import csv

from pathlib import Path
from typing import Any

from nostr.bip340 import (
    pubkey_gen,
    schnorr_sign,
    schnorr_verify,
    bytes_from_int,
    int_from_bytes,
    point_mul,
    lift_x,
    G,
    y,
    is_infinite,
    p,
    n,
    bytes_from_point,
    has_even_y,
    tagged_hash,
)

TEST_VECTORS = Path(__file__).parent / "test-vectors.csv"


def test_vectors():
    with open(TEST_VECTORS, newline="") as csvfile:
        reader = csv.reader(csvfile)
        next(reader)  # skip column titles

        for row in reader:
            (
                index,
                seckey_hex,
                pubkey_hex,
                aux_rand_hex,
                msg_hex,
                sig_hex,
                result_str,
                comment,
            ) = row

            pubkey = bytes.fromhex(pubkey_hex)
            msg = bytes.fromhex(msg_hex)
            sig = bytes.fromhex(sig_hex)
            result = result_str == "TRUE"

            if seckey_hex != "":
                seckey = bytes.fromhex(seckey_hex)
                pubkey_actual = pubkey_gen(seckey)
                assert pubkey == pubkey_actual
                aux_rand = bytes.fromhex(aux_rand_hex)
                sig_actual = schnorr_sign(msg, seckey, aux_rand)
                assert sig == sig_actual

            result_actual = schnorr_verify(msg, pubkey, sig)
            assert result == result_actual


def is_square(x):
    return int(pow(x, (p - 1) // 2, p)) == 1


def has_square_y(P):
    """Determine if P has a square Y coordinate. Used in an earlier draft of BIP340."""
    assert not is_infinite(P)
    return is_square(P[1])


def test_vector0():
    seckey = bytes_from_int(3)
    msg = bytes_from_int(0)
    aux_rand = bytes_from_int(0)
    sig = schnorr_sign(msg, seckey, aux_rand)
    pubkey = pubkey_gen(seckey)

    # We should have at least one test vector where the seckey needs to be
    # negated and one where it doesn't. In this one the seckey doesn't need to
    # be negated.
    x = int_from_bytes(seckey)
    P = point_mul(G, x)
    assert y(P) % 2 == 0

    # For historical reasons (pubkey tiebreaker was squareness and not evenness)
    # we should have at least one test vector where the the point reconstructed
    # from the public key has a square and one where it has a non-square Y
    # coordinate. In this one Y is non-square.
    pubkey_point = lift_x(pubkey)
    assert not has_square_y(pubkey_point)

    # For historical reasons (R tiebreaker was squareness and not evenness)
    # we should have at least one test vector where the the point reconstructed
    # from the R.x coordinate has a square and one where it has a non-square Y
    # coordinate. In this one Y is non-square.
    R = lift_x(sig[0:32])
    assert not has_square_y(R)

    return (seckey, pubkey, aux_rand, msg, sig, "TRUE", None)


def test_vector1():
    seckey = bytes_from_int(
        0xB7E151628AED2A6ABF7158809CF4F3C762E7160F38B4DA56A784D9045190CFEF
    )
    msg = bytes_from_int(
        0x243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89
    )
    aux_rand = bytes_from_int(1)

    sig = schnorr_sign(msg, seckey, aux_rand)

    # The point reconstructed from the R.x coordinate has a square Y coordinate.
    R = lift_x(sig[0:32])
    assert has_square_y(R)

    return (seckey, pubkey_gen(seckey), aux_rand, msg, sig, "TRUE", None)


def test_vector2():
    seckey = bytes_from_int(
        0xC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B14E5C9
    )
    msg = bytes_from_int(
        0x7E2D58D8B3BCDF1ABADEC7829054F90DDA9805AAB56C77333024B9D0A508B75C
    )
    aux_rand = bytes_from_int(
        0xC87AA53824B4D7AE2EB035A2B5BBBCCC080E76CDC6D1692C4B0B62D798E6D906
    )
    sig = schnorr_sign(msg, seckey, aux_rand)

    # The point reconstructed from the public key has a square Y coordinate.
    pubkey = pubkey_gen(seckey)
    pubkey_point = lift_x(pubkey)
    assert has_square_y(pubkey_point)

    # This signature vector would not verify if the implementer checked the
    # evenness of the X coordinate of R instead of the Y coordinate.
    R = lift_x(sig[0:32])
    assert R[0] % 2 == 1

    return (seckey, pubkey, aux_rand, msg, sig, "TRUE", None)


def test_vector3():
    seckey = bytes_from_int(
        0x0B432B2677937381AEF05BB02A66ECD012773062CF3FA2549E44F58ED2401710
    )

    # Need to negate this seckey before signing
    x = int_from_bytes(seckey)
    P = point_mul(G, x)
    assert y(P) % 2 != 0

    msg = bytes_from_int(
        0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
    )
    aux_rand = bytes_from_int(
        0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
    )

    sig = schnorr_sign(msg, seckey, aux_rand)
    return (
        seckey,
        pubkey_gen(seckey),
        aux_rand,
        msg,
        sig,
        "TRUE",
        "test fails if msg is reduced modulo p or n",
    )


# Signs with a given nonce. This can be INSECURE and is only INTENDED FOR
# GENERATING TEST VECTORS. Results in an invalid signature if y(kG) is not
# even.
def insecure_schnorr_sign_fixed_nonce(msg, seckey0, k):
    if len(msg) != 32:
        raise ValueError("The message must be a 32-byte array.")
    seckey0 = int_from_bytes(seckey0)
    if not (1 <= seckey0 <= n - 1):
        raise ValueError("The secret key must be an integer in the range 1..n-1.")
    P = point_mul(G, seckey0)
    seckey = seckey0 if has_even_y(P) else n - seckey0
    R = point_mul(G, k)
    e = (
        int_from_bytes(
            tagged_hash(
                "BIP0340/challenge", bytes_from_point(R) + bytes_from_point(P) + msg
            )
        )
        % n
    )
    return bytes_from_point(R) + bytes_from_int((k + e * seckey) % n)


# Creates a singature with a small x(R) by using k = -1/2
def test_vector4():
    one_half = n - 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
    seckey = bytes_from_int(
        0x763758E5CBEEDEE4F7D3FC86F531C36578933228998226672F13C4F0EBE855EB
    )
    msg = bytes_from_int(
        0x4DF3C3F68FCC83B27E9D42C90431A72499F17875C81A599B566C9889B9696703
    )
    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, one_half)
    return (None, pubkey_gen(seckey), None, msg, sig, "TRUE", None)


default_seckey = bytes_from_int(
    0xB7E151628AED2A6ABF7158809CF4F3C762E7160F38B4DA56A784D9045190CFEF
)
default_msg = bytes_from_int(
    0x243F6A8885A308D313198A2E03707344A4093822299F31D0082EFA98EC4E6C89
)
default_aux_rand = bytes_from_int(
    0xC87AA53824B4D7AE2EB035A2B5BBBCCC080E76CDC6D1692C4B0B62D798E6D906
)

# Public key is not on the curve
def test_vector5():
    # This creates a dummy signature that doesn't have anything to do with the
    # public key.
    seckey = default_seckey
    msg = default_msg
    sig = schnorr_sign(msg, seckey, default_aux_rand)

    pubkey = bytes_from_int(
        0xEEFDEA4CDB677750A420FEE807EACF21EB9898AE79B9768766E4FAA04A2D4A34
    )
    assert lift_x(pubkey) is None

    return (None, pubkey, None, msg, sig, "FALSE", "public key not on the curve")


def test_vector6():
    seckey = default_seckey
    msg = default_msg
    k = 6
    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, k)

    # Y coordinate of R is not even
    R = point_mul(G, k)
    assert not has_even_y(R)

    return (None, pubkey_gen(seckey), None, msg, sig, "FALSE", "has_even_y(R) is false")


def test_vector7():
    seckey = default_seckey
    msg = int_from_bytes(default_msg)
    neg_msg = bytes_from_int(n - msg)
    sig = schnorr_sign(neg_msg, seckey, default_aux_rand)
    return (
        None,
        pubkey_gen(seckey),
        None,
        bytes_from_int(msg),
        sig,
        "FALSE",
        "negated message",
    )


def test_vector8():
    seckey = default_seckey
    msg = default_msg
    sig = schnorr_sign(msg, seckey, default_aux_rand)
    sig = sig[0:32] + bytes_from_int(n - int_from_bytes(sig[32:64]))
    return (None, pubkey_gen(seckey), None, msg, sig, "FALSE", "negated s value")


def bytes_from_point_inf0(P):
    if P == None:
        return bytes_from_int(0)
    return bytes_from_int(P[0])


def test_vector9():
    seckey = default_seckey
    msg = default_msg

    # Override bytes_from_point in schnorr_sign to allow creating a signature
    # with k = 0.
    k = 0
    bytes_from_point_tmp = bytes_from_point.__code__
    bytes_from_point.__code__ = bytes_from_point_inf0.__code__
    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, k)
    bytes_from_point.__code__ = bytes_from_point_tmp

    return (
        None,
        pubkey_gen(seckey),
        None,
        msg,
        sig,
        "FALSE",
        "sG - eP is infinite. Test fails in single verification if has_even_y(inf) is defined as true and x(inf) as 0",
    )


def bytes_from_point_inf1(P):
    if P == None:
        return bytes_from_int(1)
    return bytes_from_int(P[0])


def test_vector10():
    seckey = default_seckey
    msg = default_msg

    # Override bytes_from_point in schnorr_sign to allow creating a signature
    # with k = 0.
    k = 0
    bytes_from_point_tmp = bytes_from_point.__code__
    bytes_from_point.__code__ = bytes_from_point_inf1.__code__
    sig = insecure_schnorr_sign_fixed_nonce(msg, seckey, k)
    bytes_from_point.__code__ = bytes_from_point_tmp

    return (
        None,
        pubkey_gen(seckey),
        None,
        msg,
        sig,
        "FALSE",
        "sG - eP is infinite. Test fails in single verification if has_even_y(inf) is defined as true and x(inf) as 1",
    )


# It's cryptographically impossible to create a test vector that fails if run
# in an implementation which merely misses the check that sig[0:32] is an X
# coordinate on the curve. This test vector just increases test coverage.
def test_vector11():
    seckey = default_seckey
    msg = default_msg
    sig = schnorr_sign(msg, seckey, default_aux_rand)

    # Replace R's X coordinate with an X coordinate that's not on the curve
    x_not_on_curve = bytes_from_int(
        0x4A298DACAE57395A15D0795DDBFD1DCB564DA82B0F269BC70A74F8220429BA1D
    )
    assert lift_x(x_not_on_curve) is None
    sig = x_not_on_curve + sig[32:64]

    return (
        None,
        pubkey_gen(seckey),
        None,
        msg,
        sig,
        "FALSE",
        "sig[0:32] is not an X coordinate on the curve",
    )


# It's cryptographically impossible to create a test vector that fails if run
# in an implementation which merely misses the check that sig[0:32] is smaller
# than the field size. This test vector just increases test coverage.
def test_vector12():
    seckey = default_seckey
    msg = default_msg
    sig = schnorr_sign(msg, seckey, default_aux_rand)

    # Replace R's X coordinate with an X coordinate that's equal to field size
    sig = bytes_from_int(p) + sig[32:64]

    return (
        None,
        pubkey_gen(seckey),
        None,
        msg,
        sig,
        "FALSE",
        "sig[0:32] is equal to field size",
    )


# It's cryptographically impossible to create a test vector that fails if run
# in an implementation which merely misses the check that sig[32:64] is smaller
# than the curve order. This test vector just increases test coverage.
def test_vector13():
    seckey = default_seckey
    msg = default_msg
    sig = schnorr_sign(msg, seckey, default_aux_rand)

    # Replace s with a number that's equal to the curve order
    sig = sig[0:32] + bytes_from_int(n)

    return (
        None,
        pubkey_gen(seckey),
        None,
        msg,
        sig,
        "FALSE",
        "sig[32:64] is equal to curve order",
    )


# Test out of range pubkey
# It's cryptographically impossible to create a test vector that fails if run
# in an implementation which accepts out of range pubkeys because we can't find
# a secret key for such a public key and therefore can not create a signature.
# This test vector just increases test coverage.
def test_vector14():
    # This creates a dummy signature that doesn't have anything to do with the
    # public key.
    seckey = default_seckey
    msg = default_msg
    sig = schnorr_sign(msg, seckey, default_aux_rand)
    pubkey_int = p + 1
    pubkey = bytes_from_int(pubkey_int)
    assert lift_x(pubkey) is None
    # If an implementation would reduce a given public key modulo p then the
    # pubkey would be valid
    assert lift_x(bytes_from_int(pubkey_int % p)) is not None

    return (
        None,
        pubkey,
        None,
        msg,
        sig,
        "FALSE",
        "public key is not a valid X coordinate because it exceeds the field size",
    )