#!/usr/bin/env python3

import argparse
import os
import subprocess
import yaml


class BatchManager:

    def __init__(self, config_dir):
        self.__config_list = BatchManager.__load_and_validate_config_dir(config_dir)

    @staticmethod
    def __load_and_validate_config_dir(config_dir):
        if not os.path.isdir(config_dir):
            raise ValueError(f"{config_dir} is not a directory")

        return [
            BatchManager.__load_and_validate_config_file(os.path.join(config_dir, file))
            for file in os.listdir(config_dir)
        ]


    @staticmethod
    def __load_and_validate_config_file(config_file_path):
        if not os.path.isfile(config_file_path):
            raise ValueError(f"{config_file_path} is not a file")

        with open(config_file_path, encoding="utf-8") as config_file:
            config = yaml.safe_load(config_file)

        for key in ["dataset", "backup_dataset"]:
            if key not in config:
                raise KeyError(f"{key} must be present in {config_file_path}")

        return config

    def __exec(self, source_key, destination_key):
        for config in self.__config_list:
            syncoid_cmd = ["/usr/sbin/syncoid", "--no-sync-snap", "--sendoptions=\"p\""]
            if config.get("recursive", False):
                syncoid_cmd.append("--recursive")
            if config.get("skip_parent", False):
                syncoid_cmd.append("--skip-parent")
            syncoid_cmd.append(config[source_key])
            syncoid_cmd.append(config[destination_key])

            try:
                subprocess.run(syncoid_cmd, check=True,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
            except subprocess.CalledProcessError as err:
                print(err.stdout.decode("ascii"), flush=True)
                raise

    def backup(self):
        self.__exec("dataset", "backup_dataset")

    def restore(self):
        self.__exec("backup_dataset", "dataset")


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Backup service data using syncoid")
    parser.add_argument("--config-dir", type=str, default="/etc/syncoid-batch.d",
                        help="Path to directory with YAML config files")

    subparsers = parser.add_subparsers()

    backup_parser = subparsers.add_parser("backup")
    backup_parser.set_defaults(func=BatchManager.backup)

    restore_parser = subparsers.add_parser("restore")
    restore_parser.set_defaults(func=BatchManager.restore)

    args = parser.parse_args()

    args.func(BatchManager(args.config_dir))