# Copyright 2015 Google Inc. All Rights Reserved.
#
# 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.
"""Entry points for YAPF.

The main APIs that YAPF exposes to drive the reformatting.

  FormatFile(): reformat a file.
  FormatCode(): reformat a string of code.

These APIs have some common arguments:

  style_config: (string) Either a style name or a path to a file that contains
    formatting style settings. If None is specified, use the default style
    as set in style.DEFAULT_STYLE_FACTORY
  lines: (list of tuples of integers) A list of tuples of lines, [start, end],
    that we want to format. The lines are 1-based indexed. It can be used by
    third-party code (e.g., IDEs) when reformatting a snippet of code rather
    than a whole file.
  print_diff: (bool) Instead of returning the reformatted source, return a
    diff that turns the formatted source into reformatter source.
"""

import codecs
import difflib
import re

from yapf.pyparser import pyparser
from yapf.pytree import blank_line_calculator
from yapf.pytree import comment_splicer
from yapf.pytree import continuation_splicer
from yapf.pytree import pytree_unwrapper
from yapf.pytree import pytree_utils
from yapf.pytree import split_penalty
from yapf.pytree import subtype_assigner
from yapf.yapflib import errors
from yapf.yapflib import file_resources
from yapf.yapflib import identify_container
from yapf.yapflib import reformatter
from yapf.yapflib import style


def FormatFile(filename,
               style_config=None,
               lines=None,
               print_diff=False,
               in_place=False,
               logger=None):
  """Format a single Python file and return the formatted code.

  Arguments:
    filename: (unicode) The file to reformat.
    style_config: (string) Either a style name or a path to a file that contains
      formatting style settings. If None is specified, use the default style
      as set in style.DEFAULT_STYLE_FACTORY
    lines: (list of tuples of integers) A list of tuples of lines, [start, end],
      that we want to format. The lines are 1-based indexed. It can be used by
      third-party code (e.g., IDEs) when reformatting a snippet of code rather
      than a whole file.
    print_diff: (bool) Instead of returning the reformatted source, return a
      diff that turns the formatted source into reformatter source.
    in_place: (bool) If True, write the reformatted code back to the file.
    logger: (io streamer) A stream to output logging.

  Returns:
    Tuple of (reformatted_code, encoding, changed). reformatted_code is None if
    the file is successfully written to (having used in_place). reformatted_code
    is a diff if print_diff is True.

  Raises:
    IOError: raised if there was an error reading the file.
    ValueError: raised if in_place and print_diff are both specified.
  """
  if in_place and print_diff:
    raise ValueError('Cannot pass both in_place and print_diff.')

  original_source, newline, encoding = ReadFile(filename, logger)
  reformatted_source, changed = FormatCode(
      original_source,
      style_config=style_config,
      filename=filename,
      lines=lines,
      print_diff=print_diff)
  if newline != '\n':
    reformatted_source = reformatted_source.replace('\n', newline)
  if in_place:
    if changed:
      file_resources.WriteReformattedCode(filename, reformatted_source,
                                          encoding, in_place)
    return None, encoding, changed

  return reformatted_source, encoding, changed


def FormatTree(tree, style_config=None, lines=None):
  """Format a parsed lib2to3 pytree.

  This provides an alternative entry point to YAPF.

  Arguments:
    tree: (pytree.Node) The root of the pytree to format.
    style_config: (string) Either a style name or a path to a file that contains
      formatting style settings. If None is specified, use the default style
      as set in style.DEFAULT_STYLE_FACTORY
    lines: (list of tuples of integers) A list of tuples of lines, [start, end],
      that we want to format. The lines are 1-based indexed. It can be used by
      third-party code (e.g., IDEs) when reformatting a snippet of code rather
      than a whole file.

  Returns:
    The source formatted according to the given formatting style.
  """
  style.SetGlobalStyle(style.CreateStyleFromConfig(style_config))

  # Run passes on the tree, modifying it in place.
  comment_splicer.SpliceComments(tree)
  continuation_splicer.SpliceContinuations(tree)
  subtype_assigner.AssignSubtypes(tree)
  identify_container.IdentifyContainers(tree)
  split_penalty.ComputeSplitPenalties(tree)
  blank_line_calculator.CalculateBlankLines(tree)

  llines = pytree_unwrapper.UnwrapPyTree(tree)
  for lline in llines:
    lline.CalculateFormattingInformation()

  lines = _LineRangesToSet(lines)
  _MarkLinesToFormat(llines, lines)
  return reformatter.Reformat(_SplitSemicolons(llines), lines)


def FormatAST(ast, style_config=None, lines=None):
  """Format a parsed lib2to3 pytree.

  This provides an alternative entry point to YAPF.

  Arguments:
    unformatted_source: (unicode) The code to format.
    style_config: (string) Either a style name or a path to a file that contains
      formatting style settings. If None is specified, use the default style
      as set in style.DEFAULT_STYLE_FACTORY
    lines: (list of tuples of integers) A list of tuples of lines, [start, end],
      that we want to format. The lines are 1-based indexed. It can be used by
      third-party code (e.g., IDEs) when reformatting a snippet of code rather
      than a whole file.

  Returns:
    The source formatted according to the given formatting style.
  """
  style.SetGlobalStyle(style.CreateStyleFromConfig(style_config))

  llines = pyparser.ParseCode(ast)
  for lline in llines:
    lline.CalculateFormattingInformation()

  lines = _LineRangesToSet(lines)
  _MarkLinesToFormat(llines, lines)
  return reformatter.Reformat(_SplitSemicolons(llines), lines)


def FormatCode(unformatted_source,
               filename='<unknown>',
               style_config=None,
               lines=None,
               print_diff=False):
  """Format a string of Python code.

  This provides an alternative entry point to YAPF.

  Arguments:
    unformatted_source: (unicode) The code to format.
    filename: (unicode) The name of the file being reformatted.
    style_config: (string) Either a style name or a path to a file that contains
      formatting style settings. If None is specified, use the default style
      as set in style.DEFAULT_STYLE_FACTORY
    lines: (list of tuples of integers) A list of tuples of lines, [start, end],
      that we want to format. The lines are 1-based indexed. It can be used by
      third-party code (e.g., IDEs) when reformatting a snippet of code rather
      than a whole file.
    print_diff: (bool) Instead of returning the reformatted source, return a
      diff that turns the formatted source into reformatter source.

  Returns:
    Tuple of (reformatted_source, changed). reformatted_source conforms to the
    desired formatting style. changed is True if the source changed.
  """
  try:
    tree = pytree_utils.ParseCodeToTree(unformatted_source)
  except Exception as e:
    e.filename = filename
    raise errors.YapfError(errors.FormatErrorMsg(e))

  reformatted_source = FormatTree(
      tree, style_config=style_config, lines=lines)

  if unformatted_source == reformatted_source:
    return '' if print_diff else reformatted_source, False

  if print_diff:
    code_diff = _GetUnifiedDiff(
        unformatted_source, reformatted_source, filename=filename)
    return code_diff, code_diff.strip() != ''  # pylint: disable=g-explicit-bool-comparison # noqa

  return reformatted_source, True


def ReadFile(filename, logger=None):
  """Read the contents of the file.

  An optional logger can be specified to emit messages to your favorite logging
  stream. If specified, then no exception is raised. This is external so that it
  can be used by third-party applications.

  Arguments:
    filename: (unicode) The name of the file.
    logger: (function) A function or lambda that takes a string and emits it.

  Returns:
    The contents of filename.

  Raises:
    IOError: raised if there was an error reading the file.
  """
  try:
    encoding = file_resources.FileEncoding(filename)

    # Preserves line endings.
    with codecs.open(filename, mode='r', encoding=encoding) as fd:
      lines = fd.readlines()

    line_ending = file_resources.LineEnding(lines)
    source = '\n'.join(line.rstrip('\r\n') for line in lines) + '\n'
    return source, line_ending, encoding
  except IOError as e:  # pragma: no cover
    if logger:
      logger(e)
    e.args = (e.args[0], (filename, e.args[1][1], e.args[1][2], e.args[1][3]))
    raise
  except UnicodeDecodeError as e:  # pragma: no cover
    if logger:
      logger('Could not parse %s! Consider excluding this file with --exclude.',
             filename)
      logger(e)
    e.args = (e.args[0], (filename, e.args[1][1], e.args[1][2], e.args[1][3]))
    raise


def _SplitSemicolons(lines):
  res = []
  for line in lines:
    res.extend(line.Split())
  return res


DISABLE_PATTERN = r'^#.*\b(?:yapf:\s*disable|fmt: ?off)\b'
ENABLE_PATTERN = r'^#.*\b(?:yapf:\s*enable|fmt: ?on)\b'


def _LineRangesToSet(line_ranges):
  """Return a set of lines in the range."""

  if line_ranges is None:
    return None

  line_set = set()
  for low, high in sorted(line_ranges):
    line_set.update(range(low, high + 1))

  return line_set


def _MarkLinesToFormat(llines, lines):
  """Skip sections of code that we shouldn't reformat."""
  if lines:
    for uwline in llines:
      uwline.disable = not lines.intersection(
          range(uwline.lineno, uwline.last.lineno + 1))

  # Now go through the lines and disable any lines explicitly marked as
  # disabled.
  index = 0
  while index < len(llines):
    uwline = llines[index]
    if uwline.is_comment:
      if _DisableYAPF(uwline.first.value.strip()):
        index += 1
        while index < len(llines):
          uwline = llines[index]
          line = uwline.first.value.strip()
          if uwline.is_comment and _EnableYAPF(line):
            if not _DisableYAPF(line):
              break
          uwline.disable = True
          index += 1
    elif re.search(DISABLE_PATTERN, uwline.last.value.strip(), re.IGNORECASE):
      uwline.disable = True
    index += 1


def _DisableYAPF(line):
  return (re.search(DISABLE_PATTERN,
                    line.split('\n')[0].strip(), re.IGNORECASE) or
          re.search(DISABLE_PATTERN,
                    line.split('\n')[-1].strip(), re.IGNORECASE))


def _EnableYAPF(line):
  return (re.search(ENABLE_PATTERN,
                    line.split('\n')[0].strip(), re.IGNORECASE) or
          re.search(ENABLE_PATTERN,
                    line.split('\n')[-1].strip(), re.IGNORECASE))


def _GetUnifiedDiff(before, after, filename='code'):
  """Get a unified diff of the changes.

  Arguments:
    before: (unicode) The original source code.
    after: (unicode) The reformatted source code.
    filename: (unicode) The code's filename.

  Returns:
    The unified diff text.
  """
  before = before.splitlines()
  after = after.splitlines()
  return '\n'.join(
      difflib.unified_diff(
          before,
          after,
          filename,
          filename,
          '(original)',
          '(reformatted)',
          lineterm='')) + '\n'
