git-auto-commit

#!/usr/bin/env python3
#
# See also:
#   - https://github.com/gitwatch/gitwatch

import argparse
import datetime
import logging
import os.path
import pygit2       # type: ignore
import re
import subprocess
import sys
from textwrap import dedent, wrap


STATUS_FLAGS = {
    pygit2.GIT_STATUS_CURRENT: "CURRENT",
    pygit2.GIT_STATUS_INDEX_NEW: "INDEX_NEW",
    pygit2.GIT_STATUS_INDEX_MODIFIED: "INDEX_MODIFIED",
    pygit2.GIT_STATUS_INDEX_DELETED: "INDEX_DELETED",
    pygit2.GIT_STATUS_WT_NEW: "WT_NEW",
    pygit2.GIT_STATUS_WT_MODIFIED: "WT_MODIFIED",
    pygit2.GIT_STATUS_WT_DELETED: "WT_DELETED",
    pygit2.GIT_STATUS_IGNORED: "IGNORED",
    pygit2.GIT_STATUS_CONFLICTED: "CONFLICTED",
}

FORMAT = '%(levelname)-7s | %(message)s'
logging.basicConfig(format=FORMAT)


def get_status_output(flags):
    if flags & pygit2.GIT_STATUS_IGNORED:
        return "!!"
    elif flags & pygit2.GIT_STATUS_WT_NEW:
        return "??"
    elif flags & pygit2.GIT_STATUS_WT_MODIFIED:
        return " M"
    elif flags & pygit2.GIT_STATUS_WT_DELETED:
        return " D"
    elif flags & pygit2.GIT_STATUS_INDEX_NEW:
        return "A "
    elif flags & pygit2.GIT_STATUS_INDEX_MODIFIED:
        return "M "
    elif flags & pygit2.GIT_STATUS_INDEX_DELETED:
        return "D "
    elif flags & pygit2.GIT_STATUS_CONFLICTED:
        return "UU"
    elif flags & pygit2.GIT_STATUS_CURRENT:
        return ".."
    else:
        return "  "


def get_status_flags(flags):
    return [
        descr
        for flag, descr in STATUS_FLAGS.items()
        if flags & flag
    ]


def file_is_staged(flags):
    return flags & (pygit2.GIT_STATUS_INDEX_NEW
                    | pygit2.GIT_STATUS_INDEX_MODIFIED
                    | pygit2.GIT_STATUS_INDEX_DELETED)


def file_is_conflicted(flags):
    return flags & pygit2.GIT_STATUS_CONFLICTED


def get_hostname():
    nick_file = os.path.expanduser("~/.localhost-nickname")
    if os.path.isfile(nick_file):
        with open(nick_file) as f:
            return f.readline().rstrip("\n")
    else:
        return os.getenv("HOST") or os.getenv("HOSTNAME")


def quit(msg):
    logging.debug(msg)
    sys.exit(1)


def abort(msg):
    logging.error(msg)
    sys.exit(1)


class GitAutoCommitter:
    def __init__(self, repo_path):
        self.repo_path = repo_path
        logging.debug("GitAutoCommitter on repo %s" % self.repo_path)
        self.repo = pygit2.Repository(repo_path)
        self.check_config()

    def check_config(self):
        if self.config_get("user.name") is None:
            abort("user.name is not set in git config; aborting!")
        if self.config_get("user.email") is None:
            abort("user.email is not set in git config; aborting!")

    def manual_attention_required(self):
        found_issues = False
        for filepath, flags in self.process_files():
            if self.ignored(filepath):
                # logging.debug(f"# {filepath} ignored by git")
                continue

            if self.auto_commit_policy(filepath) is None:
                logging.debug(f"# {filepath} has no autocommit policy")
                continue

            st = get_status_output(flags)
            if file_is_staged(flags):
                logging.debug(f"{st} {filepath}\t\t<-- staged")
                found_issues = True
            elif file_is_conflicted(flags):
                logging.debug(f"{st} {filepath}\t\t<-- conflicted")
                found_issues = True
            else:
                logging.debug(f"{st} {filepath}")

        return found_issues

    def auto_commit_changes(self):
        staged = self.stage_changes()
        if staged > 0:
            self.commit_changes()
        else:
            quit("Nothing to commit")

    def stage_changes(self):
        staged = 0

        for filepath, flags in self.process_files():
            if self.ignored(filepath):
                logging.debug(f"# {filepath} ignored by git")
                continue

            # Flags can be found here:
            # https://github.com/libgit2/pygit2/blob/320ee5e733039d4a3cc952b287498dbc5737c353/src/pygit2.c#L312-L320
            if self.should_commit(filepath):
                if flags & pygit2.GIT_STATUS_WT_NEW:
                    self.stage_file(filepath, "new")
                    staged += 1
                elif flags & pygit2.GIT_STATUS_WT_MODIFIED:
                    self.stage_file(filepath, "changed")
                    staged += 1

            # else:
            #     fl = " ".join(get_status_flags(flags))
            #     logging.debug(f"Not staging {filepath} with flags {fl}")

        if staged > 0:
            self.repo.index.write()
        return staged

    def auto_commit_policy(self, filepath):
        policy = self.repo.get_attr(filepath, "autocommit")
        if not policy or policy in ('false', 'none'):
            return None
        return policy

    def policy_min_age(self, policy, filepath):
        m = re.match(r'min-age=\+(\d+)([mshd])', policy)
        if not m:
            abort(f"Couldn't parse autocommit attribute {policy} for {filepath}")
        amount = int(m.group(1))
        unit = m.group(2)
        if unit == "s":
            secs = amount
        elif unit == "m":
            secs = amount * 60
        elif unit == "h":
            secs = amount * 60 * 60
        elif unit == "d":
            secs = amount * 60 * 60 * 24
        else:
            abort("BUG in policy_min_age")
        logging.debug(f"{filepath} has min-age policy of {secs} secs")
        return datetime.timedelta(seconds=secs)

    def should_commit(self, filepath):
        policy = self.auto_commit_policy(filepath)
        if policy is None:
            return False

        min_age = self.policy_min_age(policy, filepath)
        commit_age = self.time_since_last_commit(filepath)
        file_age = self.time_since_mtime(filepath)
        if commit_age < min_age:
            logging.debug(f"Not staging {filepath}, "
                          f"last committed {commit_age} ago")
            return False

        if file_age < min_age:
            logging.debug(f"Not staging {filepath}, "
                          f"last modified {file_age} ago")
            return False

        return True

    def config_get(self, name):
        try:
            return self.repo.config[name]
        except KeyError:
            return None

    def commit_changes(self):
        author = pygit2.Signature(
            self.repo.config["user.name"],
            self.repo.config["user.email"]
        )
        committer = pygit2.Signature(
            self.config_get("auto-commit.name")
            or self.config_get("user.name"),
            self.config_get("auto-commit.email")
            or self.config_get("user.email")
        )
        tree = self.repo.index.write_tree()
        head_oid = self.repo.head.resolve().target
        host = get_hostname()
        message = f"auto-commit on {host} by {__file__}"
        oid = self.repo.create_commit( # noqa
            "refs/heads/master", author, committer, message, tree,
            [head_oid]  # parent commit(s)
        )
        # commit = self.repo.get(oid)
        # logging.debug(f"\n{commit.short_id} {message}")
        logging.debug("")
        subprocess.call(["git", "show", "--format=fuller", "--name-status"])

    def process_files(self):
        for filepath, flags in self.repo.status().items():
            yield filepath, flags

    def ignored(self, filepath):
        dirname, filename = os.path.split(filepath)
        if filename.startswith(".#"):
            # emacs lock file
            return True

        return False

    def time_since_mtime(self, filepath):
        now = datetime.datetime.now()
        last_change = datetime.datetime.fromtimestamp(
            os.stat(filepath).st_mtime)
        return now - last_change

    def in_index(self, filepath):
        try:
            self.repo.index[filepath]
            return True
        except KeyError:
            return False

    def time_since_last_commit(self, filepath):
        if not self.in_index(filepath):
            logging.debug("%s not in index" % filepath)
            return datetime.timedelta(weeks=99999)

        descr = subprocess.check_output(
            ["git", "describe", "--always", f"HEAD:{filepath}"],
            encoding='utf-8')
        ref, _path = descr.split(":", 1)
        rev = self.repo.revparse_single(ref)
        now = datetime.datetime.now()
        last_change = datetime.datetime.fromtimestamp(rev.commit_time)
        return now - last_change

    def stage_file(self, filepath, reason):
        logging.debug(f"%-20s {filepath}" % f"Staged {reason} file:")
        self.repo.index.add(filepath)


def parse_args():
    descr = "\n".join(wrap(dedent("""\
        Automatically commit files according to the policy defined
        in their autocommit attribute.  Doesn't do anything if any
        change is already staged in git's index.
    """), width=int(os.getenv("COLUMNS", "70"))))

    parser = argparse.ArgumentParser(
        description=descr,
        formatter_class=argparse.RawDescriptionHelpFormatter,
    )
    parser.add_argument(
        "-d", "--debug", action="store_true",
        help="Enable debug output"
    )
    parser.add_argument(
        "repo_path", metavar="REPO-PATH", nargs="?",
        default=".", help="Path to repository to auto-commit"
    )

    return parser.parse_known_args()


def main():
    options, args = parse_args()
    if options.debug:
        logging.getLogger().setLevel(logging.DEBUG)

    gac = GitAutoCommitter(options.repo_path)

    if gac.manual_attention_required():
        abort("Manual attention required; aborting.")

    logging.debug("")
    gac.auto_commit_changes()


main()