from typing import List
import numpy as np
from PIL import Image

from enums import LANGUAGE_COLORS


def generate_gradient(language_name: str) -> Image.Image:
    # Define start and end colours and image height and width
    h, w = 1080, 1920

    # Make output image
    gradient = np.zeros((h, w, 3), np.uint8)

    # Get language name colors
    palette = LANGUAGE_COLORS.get(language_name)
    if not palette:
        raise KeyError("Language not supported")

    left_color: List[int] = palette["left"]
    right_color: List[int] = palette["right"]

    # Fill R, G and B channels with linear gradient between two end colours
    gradient[:, :, 0] = np.linspace(left_color[0], right_color[0], w, dtype=np.uint8)
    gradient[:, :, 1] = np.linspace(left_color[1], right_color[1], w, dtype=np.uint8)
    gradient[:, :, 2] = np.linspace(left_color[2], right_color[2], w, dtype=np.uint8)

    # Save result
    return Image.fromarray(gradient)