/**
 * Copyright (c) 2018-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 */

import { Sphere3D } from '../../mol-math/geometry';
import { Vec3, Mat4 } from '../../mol-math/linear-algebra';
import { BoundaryHelper } from '../../mol-math/geometry/boundary-helper';

export function calculateTextureInfo (n: number, itemSize: number) {
    n = Math.max(n, 2); // observed issues with 1 pixel textures
    const sqN = Math.sqrt(n);
    let width = Math.ceil(sqN);
    width = width + (itemSize - (width % itemSize)) % itemSize;
    const height = width > 0 ? Math.ceil(n / width) : 0;
    return { width, height, length: width * height * itemSize };
}

export interface TextureImage<T extends Uint8Array | Float32Array> {
    readonly array: T
    readonly width: number
    readonly height: number
    readonly flipY?: boolean
}

export interface TextureVolume<T extends Uint8Array | Float32Array> {
    readonly array: T
    readonly width: number
    readonly height: number
    readonly depth: number
}

export function createTextureImage<T extends Uint8Array | Float32Array>(n: number, itemSize: number, arrayCtor: new (length: number) => T, array?: T): TextureImage<T> {
    const { length, width, height } = calculateTextureInfo(n, itemSize);
    array = array && array.length >= length ? array : new arrayCtor(length);
    return { array, width, height };
}

export function printTextureImage(textureImage: TextureImage<any>, scale = 1) {
    const { array, width, height } = textureImage;
    const itemSize = array.length / (width * height);
    const data = new Uint8ClampedArray(width * height * 4);
    if (itemSize === 1) {
        for (let y = 0; y < height; ++y) {
            for (let x = 0; x < width; ++x) {
                data[(y * width + x) * 4 + 3] = array[y * width + x];
            }
        }
    } else if (itemSize === 4) {
        data.set(array);
    } else {
        console.warn(`itemSize '${itemSize}' not supported`);
    }
    return printImageData(new ImageData(data, width, height), scale);
}

export function printImageData(imageData: ImageData, scale = 1, pixelated = false) {
    const canvas = document.createElement('canvas');
    canvas.width = imageData.width;
    canvas.height = imageData.height;
    const ctx = canvas.getContext('2d');
    if (!ctx) throw new Error('Could not create canvas 2d context');
    ctx.putImageData(imageData, 0, 0);
    canvas.toBlob(imgBlob => {
        const objectURL = window.URL.createObjectURL(imgBlob);
        const img = document.createElement('img');
        img.src = objectURL;
        img.style.width = imageData.width * scale + 'px';
        img.style.height = imageData.height * scale + 'px';
        if (pixelated) {
            // not supported in Firefox and IE
            img.style.imageRendering = 'pixelated';
        }
        img.style.position = 'absolute';
        img.style.top = '0px';
        img.style.left = '0px';
        img.style.border = 'solid grey';
        img.style.pointerEvents = 'none';
        document.body.appendChild(img);
    }, 'image/png');
}

//

const v = Vec3();
const boundaryHelperCoarse = new BoundaryHelper('14');
const boundaryHelperFine = new BoundaryHelper('98');

function getHelper(count: number) {
    return count > 100_000 ? boundaryHelperCoarse : boundaryHelperFine;
}

export function calculateInvariantBoundingSphere(position: Float32Array, positionCount: number, stepFactor: number): Sphere3D {
    const step = stepFactor * 3;
    const boundaryHelper = getHelper(positionCount);

    boundaryHelper.reset();
    for (let i = 0, _i = positionCount * 3; i < _i; i += step) {
        Vec3.fromArray(v, position, i);
        boundaryHelper.includePosition(v);
    }
    boundaryHelper.finishedIncludeStep();
    for (let i = 0, _i = positionCount * 3; i < _i; i += step) {
        Vec3.fromArray(v, position, i);
        boundaryHelper.radiusPosition(v);
    }

    const sphere = boundaryHelper.getSphere();

    if (positionCount <= 98) {
        const extrema: Vec3[] = [];
        for (let i = 0, _i = positionCount * 3; i < _i; i += step) {
            extrema.push(Vec3.fromArray(Vec3(), position, i));
        }
        Sphere3D.setExtrema(sphere, extrema);
    }

    return sphere;
}

const _mat4 = Mat4();

export function calculateTransformBoundingSphere(invariantBoundingSphere: Sphere3D, transform: Float32Array, transformCount: number): Sphere3D {
    if (transformCount === 1) {
        Mat4.fromArray(_mat4, transform, 0);
        const s = Sphere3D.clone(invariantBoundingSphere);
        return Mat4.isIdentity(_mat4) ? s : Sphere3D.transform(s, s, _mat4);
    }

    const boundaryHelper = getHelper(transformCount);
    boundaryHelper.reset();

    const { center, radius, extrema } = invariantBoundingSphere;

    // only use extrema if there are not too many transforms
    if (extrema && transformCount < 50) {
        for (let i = 0, _i = transformCount; i < _i; ++i) {
            for (const e of extrema) {
                Vec3.transformMat4Offset(v, e, transform, 0, 0, i * 16);
                boundaryHelper.includePosition(v);
            }
        }
        boundaryHelper.finishedIncludeStep();
        for (let i = 0, _i = transformCount; i < _i; ++i) {
            for (const e of extrema) {
                Vec3.transformMat4Offset(v, e, transform, 0, 0, i * 16);
                boundaryHelper.radiusPosition(v);
            }
        }
    } else {
        for (let i = 0, _i = transformCount; i < _i; ++i) {
            Vec3.transformMat4Offset(v, center, transform, 0, 0, i * 16);
            boundaryHelper.includePositionRadius(v, radius);
        }
        boundaryHelper.finishedIncludeStep();
        for (let i = 0, _i = transformCount; i < _i; ++i) {
            Vec3.transformMat4Offset(v, center, transform, 0, 0, i * 16);
            boundaryHelper.radiusPositionRadius(v, radius);
        }
    }

    return boundaryHelper.getSphere();
}

export function calculateBoundingSphere(position: Float32Array, positionCount: number, transform: Float32Array, transformCount: number, padding = 0, stepFactor = 1): { boundingSphere: Sphere3D, invariantBoundingSphere: Sphere3D } {
    const invariantBoundingSphere = calculateInvariantBoundingSphere(position, positionCount, stepFactor);
    const boundingSphere = calculateTransformBoundingSphere(invariantBoundingSphere, transform, transformCount);
    Sphere3D.expand(boundingSphere, boundingSphere, padding);
    Sphere3D.expand(invariantBoundingSphere, invariantBoundingSphere, padding);
    return { boundingSphere, invariantBoundingSphere };
}