import numpy as np
 
def _slinedata(np_array):
    """
    Used when sum of splited line data
    """
    height, width = np_array.shape
    x_line = np.zeros(width)
    y_line = np.zeros(height)
    return x_line, y_line
 
def _minMax(Zdata):
    # Min = 0, Max = 1
    #Zdata = _zdata(tiff_path)
    zMin = np.min(Zdata)
    denominator = (np.max(Zdata) - zMin) + 1e-16
    return (Zdata - zMin) / denominator
 
def _exp(x,a,b,c):
    return a*np.exp(abs(b)*x)+c
 
def _fluctuation(value, fluc_coeff=(0.5,0.01,0.015),envelop_ratio=8):
    if fluc_coeff[0] >= 1:
        return 0, 0, value, 0
    """
    fluc_coeff = (position, max value of noise, exp slope)\n
        position: 0 ~ 1 ratio\n
        max value of noise [um]\n
        exp slope: 0 ~ 100\n
               high value: low freq noise\n
               low value: high freq noise\n
    envelop_ratio: (envelop amp / mean amp) ratio
    """
    point_index = int(len(value)*fluc_coeff[0])
    result_real =  value[point_index:].copy()
    result_imag =  value[point_index:].copy()
    half = int(len(result_real)/2)
    freq = np.fft.fftfreq(len(value), half*2)
    x_axis = np.linspace(0,50,half)
    exp_line = _exp(x_axis,fluc_coeff[1],fluc_coeff[2],fluc_coeff[1])
    result_real[:half] = exp_line* np.random.randn(half)
    result_real[half:] = np.flip(result_real[:half])
 
 
    result_imag[:half] = exp_line*np.random.randn(half)
    result_imag[half:] = -np.flip(result_imag[:half])
    result_imag = result_imag*1j
    result_real[half-2:half+2] *= envelop_ratio
    result_imag[half-2:half+2] *= envelop_ratio
    result = result_real + result_imag 
    result_ifft = abs(np.fft.ifft(result))
    value[point_index:] = result_ifft
    return result,result_ifft, value, point_index
 
def fluctuation(Zdata_array, x_fluc_coeff=(0,0,0), y_fluc_coeff=(0,1,0.18),envelop_ratio=8):
    """
    fluc_coeff = (position, max value of noise, exp slope)\n
        position: 0 ~ 1 ratio\n
        max value of noise [um]\n
        exp slope: 0 ~ 100\n
               high value: low freq noise\n
               low value: high freq noise\n
    envelop_ratio: (envelop amp / mean amp) ratio
    """
    x_line, y_line = _slinedata(Zdata_array)
    _, _,dist_x, _ = _fluctuation(x_line,x_fluc_coeff,envelop_ratio=8)
    _, _, dist_y, _ = _fluctuation(y_line,y_fluc_coeff,envelop_ratio=8)
    dist_x = _minMax(dist_x)*x_fluc_coeff[1]
    dist_y = _minMax(dist_y)*y_fluc_coeff[1]
    mx, my = np.meshgrid(dist_x,dist_y)
    return Zdata_array + mx + my