/*
 * Copyright 2021 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * ---------------------------------------------------------------------
 *
 * Portions of this file were modified and ported to Vala by Victor Vintorez in 2026.
 * These modifications are licensed under the European Union Public License (EUPL),
 * Version 1.2 or later. You may obtain a copy of the License at:
 * https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12
 */

using GLib;

namespace MaterialColorUtilities {
	/**
	 * Provides conversions needed for K-Means quantization. Converting input to points, and converting
	 * the final state of the K-Means algorithm to colors.
	 */
	public sealed class PointProviderLab : Object, PointProvider {
		/**
		 * Convert a color represented in ARGB to a 3-element array of L*a*b* coordinates of the color.
		 */
		public double[] from_int(int argb) {
			double[] lab = ColorUtils.lab_from_argb(argb);
			return new double[] { lab[0], lab[1], lab[2] };
		}

		/** Convert a 3-element array to a color represented in ARGB. */
		public int to_int(double[] lab) {
			return ColorUtils.argb_from_lab(lab[0], lab[1], lab[2]);
		}

		/**
		 * Standard CIE 1976 delta E formula also takes the square root, unneeded here. This method is
		 * used by quantization algorithms to compare distance, and the relative ordering is the same,
		 * with or without a square root.
		 *
		 * <p>This relatively minor optimization is helpful because this method is called at least once
		 * for each pixel in an image.
		 */
		public double distance(double[] one, double[] two) {
			double d_l = (one[0] - two[0]);
			double d_a = (one[1] - two[1]);
			double d_b = (one[2] - two[2]);
			return (d_l * d_l + d_a * d_a + d_b * d_b);
		}
	}
}
