# This file is Copyright 2019 Volatility Foundation and licensed under the Volatility Software License 1.0
# which is available at https://www.volatilityfoundation.org/license/vsl-v1.0
#

from typing import Optional, Union

from volatility3.framework import interfaces, objects, constants


def rol(value: int, count: int, max_bits: int = 64) -> int:
    """A rotate-left instruction in Python"""
    max_bits_mask = (1 << max_bits) - 1
    return (value << count % max_bits) & max_bits_mask | (
        (value & max_bits_mask) >> (max_bits - (count % max_bits))
    )


def bswap_32(value: int) -> int:
    value = ((value << 8) & 0xFF00FF00) | ((value >> 8) & 0x00FF00FF)

    return ((value << 16) | (value >> 16)) & 0xFFFFFFFF


def bswap_64(value: int) -> int:
    low = bswap_32((value >> 32))
    high = bswap_32((value & 0xFFFFFFFF))

    return ((high << 32) | low) & 0xFFFFFFFFFFFFFFFF


def array_to_string(
    array: "objects.Array", count: Optional[int] = None, errors: str = "replace"
) -> interfaces.objects.ObjectInterface:
    """Takes a volatility Array of characters and returns a string."""
    # TODO: Consider checking the Array's target is a native char
    if count is None:
        count = array.vol.count
    if not isinstance(array, objects.Array):
        raise TypeError("Array_to_string takes an Array of char")

    return array.cast("string", max_length=count, errors=errors)


def pointer_to_string(pointer: "objects.Pointer", count: int, errors: str = "replace"):
    """Takes a volatility Pointer to characters and returns a string."""
    if not isinstance(pointer, objects.Pointer):
        raise TypeError("pointer_to_string takes a Pointer")
    if count < 1:
        raise ValueError("pointer_to_string requires a positive count")
    char = pointer.dereference()
    return char.cast("string", max_length=count, errors=errors)


def array_of_pointers(
    array: interfaces.objects.ObjectInterface,
    count: int,
    subtype: Union[str, interfaces.objects.Template],
    context: interfaces.context.ContextInterface,
) -> interfaces.objects.ObjectInterface:
    """Takes an object, and recasts it as an array of pointers to subtype."""
    symbol_table = array.vol.type_name.split(constants.BANG)[0]
    if isinstance(subtype, str) and context is not None:
        subtype = context.symbol_space.get_type(subtype)
    if not isinstance(subtype, interfaces.objects.Template) or subtype is None:
        raise TypeError(
            "Subtype must be a valid template (or string name of an object template)"
        )
    # We have to clone the pointer class, or we'll be defining the pointer subtype for all future pointers
    subtype_pointer = context.symbol_space.get_type(
        symbol_table + constants.BANG + "pointer"
    ).clone()
    subtype_pointer.update_vol(subtype=subtype)
    return array.cast("array", count=count, subtype=subtype_pointer)