#!/usr/bin/env python
# Copyright (c) 2013 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.
"""Wrapper script to help run clang tools across Chromium code.

How to use run_tool.py:
If you want to run a clang tool across all Chromium code:
run_tool.py <tool> <path/to/compiledb>

If you want to include all files mentioned in the compilation database
(this will also include generated files, unlike the previous command):
run_tool.py <tool> <path/to/compiledb> --all

If you want to run the clang tool across only chrome/browser and
content/browser:
run_tool.py <tool> <path/to/compiledb> chrome/browser content/browser

Please see docs/clang_tool_refactoring.md for more information, which documents
the entire automated refactoring flow in Chromium.

Why use run_tool.py (instead of running a clang tool directly):
The clang tool implementation doesn't take advantage of multiple cores, and if
it fails mysteriously in the middle, all the generated replacements will be
lost. Additionally, if the work is simply sharded across multiple cores by
running multiple RefactoringTools, problems arise when they attempt to rewrite a
file at the same time.

run_tool.py will
1) run multiple instances of clang tool in parallel
2) gather stdout from clang tool invocations
3) "atomically" forward #2 to stdout

Output of run_tool.py can be piped into extract_edits.py and then into
apply_edits.py. These tools will extract individual edits and apply them to the
source files. These tools assume the clang tool emits the edits in the
following format:
    ...
    ==== BEGIN EDITS ====
    r:::<file path>:::<offset>:::<length>:::<replacement text>
    r:::<file path>:::<offset>:::<length>:::<replacement text>
    ...etc...
    ==== END EDITS ====
    ...

extract_edits.py extracts only lines between BEGIN/END EDITS markers
apply_edits.py reads edit lines from stdin and applies the edits
"""

from __future__ import print_function

import argparse
from collections import namedtuple
import functools
import json
import multiprocessing
import os
import os.path
import re
import subprocess
import shlex
import sys

script_dir = os.path.dirname(os.path.realpath(__file__))
tool_dir = os.path.abspath(os.path.join(script_dir, '../pylib'))
sys.path.insert(0, tool_dir)

from clang import compile_db


CompDBEntry = namedtuple('CompDBEntry', ['directory', 'filename', 'command'])

def _PruneGitFiles(git_files, paths):
  """Prunes the list of files from git to include only those that are either in
  |paths| or start with one item in |paths|.

  Args:
    git_files: List of all repository files.
    paths: Prefix filter for the returned paths. May contain multiple entries,
        and the contents should be absolute paths.

  Returns:
    Pruned list of files.
  """
  if not git_files:
    return []
  git_files.sort()
  pruned_list = []
  git_index = 0
  for path in sorted(paths):
    least = git_index
    most = len(git_files) - 1
    while least <= most:
      middle = int((least + most) / 2)
      if git_files[middle] == path:
        least = middle
        break
      elif git_files[middle] > path:
        most = middle - 1
      else:
        least = middle + 1
    while least < len(git_files) and git_files[least].startswith(path):
      pruned_list.append(git_files[least])
      least += 1
    git_index = least

  return pruned_list


def _GetFilesFromGit(paths=None):
  """Gets the list of files in the git repository if |paths| includes prefix
  path filters or is empty. All complete filenames in |paths| are also included
  in the output.

  Args:
    paths: Prefix filter for the returned paths. May contain multiple entries.
  """
  partial_paths = []
  files = []
  for p in paths:
    real_path = os.path.realpath(p)
    if os.path.isfile(real_path):
      files.append(real_path)
    else:
      partial_paths.append(real_path)
  if partial_paths or not files:
    args = []
    if sys.platform == 'win32':
      args.append('git.bat')
    else:
      args.append('git')
    args.append('ls-files')
    command = subprocess.Popen(args, stdout=subprocess.PIPE)
    output, _ = command.communicate()
    output = output.decode('utf-8')
    git_files = [os.path.realpath(p) for p in output.splitlines()]
    if partial_paths:
      git_files = _PruneGitFiles(git_files, partial_paths)
    files.extend(git_files)
  return files


def _GetEntriesFromCompileDB(build_directory, source_filenames):
  """ Gets the list of files and args mentioned in the compilation database.

  Args:
    build_directory: Directory that contains the compile database.
    source_filenames: If not None, only include entries for the given list of
      filenames.
  """

  filenames_set = None if source_filenames is None else set(source_filenames)
  entries = compile_db.Read(build_directory)
  return [
      CompDBEntry(entry['directory'], entry['file'], entry['command'])
      for entry in entries if filenames_set is None or os.path.realpath(
          os.path.join(entry['directory'], entry['file'])) in filenames_set
  ]


def _UpdateCompileCommandsIfNeeded(compile_commands, files_list,
                                   target_os=None):
  """ Filters compile database to only include required files, and makes it
  more clang-tool friendly on Windows.

  Args:
    compile_commands: List of the contents of compile database.
    files_list: List of required files for processing. Can be None to specify
      no filtering.
  Returns:
    List of the contents of the compile database after processing.
  """
  if sys.platform == 'win32' and files_list:
    relative_paths = set([os.path.relpath(f) for f in files_list])
    filtered_compile_commands = []
    for entry in compile_commands:
      file_path = os.path.relpath(
          os.path.join(entry['directory'], entry['file']))
      if file_path in relative_paths:
        filtered_compile_commands.append(entry)
  else:
    filtered_compile_commands = compile_commands

  return compile_db.ProcessCompileDatabase(filtered_compile_commands, [],
                                           target_os)


def _ExecuteTool(toolname, tool_args, build_directory, compdb_entry):
  """Executes the clang tool.

  This is defined outside the class so it can be pickled for the multiprocessing
  module.

  Args:
    toolname: Name of the clang tool to execute.
    tool_args: Arguments to be passed to the clang tool. Can be None.
    build_directory: Directory that contains the compile database.
    compdb_entry: The file and args to run the clang tool over.

  Returns:
    A dictionary that must contain the key "status" and a boolean value
    associated with it.

    If status is True, then the generated output is stored with the key
    "stdout_text" in the dictionary.

    Otherwise, the filename and the output from stderr are associated with the
    keys "filename" and "stderr_text" respectively.
  """

  args = [toolname, compdb_entry.filename]
  if (tool_args):
    args.extend(tool_args)

  args.append('--')
  args.extend([
      a for a in shlex.split(compdb_entry.command,
                             posix=(sys.platform != 'win32'))
      # 'command' contains the full command line, including the input
      # source file itself. We need to filter it out otherwise it's
      # passed to the tool twice - once directly and once via
      # the compile args.
      if a != compdb_entry.filename
        # /showIncludes is used by Ninja to track header file dependencies on
        # Windows. We don't need to do this here, and it results in lots of spam
        # and a massive log file, so we strip it.
        and a != '/showIncludes' and a != '/showIncludes:user'
        # -MMD has the same purpose on non-Windows. It may have a corresponding
        # '-MF <filename>', which we strip below.
        and a != '-MMD'
  ])

  for i, arg in enumerate(args):
    if arg == '-MF':
      del args[i:i+2]
      break

  # shlex.split escapes double quotes in non-Posix mode, so we need to strip
  # them back.
  if sys.platform == 'win32':
    args = [a.replace('\\"', '"') for a in args]
  command = subprocess.Popen(
      args, stdout=subprocess.PIPE, stderr=subprocess.PIPE, cwd=build_directory)
  stdout_text, stderr_text = command.communicate()
  stdout_text = stdout_text.decode('utf-8')
  stderr_text = stderr_text.decode('utf-8')
  stderr_text = re.sub(
      r"^warning: .*'linker' input unused \[-Wunused-command-line-argument\]\n",
      "", stderr_text, flags=re.MULTILINE)

  if command.returncode != 0:
    return {
        'status': False,
        'filename': compdb_entry.filename,
        'stderr_text': stderr_text,
    }
  else:
    return {
        'status': True,
        'filename': compdb_entry.filename,
        'stdout_text': stdout_text,
        'stderr_text': stderr_text,
    }


class _CompilerDispatcher(object):
  """Multiprocessing controller for running clang tools in parallel."""

  def __init__(self, toolname, tool_args, build_directory, compdb_entries):
    """Initializer method.

    Args:
      toolname: Path to the tool to execute.
      tool_args: Arguments to be passed to the tool. Can be None.
      build_directory: Directory that contains the compile database.
      compdb_entries: The files and args to run the tool over.
    """
    self.__toolname = toolname
    self.__tool_args = tool_args
    self.__build_directory = build_directory
    self.__compdb_entries = compdb_entries
    self.__success_count = 0
    self.__failed_count = 0

  @property
  def failed_count(self):
    return self.__failed_count

  def Run(self):
    """Does the grunt work."""
    pool = multiprocessing.Pool()
    result_iterator = pool.imap_unordered(
        functools.partial(_ExecuteTool, self.__toolname, self.__tool_args,
                          self.__build_directory),
                          self.__compdb_entries)
    for result in result_iterator:
      self.__ProcessResult(result)
    sys.stderr.write('\n')

  def __ProcessResult(self, result):
    """Handles result processing.

    Args:
      result: The result dictionary returned by _ExecuteTool.
    """
    if result['status']:
      self.__success_count += 1
      sys.stdout.write(result['stdout_text'])
      sys.stderr.write(result['stderr_text'])
    else:
      self.__failed_count += 1
      sys.stderr.write('\nFailed to process %s\n' % result['filename'])
      sys.stderr.write(result['stderr_text'])
      sys.stderr.write('\n')
    done_count = self.__success_count + self.__failed_count
    percentage = (float(done_count) / len(self.__compdb_entries)) * 100
    # Only output progress for every 100th entry, to make log files easier to
    # inspect.
    if done_count % 100 == 0 or done_count == len(self.__compdb_entries):
      sys.stderr.write(
          'Processed %d files with %s tool (%d failures) [%.2f%%]\r' %
          (done_count, self.__toolname, self.__failed_count, percentage))


def main():
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--options-file',
      help='optional file to read options from')
  args, argv = parser.parse_known_args()
  if args.options_file:
    argv = open(args.options_file).read().split()

  parser.add_argument('--tool', required=True, help='clang tool to run')
  parser.add_argument('--all', action='store_true')
  parser.add_argument(
      '--generate-compdb',
      action='store_true',
      help='regenerate the compile database before running the tool')
  parser.add_argument(
      '--shard',
      metavar='<n>-of-<count>')
  parser.add_argument(
      '-p',
      required=True,
      help='path to the directory that contains the compile database')
  parser.add_argument(
      '--target_os',
      choices=['android', 'chromeos', 'ios', 'linux', 'nacl', 'mac', 'win'],
      help='Target OS - see `gn help target_os`. Set to "win" when ' +
      'cross-compiling Windows from Linux or another host')
  parser.add_argument(
      'path_filter',
      nargs='*',
      help='optional paths to filter what files the tool is run on')
  parser.add_argument(
      '--tool-arg', nargs='?', action='append',
      help='optional arguments passed to the tool')
  parser.add_argument(
      '--tool-path', nargs='?',
      help='optional path to the tool directory')
  args = parser.parse_args(argv)

  if args.tool_path:
    tool_path = os.path.abspath(args.tool_path)
  else:
    tool_path = os.path.abspath(os.path.join(
          os.path.dirname(__file__),
          '../../../third_party/llvm-build/Release+Asserts/bin'))
  if not os.path.exists(tool_path):
    sys.stderr.write('tool not found: %s\n' % tool_path)
    return -1

  if args.all:
    # Reading source files is postponed to after possible regeneration of
    # compile_commands.json.
    source_filenames = None
  else:
    git_filenames = set(_GetFilesFromGit(args.path_filter))
    # Filter out files that aren't C/C++/Obj-C/Obj-C++.
    extensions = frozenset(('.c', '.cc', '.cpp', '.m', '.mm'))
    source_filenames = [
        f for f in git_filenames if os.path.splitext(f)[1] in extensions
    ]

  if args.generate_compdb:
    compile_commands = compile_db.GenerateWithNinja(args.p)
    compile_commands = _UpdateCompileCommandsIfNeeded(compile_commands,
                                                      source_filenames,
                                                      args.target_os)
    with open(os.path.join(args.p, 'compile_commands.json'), 'w') as f:
      f.write(json.dumps(compile_commands, indent=2))

  compdb_entries = set(_GetEntriesFromCompileDB(args.p, source_filenames))

  if args.shard:
    total_length = len(compdb_entries)
    match = re.match(r'(\d+)-of-(\d+)$', args.shard)
    # Input is 1-based, but modular arithmetic is 0-based.
    shard_number = int(match.group(1)) - 1
    shard_count = int(match.group(2))
    compdb_entries = [
        f for i, f in enumerate(sorted(compdb_entries))
        if i % shard_count == shard_number
    ]
    print('Shard %d-of-%d will process %d entries out of %d' %
          (shard_number, shard_count, len(compdb_entries), total_length))

  dispatcher = _CompilerDispatcher(os.path.join(tool_path, args.tool),
                                   args.tool_arg,
                                   args.p,
                                   compdb_entries)
  dispatcher.Run()
  return -dispatcher.failed_count


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