#!/usr/bin/env python3
# Copyright (C) 2024 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Helper tool for updating hooks from their various upstreams."""

import argparse
import base64
import json
from pathlib import Path
import sys
from typing import List, Optional
import urllib.request


assert sys.version_info >= (3, 8), "Python 3.8+ required"


TOPDIR = Path(__file__).resolve().parent.parent
HOOKS_DIR = TOPDIR / "hooks"


def update_hook_commit_msg() -> None:
    """Update commit-msg hook from Gerrit."""
    hook = HOOKS_DIR / "commit-msg"
    print(
        f"{hook.name}: Updating from https://gerrit.googlesource.com/gerrit/"
        "+/HEAD/resources/com/google/gerrit/server/tools/root/hooks/commit-msg"
    )

    # Get the current commit.
    url = "https://gerrit.googlesource.com/gerrit/+/HEAD?format=JSON"
    with urllib.request.urlopen(url) as fp:
        data = fp.read()
    # Discard the xss protection.
    data = data.split(b"\n", 1)[1]
    data = json.loads(data)
    commit = data["commit"]

    # Fetch the data for that commit.
    url = (
        f"https://gerrit.googlesource.com/gerrit/+/{commit}/"
        "resources/com/google/gerrit/server/tools/root/hooks/commit-msg"
    )
    with urllib.request.urlopen(f"{url}?format=TEXT") as fp:
        data = fp.read()

    # gitiles base64 encodes text data.
    data = base64.b64decode(data)

    # Inject header into the hook.
    lines = data.split(b"\n")
    lines = (
        lines[:1]
        + [
            b"# DO NOT EDIT THIS FILE",
            (
                b"# All updates should be sent upstream: "
                b"https://gerrit.googlesource.com/gerrit/"
            ),
            f"# This is synced from commit: {commit}".encode("utf-8"),
            b"# DO NOT EDIT THIS FILE",
        ]
        + lines[1:]
    )
    data = b"\n".join(lines)

    # Update the hook.
    hook.write_bytes(data)
    hook.chmod(0o755)


def update_hook_pre_auto_gc() -> None:
    """Update pre-auto-gc hook from git."""
    hook = HOOKS_DIR / "pre-auto-gc"
    print(
        f"{hook.name}: Updating from https://github.com/git/git/"
        "HEAD/contrib/hooks/pre-auto-gc-battery"
    )

    # Get the current commit.
    headers = {
        "Accept": "application/vnd.github+json",
        "X-GitHub-Api-Version": "2022-11-28",
    }
    url = "https://api.github.com/repos/git/git/git/refs/heads/master"
    req = urllib.request.Request(url, headers=headers)
    with urllib.request.urlopen(req) as fp:
        data = fp.read()
    data = json.loads(data)

    # Fetch the data for that commit.
    commit = data["object"]["sha"]
    url = (
        f"https://raw.githubusercontent.com/git/git/{commit}/"
        "contrib/hooks/pre-auto-gc-battery"
    )
    with urllib.request.urlopen(url) as fp:
        data = fp.read()

    # Inject header into the hook.
    lines = data.split(b"\n")
    lines = (
        lines[:1]
        + [
            b"# DO NOT EDIT THIS FILE",
            (
                b"# All updates should be sent upstream: "
                b"https://github.com/git/git/"
            ),
            f"# This is synced from commit: {commit}".encode("utf-8"),
            b"# DO NOT EDIT THIS FILE",
        ]
        + lines[1:]
    )
    data = b"\n".join(lines)

    # Update the hook.
    hook.write_bytes(data)
    hook.chmod(0o755)


def main(argv: Optional[List[str]] = None) -> Optional[int]:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.parse_args(argv)

    update_hook_commit_msg()
    update_hook_pre_auto_gc()


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))