ([
      vpython,
      '-vpython-spec',
      os.path.join(engine_path, spec),
      '-u',
      os.path.join(engine_path, 'recipe_engine', 'main.py'),
  ] + args)

  if IS_WIN:
    # No real 'exec' on windows; set these signals to ignore so that they
    # propagate to our children but we still wait for the child process to quit.
    import signal
    signal.signal(signal.SIGBREAK, signal.SIG_IGN)
    signal.signal(signal.SIGINT, signal.SIG_IGN)
    signal.signal(signal.SIGTERM, signal.SIG_IGN)
    return _subprocess_call(argv)

  os.execvp(argv[0], argv)
  return -1  # should never occur


if __name__ == '__main__':
  sys.exit(main())
