/**
 * RGB representation of a color
 **/
declare type ColorTuple = [number, number, number];
declare type RGBColorTuple = [number, number, number];
declare type LABColorTuple = [number, number, number];
declare type deltaValueType = 'rgb' | 'hex' | 'hsl' | 'lab';
declare type InputTupleTypes = 'rgb' | 'hsl' | 'lab';

declare function contrastText(color: ColorTuple, type: InputTupleTypes): ColorTuple;
declare function contrastText(color: string, type?: undefined): string;

/**
 * manually clear the internal cache.
 */
declare function clearCache(): void;
/**
 * takes two colors and measure of change in visual perception of the two given colors, returns delta-e value 0 - 100+
 *
 * more on delta-e: http://zschuessler.github.io/DeltaE/learn/
 */
declare function deltaE(color1: ColorTuple, color2: string, type: Exclude<deltaValueType, 'hex'>, nocache?: boolean): number;
declare function deltaE(color1: string, color2: ColorTuple, type: Exclude<deltaValueType, 'hex'>, nocache?: boolean): number;
declare function deltaE(color1: ColorTuple, color2: ColorTuple, type: Exclude<deltaValueType, 'hex'>, nocache?: boolean): number;
declare function deltaE(color1: string, color2: string, type?: Exclude<deltaValueType, 'hex'>, nocache?: boolean): number;

/**
 * checks if `first` would be noticebly different to the naked eye to `second`
 * returns true if they contrast enough,
 * threshold can be modified by `0 - 100` `(default = 5)`, to change how much difference the colors need to be
 * nocache can be used to disable caching for color calculations
 */
interface IsPerceivableOptions {
    threshold?: number;
    type?: InputTupleTypes;
    nocache?: boolean;
}
declare function isPerceivable(first: ColorTuple, second: ColorTuple, options?: IsPerceivableOptions): boolean;
declare function isPerceivable(first: string, second: string, options?: IsPerceivableOptions): boolean;

/**
 * gets the average color within an image, does not support crossOrigin images set img element crossOrigin to `crossOrigin=""`
 */
declare function sampleImage(imgEl: HTMLImageElement): [number, number, number];

interface SelectorOptions {
    compare: ColorTuple | string;
    type?: InputTupleTypes;
    threshold?: number;
}
/**
 * provide a base color to compare and a contrast threshold, selector will go through each
 * fallback contrast color and will pick the first fallback thats contrast meets the threshold
 * if none meet contrast ratio selector will return the last fallback supplied
 */
declare function selector(options: SelectorOptions, ...fallbacks: Array<ColorTuple | string>): ColorTuple | string;

/**
 * converts a RGBColorTuple to rgb string e.g `rgb(0,0,0)`
 */
declare function toRBGString([r, g, b]: RGBColorTuple): string;
/**
   * converts a RGBColorTuple to hsl string e.g `hsl(0,0,0)`
   */
declare function toHSLString([h, s, l]: RGBColorTuple): string;

export { ColorTuple, InputTupleTypes, LABColorTuple, RGBColorTuple, clearCache, contrastText, deltaE, deltaValueType, isPerceivable, sampleImage, selector, toHSLString, toRBGString };