# diff.py
# Copyright (C) 2008-2010 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 commit

class Diff(object):
    """
    A Diff contains diff information between two commits.
    """

    def __init__(self, repo, a_path, b_path, a_commit, b_commit, a_mode,
                 b_mode, new_file, deleted_file, rename_from,
                 rename_to, diff):
        self.repo = repo
        self.a_path = a_path
        self.b_path = b_path

        if not a_commit or re.search(r'^0{40}$', a_commit):
            self.a_commit = None
        else:
            self.a_commit = commit.Commit(repo, id=a_commit)
        if not b_commit or re.search(r'^0{40}$', b_commit):
            self.b_commit = None
        else:
            self.b_commit = commit.Commit(repo, id=b_commit)

        self.a_mode = a_mode
        self.b_mode = 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):
        diffs = []

        diff_header = re.compile(r"""
            #^diff[ ]--git
                [ ]a/(?P\S+)[ ]b/(?P\S+)\n
            (?:^similarity[ ]index[ ](?P\d+)%\n
               ^rename[ ]from[ ](?P\S+)\n
               ^rename[ ]to[ ](?P\S+)(?:\n|$))?
            (?:^old[ ]mode[ ](?P\d+)\n
               ^new[ ]mode[ ](?P\d+)(?:\n|$))?
            (?:^new[ ]file[ ]mode[ ](?P.+)(?:\n|$))?
            (?:^deleted[ ]file[ ]mode[ ](?P.+)(?:\n|$))?
            (?:^index[ ](?P[0-9A-Fa-f]+)
                \.\.(?P[0-9A-Fa-f]+)[ ]?(?P.+)?(?:\n|$))?
        """, re.VERBOSE | re.MULTILINE).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_commit, b_commit, 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_commit, b_commit,
                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