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

from uuid import uuid4

from . import logger
from ucloud.settings import settings
from ucloud.shared import shared


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):
    file_id = uuid4()

    # Get Username
    owner = pathlib.Path(file).parts[len(pathlib.Path(base_dir).parts)]

    # Get Creation Date of File
    # Here, we are assuming that ctime is creation time
    # which is mostly not true.
    creation_date = time.ctime(os.stat(file).st_ctime)

    file_path = pathlib.Path(file).parts[-1]

    # Create Entry
    entry_key = os.path.join(
        settings["etcd"]["file_prefix"], str(file_id)
    )
    entry_value = {
        "filename": file_path,
        "owner": owner,
        "sha512sum": sha512sum(file),
        "creation_date": creation_date,
        "size": os.path.getsize(file),
    }

    logger.info("Tracking %s", file)

    shared.etcd_client.put(entry_key, entry_value, value_in_json=True)
    os.setxattr(file, "user.utracked", b"True")


def main():
    base_dir = settings["storage"]["file_dir"]

    # Recursively Get All Files and Folder below BASE_DIR
    files = glob.glob("{}/**".format(base_dir), recursive=True)

    # Retain only Files
    files = [file for file in files if os.path.isfile(file)]

    untracked_files = []
    for file in files:
        try:
            os.getxattr(file, "user.utracked")
        except OSError:
            track_file(file, base_dir)
            untracked_files.append(file)


if __name__ == "__main__":
    main()