#!/usr/bin/env python3
# Copyright (c) 2023 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""A git pre-commit hook to drop staged gitlink changes.

To bypass this hook, set SKIP_GITLINK_PRECOMMIT=1.
"""

import os
import sys

ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.insert(0, ROOT_DIR)

import git_common
from gclient_eval import SYNC

SKIP_VAR = 'SKIP_GITLINK_PRECOMMIT'


def main():
    if os.getenv(SKIP_VAR) == '1':
        print(f'{SKIP_VAR} is set. Committing gitlinks, if any.')
        exit(0)

    has_deps_diff = False
    staged_gitlinks = []
    diff = git_common.run('diff-index', '--cached', 'HEAD')
    for line in diff.splitlines():
        path = line.split()[-1]
        if path == 'DEPS':
            has_deps_diff = True
            continue
        if line.startswith(':160000 160000'):
            staged_gitlinks.append(path)

    if not staged_gitlinks or has_deps_diff:
        exit(0)

    # There are staged gitlinks and DEPS wasn't changed. Get git_dependencies
    # migration state in DEPS.
    state = None
    try:
        with open('DEPS', 'r') as f:
            for l in f.readlines():
                if l.startswith('git_dependencies'):
                    state = l.split()[-1].strip(' "\'')
                    break
    except OSError:
        # Don't abort the commit if DEPS wasn't found.
        exit(0)

    if state != SYNC:
        # DEPS only has to be in sync with gitlinks when state is SYNC.
        exit(0)

    print(f'Found no change to DEPS, unstaging {len(staged_gitlinks)} '
          f'staged gitlink(s) found in diff:\n{diff}')
    git_common.run('restore', '--staged', '--', *staged_gitlinks)

    disable_msg = f'To disable this hook, set {SKIP_VAR}=1'
    if len(staged_gitlinks) == len(diff.splitlines()):
        print('Found no changes after unstaging gitlinks, aborting commit.')
        print(disable_msg)
        exit(1)
    print(disable_msg)


if __name__ == "__main__":
    main()