/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

'use strict';

import { Filter, generateSVGFeImage, isIndexOutOfBound } from '../../utils/FilterUtils';
import { SVG_NS, uuidv4 } from '../Component';
import { BITMAP_IMAGE_REGEX_CHECK, IBaseFilter, IImageFilterElement } from './ImageFilter';

/**
 * @ignore
 */
export interface IBlur extends IBaseFilter {
    radius: number;
    source: number;
}

/*
 * Apply a Gaussian blur with a specified radius. The new image is appended to the end of the array.
 * Specs: https://developer.amazon.com/en-US/docs/alexa/alexa-presentation-language/apl-filters.html#blur
 * Utilize svg <feGaussianBlur> filter
 * https://developer.mozilla.org/en-US/docs/Web/SVG/Element/feGaussianBlur
 */
export function getBlurFilter(filter: Filter, imageSrcArray: string[]): IImageFilterElement | undefined {
    const blurId: string = uuidv4().toString();
    let filterImageArray: SVGFEImageElement[] = [];
    const blur: SVGElement = document.createElementNS(SVG_NS, 'feGaussianBlur');
    blur.setAttributeNS('', 'stdDeviation', (filter as IBlur).radius.toString());
    blur.setAttributeNS('', 'result', blurId);
    /*
     * All filters that operate on a single image have a default image source property of -1;
     * that is, by default they take as input the last image in the image array.
     */
    let index: number = (filter as IBlur).source;

    // Negative case : index outside source array bounds. return undefined
    if (isIndexOutOfBound(index, imageSrcArray.length)) {
        return undefined;
    }
    if (index < 0) {
        index += imageSrcArray.length;
    }
    const imageId: string = imageSrcArray[index];
    if (imageId.match(BITMAP_IMAGE_REGEX_CHECK)) {
        filterImageArray = generateSVGFeImage(imageId, blur);
    } else {
        blur.setAttributeNS('', 'in', imageId);
    }
    return { filterId: blurId, filterElement: blur, filterImageArray };
}