# SPDX-FileCopyrightText: 2017 Paul Sokolovsky
# SPDX-FileCopyrightText: 2019 Brent Rubell for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""
`_sha256.py`
======================================================
SHA-256 Hash Algorithm.
* Author(s): Tom St Denis, Paul Sokolovsky, Brent Rubell
"""

try:
    from typing import Dict, List, Optional, Tuple, Union
except ImportError:
    # suppress because typing does not exist on circuitpython
    pass


# SHA Block size and message digest sizes, in bytes.
SHA_BLOCKSIZE = 64
SHA_DIGESTSIZE = 32


def new_shaobject():
    """Struct. for storing SHA information."""
    return {
        "digest": [0] * 8,
        "count_lo": 0,
        "count_hi": 0,
        "data": [0] * SHA_BLOCKSIZE,
        "local": 0,
        "digestsize": 0,
    }


# Various logical functions
ROR = lambda x, y: (((x & 0xFFFFFFFF) >> (y & 31)) | (x << (32 - (y & 31)))) & 0xFFFFFFFF
Ch = lambda x, y, z: (z ^ (x & (y ^ z)))
Maj = lambda x, y, z: (((x | y) & z) | (x & y))
S = ROR
R = lambda x, n: (x & 0xFFFFFFFF) >> n
Sigma0 = lambda x: (S(x, 2) ^ S(x, 13) ^ S(x, 22))
Sigma1 = lambda x: (S(x, 6) ^ S(x, 11) ^ S(x, 25))
Gamma0 = lambda x: (S(x, 7) ^ S(x, 18) ^ R(x, 3))
Gamma1 = lambda x: (S(x, 17) ^ S(x, 19) ^ R(x, 10))


def sha_transform(sha_info: Dict[str, Union[List[int], int]]) -> None:
    W = []

    d = sha_info["data"]
    for i in range(0, 16):
        W.append((d[4 * i] << 24) + (d[4 * i + 1] << 16) + (d[4 * i + 2] << 8) + d[4 * i + 3])

    for i in range(16, 64):
        W.append((Gamma1(W[i - 2]) + W[i - 7] + Gamma0(W[i - 15]) + W[i - 16]) & 0xFFFFFFFF)

    ss = sha_info["digest"][:]

    def RND(
        a: int, b: int, c: int, d: int, e: int, f: int, g: int, h: int, i: int, ki: int
    ) -> Tuple[int, int]:
        """Compress"""
        t0 = h + Sigma1(e) + Ch(e, f, g) + ki + W[i]
        t1 = Sigma0(a) + Maj(a, b, c)
        d += t0
        h = t0 + t1
        return d & 0xFFFFFFFF, h & 0xFFFFFFFF

    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 0, 0x428A2F98)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 1, 0x71374491)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 2, 0xB5C0FBCF)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 3, 0xE9B5DBA5)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 4, 0x3956C25B)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 5, 0x59F111F1)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 6, 0x923F82A4)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 7, 0xAB1C5ED5)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 8, 0xD807AA98)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 9, 0x12835B01)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 10, 0x243185BE)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 11, 0x550C7DC3)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 12, 0x72BE5D74)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 13, 0x80DEB1FE)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 14, 0x9BDC06A7)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 15, 0xC19BF174)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 16, 0xE49B69C1)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 17, 0xEFBE4786)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 18, 0x0FC19DC6)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 19, 0x240CA1CC)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 20, 0x2DE92C6F)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 21, 0x4A7484AA)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 22, 0x5CB0A9DC)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 23, 0x76F988DA)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 24, 0x983E5152)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 25, 0xA831C66D)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 26, 0xB00327C8)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 27, 0xBF597FC7)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 28, 0xC6E00BF3)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 29, 0xD5A79147)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 30, 0x06CA6351)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 31, 0x14292967)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 32, 0x27B70A85)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 33, 0x2E1B2138)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 34, 0x4D2C6DFC)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 35, 0x53380D13)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 36, 0x650A7354)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 37, 0x766A0ABB)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 38, 0x81C2C92E)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 39, 0x92722C85)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 40, 0xA2BFE8A1)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 41, 0xA81A664B)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 42, 0xC24B8B70)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 43, 0xC76C51A3)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 44, 0xD192E819)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 45, 0xD6990624)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 46, 0xF40E3585)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 47, 0x106AA070)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 48, 0x19A4C116)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 49, 0x1E376C08)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 50, 0x2748774C)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 51, 0x34B0BCB5)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 52, 0x391C0CB3)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 53, 0x4ED8AA4A)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 54, 0x5B9CCA4F)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 55, 0x682E6FF3)
    ss[3], ss[7] = RND(ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], 56, 0x748F82EE)
    ss[2], ss[6] = RND(ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], 57, 0x78A5636F)
    ss[1], ss[5] = RND(ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], ss[5], 58, 0x84C87814)
    ss[0], ss[4] = RND(ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], ss[4], 59, 0x8CC70208)
    ss[7], ss[3] = RND(ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], ss[3], 60, 0x90BEFFFA)
    ss[6], ss[2] = RND(ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], ss[2], 61, 0xA4506CEB)
    ss[5], ss[1] = RND(ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], ss[1], 62, 0xBEF9A3F7)
    ss[4], ss[0] = RND(ss[1], ss[2], ss[3], ss[4], ss[5], ss[6], ss[7], ss[0], 63, 0xC67178F2)

    # Feedback
    dig = []
    for i, x in enumerate(sha_info["digest"]):
        dig.append((x + ss[i]) & 0xFFFFFFFF)
    sha_info["digest"] = dig


def sha_init() -> Dict[str, Union[List[int], int]]:
    """Initialize the SHA digest."""
    sha_info = new_shaobject()
    sha_info["digest"] = [
        0x6A09E667,
        0xBB67AE85,
        0x3C6EF372,
        0xA54FF53A,
        0x510E527F,
        0x9B05688C,
        0x1F83D9AB,
        0x5BE0CD19,
    ]
    sha_info["count_lo"] = 0
    sha_info["count_hi"] = 0
    sha_info["local"] = 0
    sha_info["digestsize"] = 32
    return sha_info


def sha224_init() -> Dict[str, Union[List[int], int]]:
    """Initialize a SHA224 digest."""
    sha_info = new_shaobject()
    sha_info["digest"] = [
        0xC1059ED8,
        0x367CD507,
        0x3070DD17,
        0xF70E5939,
        0xFFC00B31,
        0x68581511,
        0x64F98FA7,
        0xBEFA4FA4,
    ]
    sha_info["count_lo"] = 0
    sha_info["count_hi"] = 0
    sha_info["local"] = 0
    sha_info["digestsize"] = 28
    return sha_info


def getbuf(string: Union[str, bytes]) -> bytes:
    if isinstance(string, str):
        return string.encode("ascii")
    return bytes(string)


def sha_update(sha_info: Dict[str, Union[List[int], int]], buffer: Union[str, bytes]) -> None:
    """Update the SHA digest.
    :param dict sha_info: SHA Digest.
    :param str buffer: SHA buffer size.
    """
    if isinstance(buffer, str):
        raise TypeError("Unicode strings must be encoded before hashing")
    size = len(buffer)
    buffer_idx = 0
    clo = (sha_info["count_lo"] + (size << 3)) & 0xFFFFFFFF
    if clo < sha_info["count_lo"]:
        sha_info["count_hi"] += 1
    sha_info["count_lo"] = clo

    sha_info["count_hi"] += size >> 29

    if sha_info["local"]:
        i = SHA_BLOCKSIZE - sha_info["local"]
        i = min(i, size)

        # copy sha buffer
        for x in enumerate(buffer[buffer_idx : buffer_idx + i]):
            sha_info["data"][sha_info["local"] + x[0]] = x[1]

        size -= i
        buffer_idx += i

        sha_info["local"] += i
        if sha_info["local"] == SHA_BLOCKSIZE:
            sha_transform(sha_info)
            sha_info["local"] = 0
        else:
            return

    while size >= SHA_BLOCKSIZE:
        # copy sha buffer
        sha_info["data"] = list(buffer[buffer_idx : buffer_idx + SHA_BLOCKSIZE])
        size -= SHA_BLOCKSIZE
        buffer_idx += SHA_BLOCKSIZE
        sha_transform(sha_info)

    # copy sha buffer
    pos = sha_info["local"]
    sha_info["data"][pos : pos + size] = list(buffer[buffer_idx : buffer_idx + size])
    sha_info["local"] = size


def sha_final(sha_info: Dict[str, Union[List[int], int]]) -> bytes:
    """Finish computing the SHA Digest."""
    lo_bit_count = sha_info["count_lo"]
    hi_bit_count = sha_info["count_hi"]
    count = (lo_bit_count >> 3) & 0x3F
    sha_info["data"][count] = 0x80
    count += 1
    if count > SHA_BLOCKSIZE - 8:
        # zero the bytes in data after the count
        sha_info["data"] = sha_info["data"][:count] + ([0] * (SHA_BLOCKSIZE - count))
        sha_transform(sha_info)
        # zero bytes in data
        sha_info["data"] = [0] * SHA_BLOCKSIZE
    else:
        sha_info["data"] = sha_info["data"][:count] + ([0] * (SHA_BLOCKSIZE - count))

    sha_info["data"][56] = (hi_bit_count >> 24) & 0xFF
    sha_info["data"][57] = (hi_bit_count >> 16) & 0xFF
    sha_info["data"][58] = (hi_bit_count >> 8) & 0xFF
    sha_info["data"][59] = (hi_bit_count >> 0) & 0xFF
    sha_info["data"][60] = (lo_bit_count >> 24) & 0xFF
    sha_info["data"][61] = (lo_bit_count >> 16) & 0xFF
    sha_info["data"][62] = (lo_bit_count >> 8) & 0xFF
    sha_info["data"][63] = (lo_bit_count >> 0) & 0xFF

    sha_transform(sha_info)

    dig = []
    for i in sha_info["digest"]:
        dig.extend([((i >> 24) & 0xFF), ((i >> 16) & 0xFF), ((i >> 8) & 0xFF), (i & 0xFF)])
    return bytes(dig)


class sha256:
    digest_size = digestsize = SHA_DIGESTSIZE
    block_size = SHA_BLOCKSIZE
    name = "sha256"

    def __init__(self, s: Optional[Union[str, bytes]] = None):
        """Constructs a SHA256 hash object."""
        self._sha = sha_init()
        if s:
            sha_update(self._sha, getbuf(s))

    def update(self, s: Union[str, bytes]):
        """Updates the hash object with a bytes-like object, s."""
        sha_update(self._sha, getbuf(s))

    def digest(self):
        """Returns the digest of the data passed to the update()
        method so far."""
        return sha_final(self._sha.copy())[: self._sha["digestsize"]]

    def hexdigest(self):
        """Like digest() except the digest is returned as a string object of
        double length, containing only hexadecimal digits.
        """
        return "".join(["%.2x" % i for i in self.digest()])

    def copy(self):
        """Return a copy (“clone”) of the hash object."""
        new = sha256()
        new._sha = self._sha.copy()
        return new


class sha224(sha256):
    digest_size = digestsize = 28
    name = "sha224"

    def __init__(self, s: Optional[Union[str, bytes]] = None):
        """Constructs a SHA224 hash object."""
        self._sha = sha224_init()
        if s:
            sha_update(self._sha, getbuf(s))

    def copy(self):
        """Return a copy (“clone”) of the hash object."""
        new = sha224()
        new._sha = self._sha.copy()
        return new