# Copyright (C) 2018 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 functions to communicate with Git."""

import datetime
import re
import shutil
import subprocess
from pathlib import Path

import hashtags
import reviewers


def fetch(proj_path: Path, remote_names: list[str]) -> None:
    """Runs git fetch.

    Args:
        proj_path: Path to Git repository.
        remote_names: Array of string to specify remote names.
    """
    cmd = ['git', 'fetch', '--tags', '--multiple'] + remote_names
    subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True)


def add_remote(proj_path: Path, name: str, url: str) -> None:
    """Adds a git remote.

    Args:
        proj_path: Path to Git repository.
        name: Name of the new remote.
        url: Url of the new remote.
    """
    cmd = ['git', 'remote', 'add', name, url]
    subprocess.run(cmd, cwd=proj_path, check=True)


def remove_remote(proj_path: Path, name: str) -> None:
    """Removes a git remote."""
    cmd = ['git', 'remote', 'remove', name]
    subprocess.run(cmd, cwd=proj_path, check=True)


def list_remotes(proj_path: Path) -> dict[str, str]:
    """Lists all Git remotes.

    Args:
        proj_path: Path to Git repository.

    Returns:
        A dict from remote name to remote url.
    """
    def parse_remote(line: str) -> tuple[str, str]:
        split = line.split()
        return split[0], split[1]

    cmd = ['git', 'remote', '-v']
    out = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                         text=True).stdout
    lines = out.splitlines()
    return dict([parse_remote(line) for line in lines])


def detect_default_branch(proj_path: Path, remote_name: str) -> str:
    """Gets the name of the upstream's default branch to use."""
    cmd = ['git', 'remote', 'show', remote_name]
    out = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                         text=True).stdout
    lines = out.splitlines()
    for line in lines:
        if "HEAD branch" in line:
            return line.split()[-1]
    raise RuntimeError(
        f"Could not find HEAD branch in 'git remote show {remote_name}'"
    )


def get_sha_for_branch(proj_path: Path, branch: str):
    """Gets the hash SHA for a branch."""
    cmd = ['git', 'rev-parse', branch]
    return subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                          text=True).stdout.strip()


def get_commits_ahead(proj_path: Path, branch: str,
                      base_branch: str) -> list[str]:
    """Lists commits in `branch` but not `base_branch`."""
    cmd = [
        'git', 'rev-list', '--left-only', '--ancestry-path', 'f{branch}...{base_branch}'
    ]
    out = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                         text=True).stdout
    return out.splitlines()


# pylint: disable=redefined-outer-name
def get_commit_time(proj_path: Path, commit: str) -> datetime.datetime:
    """Gets commit time of one commit."""
    cmd = ['git', 'show', '-s', '--format=%ct', commit]
    out = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                         text=True).stdout
    return datetime.datetime.fromtimestamp(int(out.strip()))


def list_remote_branches(proj_path: Path, remote_name: str) -> list[str]:
    """Lists all branches for a remote."""
    cmd = ['git', 'branch', '-r']
    lines = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                           text=True).stdout.splitlines()
    stripped = [line.strip() for line in lines]
    remote_path = remote_name + '/'
    return [
        line[len(remote_path):] for line in stripped
        if line.startswith(remote_path)
    ]


def list_local_branches(proj_path: Path) -> list[str]:
    """Lists all local branches."""
    cmd = ['git', 'branch', '--format=%(refname:short)']
    lines = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                           text=True).stdout.splitlines()
    return lines


def list_remote_tags(proj_path: Path, remote_name: str) -> list[str]:
    """Lists all tags for a remote."""
    regex = re.compile(r".*refs/tags/(?P<tag>[^\^]*).*")

    def parse_remote_tag(line: str) -> str:
        if (m := regex.match(line)) is not None:
            return m.group("tag")
        raise ValueError(f"Could not parse tag from {line}")

    cmd = ['git', "ls-remote", "--tags", remote_name]
    lines = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                           text=True).stdout.splitlines()
    tags = [parse_remote_tag(line) for line in lines]
    return list(set(tags))


COMMIT_PATTERN = r'^[a-f0-9]{40}$'
COMMIT_RE = re.compile(COMMIT_PATTERN)


# pylint: disable=redefined-outer-name
def is_commit(commit: str) -> bool:
    """Whether a string looks like a SHA1 hash."""
    return bool(COMMIT_RE.match(commit))


def merge(proj_path: Path, branch: str) -> None:
    """Merges a branch."""
    try:
        cmd = ['git', 'merge', branch, '--no-commit']
        subprocess.run(cmd, cwd=proj_path, check=True)
    except subprocess.CalledProcessError as err:
        if hasattr(err, "output"):
            print(err.output)
        if not merge_conflict(proj_path):
            raise


def merge_conflict(proj_path: Path) -> bool:
    """Checks if there was a merge conflict."""
    cmd = ['git', 'ls-files', '--unmerged']
    out = subprocess.run(cmd, capture_output=True, cwd=proj_path, check=True,
                         text=True).stdout
    return bool(out)


def add_file(proj_path: Path, file_name: str) -> None:
    """Stages a file."""
    cmd = ['git', 'add', file_name]
    subprocess.run(cmd, cwd=proj_path, check=True)


def remove_gitmodules(proj_path: Path) -> None:
    """Deletes .gitmodules files."""
    cmd = ['find', '.', '-name', '.gitmodules', '-delete']
    subprocess.run(cmd, cwd=proj_path, check=True)


def delete_branch(proj_path: Path, branch_name: str) -> None:
    """Force delete a branch."""
    cmd = ['git', 'branch', '-D', branch_name]
    subprocess.run(cmd, cwd=proj_path, check=True)


def tree_uses_pore(proj_path: Path) -> bool:
    """Returns True if the tree uses pore rather than repo.

    https://github.com/jmgao/pore
    """
    if shutil.which("pore") is None:
        # Fast path for users that don't have pore installed, since that's almost
        # everyone.
        return False

    if proj_path == Path(proj_path.root):
        return False
    if (proj_path / ".pore").exists():
        return True
    return tree_uses_pore(proj_path.parent)


def start_branch(proj_path: Path, branch_name: str) -> None:
    """Starts a new repo branch."""
    repo = 'repo'
    if tree_uses_pore(proj_path):
        repo = 'pore'
    cmd = [repo, 'start', branch_name]
    subprocess.run(cmd, cwd=proj_path, check=True)


def commit(proj_path: Path, message: str) -> None:
    """Commits changes."""
    cmd = ['git', 'commit', '-m', message]
    subprocess.run(cmd, cwd=proj_path, check=True)


def checkout(proj_path: Path, branch_name: str) -> None:
    """Checkouts a branch."""
    cmd = ['git', 'checkout', branch_name]
    subprocess.run(cmd, cwd=proj_path, check=True)


def push(proj_path: Path, remote_name: str, has_errors: bool) -> None:
    """Pushes change to remote."""
    cmd = ['git', 'push', remote_name, 'HEAD:refs/for/master']
    if revs := reviewers.find_reviewers(str(proj_path)):
        cmd.extend(['-o', revs])
    if tag := hashtags.find_hashtag(proj_path):
        cmd.extend(['-o', 't=' + tag])
    if has_errors:
        cmd.extend(['-o', 'l=Verified-1'])
    subprocess.run(cmd, cwd=proj_path, check=True)


def reset_hard(proj_path: Path) -> None:
    """Resets current HEAD and discards changes to tracked files."""
    cmd = ['git', 'reset', '--hard']
    subprocess.run(cmd, cwd=proj_path, check=True)


def clean(proj_path: Path) -> None:
    """Removes untracked files and directories."""
    cmd = ['git', 'clean', '-fdx']
    subprocess.run(cmd, cwd=proj_path, check=True)


def is_valid_url(proj_path: Path, url: str) -> bool:
    cmd = ['git', "ls-remote", url]
    return subprocess.run(cmd, cwd=proj_path, stdin=subprocess.DEVNULL,
                          stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
                          start_new_session=True).returncode == 0