#!/usr/bin/env python3
# ******************************************************************************
#  $Id$
#
#  Name:     rgb2pct
#  Project:  GDAL Python Interface
#  Purpose:  Application for converting an RGB image to a pseudocolored image.
#  Author:   Frank Warmerdam, warmerdam@pobox.com
#
# ******************************************************************************
#  Copyright (c) 2001, Frank Warmerdam
#  Copyright (c) 2020-2021, Idan Miara <idan@miara.com>
#
# SPDX-License-Identifier: MIT
# ******************************************************************************

import os.path
import sys
import textwrap
from typing import Optional

from osgeo import gdal
from osgeo_utils.auxiliary.base import PathLikeOrStr
from osgeo_utils.auxiliary.color_table import get_color_table
from osgeo_utils.auxiliary.gdal_argparse import GDALArgumentParser, GDALScript
from osgeo_utils.auxiliary.util import (
    GetOutputDriverFor,
    enable_gdal_exceptions,
    open_ds,
)


@enable_gdal_exceptions
def rgb2pct(
    src_filename: PathLikeOrStr,
    pct_filename: Optional[PathLikeOrStr] = None,
    dst_filename: Optional[PathLikeOrStr] = None,
    color_count: int = 256,
    driver_name: Optional[str] = None,
):
    # Open source file
    src_ds = open_ds(src_filename)
    if src_ds is None:
        raise Exception(f"Unable to open {src_filename}")

    if src_ds.RasterCount < 3:
        raise Exception(
            f"{src_filename} has {src_ds.RasterCount} band(s), need 3 for inputs red, green and blue."
        )

    # Ensure we recognise the driver.
    if not driver_name:
        driver_name = GetOutputDriverFor(dst_filename)

    dst_driver = gdal.GetDriverByName(driver_name)
    if dst_driver is None:
        raise Exception(f'"{driver_name}" driver not registered.')

    # Generate palette
    if pct_filename is None:
        ct = gdal.ColorTable()
        err = gdal.ComputeMedianCutPCT(
            src_ds.GetRasterBand(1),
            src_ds.GetRasterBand(2),
            src_ds.GetRasterBand(3),
            color_count,
            ct,
            callback=gdal.TermProgress_nocb,
        )
    else:
        ct = get_color_table(pct_filename)

    # Create the working file.  We have to use TIFF since there are few formats
    # that allow setting the color table after creation.

    if driver_name.lower() == "gtiff":
        tif_filename = dst_filename
    else:
        import tempfile

        tif_filedesc, tif_filename = tempfile.mkstemp(suffix=".tif")

    gtiff_driver = gdal.GetDriverByName("GTiff")

    tif_ds = gtiff_driver.Create(
        tif_filename, src_ds.RasterXSize, src_ds.RasterYSize, 1
    )

    tif_ds.GetRasterBand(1).SetRasterColorTable(ct)

    # ----------------------------------------------------------------------------
    # We should copy projection information and so forth at this point.

    tif_ds.SetProjection(src_ds.GetProjection())
    tif_ds.SetGeoTransform(src_ds.GetGeoTransform())
    if src_ds.GetGCPCount() > 0:
        tif_ds.SetGCPs(src_ds.GetGCPs(), src_ds.GetGCPProjection())

    # ----------------------------------------------------------------------------
    # Actually transfer and dither the data.

    err = gdal.DitherRGB2PCT(
        src_ds.GetRasterBand(1),
        src_ds.GetRasterBand(2),
        src_ds.GetRasterBand(3),
        tif_ds.GetRasterBand(1),
        ct,
        callback=gdal.TermProgress_nocb,
    )
    if err != gdal.CE_None:
        raise Exception("DitherRGB2PCT failed")

    if tif_filename == dst_filename:
        dst_ds = tif_ds
    else:
        dst_ds = dst_driver.CreateCopy(dst_filename or "", tif_ds)
        tif_ds = None
        os.close(tif_filedesc)
        gtiff_driver.Delete(tif_filename)

    return dst_ds


def doit(**kwargs):
    try:
        ds = rgb2pct(**kwargs)
        return ds, 0
    except Exception:
        return None, 1


class RGB2PCT(GDALScript):
    def __init__(self):
        super().__init__()
        self.title = "Convert a 24bit RGB image to 8bit paletted image"
        self.description = textwrap.dedent(
            """\
            This utility will compute an optimal pseudo-color table for a given RGB image
            using a median cut algorithm on a downsampled RGB histogram.
            Then it converts the image into a pseudo-colored image using the color table.
            This conversion utilizes Floyd-Steinberg dithering (error diffusion)
            to maximize output image visual quality."""
        )

    def get_parser(self, argv) -> GDALArgumentParser:
        parser = self.parser

        parser.add_argument(
            "-of",
            dest="driver_name",
            metavar="gdal_format",
            help="Select the output format. "
            "if not specified, the format is guessed from the extension. "
            "Use the short format name.",
        )

        group = parser.add_mutually_exclusive_group()
        group.add_argument(
            "-n",
            dest="color_count",
            type=int,
            default=256,
            metavar="color",
            choices=tuple(range(2, 257)),
            help="Select the number of colors in the generated color table. "
            "Defaults to 256. Must be between 2 and 256.",
        )

        group.add_argument(
            "-pct",
            dest="pct_filename",
            type=str,
            help="Extract the color table from <palette_file> instead of computing it. "
            "Can be used to have a consistent color table for multiple files. "
            "The palette file must be either a raster file in a GDAL supported format with a "
            "palette or a color file in a supported format (txt, qml, qlr).",
        )

        parser.add_argument("src_filename", type=str, help="The input RGB file.")

        parser.add_argument(
            "dst_filename",
            type=str,
            help="The output pseudo-colored file that will be created.",
        )

        return parser

    def doit(self, **kwargs):
        return rgb2pct(**kwargs)


def main(argv=sys.argv):
    return RGB2PCT().main(argv)


if __name__ == "__main__":
    sys.exit(main(sys.argv))