#!/usr/bin/env python3

#
# Copyright 2015, The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

"""Script that is used by developers to run style checks on Java files."""

from __future__ import print_function

import argparse
import errno
import os
import shutil
import subprocess
import sys
import tempfile
import xml.dom.minidom
import gitlint.git as git


def _FindFoldersContaining(root, wanted):
  """Recursively finds directories that have a file with the given name.

  Args:
    root: Root folder to start the search from.
    wanted: The filename that we are looking for.

  Returns:
    List of folders that has a file with the given name
  """

  if not root:
    return []
  if os.path.islink(root):
    return []
  result = []
  for file_name in os.listdir(root):
    file_path = os.path.join(root, file_name)
    if os.path.isdir(file_path):
      sub_result = _FindFoldersContaining(file_path, wanted)
      result.extend(sub_result)
    else:
      if file_name == wanted:
        result.append(root)
  return result

MAIN_DIRECTORY = os.path.normpath(os.path.dirname(__file__))
CHECKSTYLE_JAR = os.path.join(MAIN_DIRECTORY, 'checkstyle.jar')
CHECKSTYLE_STYLE = os.path.join(MAIN_DIRECTORY, 'android-style.xml')
FORCED_RULES = ['com.puppycrawl.tools.checkstyle.checks.imports.ImportOrderCheck',
                'com.puppycrawl.tools.checkstyle.checks.imports.UnusedImportsCheck']
SKIPPED_RULES_FOR_TEST_FILES = ['com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocTypeCheck',
                                'com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocMethodCheck']
SUBPATH_FOR_TEST_FILES = ['/tests/', '/test/', '/androidTest/', '/perftests/', '/gts-tests/',
                          '/hostsidetests/', '/jvmTest/', '/robotests/', '/robolectric/']
SUBPATH_FOR_TEST_DATA_FILES = _FindFoldersContaining(git.repository_root(),
                                                     'IGNORE_CHECKSTYLE')
ERROR_UNCOMMITTED = 'You need to commit all modified files before running Checkstyle\n'
ERROR_UNTRACKED = 'You have untracked java files that are not being checked:\n'


def RunCheckstyleOnFiles(java_files, classpath=CHECKSTYLE_JAR, config_xml=CHECKSTYLE_STYLE):
  """Runs Checkstyle checks on a given set of java_files.

  Args:
    java_files: A list of files to check.
    classpath: The colon-delimited list of JARs in the classpath.
    config_xml: Path of the checkstyle XML configuration file.

  Returns:
    A tuple of errors and warnings.
  """
  print('Running Checkstyle on inputted files')
  java_files = list(map(os.path.abspath, java_files))
  stdout = _ExecuteCheckstyle(java_files, classpath, config_xml)
  (errors, warnings) = _ParseAndFilterOutput(stdout)
  _PrintErrorsAndWarnings(errors, warnings)
  return errors, warnings


def RunCheckstyleOnACommit(commit,
                           classpath=CHECKSTYLE_JAR,
                           config_xml=CHECKSTYLE_STYLE,
                           file_whitelist=None):
  """Runs Checkstyle checks on a given commit.

  It will run Checkstyle on the changed Java files in a specified commit SHA-1
  and if that is None it will fallback to check the latest commit of the
  currently checked out branch.

  Args:
    commit: A full 40 character SHA-1 of a commit to check.
    classpath: The colon-delimited list of JARs in the classpath.
    config_xml: Path of the checkstyle XML configuration file.
    file_whitelist: A list of whitelisted file paths that should be checked.

  Returns:
    A tuple of errors and warnings.
  """
  if not git.repository_root():
    print('FAILURE: not inside a git repository')
    sys.exit(1)
  explicit_commit = commit is not None
  if not explicit_commit:
    _WarnIfUntrackedFiles()
    commit = git.last_commit()
  print('Running Checkstyle on %s commit' % commit)
  commit_modified_files = _GetModifiedFiles(commit, explicit_commit)
  commit_modified_files = _FilterFiles(commit_modified_files, file_whitelist)
  if not list(commit_modified_files.keys()):
    print('No Java files to check')
    return [], []

  (tmp_dir, tmp_file_map) = _GetTempFilesForCommit(
      list(commit_modified_files.keys()), commit)

  java_files = list(tmp_file_map.keys())
  stdout = _ExecuteCheckstyle(java_files, classpath, config_xml)

  # Remove all the temporary files.
  shutil.rmtree(tmp_dir)

  (errors, warnings) = _ParseAndFilterOutput(stdout,
                                             commit,
                                             commit_modified_files,
                                             tmp_file_map)
  _PrintErrorsAndWarnings(errors, warnings)
  return errors, warnings


def _WarnIfUntrackedFiles(out=sys.stdout):
  """Prints a warning and a list of untracked files if needed."""
  root = git.repository_root()
  untracked_files = git.modified_files(root, False)
  untracked_files = {f for f in untracked_files if f.endswith('.java')}
  if untracked_files:
    out.write(ERROR_UNTRACKED)
    for untracked_file in untracked_files:
      out.write(untracked_file + '\n')
    out.write('\n')


def _PrintErrorsAndWarnings(errors, warnings):
  """Prints given errors and warnings."""
  if errors:
    print('ERRORS:\n' + '\n'.join(errors))
  if warnings:
    print('WARNINGS:\n' + '\n'.join(warnings))

def _CheckForJava():
  try:
    java_env = os.environ.copy()
    java_env['JAVA_CMD'] = 'java'
    check = subprocess.Popen(['java', '--help'],
                             stdout=subprocess.PIPE, env=java_env,
                             universal_newlines=True)
    stdout, _ = check.communicate()
    stdout_lines = stdout.splitlines()
  except OSError as e:
    if e.errno == errno.ENOENT:
      print('Error: Could not find `java` on path!')
      sys.exit(1)

def _ExecuteCheckstyle(java_files, classpath, config_xml):
  """Runs Checkstyle to check give Java files for style errors.

  Args:
    java_files: A list of Java files that needs to be checked.
    classpath: The colon-delimited list of JARs in the classpath.
    config_xml: Path of the checkstyle XML configuration file.

  Returns:
    Checkstyle output in XML format.
  """
  # Run checkstyle
  checkstyle_env = os.environ.copy()
  checkstyle_env['JAVA_CMD'] = 'java'

  try:
    check = subprocess.Popen(['java',
                              '-Dcheckstyle.enableExternalDtdLoad=true',
                              '-cp', classpath,
                              'com.puppycrawl.tools.checkstyle.Main', '-c',
                              config_xml, '-f', 'xml'] + java_files,
                             stdout=subprocess.PIPE, env=checkstyle_env,
                             universal_newlines=True)
    stdout, _ = check.communicate()
    stdout_lines = stdout.splitlines()
    # A work-around for Checkstyle printing error count to stdio.
    if len(stdout_lines) < 2:
      stdout = stdout_lines[0]
    elif len(stdout_lines) >= 2 and '</checkstyle>' in stdout_lines[-2]:
      stdout = '\n'.join(stdout_lines[:-1])
    return stdout
  except OSError as e:
    if e.errno == errno.ENOENT:
      _CheckForJava()
      print('Error running Checkstyle!')
      sys.exit(1)


def _ParseAndFilterOutput(stdout,
                          sha=None,
                          commit_modified_files=None,
                          tmp_file_map=None):
  result_errors = []
  result_warnings = []
  root = xml.dom.minidom.parseString(stdout)
  for file_element in root.getElementsByTagName('file'):
    file_name = file_element.attributes['name'].value
    if tmp_file_map:
      file_name = tmp_file_map[file_name]
    modified_lines = None
    if commit_modified_files:
      modified_lines = git.modified_lines(file_name,
                                          commit_modified_files[file_name],
                                          sha)
    test_class = any(substring in file_name for substring
                     in SUBPATH_FOR_TEST_FILES)
    test_data_class = any(substring in file_name for substring
                          in SUBPATH_FOR_TEST_DATA_FILES)
    file_name = os.path.relpath(file_name)
    errors = file_element.getElementsByTagName('error')
    for error in errors:
      line = int(error.attributes['line'].value)
      rule = error.attributes['source'].value
      if _ShouldSkip(commit_modified_files, modified_lines, line, rule,
                     test_class, test_data_class):
        continue

      column = ''
      if error.hasAttribute('column'):
        column = '%s:' % error.attributes['column'].value
      message = error.attributes['message'].value
      project = ''
      if os.environ.get('REPO_PROJECT'):
        project = '[' + os.environ.get('REPO_PROJECT') + '] '

      result = '  %s%s:%s:%s %s' % (project, file_name, line, column, message)

      severity = error.attributes['severity'].value
      if severity == 'error':
        result_errors.append(result)
      elif severity == 'warning':
        result_warnings.append(result)
  return result_errors, result_warnings


def _ShouldSkip(commit_check, modified_lines, line, rule, test_class=False,
                test_data_class=False):
  """Returns whether an error on a given line should be skipped.

  Args:
    commit_check: Whether Checkstyle is being run on a specific commit.
    modified_lines: A list of lines that has been modified.
    line: The line that has a rule violation.
    rule: The type of rule that a given line is violating.
    test_class: Whether the file being checked is a test class.
    test_data_class: Whether the file being check is a class used as test data.

  Returns:
    A boolean whether a given line should be skipped in the reporting.
  """
  # None modified_lines means checked file is new and nothing should be skipped.
  if test_data_class:
    return True
  if test_class and rule in SKIPPED_RULES_FOR_TEST_FILES:
    return True
  if not commit_check:
    return False
  if modified_lines is None:
    return False
  return line not in modified_lines and rule not in FORCED_RULES


def _GetModifiedFiles(commit, explicit_commit=False, out=sys.stdout):
  root = git.repository_root()
  pending_files = git.modified_files(root, True)
  if pending_files and not explicit_commit:
    out.write(ERROR_UNCOMMITTED)
    sys.exit(1)

  modified_files = git.modified_files(root, True, commit)
  modified_files = {f: modified_files[f] for f
                    in modified_files if f.endswith('.java')}
  return modified_files


def _FilterFiles(files, file_whitelist):
  if not file_whitelist:
    return files
  return {f: files[f] for f in files
          for whitelist in file_whitelist if whitelist in f}


def _GetTempFilesForCommit(file_names, commit):
  """Creates a temporary snapshot of the files in at a commit.

  Retrieves the state of every file in file_names at a given commit and writes
  them all out to a temporary directory.

  Args:
    file_names: A list of files that need to be retrieved.
    commit: A full 40 character SHA-1 of a commit.

  Returns:
    A tuple of temprorary directory name and a directionary of
    temp_file_name: filename. For example:

    ('/tmp/random/', {'/tmp/random/blarg.java': 'real/path/to/file.java' }
  """
  tmp_dir_name = tempfile.mkdtemp()
  tmp_file_names = {}
  for file_name in file_names:
    rel_path = os.path.relpath(file_name)
    content = subprocess.check_output(
        ['git', 'show', commit + ':' + rel_path])

    tmp_file_name = os.path.join(tmp_dir_name, rel_path)
    # create directory for the file if it doesn't exist
    if not os.path.exists(os.path.dirname(tmp_file_name)):
      os.makedirs(os.path.dirname(tmp_file_name))

    tmp_file = open(tmp_file_name, 'wb')
    tmp_file.write(content)
    tmp_file.close()
    tmp_file_names[tmp_file_name] = file_name
  return tmp_dir_name, tmp_file_names


def main(args=None):
  """Runs Checkstyle checks on a given set of java files or a commit.

  It will run Checkstyle on the list of java files first, if unspecified,
  then the check will be run on a specified commit SHA-1 and if that
  is None it will fallback to check the latest commit of the currently checked
  out branch.
  """
  parser = argparse.ArgumentParser()
  parser.add_argument('--file', '-f', nargs='+')
  parser.add_argument('--sha', '-s')
  parser.add_argument('--config_xml', '-c')
  parser.add_argument('--file_whitelist', '-fw', nargs='+')
  parser.add_argument('--add_classpath', '-p')
  args = parser.parse_args()

  config_xml = args.config_xml or CHECKSTYLE_STYLE

  if not os.path.exists(config_xml):
    print('Java checkstyle configuration file is missing')
    sys.exit(1)

  classpath = CHECKSTYLE_JAR

  if args.add_classpath:
    classpath = args.add_classpath + ':' + classpath

  if args.file:
    # Files to check were specified via command line.
    (errors, warnings) = RunCheckstyleOnFiles(args.file, classpath, config_xml)
  else:
    (errors, warnings) = RunCheckstyleOnACommit(args.sha, classpath, config_xml,
                                                args.file_whitelist)

  if errors or warnings:
    sys.exit(1)

  print('SUCCESS! NO ISSUES FOUND')
  sys.exit(0)


if __name__ == '__main__':
  main()