# diff.py
# Copyright (C) 2008, 2009 Michael Trier (mtrier@gmail.com) and contributors
#
# This module is part of GitPython and is released under
# the BSD License: http://www.opensource.org/licenses/bsd-license.php

import re
import objects.blob as blob

class Diff(object):
	"""
	A Diff contains diff information between two commits.
	
	It contains two sides a and b of the diff, members are prefixed with 
	"a" and "b" respectively to inidcate that.
	
	Diffs keep information about the changed blob objects, the file mode, renames, 
	deletions and new files.
	
	There are a few cases where None has to be expected as member variable value:
	
	``New File``::
	
		a_mode is None
		a_blob is None
		
	``Deleted File``::
	
		b_mode is None
		b_blob is NOne
	"""
	
	# precompiled regex
	re_header = re.compile(r"""
								#^diff[ ]--git
									[ ]a/(?P<a_path>\S+)[ ]b/(?P<b_path>\S+)\n
								(?:^similarity[ ]index[ ](?P<similarity_index>\d+)%\n
								   ^rename[ ]from[ ](?P<rename_from>\S+)\n
								   ^rename[ ]to[ ](?P<rename_to>\S+)(?:\n|$))?
								(?:^old[ ]mode[ ](?P<old_mode>\d+)\n
								   ^new[ ]mode[ ](?P<new_mode>\d+)(?:\n|$))?
								(?:^new[ ]file[ ]mode[ ](?P<new_file_mode>.+)(?:\n|$))?
								(?:^deleted[ ]file[ ]mode[ ](?P<deleted_file_mode>.+)(?:\n|$))?
								(?:^index[ ](?P<a_blob_id>[0-9A-Fa-f]+)
									\.\.(?P<b_blob_id>[0-9A-Fa-f]+)[ ]?(?P<b_mode>.+)?(?:\n|$))?
							""", re.VERBOSE | re.MULTILINE)
	re_is_null_hexsha = re.compile( r'^0{40}$' )
	__slots__ = ("a_blob", "b_blob", "a_mode", "b_mode", "new_file", "deleted_file", 
				 "rename_from", "rename_to", "renamed", "diff")

	def __init__(self, repo, a_path, b_path, a_blob_id, b_blob_id, a_mode,
				 b_mode, new_file, deleted_file, rename_from,
				 rename_to, diff):
		if not a_blob_id or self.re_is_null_hexsha.search(a_blob_id):
			self.a_blob = None
		else:
			self.a_blob = blob.Blob(repo, id=a_blob_id, mode=a_mode, path=a_path)
		if not b_blob_id or self.re_is_null_hexsha.search(b_blob_id):
			self.b_blob = None
		else:
			self.b_blob = blob.Blob(repo, id=b_blob_id, mode=b_mode, path=b_path)

		self.a_mode = a_mode
		self.b_mode = b_mode
		if self.a_mode:
			self.a_mode = blob.Blob._mode_str_to_int( self.a_mode )
		if self.b_mode:
			self.b_mode = blob.Blob._mode_str_to_int( self.b_mode )
		self.new_file = new_file
		self.deleted_file = deleted_file
		self.rename_from = rename_from
		self.rename_to = rename_to
		self.renamed = rename_from != rename_to
		self.diff = diff

	@classmethod
	def _list_from_string(cls, repo, text):
		"""
		Create a new diff object from the given text
		``repo``
			is the repository we are operating on - it is required 
		
		``text``
			result of 'git diff' between two commits or one commit and the index
		
		Returns
			git.Diff[]
		"""
		diffs = []

		diff_header = cls.re_header.match
		for diff in ('\n' + text).split('\ndiff --git')[1:]:
			header = diff_header(diff)

			a_path, b_path, similarity_index, rename_from, rename_to, \
				old_mode, new_mode, new_file_mode, deleted_file_mode, \
				a_blob_id, b_blob_id, b_mode = header.groups()
			new_file, deleted_file = bool(new_file_mode), bool(deleted_file_mode)

			diffs.append(Diff(repo, a_path, b_path, a_blob_id, b_blob_id,
				old_mode or deleted_file_mode, new_mode or new_file_mode or b_mode,
				new_file, deleted_file, rename_from, rename_to, diff[header.end():]))

		return diffs