/**
 * Copyright (c) 2022 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 */

import { QuadPositions, } from '../../mol-gl/compute/util';
import { ComputeRenderable, createComputeRenderable } from '../../mol-gl/renderable';
import { AttributeSpec, DefineSpec, TextureSpec, UniformSpec, Values, ValueSpec } from '../../mol-gl/renderable/schema';
import { ShaderCode } from '../../mol-gl/shader-code';
import { background_frag } from '../../mol-gl/shader/background.frag';
import { background_vert } from '../../mol-gl/shader/background.vert';
import { WebGLContext } from '../../mol-gl/webgl/context';
import { createComputeRenderItem } from '../../mol-gl/webgl/render-item';
import { createNullTexture, CubeFaces, Texture } from '../../mol-gl/webgl/texture';
import { Mat4 } from '../../mol-math/linear-algebra/3d/mat4';
import { ValueCell } from '../../mol-util/value-cell';
import { ParamDefinition as PD } from '../../mol-util/param-definition';
import { isTimingMode } from '../../mol-util/debug';
import { Camera, ICamera } from '../camera';
import { Vec3 } from '../../mol-math/linear-algebra/3d/vec3';
import { Vec2 } from '../../mol-math/linear-algebra/3d/vec2';
import { Color } from '../../mol-util/color';
import { Asset, AssetManager } from '../../mol-util/assets';
import { Vec4 } from '../../mol-math/linear-algebra/3d/vec4';

const SharedParams = {
    opacity: PD.Numeric(1, { min: 0.0, max: 1.0, step: 0.01 }),
    saturation: PD.Numeric(0, { min: -1, max: 1, step: 0.01 }),
    lightness: PD.Numeric(0, { min: -1, max: 1, step: 0.01 }),
};

const SkyboxParams = {
    faces: PD.MappedStatic('urls', {
        urls: PD.Group({
            nx: PD.Text('', { label: 'Negative X' }),
            ny: PD.Text('', { label: 'Negative Y' }),
            nz: PD.Text('', { label: 'Negative Z' }),
            px: PD.Text('', { label: 'Positive X' }),
            py: PD.Text('', { label: 'Positive Y' }),
            pz: PD.Text('', { label: 'Positive Z' }),
        }, { isExpanded: true, label: 'URLs' }),
        files: PD.Group({
            nx: PD.File({ label: 'Negative X', accept: 'image/*' }),
            ny: PD.File({ label: 'Negative Y', accept: 'image/*' }),
            nz: PD.File({ label: 'Negative Z', accept: 'image/*' }),
            px: PD.File({ label: 'Positive X', accept: 'image/*' }),
            py: PD.File({ label: 'Positive Y', accept: 'image/*' }),
            pz: PD.File({ label: 'Positive Z', accept: 'image/*' }),
        }, { isExpanded: true, label: 'Files' }),
    }),
    ...SharedParams,
};
type SkyboxProps = PD.Values<typeof SkyboxParams>

const ImageParams = {
    source: PD.MappedStatic('url', {
        url: PD.Text(''),
        file: PD.File({ accept: 'image/*' }),
    }),
    ...SharedParams,
    coverage: PD.Select('viewport', PD.arrayToOptions(['viewport', 'canvas'])),
};
type ImageProps = PD.Values<typeof ImageParams>

const HorizontalGradientParams = {
    topColor: PD.Color(Color(0xDDDDDD)),
    bottomColor: PD.Color(Color(0xEEEEEE)),
    ratio: PD.Numeric(0.5, { min: 0.0, max: 1.0, step: 0.01 }),
    coverage: PD.Select('viewport', PD.arrayToOptions(['viewport', 'canvas'])),
};

const RadialGradientParams = {
    centerColor: PD.Color(Color(0xDDDDDD)),
    edgeColor: PD.Color(Color(0xEEEEEE)),
    ratio: PD.Numeric(0.5, { min: 0.0, max: 1.0, step: 0.01 }),
    coverage: PD.Select('viewport', PD.arrayToOptions(['viewport', 'canvas'])),
};

export const BackgroundParams = {
    variant: PD.MappedStatic('off', {
        off: PD.EmptyGroup(),
        skybox: PD.Group(SkyboxParams, { isExpanded: true }),
        image: PD.Group(ImageParams, { isExpanded: true }),
        horizontalGradient: PD.Group(HorizontalGradientParams, { isExpanded: true }),
        radialGradient: PD.Group(RadialGradientParams, { isExpanded: true }),
    }, { label: 'Environment' }),
};
export type BackgroundProps = PD.Values<typeof BackgroundParams>

export class BackgroundPass {
    private renderable: BackgroundRenderable;

    private skybox: {
        texture: Texture
        props: SkyboxProps
        assets: Asset[]
        loaded: boolean
    } | undefined;

    private image: {
        texture: Texture
        props: ImageProps
        asset: Asset
        loaded: boolean
    } | undefined;

    private readonly camera = new Camera();
    private readonly target = Vec3();
    private readonly position = Vec3();
    private readonly dir = Vec3();

    readonly texture: Texture;

    constructor(private readonly webgl: WebGLContext, private readonly assetManager: AssetManager, width: number, height: number) {
        this.renderable = getBackgroundRenderable(webgl, width, height);
    }

    setSize(width: number, height: number) {
        const [w, h] = this.renderable.values.uTexSize.ref.value;

        if (width !== w || height !== h) {
            ValueCell.update(this.renderable.values.uTexSize, Vec2.set(this.renderable.values.uTexSize.ref.value, width, height));
        }
    }

    private clearSkybox() {
        if (this.skybox !== undefined) {
            this.skybox.texture.destroy();
            this.skybox.assets.forEach(a => this.assetManager.release(a));
            this.skybox = undefined;
        }
    }

    private updateSkybox(camera: ICamera, props: SkyboxProps, onload?: (changed: boolean) => void) {
        const tf = this.skybox?.props.faces;
        const f = props.faces.params;
        if (!f.nx || !f.ny || !f.nz || !f.px || !f.py || !f.pz) {
            this.clearSkybox();
            if (onload) onload(false);
            return;
        }
        if (!this.skybox || !tf || !areSkyboxTexturePropsEqual(props.faces, this.skybox.props.faces)) {
            this.clearSkybox();
            const { texture, assets } = getSkyboxTexture(this.webgl, this.assetManager, props.faces, () => {
                if (this.skybox) this.skybox.loaded = true;
                if (onload) onload(true);
            });
            this.skybox = { texture, props: { ...props }, assets, loaded: false };
            ValueCell.update(this.renderable.values.tSkybox, texture);
            this.renderable.update();
        } else {
            if (onload) onload(false);
        }
        if (!this.skybox) return;

        let cam = camera;
        if (camera.state.mode === 'orthographic') {
            this.camera.setState({ ...camera.state, mode: 'perspective' });
            this.camera.update();
            cam = this.camera;
        }

        const m = this.renderable.values.uViewDirectionProjectionInverse.ref.value;
        Vec3.sub(this.dir, cam.state.position, cam.state.target);
        Vec3.setMagnitude(this.dir, this.dir, 0.1);
        Vec3.copy(this.position, this.dir);
        Mat4.lookAt(m, this.position, this.target, cam.state.up);
        Mat4.mul(m, cam.projection, m);
        Mat4.invert(m, m);
        ValueCell.update(this.renderable.values.uViewDirectionProjectionInverse, m);

        ValueCell.updateIfChanged(this.renderable.values.uOpacity, props.opacity);
        ValueCell.updateIfChanged(this.renderable.values.uSaturation, props.saturation);
        ValueCell.updateIfChanged(this.renderable.values.uLightness, props.lightness);
        ValueCell.updateIfChanged(this.renderable.values.dVariant, 'skybox');
        this.renderable.update();
    }

    private clearImage() {
        if (this.image !== undefined) {
            this.image.texture.destroy();
            this.assetManager.release(this.image.asset);
            this.image = undefined;
        }
    }

    private updateImage(props: ImageProps, onload?: (loaded: boolean) => void) {
        if (!props.source.params) {
            this.clearImage();
            if (onload) onload(false);
            return;
        }
        if (!this.image || !this.image.props.source.params || !areImageTexturePropsEqual(props.source, this.image.props.source)) {
            this.clearImage();
            const { texture, asset } = getImageTexture(this.webgl, this.assetManager, props.source, () => {
                if (this.image) this.image.loaded = true;
                if (onload) onload(true);
            });
            this.image = { texture, props: { ...props }, asset, loaded: false };
            ValueCell.update(this.renderable.values.tImage, texture);
            this.renderable.update();
        } else {
            if (onload) onload(false);
        }
        if (!this.image) return;

        ValueCell.updateIfChanged(this.renderable.values.uOpacity, props.opacity);
        ValueCell.updateIfChanged(this.renderable.values.uSaturation, props.saturation);
        ValueCell.updateIfChanged(this.renderable.values.uLightness, props.lightness);
        ValueCell.updateIfChanged(this.renderable.values.uViewportAdjusted, props.coverage === 'viewport' ? true : false);
        ValueCell.updateIfChanged(this.renderable.values.dVariant, 'image');
        this.renderable.update();
    }

    private updateImageScaling() {
        const v = this.renderable.values;
        const [w, h] = v.uTexSize.ref.value;
        const iw = this.image?.texture.getWidth() || 0;
        const ih = this.image?.texture.getHeight() || 0;
        const r = w / h;
        const ir = iw / ih;
        // responsive scaling with offset
        if (r < ir) {
            ValueCell.update(v.uImageScale, Vec2.set(v.uImageScale.ref.value, iw * h / ih, h));
        } else {
            ValueCell.update(v.uImageScale, Vec2.set(v.uImageScale.ref.value, w, ih * w / iw));
        }
        const [rw, rh] = v.uImageScale.ref.value;
        const sr = rw / rh;
        if (sr > r) {
            ValueCell.update(v.uImageOffset, Vec2.set(v.uImageOffset.ref.value, (1 - r / sr) / 2, 0));
        } else {
            ValueCell.update(v.uImageOffset, Vec2.set(v.uImageOffset.ref.value, 0, (1 - sr / r) / 2));
        }
    }

    private updateGradient(colorA: Color, colorB: Color, ratio: number, variant: 'horizontalGradient' | 'radialGradient', viewportAdjusted: boolean) {
        ValueCell.update(this.renderable.values.uGradientColorA, Color.toVec3Normalized(this.renderable.values.uGradientColorA.ref.value, colorA));
        ValueCell.update(this.renderable.values.uGradientColorB, Color.toVec3Normalized(this.renderable.values.uGradientColorB.ref.value, colorB));
        ValueCell.updateIfChanged(this.renderable.values.uGradientRatio, ratio);
        ValueCell.updateIfChanged(this.renderable.values.uViewportAdjusted, viewportAdjusted);
        ValueCell.updateIfChanged(this.renderable.values.dVariant, variant);
        this.renderable.update();
    }

    update(camera: ICamera, props: BackgroundProps, onload?: (changed: boolean) => void) {
        if (props.variant.name === 'off') {
            this.clearSkybox();
            this.clearImage();
            if (onload) onload(false);
            return;
        } else if (props.variant.name === 'skybox') {
            this.clearImage();
            this.updateSkybox(camera, props.variant.params, onload);
        } else if (props.variant.name === 'image') {
            this.clearSkybox();
            this.updateImage(props.variant.params, onload);
        } else if (props.variant.name === 'horizontalGradient') {
            this.clearSkybox();
            this.clearImage();
            this.updateGradient(props.variant.params.topColor, props.variant.params.bottomColor, props.variant.params.ratio, props.variant.name, props.variant.params.coverage === 'viewport' ? true : false);
            if (onload) onload(false);
        } else if (props.variant.name === 'radialGradient') {
            this.clearSkybox();
            this.clearImage();
            this.updateGradient(props.variant.params.centerColor, props.variant.params.edgeColor, props.variant.params.ratio, props.variant.name, props.variant.params.coverage === 'viewport' ? true : false);
            if (onload) onload(false);
        }

        const { x, y, width, height } = camera.viewport;
        ValueCell.update(this.renderable.values.uViewport, Vec4.set(this.renderable.values.uViewport.ref.value, x, y, width, height));
    }

    isEnabled(props: BackgroundProps) {
        return !!(
            (this.skybox && this.skybox.loaded) ||
            (this.image && this.image.loaded) ||
            props.variant.name === 'horizontalGradient' ||
            props.variant.name === 'radialGradient'
        );
    }

    private isReady() {
        return !!(
            (this.skybox && this.skybox.loaded) ||
            (this.image && this.image.loaded) ||
            this.renderable.values.dVariant.ref.value === 'horizontalGradient' ||
            this.renderable.values.dVariant.ref.value === 'radialGradient'
        );
    }

    render() {
        if (!this.isReady()) return;

        if (this.renderable.values.dVariant.ref.value === 'image') {
            this.updateImageScaling();
        }

        if (isTimingMode) this.webgl.timer.mark('BackgroundPass.render');
        this.renderable.render();
        if (isTimingMode) this.webgl.timer.markEnd('BackgroundPass.render');
    }

    dispose() {
        this.clearSkybox();
        this.clearImage();
    }
}

//

const SkyboxName = 'background-skybox';

type CubeAssets = { [k in keyof CubeFaces]: Asset };

function getCubeAssets(assetManager: AssetManager, faces: SkyboxProps['faces']): CubeAssets {
    if (faces.name === 'urls') {
        return {
            nx: Asset.getUrlAsset(assetManager, faces.params.nx),
            ny: Asset.getUrlAsset(assetManager, faces.params.ny),
            nz: Asset.getUrlAsset(assetManager, faces.params.nz),
            px: Asset.getUrlAsset(assetManager, faces.params.px),
            py: Asset.getUrlAsset(assetManager, faces.params.py),
            pz: Asset.getUrlAsset(assetManager, faces.params.pz),
        };
    } else {
        return {
            nx: faces.params.nx!,
            ny: faces.params.ny!,
            nz: faces.params.nz!,
            px: faces.params.px!,
            py: faces.params.py!,
            pz: faces.params.pz!,
        };
    }
}

function getCubeFaces(assetManager: AssetManager, cubeAssets: CubeAssets): CubeFaces {
    const resolve = (asset: Asset) => {
        return assetManager.resolve(asset, 'binary').run().then(a => new Blob([a.data]));
    };

    return {
        nx: resolve(cubeAssets.nx),
        ny: resolve(cubeAssets.ny),
        nz: resolve(cubeAssets.nz),
        px: resolve(cubeAssets.px),
        py: resolve(cubeAssets.py),
        pz: resolve(cubeAssets.pz),
    };
}

function getSkyboxHash(faces: SkyboxProps['faces']) {
    if (faces.name === 'urls') {
        return `${SkyboxName}_${faces.params.nx}|${faces.params.ny}|${faces.params.nz}|${faces.params.px}|${faces.params.py}|${faces.params.pz}`;
    } else {
        return `${SkyboxName}_${faces.params.nx?.id}|${faces.params.ny?.id}|${faces.params.nz?.id}|${faces.params.px?.id}|${faces.params.py?.id}|${faces.params.pz?.id}`;
    }
}

function areSkyboxTexturePropsEqual(facesA: SkyboxProps['faces'], facesB: SkyboxProps['faces']) {
    return getSkyboxHash(facesA) === getSkyboxHash(facesB);
}

function getSkyboxTexture(ctx: WebGLContext, assetManager: AssetManager, faces: SkyboxProps['faces'], onload?: () => void): { texture: Texture, assets: Asset[] } {
    const cubeAssets = getCubeAssets(assetManager, faces);
    const cubeFaces = getCubeFaces(assetManager, cubeAssets);
    const assets = [cubeAssets.nx, cubeAssets.ny, cubeAssets.nz, cubeAssets.px, cubeAssets.py, cubeAssets.pz];
    const texture = ctx.resources.cubeTexture(cubeFaces, false, onload);
    return { texture, assets };
}

//

const ImageName = 'background-image';

function getImageHash(source: ImageProps['source']) {
    if (source.name === 'url') {
        return `${ImageName}_${source.params}`;
    } else {
        return `${ImageName}_${source.params?.id}`;
    }
}

function areImageTexturePropsEqual(sourceA: ImageProps['source'], sourceB: ImageProps['source']) {
    return getImageHash(sourceA) === getImageHash(sourceB);
}

function getImageTexture(ctx: WebGLContext, assetManager: AssetManager, source: ImageProps['source'], onload?: () => void): { texture: Texture, asset: Asset } {
    const texture = ctx.resources.texture('image-uint8', 'rgba', 'ubyte', 'linear');
    const img = new Image();
    img.onload = () => {
        texture.load(img);
        onload?.();
    };
    const asset = source.name === 'url'
        ? Asset.getUrlAsset(assetManager, source.params)
        : source.params!;
    assetManager.resolve(asset, 'binary').run().then(a => {
        const blob = new Blob([a.data]);
        img.src = URL.createObjectURL(blob);
    });
    return { texture, asset };
}

//

const BackgroundSchema = {
    drawCount: ValueSpec('number'),
    instanceCount: ValueSpec('number'),
    aPosition: AttributeSpec('float32', 2, 0),
    tSkybox: TextureSpec('texture', 'rgba', 'ubyte', 'linear'),
    tImage: TextureSpec('texture', 'rgba', 'ubyte', 'linear'),
    uImageScale: UniformSpec('v2'),
    uImageOffset: UniformSpec('v2'),
    uTexSize: UniformSpec('v2'),
    uViewport: UniformSpec('v4'),
    uViewportAdjusted: UniformSpec('b'),
    uViewDirectionProjectionInverse: UniformSpec('m4'),
    uGradientColorA: UniformSpec('v3'),
    uGradientColorB: UniformSpec('v3'),
    uGradientRatio: UniformSpec('f'),
    uOpacity: UniformSpec('f'),
    uSaturation: UniformSpec('f'),
    uLightness: UniformSpec('f'),
    dVariant: DefineSpec('string', ['skybox', 'image', 'verticalGradient', 'horizontalGradient', 'radialGradient']),
};
const SkyboxShaderCode = ShaderCode('background', background_vert, background_frag);
type BackgroundRenderable = ComputeRenderable<Values<typeof BackgroundSchema>>

function getBackgroundRenderable(ctx: WebGLContext, width: number, height: number): BackgroundRenderable {
    const values: Values<typeof BackgroundSchema> = {
        drawCount: ValueCell.create(6),
        instanceCount: ValueCell.create(1),
        aPosition: ValueCell.create(QuadPositions),
        tSkybox: ValueCell.create(createNullTexture()),
        tImage: ValueCell.create(createNullTexture()),
        uImageScale: ValueCell.create(Vec2()),
        uImageOffset: ValueCell.create(Vec2()),
        uTexSize: ValueCell.create(Vec2.create(width, height)),
        uViewport: ValueCell.create(Vec4()),
        uViewportAdjusted: ValueCell.create(true),
        uViewDirectionProjectionInverse: ValueCell.create(Mat4()),
        uGradientColorA: ValueCell.create(Vec3()),
        uGradientColorB: ValueCell.create(Vec3()),
        uGradientRatio: ValueCell.create(0.5),
        uOpacity: ValueCell.create(1),
        uSaturation: ValueCell.create(0),
        uLightness: ValueCell.create(0),
        dVariant: ValueCell.create('skybox'),
    };

    const schema = { ...BackgroundSchema };
    const renderItem = createComputeRenderItem(ctx, 'triangles', SkyboxShaderCode, schema, values);

    return createComputeRenderable(renderItem, values);
}