#!/usr/bin/env python3

import argparse
import os
import subprocess


def get_service_data_paths(data_root):
    dirs = os.listdir(data_root)
    return { d: os.path.join(data_root, d) for d in dirs }

def get_last_daily_snapshot_name(dataset_path):
    dataset = ''.join(["rpool", dataset_path])
    snapshots = subprocess.getoutput(
        f"zfs list -t snapshot -H -r {dataset} -o name -s creation"
    )
    daily_snapshots = filter(lambda s: s.endswith("_daily"), snapshots.split('\n'))
    return list(daily_snapshots)[-1]

def get_snapshot_mount_path(snapshot):
    return snapshot.replace("rpool/", "/", 1).replace("@", "/.zfs/snapshot/", 1)

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Backup service data using restic")
    parser.add_argument("--data-root", type=str, required=True,
                        help="Service data root")
    parser.add_argument("--bucket-endpoint", type=str, required=True,
                        help="S3 bucket endpoint")
    parser.add_argument("--password-file", type=str, required=True,
                        help="Password file for restic repo")
    args = parser.parse_args()

    snapshots_for_backup = {}
    for service, service_data_root in get_service_data_paths(args.data_root).items():
        last_daily_snapshot = get_last_daily_snapshot_name(service_data_root)
        snapshots_for_backup[service] = get_snapshot_mount_path(last_daily_snapshot)

    for service, snapshot_path in snapshots_for_backup.items():
        print(f"Backing up {service} @ {snapshot_path}")

        restic_cmd_base = "restic " \
            f"--password-file {args.password_file} " \
            f"--repo s3:https://{args.bucket_endpoint}/{{ ansible_hostname }}-{service}"

        subprocess.run(f"{restic_cmd_base} snapshots || {restic_cmd_base} init",
                      shell=True, check=True)
        subprocess.run(f"{restic_cmd_base} backup -o s3.storage-class=ONEZONE_IA {snapshot_path}",
                       shell=True, check=True)