import numba
import numpy as np

rescale_functions = {}

def rescale_clip_source(xx, scale, offset, vmin, vmax, yy):
    for i in range(xx.size):
        val = (xx[i] - offset) * scale
        yy[i] = min(max(val, vmin), vmax)

def rescaleData(data, scale, offset, dtype, clip):
    data_out = np.empty_like(data, dtype=dtype)
    key = (data.dtype.name, data_out.dtype.name)
    func = rescale_functions.get(key)
    if func is None:
        func = numba.guvectorize(
            [f'{key[0]}[:],f8,f8,f8,f8,{key[1]}[:]'],
            '(n),(),(),(),()->(n)',
            nopython=True)(rescale_clip_source)
        rescale_functions[key] = func
    func(data, scale, offset, clip[0], clip[1], out=data_out)
    return data_out

@numba.jit(nopython=True)
def rescale_and_lookup(data, scale, offset, lut):
    # data should be floating point and 2d
    # lut is 1d
    vmin, vmax = 0, lut.shape[0] - 1
    out = np.empty_like(data, dtype=lut.dtype)
    for (x, y) in np.nditer((data, out)):
        val = (x - offset) * scale
        val = min(max(val, vmin), vmax)
        y[...] = lut[int(val)]
    return out

@numba.jit(nopython=True)
def rescale_and_clip(data, scale, offset, vmin, vmax):
    # vmin and vmax <= 255
    out = np.empty_like(data, dtype=np.uint8)
    for (x, y) in np.nditer((data, out)):
        val = (x - offset) * scale
        val = min(max(val, vmin), vmax)
        y[...] = val
    return out

@numba.jit(nopython=True)
def numba_take(lut, data):
    # numba supports only the 1st two arguments of np.take
    return np.take(lut, data)