git-split

#!/usr/bin/env python3
from gitz.git import GIT
from gitz.git import functions
from gitz.git import root
from gitz.program import ARGS
from gitz.program import PROGRAM

SUMMARY = 'Split a range of commits into many single-file commits'

DANGER = 'Rewrites history!'
HELP = """
`git split` squashes together a range of commits and the staging area, then
splits out a sequence of individual commits, one for each file changed.
"""
EXAMPLES = """
git split
    Split the staging area if it's not empty, otherwise HEAD

git split HEAD
    Split the squash of the staging area and HEAD

git split HEAD~
    Split the squash of the staging area, HEAD and HEAD~
"""


def git_split():
    root.cd_root()
    not_added = []

    for line in GIT.status('--porcelain', info=True):
        mode, filenames = line.split(maxsplit=1)
        if mode == '??':
            not_added.append(filenames)

    if ARGS.commit:
        commit = ARGS.commit + '~'
    elif root.is_workspace_dirty():
        commit = 'HEAD'
    else:
        commit = 'HEAD~'

    commit_id = functions.commit_id(commit)
    functions.check_is_ancestor(commit_id)

    removed_commits = []
    cid = functions.commit_id()
    while cid != commit_id:
        removed_commits.append('%s: %s' % functions.commit_message(cid))
        cid = functions.commit_id(cid + '~')

    GIT.reset('--soft', commit_id)
    lines = GIT.status('--porcelain', info=True)

    GIT.reset(commit_id)
    commit_count = 0

    PROGRAM.message('Added:')
    for line in lines:
        mode, filenames = line.split(maxsplit=1)
        filenames_split = filenames.split(' -> ')
        mode = mode.strip()
        if mode == '??':
            if filenames in not_added:
                continue
            mode = 'R' if len(filenames_split) > 1 else 'A'
        mode_name = NAMES[mode[0]]

        # Renaming is a special case with two files on a line
        # separated by -> and with mode = '??'
        try:
            GIT.add(*filenames_split)
            pre = ARGS.prefix
            pre += bool(pre) * ' '
            msg = '%s%s %s' % (pre, mode_name, filenames)
            GIT.commit('-m', msg)
            PROGRAM.message('+', functions.commit_id() + ':', msg)
            commit_count += 1

        except Exception:
            PROGRAM.error("couldn't commit filenames", filenames)
            raise

    if removed_commits:
        PROGRAM.message('')
        PROGRAM.message('Removed:')
        for rc in removed_commits:
            PROGRAM.message('-', rc)


def add_arguments(parser):
    parser.add_argument('commit', nargs='?', default='', help=_HELP_COMMIT)
    parser.add_argument('-p', '--prefix', default='', help=_HELP_PREFIX)


NAMES = 'Add', 'Delete', 'Modify', 'Rename'
NAMES = {name[0]: name for name in NAMES}
_HELP_COMMIT = 'Optional commit ID to split from'
_HELP_PREFIX = 'Prefix for each commit message'


if __name__ == '__main__':
    PROGRAM.ALLOW_NO_RUN = False
    PROGRAM.start()