Source code for mimesis.random

"""Implements various helpers which are used in the various data providers.

This module contains custom ``Random()`` class where implemented a lot of
methods which are not included in standard :py:class:`random.Random`,
but frequently used in this project.
"""

import random as random_module
import string
import typing as t
import uuid

from mimesis.types import MissingSeed, Seed

__all__ = ["Random", "random"]

#: Different plugins (like `pytest-randomly`)
#: can set custom values to a global seed,
#: which are going to be the new default.
global_seed: Seed = MissingSeed


class Random(random_module.Random):
    """A custom random class.

    It is a subclass of the :py:class:`random.Random` class from the standard
    library's random module. The class incorporates additional custom methods.

    This class can be extended according to specific requirements.
    """

    def randints(self, amount: int = 3, a: int = 1, b: int = 100) -> t.List[int]:
        """Generate list of random integers.

        :param amount: Amount of elements.
        :param a: Minimum value of range.
        :param b: Maximum value of range.
        :return: List of random integers.
        :raises ValueError: if amount less or equal to zero.
        """
        if amount <= 0:
            raise ValueError("Amount out of range.")

        return [int(self.random() * (b - a)) + a for _ in range(amount)]

    def _generate_string(self, str_seq: str, length: int = 10) -> str:
        """Generate random string created from string sequence.

        :param str_seq: String sequence of letters or digits.
        :param length: Max value.
        :return: Single string.
        """
        return "".join(self.choices(str_seq, k=length))

    def custom_code(self, mask: str = "@###", char: str = "@", digit: str = "#") -> str:
        """Generate custom code using ascii uppercase and random integers.

        :param mask: Mask of code.
        :param char: Placeholder for characters.
        :param digit: Placeholder for digits.
        :return: Custom code.
        """
        char_code = ord(char)
        digit_code = ord(digit)

        if char_code == digit_code:
            raise ValueError(
                "The same placeholder cannot be "
                "used for both numbers and characters."
            )

        def random_int(a: int, b: int) -> int:
            b = b - a
            return int(self.random() * b) + a

        _mask = mask.encode()
        code = bytearray(len(_mask))
        for i, p in enumerate(_mask):
            if p == char_code:
                a = random_int(65, 91)  # A-Z
            elif p == digit_code:
                a = random_int(48, 58)  # 0-9
            else:
                a = p
            code[i] = a
        return code.decode()

    def uniform(self, a: float, b: float, precision: int = 15) -> float:
        """Get a random number in the range [a, b) or [a, b] depending on rounding.

        :param a: Minimum value.
        :param b: Maximum value.
        :param precision: Round a number to a given
            precision in decimal digits, default is 15.
        """
        return round(a + (b - a) * self.random(), precision)

    def _randstr(self, unique: bool = False, length: t.Optional[int] = None) -> str:
        """Generate random string value.

        This method can be especially useful when you need to generate
        only unique values in your provider. Just pass parameter unique=True.

        Basically, this method is just a simple wrapper around :py:class:`uuid.UUID`.

        :param unique: Generate only unique values.
        :param length: Length of string. Default range is [a, b].
        :return: Random string.

        """
        if unique:
            return str(uuid.uuid4().hex)

        if length is None:
            length = self.randint(16, 128)

        characters = string.ascii_letters + string.digits
        return "".join(self.choices(characters, k=length))

    def randbytes(self, n: int = 16) -> bytes:
        """Generate n random bytes."""
        return self.getrandbits(n * 8).to_bytes(n, "little")

    def weighted_choice(self, choices: t.Dict[t.Any, float]) -> t.Any:
        """Returns a random element according to the specified weights.

        :param choices: A dictionary where keys are choices and values are weights.
        :raises ValueError: if choices is empty.
        :return: Random key from dictionary.
        """
        if not choices:
            raise ValueError("Choices cannot be empty.")

        population = list(choices.keys())
        weights = list(choices.values())
        return self.choices(population, weights=weights, k=1)[0]

    def choice_enum_item(self, enum: t.Any) -> t.Any:
        """Get random value of enum object.

        :param enum: Enum object.
        :return: Random value of enum.
        """
        return self.choice(list(enum))


# Compat
# See: https://github.com/lk-geimfari/mimesis/issues/469
random = Random()