#
# The Python Imaging Library.
# $Id$
#
# image enhancement classes
#
# For a background, see "Image Processing By Interpolation and
# Extrapolation", Paul Haeberli and Douglas Voorhies.  Available
# at http://www.graficaobscura.com/interp/index.html
#
# History:
# 1996-03-23 fl  Created
# 2009-06-16 fl  Fixed mean calculation
#
# Copyright (c) Secret Labs AB 1997.
# Copyright (c) Fredrik Lundh 1996.
#
# See the README file for information on usage and redistribution.
#
from __future__ import annotations

from . import Image, ImageFilter, ImageStat


class _Enhance:
    image: Image.Image
    degenerate: Image.Image

    def enhance(self, factor: float) -> Image.Image:
        """
        Returns an enhanced image.

        :param factor: A floating point value controlling the enhancement.
                       Factor 1.0 always returns a copy of the original image,
                       lower factors mean less color (brightness, contrast,
                       etc), and higher values more. There are no restrictions
                       on this value.
        """
        return Image.blend(self.degenerate, self.image, factor)


class Color(_Enhance):
    """Adjust image color balance.

    This class can be used to adjust the colour balance of an image, in
    a manner similar to the controls on a colour TV set. An enhancement
    factor of 0.0 gives a black and white image. A factor of 1.0 gives
    the original image.
    """

    def __init__(self, image: Image.Image) -> None:
        self.image = image
        self.intermediate_mode = "L"
        if "A" in image.getbands():
            self.intermediate_mode = "LA"

        if self.intermediate_mode != image.mode:
            image = image.convert(self.intermediate_mode).convert(image.mode)
        self.degenerate = image


class Contrast(_Enhance):
    """Adjust image contrast.

    This class can be used to control the contrast of an image, similar
    to the contrast control on a TV set. An enhancement factor of 0.0
    gives a solid gray image. A factor of 1.0 gives the original image.
    """

    def __init__(self, image: Image.Image) -> None:
        self.image = image
        if image.mode != "L":
            image = image.convert("L")
        mean = int(ImageStat.Stat(image).mean[0] + 0.5)
        self.degenerate = Image.new("L", image.size, mean)
        if self.degenerate.mode != self.image.mode:
            self.degenerate = self.degenerate.convert(self.image.mode)

        if "A" in self.image.getbands():
            self.degenerate.putalpha(self.image.getchannel("A"))


class Brightness(_Enhance):
    """Adjust image brightness.

    This class can be used to control the brightness of an image.  An
    enhancement factor of 0.0 gives a black image. A factor of 1.0 gives the
    original image.
    """

    def __init__(self, image: Image.Image) -> None:
        self.image = image
        self.degenerate = Image.new(image.mode, image.size, 0)

        if "A" in image.getbands():
            self.degenerate.putalpha(image.getchannel("A"))


class Sharpness(_Enhance):
    """Adjust image sharpness.

    This class can be used to adjust the sharpness of an image. An
    enhancement factor of 0.0 gives a blurred image, a factor of 1.0 gives the
    original image, and a factor of 2.0 gives a sharpened image.
    """

    def __init__(self, image: Image.Image) -> None:
        self.image = image
        self.degenerate = image.filter(ImageFilter.SMOOTH)

        if "A" in image.getbands():
            self.degenerate.putalpha(image.getchannel("A"))