/**
 * Copyright (c) 2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 */

import { ValueCell } from 'mol-util/value-cell'
import { Vec2 } from 'mol-math/linear-algebra'
import { TextureImage, createTextureImage } from 'mol-gl/renderable/util';
import { Color } from 'mol-util/color';

export type OverpaintData = {
    tOverpaint: ValueCell<TextureImage<Uint8Array>>
    uOverpaintTexDim: ValueCell<Vec2>
    dOverpaint: ValueCell<boolean>,
}

export function applyOverpaintColor(array: Uint8Array, start: number, end: number, color: Color, alpha: number) {
    for (let i = start; i < end; ++i) {
        Color.toArray(color, array, i * 4)
        array[i * 4 + 3] = alpha * 255
    }
    return true
}

export function clearOverpaint(array: Uint8Array, start: number, end: number) {
    array.fill(0, start, end)
}

export function createOverpaint(count: number, overpaintData?: OverpaintData): OverpaintData {
    const overpaint = createTextureImage(Math.max(1, count), 4, Uint8Array, overpaintData && overpaintData.tOverpaint.ref.value.array)
    if (overpaintData) {
        ValueCell.update(overpaintData.tOverpaint, overpaint)
        ValueCell.update(overpaintData.uOverpaintTexDim, Vec2.create(overpaint.width, overpaint.height))
        ValueCell.update(overpaintData.dOverpaint, count > 0)
        return overpaintData
    } else {
        return {
            tOverpaint: ValueCell.create(overpaint),
            uOverpaintTexDim: ValueCell.create(Vec2.create(overpaint.width, overpaint.height)),
            dOverpaint: ValueCell.create(count > 0),
        }
    }
}

const emptyOverpaintTexture = { array: new Uint8Array(4), width: 1, height: 1 }
export function createEmptyOverpaint(overpaintData?: OverpaintData): OverpaintData {
    if (overpaintData) {
        ValueCell.update(overpaintData.tOverpaint, emptyOverpaintTexture)
        ValueCell.update(overpaintData.uOverpaintTexDim, Vec2.create(1, 1))
        return overpaintData
    } else {
        return {
            tOverpaint: ValueCell.create(emptyOverpaintTexture),
            uOverpaintTexDim: ValueCell.create(Vec2.create(1, 1)),
            dOverpaint: ValueCell.create(false),
        }
    }
}