/**
 * Copyright (c) 2017-2020 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author Alexander Rose <alexander.rose@weirdbyte.de>
 * @author Michael Krone <michael.krone@uni-tuebingen.de>
 */

import { PositionData, DensityData, DensityTextureData } from '../common'
import { Box3D } from '../../geometry'
import { GaussianDensityGPUProps } from '../gaussian-density'
import { OrderedSet } from '../../../mol-data/int'
import { Vec3, Tensor, Mat4, Vec2 } from '../../linear-algebra'
import { ValueCell } from '../../../mol-util'
import { createComputeRenderable, ComputeRenderable } from '../../../mol-gl/renderable'
import { WebGLContext } from '../../../mol-gl/webgl/context';
import { Texture } from '../../../mol-gl/webgl/texture';
import { decodeFloatRGB } from '../../../mol-util/float-packing';
import { ShaderCode } from '../../../mol-gl/shader-code';
import { createComputeRenderItem } from '../../../mol-gl/webgl/render-item';
import { ValueSpec, AttributeSpec, UniformSpec, TextureSpec, DefineSpec, Values } from '../../../mol-gl/renderable/schema';
import gaussian_density_vert from '../../../mol-gl/shader/gaussian-density.vert'
import gaussian_density_frag from '../../../mol-gl/shader/gaussian-density.frag'

export const GaussianDensitySchema = {
    drawCount: ValueSpec('number'),
    instanceCount: ValueSpec('number'),

    aRadius: AttributeSpec('float32', 1, 0),
    aPosition: AttributeSpec('float32', 3, 0),
    aGroup: AttributeSpec('float32', 1, 0),

    uCurrentSlice: UniformSpec('f'),
    uCurrentX: UniformSpec('f'),
    uCurrentY: UniformSpec('f'),
    uBboxMin: UniformSpec('v3', true),
    uBboxSize: UniformSpec('v3', true),
    uGridDim: UniformSpec('v3', true),
    uGridTexDim: UniformSpec('v3', true),
    uGridTexScale: UniformSpec('v2', true),
    uAlpha: UniformSpec('f', true),
    uResolution: UniformSpec('f', true),
    tMinDistanceTex: TextureSpec('texture', 'rgba', 'float', 'nearest'),

    dGridTexType: DefineSpec('string', ['2d', '3d']),
    dCalcType: DefineSpec('string', ['density', 'minDistance', 'groupId']),
}

export const GaussianDensityShaderCode = ShaderCode(
    gaussian_density_vert, gaussian_density_frag,
    { standardDerivatives: false, fragDepth: false }
)

export function GaussianDensityGPU(position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps, webgl: WebGLContext): DensityData {
    // always use texture2d when the gaussian density needs to be downloaded from the GPU,
    // it's faster than texture3d
    // console.time('GaussianDensityTexture2d')
    const { scale, bbox, texture, gridDim, gridTexDim } = calcGaussianDensityTexture2d(webgl, position, box, radius, props)
    // webgl.waitForGpuCommandsCompleteSync()
    // console.timeEnd('GaussianDensityTexture2d')
    const { field, idField } = fieldFromTexture2d(webgl, texture, gridDim, gridTexDim)

    return { field, idField, transform: getTransform(scale, bbox) }
}

export function GaussianDensityTexture(webgl: WebGLContext, position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps, oldTexture?: Texture): DensityTextureData {
    return webgl.isWebGL2 ?
        GaussianDensityTexture3d(webgl, position, box, radius, props, oldTexture) :
        GaussianDensityTexture2d(webgl, position, box, radius, props, oldTexture)
}

export function GaussianDensityTexture2d(webgl: WebGLContext, position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps, oldTexture?: Texture): DensityTextureData {
    return finalizeGaussianDensityTexture(calcGaussianDensityTexture2d(webgl, position, box, radius, props, oldTexture))
}

export function GaussianDensityTexture3d(webgl: WebGLContext, position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps, oldTexture?: Texture): DensityTextureData {
    return finalizeGaussianDensityTexture(calcGaussianDensityTexture3d(webgl, position, box, radius, props, oldTexture))
}

function finalizeGaussianDensityTexture({ texture, scale, bbox, gridDim, gridTexDim, gridTexScale }: GaussianDensityTextureData): DensityTextureData {
    return { transform: getTransform(scale, bbox), texture, bbox, gridDim, gridTexDim, gridTexScale }
}

function getTransform(scale: Vec3, bbox: Box3D) {
    const transform = Mat4.identity()
    Mat4.fromScaling(transform, scale)
    Mat4.setTranslation(transform, bbox.min)
    return transform
}

//

type GaussianDensityTextureData = {
    texture: Texture,
    scale: Vec3,
    bbox: Box3D,
    gridDim: Vec3,
    gridTexDim: Vec3
    gridTexScale: Vec2
}

function calcGaussianDensityTexture2d(webgl: WebGLContext, position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps, texture?: Texture): GaussianDensityTextureData {
    const { smoothness } = props

    const { drawCount, positions, radii, groups, scale, expandedBox, dim } = prepareGaussianDensityData(position, box, radius, props)
    const [ dx, dy, dz ] = dim
    const { texDimX, texDimY, texCols, powerOfTwoSize } = getTexture2dSize(dim)
    // console.log({ texDimX, texDimY, texCols, powerOfTwoSize, dim })
    const gridTexDim = Vec3.create(texDimX, texDimY, 0)
    const gridTexScale = Vec2.create(texDimX / powerOfTwoSize, texDimY / powerOfTwoSize)

    const minDistanceTexture = webgl.resources.texture('image-float32', 'rgba', 'float', 'nearest')
    minDistanceTexture.define(powerOfTwoSize, powerOfTwoSize)

    const renderable = getGaussianDensityRenderable(webgl, drawCount, positions, radii, groups, minDistanceTexture, expandedBox, dim, gridTexDim, gridTexScale, smoothness, props.resolution)

    //

    const { gl, resources, state } = webgl
    const { uCurrentSlice, uCurrentX, uCurrentY } = renderable.values

    const framebuffer = resources.framebuffer()
    framebuffer.bind()
    setRenderingDefaults(webgl)

    if (!texture) {
        texture = resources.texture('image-float32', 'rgba', 'float', 'nearest')
        texture.define(powerOfTwoSize, powerOfTwoSize)
    } else if (texture.getWidth() !== powerOfTwoSize || texture.getHeight() !== powerOfTwoSize) {
        texture.define(powerOfTwoSize, powerOfTwoSize)
    }

    // console.log(renderable)

    function render(fbTex: Texture, clear: boolean) {
        state.currentRenderItemId = -1
        fbTex.attachFramebuffer(framebuffer, 0)
        if (clear) gl.clear(gl.COLOR_BUFFER_BIT)
        let currCol = 0
        let currY = 0
        let currX = 0
        for (let i = 0; i < dz; ++i) {
            if (currCol >= texCols) {
                currCol -= texCols
                currY += dy
                currX = 0
                ValueCell.update(uCurrentY, currY)
            }
            // console.log({ i, currX, currY })
            ValueCell.update(uCurrentX, currX)
            ValueCell.update(uCurrentSlice, i)
            gl.viewport(currX, currY, dx, dy)
            renderable.render()
            ++currCol
            currX += dx
        }
        gl.finish()
    }

    setupDensityRendering(webgl, renderable)
    render(texture, true)

    setupMinDistanceRendering(webgl, renderable)
    render(minDistanceTexture, true)

    setupGroupIdRendering(webgl, renderable)
    render(texture, false)

    // printTexture(webgl, texture, 1)

    return { texture, scale, bbox: expandedBox, gridDim: dim, gridTexDim, gridTexScale }
}

function calcGaussianDensityTexture3d(webgl: WebGLContext, position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps, texture?: Texture): GaussianDensityTextureData {
    const { gl, resources } = webgl
    const { smoothness } = props

    const { drawCount, positions, radii, groups, scale, expandedBox, dim } = prepareGaussianDensityData(position, box, radius, props)
    const [ dx, dy, dz ] = dim
    const minDistanceTexture = resources.texture('volume-float32', 'rgba', 'float', 'nearest')
    minDistanceTexture.define(dx, dy, dz)

    const gridTexScale = Vec2.create(1, 1)

    const renderable = getGaussianDensityRenderable(webgl, drawCount, positions, radii, groups, minDistanceTexture, expandedBox, dim, dim, gridTexScale, smoothness, props.resolution)

    //

    const { uCurrentSlice } = renderable.values

    const framebuffer = resources.framebuffer()
    framebuffer.bind()
    setRenderingDefaults(webgl)
    gl.viewport(0, 0, dx, dy)

    if (!texture) texture = resources.texture('volume-float32', 'rgba', 'float', 'nearest')
    texture.define(dx, dy, dz)

    function render(fbTex: Texture) {
        for (let i = 0; i < dz; ++i) {
            ValueCell.update(uCurrentSlice, i)
            fbTex.attachFramebuffer(framebuffer, 0, i)
            renderable.render()
        }
    }

    setupMinDistanceRendering(webgl, renderable)
    render(minDistanceTexture)

    setupDensityRendering(webgl, renderable)
    render(texture)

    setupGroupIdRendering(webgl, renderable)
    render(texture)

    return { texture, scale, bbox: expandedBox, gridDim: dim, gridTexDim: dim, gridTexScale }
}

//

function prepareGaussianDensityData(position: PositionData, box: Box3D, radius: (index: number) => number, props: GaussianDensityGPUProps) {
    const { resolution, radiusOffset } = props
    const scaleFactor = 1 / resolution

    const { indices, x, y, z, id } = position
    const n = OrderedSet.size(indices)

    const positions = new Float32Array(n * 3)
    const radii = new Float32Array(n)
    const groups = new Float32Array(n)

    let maxRadius = 0

    for (let i = 0; i < n; ++i) {
        const j = OrderedSet.getAt(indices, i);

        positions[i * 3] = x[j]
        positions[i * 3 + 1] = y[j]
        positions[i * 3 + 2] = z[j]
        const r = radius(j) + radiusOffset
        if (maxRadius < r) maxRadius = r
        radii[i] = r
        groups[i] = id ? id[i] : i
    }

    const pad = maxRadius * 2 + resolution * 4
    const expandedBox = Box3D.expand(Box3D(), box, Vec3.create(pad, pad, pad));
    const scaledBox = Box3D.scale(Box3D(), expandedBox, scaleFactor)
    const dim = Box3D.size(Vec3(), scaledBox)
    Vec3.ceil(dim, dim)

    const scale = Vec3.create(resolution, resolution, resolution)

    return { drawCount: n, positions, radii, groups, scale, expandedBox, dim }
}

function getGaussianDensityRenderable(webgl: WebGLContext, drawCount: number, positions: Float32Array, radii: Float32Array, groups: Float32Array, minDistanceTexture: Texture, box: Box3D, gridDim: Vec3, gridTexDim: Vec3, gridTexScale: Vec2, smoothness: number, resolution: number) {
    const extent = Vec3.sub(Vec3.zero(), box.max, box.min)

    const values: Values<typeof GaussianDensitySchema> = {
        drawCount: ValueCell.create(drawCount),
        instanceCount: ValueCell.create(1),

        aRadius: ValueCell.create(radii),
        aPosition: ValueCell.create(positions),
        aGroup: ValueCell.create(groups),

        uCurrentSlice: ValueCell.create(0),
        uCurrentX: ValueCell.create(0),
        uCurrentY: ValueCell.create(0),
        uBboxMin: ValueCell.create(box.min),
        uBboxSize: ValueCell.create(extent),
        uGridDim: ValueCell.create(gridDim),
        uGridTexDim: ValueCell.create(gridTexDim),
        uGridTexScale: ValueCell.create(gridTexScale),
        uAlpha: ValueCell.create(smoothness),
        uResolution: ValueCell.create(resolution),
        tMinDistanceTex: ValueCell.create(minDistanceTexture),

        dGridTexType: ValueCell.create(minDistanceTexture.getDepth() > 0 ? '3d' : '2d'),
        dCalcType: ValueCell.create('minDistance'),
    }

    const schema = { ...GaussianDensitySchema }
    const shaderCode = GaussianDensityShaderCode
    const renderItem =  createComputeRenderItem(webgl, 'points', shaderCode, schema, values)

    return createComputeRenderable(renderItem, values)
}

function setRenderingDefaults(ctx: WebGLContext) {
    const { gl, state } = ctx
    state.disable(gl.CULL_FACE)
    state.enable(gl.BLEND)
    state.disable(gl.DEPTH_TEST)
    state.disable(gl.SCISSOR_TEST)
    state.depthMask(false)
    state.clearColor(0, 0, 0, 0)
}

function setupMinDistanceRendering(webgl: WebGLContext, renderable: ComputeRenderable<any>) {
    const { gl, state } = webgl
    ValueCell.update(renderable.values.dCalcType, 'minDistance')
    renderable.update()
    state.colorMask(false, false, false, true)
    state.blendFunc(gl.ONE, gl.ONE)
    // the shader writes 1 - dist so we set blending to MAX
    if (!webgl.extensions.blendMinMax) {
        throw new Error('GPU gaussian surface calculation requires EXT_blend_minmax')
    }
    state.blendEquation(webgl.extensions.blendMinMax.MAX)
}

function setupDensityRendering(webgl: WebGLContext, renderable: ComputeRenderable<any>) {
    const { gl, state } = webgl
    ValueCell.update(renderable.values.dCalcType, 'density')
    renderable.update()
    state.colorMask(false, false, false, true)
    state.blendFunc(gl.ONE, gl.ONE)
    // state.colorMask(true, true, true, true)
    // state.blendFuncSeparate(gl.ONE, gl.ZERO, gl.ONE, gl.ONE)
    state.blendEquation(gl.FUNC_ADD)
}

function setupGroupIdRendering(webgl: WebGLContext, renderable: ComputeRenderable<any>) {
    const { gl, state } = webgl
    ValueCell.update(renderable.values.dCalcType, 'groupId')
    renderable.update()
    // overwrite color, don't change alpha
    state.colorMask(true, true, true, false)
    state.blendFunc(gl.ONE, gl.ZERO)
    state.blendEquation(gl.FUNC_ADD)
}

function getTexture2dSize(gridDim: Vec3) {
    const area = gridDim[0] * gridDim[1] * gridDim[2]
    const squareDim = Math.sqrt(area)
    const powerOfTwoSize = Math.pow(2, Math.ceil(Math.log(squareDim) / Math.log(2)))

    let texDimX = 0
    let texDimY = gridDim[1]
    let texRows = 1
    let texCols = gridDim[2]
    if (powerOfTwoSize < gridDim[0] * gridDim[2]) {
        texCols = Math.floor(powerOfTwoSize / gridDim[0])
        texRows = Math.ceil(gridDim[2] / texCols)
        texDimX = texCols * gridDim[0]
        texDimY *= texRows
    } else {
        texDimX = gridDim[0] * gridDim[2]
    }
    return { texDimX, texDimY, texRows, texCols, powerOfTwoSize: texDimY < powerOfTwoSize ? powerOfTwoSize : powerOfTwoSize * 2 }
}

export function fieldFromTexture2d(ctx: WebGLContext, texture: Texture, dim: Vec3, texDim: Vec3) {
    // console.time('fieldFromTexture2d')
    const { resources } = ctx
    const [ dx, dy, dz ] = dim
    // const { width, height } = texture
    const [ width, height ] = texDim
    const fboTexCols = Math.floor(width / dx)

    const space = Tensor.Space(dim, [2, 1, 0], Float32Array)
    const data = space.create()
    const field = Tensor.create(space, data)
    const idData = space.create()
    const idField = Tensor.create(space, idData)

    // const image = new Uint8Array(width * height * 4)
    const image = new Float32Array(width * height * 4)

    const framebuffer = resources.framebuffer()
    framebuffer.bind()
    texture.attachFramebuffer(framebuffer, 0)
    ctx.readPixels(0, 0, width, height, image)

    // printImageData(createImageData(image, width, height), 1/3)

    let j = 0
    let tmpCol = 0
    let tmpRow = 0
    for (let iz = 0; iz < dz; ++iz) {
        if (tmpCol >= fboTexCols ) {
            tmpCol = 0
            tmpRow += dy
        }
        for (let iy = 0; iy < dy; ++iy) {
            for (let ix = 0; ix < dx; ++ix) {
                const idx = 4 * (tmpCol * dx + (iy + tmpRow) * width + ix)
                data[j] = image[idx + 3] // / 255
                idData[j] = decodeFloatRGB(image[idx] * 255, image[idx + 1] * 255, image[idx + 2] * 255)
                j++
            }
        }
        tmpCol++
    }

    // console.timeEnd('fieldFromTexture2d')

    return { field, idField }
}