import re
import os
from common.constants import LOCATOR_LEN_HEX


def check_sha256_hex_format(value):
    """
    Checks if a given value is a 32-byte hex encoded string.

    Args:
        value(:mod:`str`): the value to be checked.

    Returns:
        :mod:`bool`: Whether or not the value matches the format.
    """
    return isinstance(value, str) and re.match(r"^[0-9A-Fa-f]{64}$", value) is not None


def check_locator_format(value):
    """
    Checks if a given value is a 16-byte hex encoded string.

    Args:
        value(:mod:`str`): the value to be checked.

    Returns:
        :mod:`bool`: Whether or not the value matches the format.
    """
    return isinstance(value, str) and re.match(r"^[0-9A-Fa-f]{32}$", value) is not None


def compute_locator(tx_id):
    """
    Computes an appointment locator given a transaction id.
    Args:
        tx_id (:obj:`str`): the transaction id used to compute the locator.
    Returns:
       (:obj:`str`): The computed locator.
    """

    return tx_id[:LOCATOR_LEN_HEX]


def setup_data_folder(data_folder, logger):
    if not os.path.isdir(data_folder):
        logger.info("Data folder not found. Creating it")
        os.makedirs(data_folder, exist_ok=True)


def check_conf_fields(conf_fields):
    conf_dict = {}

    for field in conf_fields:
        value = conf_fields[field]["value"]
        correct_type = conf_fields[field]["type"]

        if (value is not None) and isinstance(value, correct_type):
            conf_dict[field] = value
        else:
            err_msg = "{} variable in config is of the wrong type".format(field)
            raise ValueError(err_msg)

    return conf_dict


def extend_paths(base_path, config_fields):
    for key, field in config_fields.items():
        if field.get("path"):
            config_fields[key]["value"] = base_path + config_fields[key]["value"]

    return config_fields