from collections import Set
from colormath.color_objects import sRGBColor, LabColor
from colormath.color_conversions import convert_color
from colormath.color_diff import delta_e_cie1994

from .color import ThreadColor


def compare_thread_colors(color1, color2):
    # K_L=2 indicates textiles
    return delta_e_cie1994(color1, color2, K_L=2)


class ThreadPalette(Set):
    """Holds a set of ThreadColors all from the same manufacturer."""

    def __init__(self, palette_file):
        self.threads = dict()
        self.parse_palette_file(palette_file)

    def parse_palette_file(self, palette_file):
        """Read a GIMP palette file and load thread colors.

        Example file:

        GIMP Palette
        Name: Ink/Stitch: Metro
        Columns: 4
        # RGB Value                                 Color Name Number
        240     186     212                         Sugar Pink   1624
        237     171     194                           Carnatio   1636

        """

        with open(palette_file) as palette:
            line = palette.readline().strip()
            if line.lower() != "gimp palette":
                raise ValueError("Invalid gimp palette header")

            self.name = palette.readline().strip()
            if self.name.lower().startswith('name: ink/stitch: '):
                self.name = self.name[18:]

            # number of columns
            palette.readline()

            # headers
            palette.readline()

            for line in palette:
                fields = line.split("\t", 3)
                thread_color = [int(field) for field in fields[:3]]
                thread_name, thread_number = fields[3].strip().rsplit(" ", 1)
                thread_name = thread_name.strip()

                thread = ThreadColor(thread_color, thread_name, thread_number, manufacturer=self.name)
                self.threads[thread] = convert_color(sRGBColor(*thread_color, is_upscaled=True), LabColor)

    def __contains__(self, thread):
        return thread in self.threads

    def __iter__(self):
        return iter(self.threads)

    def __len__(self):
        return len(self.threads)

    def nearest_color(self, color):
        """Find the thread in this palette that looks the most like the specified color."""

        if isinstance(color, ThreadColor):
            color = color.rgb

        color = convert_color(sRGBColor(*color, is_upscaled=True), LabColor)

        return min(self, key=lambda thread: compare_thread_colors(self.threads[thread], color))