////
/// @author Giana Blantin
////

/// Get the best contrasted color when compared against two colors
/// @link https://www.w3.org/TR/2016/NOTE-WCAG20-TECHS-20161007/G18#G18-procedure 18th Technique for WCAG 2.0: Contrast Test Procedure
/// @since 1.12.0 - The Sith
/// @param {Color} $color - Color to be modified
/// @param {Color} $color1 - 1st color to test the contrast against
/// @param {Color} $color2 - 2nd color to test the contrast against
/// @param {String | Number} $ratio1 ["AA"] - minimum ratio to test against. Accepted values for this ratio argument are AA and AAALG (4.5:1), AALG (3:1) and AAA (7:1) or a number between 1 and 21.
/// @param {String | Number} $ratio2 ["$ratio1"] - a second minimum ration to test against. Accepted values for this ratio argument are AA and AAALG (4.5:1), AALG (3:1) and AAA (7:1) or a number between 1 and 21.
/// @return {Color} - Updated color
/// @throw Warning if color fails to contrast with `$color1` and/or `$color2`
/// @example scss
///   // using recommended ratio for links
///   best-contrast(blue, white, black, 4.5, 3)
///   // #4d4dff
///
///   // usage
///   .image-caption a {
///     color: best-contrast(blue, gray, white);
///   }
@function best-contrast($color, $color1, $color2, $ratio1: "AA", $ratio2: $ratio1) {
	@if (not check-contrast($color, $color1, $ratio1) or not check-contrast($color, $color2, $ratio2)) {
		// First get the luminance of the two static colors
		$lum1: luminance(fix-color($color1, $color1, $ratio1));
		$lum2: luminance(fix-color($color2, $color2, $ratio2));

		// Average the luminance together to get the maximum difference
		$average-lum: ($lum1 + $lum2) / 2;

		// Then set changing color to this luminance
		$color: scale-luminance($color, $average-lum);

		// Warn if it fails contrast check
		@if (not check-contrast($color, $color1, $ratio1)) {
			@warn "Your color fails to contrast with #{$color1}";
		}
		@if (not check-contrast($color, $color2, $ratio2)) {
			@warn "Your color fails to contrast with #{$color2}";
		}
	}

	@return $color;
}