retag.py

#!/usr/bin/env python3

import datetime
import os
import re
import subprocess
import sys

def retag(tag):
    cat_file = subprocess.run(["git", "cat-file", "-p", "v" + tag], capture_output=True)

    author_name = None
    tagger_name = None

    for line_unstripped in cat_file.stdout.decode("utf-8").splitlines():
        line = line_unstripped.rstrip()
        if line.startswith("tree"):
            match = re.search("tree ([0-9a-f]+)", line)
            tree = match.group(1)
        elif line.startswith("parent"):
            match = re.search("parent ([0-9a-f]+)", line)
            parent = match.group(1)
        elif line.startswith("author"):
            match = re.search("author (.+) \<(.+)\> ([0-9]+) ([-+0-9]+)", line)
            author_name = match.group(1)
            author_email = match.group(2)
            author_timestamp = match.group(3)
            author_timezone_name = match.group(4)
            author_timezone = datetime.datetime.strptime(author_timezone_name, "%z").tzinfo
            author_datetime = datetime.datetime.fromtimestamp(int(author_timestamp), author_timezone)
        elif line.startswith("committer"):
            match = re.search("committer (.+) \<(.+)\> ([0-9]+) ([-+0-9]+)", line)
            committer_name = match.group(1)
            committer_email = match.group(2)
            committer_timestamp = match.group(3)
            committer_timezone_name = match.group(4)
            committer_timezone = datetime.datetime.strptime(committer_timezone_name, "%z").tzinfo
            committer_datetime = datetime.datetime.fromtimestamp(int(committer_timestamp), committer_timezone)
        elif line.startswith("tagger"):
            match = re.search("tagger (.+) \<(.+)\> ([0-9]+) ([-+0-9]+)", line)
            tagger_name = match.group(1)
            tagger_email = match.group(2)
            tagger_timestamp = match.group(3)
            tagger_timezone_name = match.group(4)
            tagger_timezone = datetime.datetime.strptime(tagger_timezone_name, "%z").tzinfo
            tagger_datetime = datetime.datetime.fromtimestamp(int(tagger_timestamp), tagger_timezone)
        else:
            continue

    if tagger_name:
        name = tagger_name
        email = tagger_email
        date = tagger_datetime
    elif author_name:
        name = author_name
        email = author_email
        date = author_datetime
    else:
        raise

    rev_list = subprocess.run(["git", "rev-list", "-n", "1", "v" + tag], capture_output=True)
    commit_lines = rev_list.stdout.decode("utf-8").splitlines()
    commit = commit_lines[0].rstrip()

    delete_cmd = ["git", "tag", "-d", "v" + tag]
    print(delete_cmd)
    tag_delete = subprocess.run(delete_cmd)

    annotate_cmd = ["git", "tag", "-F", tag, "v" + tag, commit]
    print(annotate_cmd)
    annotate_env = {
        "GIT_AUTHOR_NAME": name,
        "GIT_AUTHOR_EMAIL": email,
        "GIT_AUTHOR_DATE": date.strftime("%a %b %d %H:%M:%S %Y %z"),
        "GIT_COMMITTER_NAME": name,
        "GIT_COMMITTER_EMAIL": email,
        "GIT_COMMITTER_DATE": date.strftime("%a %b %d %H:%M:%S %Y %z"),
    }
    tag_annotate = subprocess.run(annotate_cmd, env=dict(os.environ, **annotate_env))

    return 0

def main(args):
    if len(args) <= 1:
        raise

    for arg in args[1:]:
        print("Tag: " + arg)
        retag(arg)
        print("")

if __name__ == '__main__':
    sys.exit(main(sys.argv))