#!/usr/bin/env python3

"""
(brewer_colors, svgcolor_names, color_names) → colortbl.h generator
"""

import argparse
import locale
import re
import sys


def rgb_to_hsv(r: int, g: int, b: int) -> tuple[int, int, int]:
    """transform an RGB color into HSV format"""

    r /= 255.0
    g /= 255.0
    b /= 255.0

    max_ = max((r, g, b))
    min_ = min((r, g, b))

    v = max_

    if max_ != 0:
        s = (max_ - min_) / max_
    else:
        s = 0

    if s == 0:
        h = 0
    else:
        delta = max_ - min_
        rc = (max_ - r) / delta
        gc = (max_ - g) / delta
        bc = (max_ - b) / delta
        if r == max_:
            h = bc - gc
        elif g == max_:
            h = 2.0 + (rc - bc)
        else:
            h = 4.0 + (gc - rc)
        h *= 60.0
        if h < 0.0:
            h += 360.0

    return int(h / 360.0 * 255.0), int(s * 255.0), int(v * 255.0)


def main(args: list[str]) -> int:
    """entry point"""

    # avoid sorting issues due to locale differences
    locale.setlocale(locale.LC_ALL, "C")

    # parse command line arguments
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument(
        "brewer_colors",
        type=argparse.FileType("rt"),
        help="input Brewer color table entries",
    )
    parser.add_argument(
        "svgcolor_names",
        type=argparse.FileType("rt"),
        help="input SVG color table entries",
    )
    parser.add_argument(
        "color_names",
        type=argparse.FileType("rt"),
        help="input other color table entries",
    )
    parser.add_argument(
        "output", type=argparse.FileType("wt"), help="output color table C header"
    )
    options = parser.parse_args(args[1:])

    options.output.write("static const hsvrgbacolor_t color_lib[] = {\n")

    # collect all color entries
    entries = (
        options.brewer_colors.readlines()
        + options.svgcolor_names.readlines()
        + options.color_names.readlines()
    )

    # sort these so `bsearch` for a color will work correctly
    entries = sorted(entries, key=locale.strxfrm)

    for entry in entries:
        # ignore blank lines
        if entry.strip() == "":
            continue
        # ignore commented lines
        if re.match(r"\s*#", entry) is not None:
            continue

        # extract fields of the entry
        m = re.match(
            r"(?P<name>\S+) (?P<r>\d+) (?P<g>\d+) (?P<b>\d+) (?P<a>\d+)", entry
        )
        assert m is not None, f'unexpected entry format "{entry}"'

        # transform an RGB color into HSV
        r = int(m.group("r"))
        g = int(m.group("g"))
        b = int(m.group("b"))
        h, s, v = rgb_to_hsv(r, g, b)

        # write this out as a C array entry
        name = m.group("name")
        a = int(m.group("a"))
        options.output.write(f'{{"{name}",{h},{s},{v},{r},{g},{b},{a}}},\n')

    options.output.write("};\n")

    return 0


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