git-unmerged-normalization

#!/usr/bin/env python3

import os
import sys
import re
import shutil

SPECIAL_SUFFIX1 = "GIT_BOTTLE_UNMERGED_NORMALIZED"
SPECIAL_SUFFIX2 = "GIT_BOTTLE_UNMERGED_CHECKOUT"
SPECIAL_SUFFIX3 = "GIT_BOTTLE_UNMERGED_UNTRACKED"
SPECIAL_SUFFIX4 = "GIT_BOTTLE_UNMERGED_UNCOMMITED"
SPECIAL_FILENAME_MERGE_HEAD = ".GIT_BOTTLE_MERGE_HEAD"
SPECIAL_FILENAME_MERGE_MSG = ".GIT_BOTTLE_MERGE_MSG"
SPECIAL_FILENAME_MERGE_MODE = ".GIT_BOTTLE_MERGE_MODE"
SPECIAL_MERGE_COMMIT_PREFIX = "GIT_BOTTLE_STATE_MERGE: "

def update_index(updates):
    p = os.popen('git update-index --index-info', 'w')
    data = '\n'.join(updates)
    p.write(data)
    r = p.close()
    if r != None:
        print >>sys.stderr, "git-update-index failed"
        sys.exit(r)

def add(lst):
    params = ['git', 'add', '-f', '--'] + list(lst)
    r = os.spawnvp(os.P_WAIT, 'git', params)
    if r != 0:
        print >>sys.stderr, "git-add failed (%d)" % (r, )
        sys.exit(r)

def remove(lst):
    params = ['git', 'rm', '-f', '--'] + list(lst)
    r = os.spawnvp(os.P_WAIT, 'git', params)
    if r != 0:
        print >>sys.stderr, "git-add failed (%d)" % (r, )
        sys.exit(r)

def checkout(files, params=None):
    if not params:
        params = []
    else:
        params = params
    params = ['git', 'checkout'] + params + ['--'] + list(files)
    r = os.spawnvp(os.P_WAIT, 'git', params)
    if r != 0:
        print >>sys.stderr, "git-checkout failed (%d)" % (r, )
        sys.exit(r)

def reset(files, params=None):
    if not params:
        params = []
    else:
        params = params
    params = ['git', 'reset'] + params + ['--'] + list(files)
    r = os.spawnvp(os.P_WAIT, 'git', params)
    if r != 0:
        print >>sys.stderr, "git-reset failed (%d)" % (r, )
        sys.exit(r)

def save_unstaged_changes_files(unmerged_filenames):
    def move_modified(suffix):
        lst = []
        files_to_checkout = []
        for line in os.popen('git status --porcelain').read().splitlines():
            if line[1] == 'M':
                filename = line[3:]
                filename_temp = filename + '.' + suffix
                os.rename(filename, filename_temp)
                files_to_checkout.append(filename)
                lst.append((filename_temp, filename))
        if files_to_checkout:
            checkout(files_to_checkout)
        return lst

    lst = move_modified(SPECIAL_SUFFIX3)

    files_to_reset = []
    for line in os.popen('git status --porcelain').read().splitlines():
        if line[0:2] == 'M ':
            filename = line[3:]
            if filename not in unmerged_filenames:
                files_to_reset.append(filename)
    if files_to_reset:
        reset(files_to_reset)

    lst2 = move_modified(SPECIAL_SUFFIX4)

    return (lst, lst2)

def encode():
    """Turn the unmerged paths, if exist, to a commit (or a merge commit)"""
    updates = []
    unmerged_filenames = set({})
    unmerged_bogus_filenames = set()

    for line in os.popen('git ls-files --unmerged').read().splitlines():
        meta, filename = line.split('\t')
        mode, sha1hash, stage = meta.split(' ')
        if stage != "0":
            unmerged_filenames.add(filename)
        bogus_filename = filename + ".%s.%s" % (stage, SPECIAL_SUFFIX1)
        unmerged_bogus_filenames.add(bogus_filename)
        updates += ["%s %s 0\t%s" % (mode, sha1hash, bogus_filename)]

    if not updates:
        return

    update_index(updates)
    add(unmerged_filenames)
    checkout(unmerged_bogus_filenames)

    modified_list = []
    staged_list = []
    if os.path.exists(".git/MERGE_MODE"):
        # For MERGE_MODE, git won't let us do partial merges, so we need
        # to save aside all modified files that were not stage. Otheriwse,
        # we get 'fatal: cannot do a partial commit during a merge.'

        modified_list, staged_list = save_unstaged_changes_files(unmerged_filenames)

        shutil.copy(".git/MERGE_HEAD", SPECIAL_FILENAME_MERGE_HEAD)
        shutil.copy(".git/MERGE_MSG", SPECIAL_FILENAME_MERGE_MSG)
        shutil.copy(".git/MERGE_MODE", SPECIAL_FILENAME_MERGE_MODE)

        add([SPECIAL_FILENAME_MERGE_HEAD,
             SPECIAL_FILENAME_MERGE_MSG,
             SPECIAL_FILENAME_MERGE_MODE])

        content = SPECIAL_MERGE_COMMIT_PREFIX + open(".git/MERGE_MSG").read()
        f = open(".git/MERGE_MSG", "w")
        f.write(content)
        f.close()

        params = ['git', 'commit', '-a', '--no-edit']
    else:
        params = ['git', 'commit', '-m', "GIT_BOTTLE_STATE: unmerged-paths-normalization",
                  '--'] + (list(unmerged_bogus_filenames) +
                           list(unmerged_filenames))

    r = os.spawnvp(os.P_WAIT, 'git', params)
    if staged_list:
        lst = []
        for filename_temp, filename in staged_list:
            os.rename(filename_temp, filename)
            lst += [filename]
        add(lst)

    for filename_temp, filename in modified_list:
        os.rename(filename_temp, filename)

    if r != 0:
        print >>sys.stderr, "git-commit failed (%d)" % (r, )
        sys.exit(r)

def decode():
    """Turn a special 'unmerged paths' commit back to unmerged files in index"""
    rev = os.popen('git rev-parse HEAD').read().strip()

    cmd = os.popen('git show HEAD --format="%s" -s').read().strip()

    merge_commit = False
    if cmd != "GIT_BOTTLE_STATE: unmerged-paths-normalization":
        if cmd.startswith(SPECIAL_MERGE_COMMIT_PREFIX):
            merge_commit = True
        else:
            return

    params = ['git', 'reset', '--soft' ,'HEAD^']
    r = os.spawnvp(os.P_WAIT, 'git', params)
    if r != 0:
        print >>sys.stderr, "git-reset failed (%d)" % (r, )
        sys.exit(r)

    r = re.compile("(.*)[.]([0-9]+)[.]" + SPECIAL_SUFFIX1 + '$')
    lines = os.popen('git ls-files --stage').read().splitlines()
    unmerged_paths = set()
    removals = set()
    updates = []
    for line in lines:
        meta, filename = line.split('\t')
        mode, sha1hash, _ = meta.split(' ')
        m = r.match(filename)
        if not m:
            continue

        removals.add(filename)
        filename, stage = m.groups(0)
        updates += ["%s %s %s\t%s" % (mode, sha1hash, stage, filename)]
        unmerged_paths.add(filename)

    checkouts = []
    for line in lines:
        meta, filename = line.split('\t')
        mode, sha1hash, stage = meta.split(' ')
        if filename in unmerged_paths:
            checkouts += [filename]
            os.rename(filename, filename + SPECIAL_SUFFIX2)
            removals.add(filename)

    remove(removals)
    update_index(updates)
    for filename in checkouts:
        os.rename(filename + SPECIAL_SUFFIX2, filename)

    if merge_commit:
        # Restore the merge state
        reset([SPECIAL_FILENAME_MERGE_HEAD,
               SPECIAL_FILENAME_MERGE_MSG,
               SPECIAL_FILENAME_MERGE_MODE])
        os.rename(SPECIAL_FILENAME_MERGE_HEAD, ".git/MERGE_HEAD")
        os.rename(SPECIAL_FILENAME_MERGE_MSG, ".git/MERGE_MSG")
        os.rename(SPECIAL_FILENAME_MERGE_MODE, ".git/MERGE_MODE")

def main():
    top_dir = os.popen('git rev-parse --show-toplevel').read().strip()
    os.chdir(top_dir)

    if sys.argv[1:] == ["encode"]:
        encode()
    elif sys.argv[1:] == ["decode"]:
        decode()
    else:
        pass

if __name__ == '__main__':
    main()