#!/bin/env python3
import argparse
import json
import yaml

from typing import List, TypedDict
from yaml.loader import SafeLoader

# A list of Gerrit users (email addresses).
UsersList = List[str]

# A YAML node with an extra line number.
class NumberedNode(TypedDict):
    line_number: int


# The root YAML node of an OWNERS file
class OwnersData(NumberedNode, TypedDict, total=False):
    owners: UsersList
    reviewers: UsersList


# A YAML loader that adds the start line number onto each node (for
# later linting support)
class YamlLoader(SafeLoader):
    def construct_mapping(
        self, node: yaml.nodes.Node, deep: bool = False
    ) -> NumberedNode:
        mapping: NumberedNode = super(YamlLoader, self).construct_mapping(
            node, deep=deep
        )  # type: ignore
        mapping["line_number"] = node.start_mark.line + 1
        return mapping

    # Load a file and return the OwnersData.
    @staticmethod
    def load(file: str) -> OwnersData:
        data: OwnersData
        with open(file, "r") as f:
            data = yaml.load(f, Loader=YamlLoader)
        return data


# Class to match commit information with OWNERS files.
# TODO: git commit piece not yet supported.
class CommitMatch:
    def __init__(self, owners: OwnersData):
        self.data = owners

    def owners(self) -> UsersList:
        return self.data["owners"] if "owners" in self.data else []

    def reviewers(self) -> UsersList:
        return self.data["reviewers"] if "reviewers" in self.data else []


# The subcommand to get the reviewers.
def subcmd_reviewers(args: argparse.Namespace, data: OwnersData) -> None:
    matcher = CommitMatch(data)

    # Print in `git push refs/for/branch%<reviewers>` format.
    if args.push_args:
        result = []
        for o in matcher.owners():
            # Gerrit uses 'r' for the required reviewers (owners).
            result.append(f"r={o}")
        for r in matcher.reviewers():
            # Gerrit uses 'cc' for the optional reviewers.
            result.append(f"cc={r}")
        print(",".join(result))
    # Print as Gerrit Add Reviewers POST format.
    # https://gerrit.openbmc.org/Documentation/rest-api-changes.html#add-reviewer
    else:
        for o in matcher.owners():
            print(json.dumps({"reviewer": o, "state": "REVIEWER"}))
        for r in matcher.reviewers():
            print(json.dumps({"reviewer": r, "state": "CC"}))


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument(
        "-p", "--path", default=".", help="Root path to analyse"
    )
    subparsers = parser.add_subparsers()

    parser_reviewers = subparsers.add_parser(
        "reviewers", help="Generate List of Reviewers"
    )
    parser_reviewers.add_argument(
        "--push-args",
        action=argparse.BooleanOptionalAction,
        help="Format as git push options",
    )
    parser_reviewers.set_defaults(func=subcmd_reviewers)

    args = parser.parse_args()

    file = YamlLoader.load(args.path + "/OWNERS")
    args.func(args, file)


if __name__ == "__main__":
    main()