# Copyright 2014 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.
"""Utility functions used by Generational and Mutational ClusterFuzz
fuzzers."""

import argparse
import os
import random
import string
import sys
import tempfile

BUILD_DIR_KEY = 'BUILD_DIR'
FLAGS_PREFIX = 'flags-'
FUZZ_PREFIX = 'fuzz-'
IPC_FUZZER_APPLICATION = 'ipc_fuzzer'
IPC_REPLAY_APPLICATION = 'ipc_fuzzer_replay'
IPCDUMP_EXTENSION = '.ipcdump'
UNCOMMON_PREFIX_CHANCE = 10  # 1 in 10
COMMON_LAUNCH_PREFIXES = [
    '--renderer-cmd-prefix',
]
UNCOMMON_LAUNCH_PREFIXES = [
    '--plugin-launcher',
    '--ppapi-plugin-launcher',
    '--utility-cmd-prefix',
]


def application_name_for_platform(application_name):
  """Return application name for current platform."""
  if platform() == 'WINDOWS':
    return application_name + '.exe'
  return application_name


def create_flags_file(ipcdump_testcase_path):
  """Create a flags file to add launch prefix to application command line."""
  prefixes = (UNCOMMON_LAUNCH_PREFIXES if
              random.randint(1, UNCOMMON_PREFIX_CHANCE) == 1 else
              COMMON_LAUNCH_PREFIXES)
  random_launch_prefix = random.choice(prefixes)
  application_name = application_name_for_platform(IPC_REPLAY_APPLICATION)
  file_content = '%s=%%APP_DIR%%%s%s' % (random_launch_prefix, os.path.sep,
                                         application_name)

  flags_file_path = ipcdump_testcase_path.replace(FUZZ_PREFIX, FLAGS_PREFIX)
  file_handle = open(flags_file_path, 'w')
  file_handle.write(file_content)
  file_handle.close()


def create_temp_file():
  """Create a temporary file."""
  temp_file = tempfile.NamedTemporaryFile(delete=False)
  temp_file.close()
  return temp_file.name


def get_fuzzer_application_name():
  """Get the application name for the fuzzer binary."""
  return application_name_for_platform(IPC_FUZZER_APPLICATION)


def get_replay_application_name():
  """Get the application name for the replay binary."""
  return application_name_for_platform(IPC_REPLAY_APPLICATION)


def parse_arguments():
  """Parse fuzzer arguments."""
  parser = argparse.ArgumentParser()
  parser.add_argument('--input_dir')
  parser.add_argument('--output_dir')
  parser.add_argument('--no_of_files', type=int)
  args = parser.parse_args()
  if (not args.input_dir or not args.output_dir or not args.no_of_files):
    parser.print_help()
    sys.exit(1)

  return args


def random_id(size=16, chars=string.ascii_lowercase):
  """Return a random id string, default 16 characters long."""
  return ''.join(random.choice(chars) for _ in range(size))


def random_ipcdump_testcase_path(ipcdump_directory):
  """Return a random ipc testcase path."""
  return os.path.join(ipcdump_directory,
                      '%s%s%s' % (FUZZ_PREFIX, random_id(), IPCDUMP_EXTENSION))


def platform():
  """Return running platform."""
  if sys.platform.startswith('win'):
    return 'WINDOWS'
  if sys.platform.startswith('linux'):
    return 'LINUX'
  if sys.platform == 'darwin':
    return 'MAC'

  assert False, 'Unknown platform'


def get_application_path(application_name):
  """Return chrome application path."""
  if BUILD_DIR_KEY not in os.environ:
    sys.exit('Environment variable %s should be set to chrome directory.' %
             BUILD_DIR_KEY)

  for root, _, files in os.walk(os.environ[BUILD_DIR_KEY]):
    for filename in files:
      if filename == application_name:
        return os.path.join(root, application_name)

  sys.exit('Application %s was not found in chrome directory.' %
           application_name)