import os
import argparse
from pathlib import Path
import datetime
from functools import wraps

from sh.contrib import git
import boto3

s3 = boto3.resource('s3')


parser = argparse.ArgumentParser()
subparsers = parser.add_subparsers(dest='cmd', help='sub-command help')

parser_backup= subparsers.add_parser('backup', help='backup repositories')
parser_backup.add_argument('repositories', help='directory with repos')

# create the parser for the "b" command
parser_b = subparsers.add_parser('b', help='b help')
parser_b.add_argument('--baz', choices='XYZ', help='baz help')

args = parser.parse_args()


def logit(func):
    @wraps(func)
    def with_logging(*args, **kwargs):
        print(func.__name__ + " was called")
        return func(*args, **kwargs)
    return with_logging

def cloud_object(bundle, prefix, bucket):
    obj = s3.Object(bucket, f'{prefix}/{bundle.name}')
    obj.upload_file(str(bundle))
    return obj

def backup_repo(repo, repo_name):
    # new repo or backup
    ts = datetime.datetime.utcnow().timestamp()
    bundle_path = Path(f'{repo_name}.{ts}.bundle')
    repo.bundle('create', bundle_path, '--all')
    return bundle_path

def tag_checkpoint(repo):
    last_hash = repo('rev-list', '-n', 1, '--all').strip()
    repo.tag('-f', 'CHECKPOINT', last_hash)

def requires_backup(repo):
    last_hash = repo.rev_list('rev-list', '-n', 1, '--all').strip()
    # empty repo
    if not last_hash:
        return False
    try:
        checkpoint = repo.rev_list('rev-list', '-n', 1, 'CHECKPOINT').strip()
    # no checkpoint exists
    except sh.ErrorReturnCode_1:
        return True
    return True ^ (last_hash == checkpoint)

def run_restore(bundle):
    pass

def run_backup(base):
    repo_base_path = Path(base)
    for repo_path in repo_base_path.glob('*.git'):
        repo = git.bake(f'--git-dir={repo_path}/')
        if requires_backup:
            bundle_path = backup_repo(repo, repo_path.name.split('.')[0])
            obj = cloud_object(bundle_path, '2', 'privategit')
            tag_checkpoint(repo)

if args.cmd == 'backup':
    run_backup(args.repositories)
elif args.cmd == 'restore':
    run_restore(args.bundle)