# Copyright (C) 2022-2025 Exaloop Inc. <https://exaloop.io>

from .ndarray import ndarray
from .routines import *
from .const import pi
import util

def bartlett(M: int):
    if M < 1:
        return empty(0, float)
    if M == 1:
        return ones(1, float)

    ans = empty(M, float)
    p = ans.data
    i = 0

    for n in range(1 - M, M, 2):
        if n <= 0:
            p[i] = 1 + n/(M-1)
        else:
            p[i] = 1 - n/(M-1)
        i += 1

    return ans

def blackman(M: int):
    if M < 1:
        return empty(0, float)
    if M == 1:
        return ones(1, float)

    ans = empty(M, float)
    p = ans.data
    i = 0

    for n in range(1 - M, M, 2):
        p[i] = 0.42 + 0.5*util.cos(pi*n/(M-1)) + 0.08*util.cos(2.0*pi*n/(M-1))
        i += 1

    return ans

def hamming(M: int):
    if M < 1:
        return empty(0, float)
    if M == 1:
        return ones(1, float)

    ans = empty(M, float)
    p = ans.data
    i = 0

    for n in range(1 - M, M, 2):
        p[i] = 0.54 + 0.46*util.cos(pi*n/(M-1))
        i += 1

    return ans

def hanning(M: int):
    if M < 1:
        return empty(0, float)
    if M == 1:
        return ones(1, float)

    ans = empty(M, float)
    p = ans.data
    i = 0

    for n in range(1 - M, M, 2):
        p[i] = 0.5 + 0.5*util.cos(pi*n/(M-1))
        i += 1

    return ans

def kaiser(M: int, beta: float):
    if M < 1:
        return empty(0, float)
    if M == 1:
        return ones(1, float)

    alpha = (M-1)/2.0
    denom = util.i0(beta)
    ans = empty(M, float)
    p = ans.data
    i = 0

    for n in range(0, M):
        p[i] = util.i0(beta * util.sqrt(1-((n-alpha)/alpha)**2.0))/denom
        i += 1

    return ans