import glob
import os
import pathlib
import subprocess as sp
import time
import argparse
import bitmath

from uuid import uuid4

from . import logger
from uncloud.common.settings import settings
from uncloud.shared import shared


arg_parser = argparse.ArgumentParser('filescanner', add_help=False)
arg_parser.add_argument('--hostname', required=True)


def sha512sum(file: str):
    """Use sha512sum utility to compute sha512 sum of arg:file

       IF arg:file does not exists:
        raise FileNotFoundError exception
       ELSE IF sum successfully computer:
        return computed sha512 sum
       ELSE:
        return None
    """
    if not isinstance(file, str):
        raise TypeError
    try:
        output = sp.check_output(['sha512sum', file], stderr=sp.PIPE)
    except sp.CalledProcessError as e:
        error = e.stderr.decode('utf-8')
        if 'No such file or directory' in error:
            raise FileNotFoundError from None
    else:
        output = output.decode('utf-8').strip()
        output = output.split(' ')
        return output[0]
    return None


def track_file(file, base_dir, host):
    file_path = file.relative_to(base_dir)
    file_str = str(file)
    # Get Username
    try:
        owner = file_path.parts[0]
    except IndexError:
        pass
    else:
        file_path = file_path.relative_to(owner)
        creation_date = time.ctime(os.stat(file_str).st_ctime)

        entry_key = os.path.join(settings['etcd']['file_prefix'], str(uuid4()))
        entry_value = {
            'filename': str(file_path),
            'owner': owner,
            'sha512sum': sha512sum(file_str),
            'creation_date': creation_date,
            'size': str(bitmath.Byte(os.path.getsize(file_str)).to_MB()),
            'host': host
        }

        logger.info('Tracking %s', file_str)

        shared.etcd_client.put(entry_key, entry_value, value_in_json=True)


def main(hostname, debug=False):
    base_dir = settings['storage']['file_dir']
    # Recursively Get All Files and Folder below BASE_DIR
    files = glob.glob('{}/**'.format(base_dir), recursive=True)
    files = [pathlib.Path(f) for f in files if pathlib.Path(f).is_file()]

    # Files that are already tracked
    tracked_files = [
        pathlib.Path(os.path.join(base_dir, f.value['owner'], f.value['filename']))
        for f in shared.etcd_client.get_prefix(settings['etcd']['file_prefix'], value_in_json=True)
        if f.value['host'] == hostname
    ]
    untracked_files = set(files) - set(tracked_files)
    for file in untracked_files:
        track_file(file, base_dir, hostname)