import type { Filter } from "@vibrant/color";

export { Histogram } from "./histogram";
export type { HistogramOptions } from "./histogram";

/**
 * HTMLImageElement - browser only
 * Buffer - Node.js only
 */
export type ImageSource = string | HTMLImageElement | Buffer;

export type Pixels = Uint8ClampedArray | Buffer;
export interface ImageData {
	data: Pixels;
	width: number;
	height: number;
}

export interface ImageOptions {
	/**
	 * Scale down factor used in downsampling stage. 1 means no downsampling. If `maxDimension` is set, this value will not be used.
	 * @default 5
	 */
	quality: number;
	/**
	 * The max size of the image's longer side used in downsampling stage. This field will override `quality`.
	 * @default undefined
	 */
	maxDimension: number;
}

export interface Image {
	load(image: ImageSource): Promise<Image>;
	clear(): void;
	update(imageData: ImageData): void;
	getWidth(): number;
	getHeight(): number;
	resize(targetWidth: number, targetHeight: number, ratio: number): void;
	getPixelCount(): number;
	getImageData(): ImageData;
	remove(): void;
	scaleDown(opts: ImageOptions): void;
}

export interface ImageClass {
	new (): Image;
}

export abstract class ImageBase implements Image {
	abstract load(image: ImageSource): Promise<ImageBase>;
	abstract clear(): void;
	abstract update(imageData: ImageData): void;
	abstract getWidth(): number;
	abstract getHeight(): number;
	abstract resize(
		targetWidth: number,
		targetHeight: number,
		ratio: number,
	): void;
	abstract getPixelCount(): number;
	abstract getImageData(): ImageData;
	abstract remove(): void;

	scaleDown(opts: ImageOptions): void {
		const width: number = this.getWidth();
		const height: number = this.getHeight();

		let ratio = 1;

		if (opts.maxDimension > 0) {
			const maxSide: number = Math.max(width, height);
			if (maxSide > opts.maxDimension) ratio = opts.maxDimension / maxSide;
		} else {
			ratio = 1 / opts.quality;
		}

		if (ratio < 1) this.resize(width * ratio, height * ratio, ratio);
	}
}

/**
 * @private
 */
export function applyFilters(imageData: ImageData, filters: Filter[]) {
	if (filters.length > 0) {
		const pixels = imageData.data;
		const n = pixels.length / 4;
		let offset;
		let r;
		let g;
		let b;
		let a;
		for (let i = 0; i < n; i++) {
			offset = i * 4;
			r = pixels[offset + 0]!;
			g = pixels[offset + 1]!;
			b = pixels[offset + 2]!;
			a = pixels[offset + 3]!;
			// Mark ignored color
			for (let j = 0; j < filters.length; j++) {
				if (!filters[j]?.(r, g, b, a)) {
					pixels[offset + 3] = 0;
					break;
				}
			}
		}
	}

	return imageData;
}