# Copyright (C) 2011-2018 YouCompleteMe contributors
#
# This file is part of YouCompleteMe.
#
# YouCompleteMe is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# YouCompleteMe is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.

from __future__ import unicode_literals
from __future__ import print_function
from __future__ import division
from __future__ import absolute_import
# Not installing aliases from python-future; it's unreliable and slow.
from builtins import *  # noqa

from future.utils import PY2
from mock import MagicMock, patch
from hamcrest import assert_that, equal_to
import contextlib
import functools
import nose
import os
import re
import sys

from ycmd.utils import GetCurrentDirectory, ToBytes, ToUnicode


BUFNR_REGEX = re.compile( '^bufnr\(\'(?P<buffer_filename>.+)\', ([01])\)$' )
BUFWINNR_REGEX = re.compile( '^bufwinnr\((?P<buffer_number>[0-9]+)\)$' )
BWIPEOUT_REGEX = re.compile(
  '^(?:silent! )bwipeout!? (?P<buffer_number>[0-9]+)$' )
GETBUFVAR_REGEX = re.compile(
  '^getbufvar\((?P<buffer_number>[0-9]+), "(?P<option>.+)"\)$' )
MATCHADD_REGEX = re.compile(
  '^matchadd\(\'(?P<group>.+)\', \'(?P<pattern>.+)\'\)$' )
MATCHDELETE_REGEX = re.compile( '^matchdelete\((?P<id>\d+)\)$' )
OMNIFUNC_REGEX_FORMAT = (
  '^{omnifunc_name}\((?P<findstart>[01]),[\'"](?P<base>.*)[\'"]\)$' )
FNAMEESCAPE_REGEX = re.compile( '^fnameescape\(\'(?P<filepath>.+)\'\)$' )

# One-and only instance of mocked Vim object. The first 'import vim' that is
# executed binds the vim module to the instance of MagicMock that is created,
# and subsquent assignments to sys.modules[ 'vim' ] don't retrospectively
# update them. The result is that while running the tests, we must assign only
# one instance of MagicMock to sys.modules[ 'vim' ] and always return it.
#
# More explanation is available:
# https://github.com/Valloric/YouCompleteMe/pull/1694
VIM_MOCK = MagicMock()

VIM_MATCHES = []


@contextlib.contextmanager
def CurrentWorkingDirectory( path ):
  old_cwd = GetCurrentDirectory()
  os.chdir( path )
  try:
    yield
  finally:
    os.chdir( old_cwd )


def _MockGetBufferNumber( buffer_filename ):
  for vim_buffer in VIM_MOCK.buffers:
    if vim_buffer.name == buffer_filename:
      return vim_buffer.number
  return -1


def _MockGetBufferWindowNumber( buffer_number ):
  for vim_buffer in VIM_MOCK.buffers:
    if vim_buffer.number == buffer_number and vim_buffer.window:
      return vim_buffer.window
  return -1


def _MockGetBufferVariable( buffer_number, option ):
  for vim_buffer in VIM_MOCK.buffers:
    if vim_buffer.number == buffer_number:
      if option == '&mod':
        return vim_buffer.modified
      if option == '&ft':
        return vim_buffer.filetype
      if option == 'changedtick':
        return vim_buffer.changedtick
      if option == '&bh':
        return vim_buffer.bufhidden
      return ''
  return ''


def _MockVimBufferEval( value ):
  if value == '&omnifunc':
    return VIM_MOCK.current.buffer.omnifunc_name

  if value == '&filetype':
    return VIM_MOCK.current.buffer.filetype

  match = BUFNR_REGEX.search( value )
  if match:
    buffer_filename = match.group( 'buffer_filename' )
    return _MockGetBufferNumber( buffer_filename )

  match = BUFWINNR_REGEX.search( value )
  if match:
    buffer_number = int( match.group( 'buffer_number' ) )
    return _MockGetBufferWindowNumber( buffer_number )

  match = GETBUFVAR_REGEX.search( value )
  if match:
    buffer_number = int( match.group( 'buffer_number' ) )
    option = match.group( 'option' )
    return _MockGetBufferVariable( buffer_number, option )

  current_buffer = VIM_MOCK.current.buffer
  match = re.search( OMNIFUNC_REGEX_FORMAT.format(
                         omnifunc_name = current_buffer.omnifunc_name ),
                     value )
  if match:
    findstart = int( match.group( 'findstart' ) )
    base = match.group( 'base' )
    value = current_buffer.omnifunc( findstart, base )
    return value if findstart else ToBytesOnPY2( value )

  return None


def _MockVimOptionsEval( value ):
  if value == '&previewheight':
    return 12

  if value == '&columns':
    return 80

  if value == '&ruler':
    return 0

  if value == '&showcmd':
    return 1

  if value == '&hidden':
    return 0

  if value == '&expandtab':
    return 1

  return None


def _MockVimMatchEval( value ):
  if value == 'getmatches()':
    # Returning a copy, because ClearYcmSyntaxMatches() gets the result of
    # getmatches(), iterates over it and removes elements from VIM_MATCHES.
    return list( VIM_MATCHES )

  match = MATCHADD_REGEX.search( value )
  if match:
    group = match.group( 'group' )
    option = match.group( 'pattern' )
    vim_match = VimMatch( group, option )
    VIM_MATCHES.append( vim_match )
    return vim_match.id

  match = MATCHDELETE_REGEX.search( value )
  if match:
    identity = int( match.group( 'id' ) )
    for index, vim_match in enumerate( VIM_MATCHES ):
      if vim_match.id == identity:
        VIM_MATCHES.pop( index )
        return -1
    return 0

  return None


# This variable exists to easily mock the 'g:ycm_server_python_interpreter'
# option in tests.
server_python_interpreter = ''


def _MockVimEval( value ):
  if value == 'g:ycm_min_num_of_chars_for_completion':
    return 0

  if value == 'g:ycm_server_python_interpreter':
    return server_python_interpreter

  if value == 'tempname()':
    return '_TEMP_FILE_'

  if value == 'tagfiles()':
    return [ 'tags' ]

  if value == 'shiftwidth()':
    return 2

  result = _MockVimOptionsEval( value )
  if result is not None:
    return result

  result = _MockVimBufferEval( value )
  if result is not None:
    return result

  result = _MockVimMatchEval( value )
  if result is not None:
    return result

  match = FNAMEESCAPE_REGEX.search( value )
  if match:
    return match.group( 'filepath' )

  raise VimError( 'Unexpected evaluation: {0}'.format( value ) )


def _MockWipeoutBuffer( buffer_number ):
  buffers = VIM_MOCK.buffers

  for index, buffer in enumerate( buffers ):
    if buffer.number == buffer_number:
      return buffers.pop( index )


def MockVimCommand( command ):
  match = BWIPEOUT_REGEX.search( command )
  if match:
    return _MockWipeoutBuffer( int( match.group( 1 ) ) )

  raise RuntimeError( 'Unexpected command: ' + command )


class VimBuffer( object ):
  """An object that looks like a vim.buffer object:
   - |name|     : full path of the buffer with symbolic links resolved;
   - |number|   : buffer number;
   - |contents| : list of lines representing the buffer contents;
   - |filetype| : buffer filetype. Empty string if no filetype is set;
   - |modified| : True if the buffer has unsaved changes, False otherwise;
   - |bufhidden|: value of the 'bufhidden' option (see :h bufhidden);
   - |window|   : number of the buffer window. None if the buffer is hidden;
   - |omnifunc| : omni completion function used by the buffer. Must be a Python
                  function that takes the same arguments and returns the same
                  values as a Vim completion function (:h complete-functions).
                  Example:

                    def Omnifunc( findstart, base ):
                      if findstart:
                        return 5
                      return [ 'a', 'b', 'c' ]"""

  def __init__( self, name,
                      number = 1,
                      contents = [ '' ],
                      filetype = '',
                      modified = False,
                      bufhidden = '',
                      window = None,
                      omnifunc = None,
                      visual_start = None,
                      visual_end = None ):
    self.name = os.path.realpath( name ) if name else ''
    self.number = number
    self.contents = contents
    self.filetype = filetype
    self.modified = modified
    self.bufhidden = bufhidden
    self.window = window
    self.omnifunc = omnifunc
    self.omnifunc_name = omnifunc.__name__ if omnifunc else ''
    self.changedtick = 1
    self.options = {
     'mod': modified,
     'bh': bufhidden
    }
    self.visual_start = visual_start
    self.visual_end = visual_end


  def __getitem__( self, index ):
    """Returns the bytes for a given line at index |index|."""
    return self.contents[ index ]


  def __len__( self ):
    return len( self.contents )


  def __setitem__( self, key, value ):
    return self.contents.__setitem__( key, value )


  def GetLines( self ):
    """Returns the contents of the buffer as a list of unicode strings."""
    return [ ToUnicode( x ) for x in self.contents ]


  def mark( self, name ):
    if name == '<':
      return self.visual_start
    if name == '>':
      return self.visual_end
    raise ValueError( 'Unexpected mark: {name}'.format( name = name ) )


class VimBuffers( object ):
  """An object that looks like a vim.buffers object."""

  def __init__( self, *buffers ):
    """Arguments are VimBuffer objects."""
    self._buffers = buffers


  def __getitem__( self, number ):
    """Emulates vim.buffers[ number ]"""
    for buffer_object in self._buffers:
      if number == buffer_object.number:
        return buffer_object
    raise KeyError( number )


  def __iter__( self ):
    """Emulates for loop on vim.buffers"""
    return iter( self._buffers )


class VimMatch( object ):

  def __init__( self, group, pattern ):
    self.id = len( VIM_MATCHES )
    self.group = group
    self.pattern = pattern


  def __eq__( self, other ):
    return self.group == other.group and self.pattern == other.pattern


  def __repr__( self ):
    return "VimMatch( group = '{0}', pattern = '{1}' )".format( self.group,
                                                                self.pattern )


  def __getitem__( self, key ):
    if key == 'group':
      return self.group
    elif key == 'id':
      return self.id


@contextlib.contextmanager
def MockVimBuffers( buffers, current_buffer, cursor_position = ( 1, 1 ) ):
  """Simulates the Vim buffers list |buffers| where |current_buffer| is the
  buffer displayed in the current window and |cursor_position| is the current
  cursor position. All buffers are represented by a VimBuffer object."""
  if current_buffer not in buffers:
    raise RuntimeError( 'Current buffer must be part of the buffers list.' )

  line = current_buffer.contents[ cursor_position[ 0 ] - 1 ]

  with patch( 'vim.buffers', VimBuffers( *buffers ) ):
    with patch( 'vim.current.buffer', current_buffer ):
      with patch( 'vim.current.window.cursor', cursor_position ):
        with patch( 'vim.current.line', line ):
          yield VIM_MOCK


def MockVimModule():
  """The 'vim' module is something that is only present when running inside the
  Vim Python interpreter, so we replace it with a MagicMock for tests. If you
  need to add additional mocks to vim module functions, then use 'patch' from
  mock module, to ensure that the state of the vim mock is returned before the
  next test. That is:

    from ycm.tests.test_utils import MockVimModule
    from mock import patch

    # Do this once
    MockVimModule()

    @patch( 'vim.eval', return_value='test' )
    @patch( 'vim.command', side_effect=ValueError )
    def test( vim_command, vim_eval ):
      # use vim.command via vim_command, e.g.:
      vim_command.assert_has_calls( ... )

  Failure to use this approach may lead to unexpected failures in other
  tests."""

  VIM_MOCK.buffers = {}
  VIM_MOCK.eval = MagicMock( side_effect = _MockVimEval )
  VIM_MOCK.error = VimError
  sys.modules[ 'vim' ] = VIM_MOCK

  return VIM_MOCK


class VimError( Exception ):

  def __init__( self, code ):
      self.code = code


  def __str__( self ):
      return repr( self.code )


class ExtendedMock( MagicMock ):
  """An extension to the MagicMock class which adds the ability to check that a
  callable is called with a precise set of calls in a precise order.

  Example Usage:
    from ycm.tests.test_utils import ExtendedMock
    @patch( 'test.testing', new_callable = ExtendedMock, ... )
    def my_test( test_testing ):
      ...
  """

  def assert_has_exact_calls( self, calls, any_order = False ):
    self.assert_has_calls( calls, any_order )
    assert_that( self.call_count, equal_to( len( calls ) ) )


def ExpectedFailure( reason, *exception_matchers ):
  """Defines a decorator to be attached to tests. This decorator
  marks the test as being known to fail, e.g. where documenting or exercising
  known incorrect behaviour.

  The parameters are:
    - |reason| a textual description of the reason for the known issue. This
               is used for the skip reason
    - |exception_matchers| additional arguments are hamcrest matchers to apply
                 to the exception thrown. If the matchers don't match, then the
                 test is marked as error, with the original exception.

  If the test fails (for the correct reason), then it is marked as skipped.
  If it fails for any other reason, it is marked as failed.
  If the test passes, then it is also marked as failed."""
  def decorator( test ):
    @functools.wraps( test )
    def Wrapper( *args, **kwargs ):
      try:
        test( *args, **kwargs )
      except Exception as test_exception:
        # Ensure that we failed for the right reason
        test_exception_message = ToUnicode( test_exception )
        try:
          for matcher in exception_matchers:
            assert_that( test_exception_message, matcher )
        except AssertionError:
          # Failed for the wrong reason!
          import traceback
          print( 'Test failed for the wrong reason: ' + traceback.format_exc() )
          # Real failure reason is the *original* exception, we're only trapping
          # and ignoring the exception that is expected.
          raise test_exception

        # Failed for the right reason
        raise nose.SkipTest( reason )
      else:
        raise AssertionError( 'Test was expected to fail: {0}'.format(
          reason ) )
    return Wrapper

  return decorator


def ToBytesOnPY2( data ):
  # To test the omnifunc, etc. returning strings, which can be of different
  # types depending on python version, we use ToBytes on PY2 and just the native
  # str on python3. This roughly matches what happens between py2 and py3
  # versions within Vim.
  if not PY2:
    return data

  if isinstance( data, list ):
    return [ ToBytesOnPY2( item ) for item in data ]
  if isinstance( data, dict ):
    for item in data:
      data[ item ] = ToBytesOnPY2( data[ item ] )
    return data
  return ToBytes( data )