import { Nullable } from "../types";
import { Tools } from "./tools";
import { Vector3 } from "../Maths/math.vector";
import { Scalar } from "../Maths/math.scalar";
import { SphericalPolynomial } from "../Maths/sphericalPolynomial";
import { InternalTexture, InternalTextureSource } from "../Materials/Textures/internalTexture";
import { BaseTexture } from "../Materials/Textures/baseTexture";
import { Constants } from "../Engines/constants";
import { Scene } from "../scene";
import { PostProcess } from "../PostProcesses/postProcess";
import { Logger } from "../Misc/logger";

import "../Engines/Extensions/engine.renderTargetCube";
import "../Engines/Extensions/engine.readTexture";
import "../Materials/Textures/baseTexture.polynomial";

import "../Shaders/rgbdEncode.fragment";
import "../Shaders/rgbdDecode.fragment";
import { Engine } from '../Engines/engine';
import { ThinEngine } from '../Engines/thinEngine';
import { RGBDTextureTools } from './rgbdTextureTools';

/**
 * Raw texture data and descriptor sufficient for WebGL texture upload
 */
export interface EnvironmentTextureInfo {
    /**
     * Version of the environment map
     */
    version: number;

    /**
     * Width of image
     */
    width: number;

    /**
     * Irradiance information stored in the file.
     */
    irradiance: any;

    /**
     * Specular information stored in the file.
     */
    specular: any;
}

/**
 * Defines One Image in the file. It requires only the position in the file
 * as well as the length.
 */
interface BufferImageData {
    /**
     * Length of the image data.
     */
    length: number;
    /**
     * Position of the data from the null terminator delimiting the end of the JSON.
     */
    position: number;
}

/**
 * Defines the specular data enclosed in the file.
 * This corresponds to the version 1 of the data.
 */
export interface EnvironmentTextureSpecularInfoV1 {
    /**
     * Defines where the specular Payload is located. It is a runtime value only not stored in the file.
     */
    specularDataPosition?: number;
    /**
     * This contains all the images data needed to reconstruct the cubemap.
     */
    mipmaps: Array<BufferImageData>;
    /**
     * Defines the scale applied to environment texture. This manages the range of LOD level used for IBL according to the roughness.
     */
    lodGenerationScale: number;
}

/**
 * Defines the required storage to save the environment irradiance information.
 */
interface EnvironmentTextureIrradianceInfoV1 {
    x: Array<number>;
    y: Array<number>;
    z: Array<number>;

    xx: Array<number>;
    yy: Array<number>;
    zz: Array<number>;

    yz: Array<number>;
    zx: Array<number>;
    xy: Array<number>;
}

/**
 * Sets of helpers addressing the serialization and deserialization of environment texture
 * stored in a BabylonJS env file.
 * Those files are usually stored as .env files.
 */
export class EnvironmentTextureTools {

    /**
     * Magic number identifying the env file.
     */
    private static _MagicBytes = [0x86, 0x16, 0x87, 0x96, 0xf6, 0xd6, 0x96, 0x36];

    /**
     * Gets the environment info from an env file.
     * @param data The array buffer containing the .env bytes.
     * @returns the environment file info (the json header) if successfully parsed.
     */
    public static GetEnvInfo(data: ArrayBufferView): Nullable<EnvironmentTextureInfo> {
        let dataView = new DataView(data.buffer, data.byteOffset, data.byteLength);
        let pos = 0;

        for (let i = 0; i < EnvironmentTextureTools._MagicBytes.length; i++) {
            if (dataView.getUint8(pos++) !== EnvironmentTextureTools._MagicBytes[i]) {
                Logger.Error('Not a babylon environment map');
                return null;
            }
        }

        // Read json manifest - collect characters up to null terminator
        let manifestString = '';
        let charCode = 0x00;
        while ((charCode = dataView.getUint8(pos++))) {
            manifestString += String.fromCharCode(charCode);
        }

        let manifest: EnvironmentTextureInfo = JSON.parse(manifestString);
        if (manifest.specular) {
            // Extend the header with the position of the payload.
            manifest.specular.specularDataPosition = pos;
            // Fallback to 0.8 exactly if lodGenerationScale is not defined for backward compatibility.
            manifest.specular.lodGenerationScale = manifest.specular.lodGenerationScale || 0.8;
        }

        return manifest;
    }

    /**
     * Creates an environment texture from a loaded cube texture.
     * @param texture defines the cube texture to convert in env file
     * @return a promise containing the environment data if succesfull.
     */
    public static async CreateEnvTextureAsync(texture: BaseTexture): Promise<ArrayBuffer> {
        let internalTexture = texture.getInternalTexture();
        if (!internalTexture) {
            return Promise.reject("The cube texture is invalid.");
        }

        let engine = internalTexture.getEngine() as Engine;

        if (texture.textureType === Constants.TEXTURETYPE_UNSIGNED_INT) {
            return Promise.reject("The cube texture should allow HDR (Full Float or Half Float).");
        }

        let textureType = Constants.TEXTURETYPE_FLOAT;
        if (!engine.getCaps().textureFloatRender) {
            textureType = Constants.TEXTURETYPE_HALF_FLOAT;
            if (!engine.getCaps().textureHalfFloatRender) {
                return Promise.reject("Env texture can only be created when the browser supports half float or full float rendering.");
            }
        }

        let cubeWidth = internalTexture.width;
        let hostingScene = new Scene(engine);
        let specularTextures: { [key: number]: ArrayBuffer } = {};

        // As we are going to readPixels the faces of the cube, make sure the drawing/update commands for the cube texture are fully sent to the GPU in case it is drawn for the first time in this very frame!
        engine.flushFramebuffer();

        // Read and collect all mipmaps data from the cube.
        let mipmapsCount = Scalar.ILog2(internalTexture.width);
        for (let i = 0; i <= mipmapsCount; i++) {
            let faceWidth = Math.pow(2, mipmapsCount - i);

            // All faces of the cube.
            for (let face = 0; face < 6; face++) {
                let faceData = await texture.readPixels(face, i);

                let tempTexture = engine.createRawTexture(faceData, faceWidth, faceWidth, Constants.TEXTUREFORMAT_RGBA, false, true, Constants.TEXTURE_NEAREST_SAMPLINGMODE, null, textureType);

                await RGBDTextureTools.EncodeTextureToRGBD(tempTexture, hostingScene, textureType);

                engine.flushFramebuffer(); // make sure the tempTexture has its data up to date when reading them just below

                const rgbdEncodedData = await engine._readTexturePixels(tempTexture, faceWidth, faceWidth);

                const pngEncodedata = await Tools.DumpDataAsync(faceWidth, faceWidth, rgbdEncodedData, "image/png", undefined, false, true);

                specularTextures[i * 6 + face] = pngEncodedata as ArrayBuffer;

                tempTexture.dispose();
            }
        }

        // We can delete the hosting scene keeping track of all the creation objects
        hostingScene.dispose();

        // Creates the json header for the env texture
        let info: EnvironmentTextureInfo = {
            version: 1,
            width: cubeWidth,
            irradiance: this._CreateEnvTextureIrradiance(texture),
            specular: {
                mipmaps: [],
                lodGenerationScale: texture.lodGenerationScale
            }
        };

        // Sets the specular image data information
        let position = 0;
        for (let i = 0; i <= mipmapsCount; i++) {
            for (let face = 0; face < 6; face++) {
                let byteLength = specularTextures[i * 6 + face].byteLength;
                info.specular.mipmaps.push({
                    length: byteLength,
                    position: position
                });
                position += byteLength;
            }
        }

        // Encode the JSON as an array buffer
        let infoString = JSON.stringify(info);
        let infoBuffer = new ArrayBuffer(infoString.length + 1);
        let infoView = new Uint8Array(infoBuffer); // Limited to ascii subset matching unicode.
        for (let i = 0, strLen = infoString.length; i < strLen; i++) {
            infoView[i] = infoString.charCodeAt(i);
        }
        // Ends up with a null terminator for easier parsing
        infoView[infoString.length] = 0x00;

        // Computes the final required size and creates the storage
        let totalSize = EnvironmentTextureTools._MagicBytes.length + position + infoBuffer.byteLength;
        let finalBuffer = new ArrayBuffer(totalSize);
        let finalBufferView = new Uint8Array(finalBuffer);
        let dataView = new DataView(finalBuffer);

        // Copy the magic bytes identifying the file in
        let pos = 0;
        for (let i = 0; i < EnvironmentTextureTools._MagicBytes.length; i++) {
            dataView.setUint8(pos++, EnvironmentTextureTools._MagicBytes[i]);
        }

        // Add the json info
        finalBufferView.set(new Uint8Array(infoBuffer), pos);
        pos += infoBuffer.byteLength;

        // Finally inserts the texture data
        for (let i = 0; i <= mipmapsCount; i++) {
            for (let face = 0; face < 6; face++) {
                let dataBuffer = specularTextures[i * 6 + face];
                finalBufferView.set(new Uint8Array(dataBuffer), pos);
                pos += dataBuffer.byteLength;
            }
        }

        // Voila
        return finalBuffer;
    }

    /**
     * Creates a JSON representation of the spherical data.
     * @param texture defines the texture containing the polynomials
     * @return the JSON representation of the spherical info
     */
    private static _CreateEnvTextureIrradiance(texture: BaseTexture): Nullable<EnvironmentTextureIrradianceInfoV1> {
        let polynmials = texture.sphericalPolynomial;
        if (polynmials == null) {
            return null;
        }

        return {
            x: [polynmials.x.x, polynmials.x.y, polynmials.x.z],
            y: [polynmials.y.x, polynmials.y.y, polynmials.y.z],
            z: [polynmials.z.x, polynmials.z.y, polynmials.z.z],

            xx: [polynmials.xx.x, polynmials.xx.y, polynmials.xx.z],
            yy: [polynmials.yy.x, polynmials.yy.y, polynmials.yy.z],
            zz: [polynmials.zz.x, polynmials.zz.y, polynmials.zz.z],

            yz: [polynmials.yz.x, polynmials.yz.y, polynmials.yz.z],
            zx: [polynmials.zx.x, polynmials.zx.y, polynmials.zx.z],
            xy: [polynmials.xy.x, polynmials.xy.y, polynmials.xy.z]
        } as any;
    }

    /**
     * Creates the ArrayBufferViews used for initializing environment texture image data.
     * @param data the image data
     * @param info parameters that determine what views will be created for accessing the underlying buffer
     * @return the views described by info providing access to the underlying buffer
     */
    public static CreateImageDataArrayBufferViews(data: ArrayBufferView, info: EnvironmentTextureInfo): Array<Array<ArrayBufferView>> {
        if (info.version !== 1) {
            throw new Error(`Unsupported babylon environment map version "${info.version}"`);
        }

        const specularInfo = info.specular as EnvironmentTextureSpecularInfoV1;

        // Double checks the enclosed info
        let mipmapsCount = Scalar.Log2(info.width);
        mipmapsCount = Math.round(mipmapsCount) + 1;
        if (specularInfo.mipmaps.length !== 6 * mipmapsCount) {
            throw new Error(`Unsupported specular mipmaps number "${specularInfo.mipmaps.length}"`);
        }

        const imageData = new Array<Array<ArrayBufferView>>(mipmapsCount);
        for (let i = 0; i < mipmapsCount; i++) {
            imageData[i] = new Array<ArrayBufferView>(6);
            for (let face = 0; face < 6; face++) {
                const imageInfo = specularInfo.mipmaps[i * 6 + face];
                imageData[i][face] = new Uint8Array(data.buffer, data.byteOffset + specularInfo.specularDataPosition! + imageInfo.position, imageInfo.length);
            }
        }

        return imageData;
    }

    /**
     * Uploads the texture info contained in the env file to the GPU.
     * @param texture defines the internal texture to upload to
     * @param data defines the data to load
     * @param info defines the texture info retrieved through the GetEnvInfo method
     * @returns a promise
     */
    public static UploadEnvLevelsAsync(texture: InternalTexture, data: ArrayBufferView, info: EnvironmentTextureInfo): Promise<void> {
        if (info.version !== 1) {
            throw new Error(`Unsupported babylon environment map version "${info.version}"`);
        }

        const specularInfo = info.specular as EnvironmentTextureSpecularInfoV1;
        if (!specularInfo) {
            // Nothing else parsed so far
            return Promise.resolve();
        }

        texture._lodGenerationScale = specularInfo.lodGenerationScale;

        const imageData = EnvironmentTextureTools.CreateImageDataArrayBufferViews(data, info);

        return EnvironmentTextureTools.UploadLevelsAsync(texture, imageData);
    }

    private static _OnImageReadyAsync(image: HTMLImageElement | ImageBitmap, engine: Engine, expandTexture: boolean,
        rgbdPostProcess:  Nullable<PostProcess>, url: string, face: number, i: number, generateNonLODTextures: boolean,
        lodTextures: Nullable<{ [lod: number]: BaseTexture }>, cubeRtt: Nullable<InternalTexture>, texture: InternalTexture
        ): Promise<void> {
            return new Promise((resolve, reject) => {
                if (expandTexture) {
                    let tempTexture = engine.createTexture(null, true, true, null, Constants.TEXTURE_NEAREST_SAMPLINGMODE, null,
                        (message) => {
                            reject(message);
                        },
                        image);

                    rgbdPostProcess!.getEffect().executeWhenCompiled(() => {
                        // Uncompress the data to a RTT
                        rgbdPostProcess!.onApply = (effect) => {
                            effect._bindTexture("textureSampler", tempTexture);
                            effect.setFloat2("scale", 1, 1);
                        };

                        engine.scenes[0].postProcessManager.directRender([rgbdPostProcess!], cubeRtt, true, face, i);

                        // Cleanup
                        engine.restoreDefaultFramebuffer();
                        tempTexture.dispose();
                        URL.revokeObjectURL(url);
                        resolve();
                    });
                }
                else {
                    engine._uploadImageToTexture(texture, image, face, i);

                    // Upload the face to the non lod texture support
                    if (generateNonLODTextures) {
                        let lodTexture = lodTextures![i];
                        if (lodTexture) {
                            engine._uploadImageToTexture(lodTexture._texture!, image, face, 0);
                        }
                    }
                    resolve();
                }
            }
        );
    }

    /**
     * Uploads the levels of image data to the GPU.
     * @param texture defines the internal texture to upload to
     * @param imageData defines the array buffer views of image data [mipmap][face]
     * @returns a promise
     */
    public static UploadLevelsAsync(texture: InternalTexture, imageData: ArrayBufferView[][]): Promise<void> {
        if (!Tools.IsExponentOfTwo(texture.width)) {
            throw new Error("Texture size must be a power of two");
        }

        const mipmapsCount = Scalar.ILog2(texture.width) + 1;

        // Gets everything ready.
        let engine = texture.getEngine() as Engine;
        let expandTexture = false;
        let generateNonLODTextures = false;
        let rgbdPostProcess: Nullable<PostProcess> = null;
        let cubeRtt: Nullable<InternalTexture> = null;
        let lodTextures: Nullable<{ [lod: number]: BaseTexture }> = null;
        let caps = engine.getCaps();

        texture.format = Constants.TEXTUREFORMAT_RGBA;
        texture.type = Constants.TEXTURETYPE_UNSIGNED_INT;
        texture.generateMipMaps = true;
        texture._cachedAnisotropicFilteringLevel = null;
        engine.updateTextureSamplingMode(Constants.TEXTURE_TRILINEAR_SAMPLINGMODE, texture);

        // Add extra process if texture lod is not supported
        if (!caps.textureLOD) {
            expandTexture = false;
            generateNonLODTextures = true;
            lodTextures = {};
        }
        // in webgl 1 there are no ways to either render or copy lod level information for float textures.
        else if (!ThinEngine.Features.supportRenderAndCopyToLodForFloatTextures) {
            expandTexture = false;
        }
        // If half float available we can uncompress the texture
        else if (caps.textureHalfFloatRender && caps.textureHalfFloatLinearFiltering) {
            expandTexture = true;
            texture.type = Constants.TEXTURETYPE_HALF_FLOAT;
        }
        // If full float available we can uncompress the texture
        else if (caps.textureFloatRender && caps.textureFloatLinearFiltering) {
            expandTexture = true;
            texture.type = Constants.TEXTURETYPE_FLOAT;
        }

        // Expand the texture if possible
        if (expandTexture) {
            // Simply run through the decode PP
            rgbdPostProcess = new PostProcess("rgbdDecode", "rgbdDecode", null, null, 1, null, Constants.TEXTURE_TRILINEAR_SAMPLINGMODE, engine, false, undefined, texture.type, undefined, null, false);

            texture._isRGBD = false;
            texture.invertY = false;
            cubeRtt = engine.createRenderTargetCubeTexture(texture.width, {
                generateDepthBuffer: false,
                generateMipMaps: true,
                generateStencilBuffer: false,
                samplingMode: Constants.TEXTURE_TRILINEAR_SAMPLINGMODE,
                type: texture.type,
                format: Constants.TEXTUREFORMAT_RGBA
            });
        }
        else {
            texture._isRGBD = true;
            texture.invertY = true;

            // In case of missing support, applies the same patch than DDS files.
            if (generateNonLODTextures) {
                let mipSlices = 3;
                let scale = texture._lodGenerationScale;
                let offset = texture._lodGenerationOffset;

                for (let i = 0; i < mipSlices; i++) {
                    //compute LOD from even spacing in smoothness (matching shader calculation)
                    let smoothness = i / (mipSlices - 1);
                    let roughness = 1 - smoothness;

                    let minLODIndex = offset; // roughness = 0
                    let maxLODIndex = (mipmapsCount - 1) * scale + offset; // roughness = 1 (mipmaps start from 0)

                    let lodIndex = minLODIndex + (maxLODIndex - minLODIndex) * roughness;
                    let mipmapIndex = Math.round(Math.min(Math.max(lodIndex, 0), maxLODIndex));

                    let glTextureFromLod = new InternalTexture(engine, InternalTextureSource.Temp);
                    glTextureFromLod.isCube = true;
                    glTextureFromLod.invertY = true;
                    glTextureFromLod.generateMipMaps = false;
                    engine.updateTextureSamplingMode(Constants.TEXTURE_LINEAR_LINEAR, glTextureFromLod);

                    // Wrap in a base texture for easy binding.
                    let lodTexture = new BaseTexture(null);
                    lodTexture.isCube = true;
                    lodTexture._texture = glTextureFromLod;
                    lodTextures![mipmapIndex] = lodTexture;

                    switch (i) {
                        case 0:
                            texture._lodTextureLow = lodTexture;
                            break;
                        case 1:
                            texture._lodTextureMid = lodTexture;
                            break;
                        case 2:
                            texture._lodTextureHigh = lodTexture;
                            break;
                    }
                }
            }
        }

        let promises: Promise<void>[] = [];
        // All mipmaps up to provided number of images
        for (let i = 0; i < imageData.length; i++) {
            // All faces
            for (let face = 0; face < 6; face++) {
                // Constructs an image element from image data
                let bytes = imageData[i][face];
                let blob = new Blob([bytes], { type: 'image/png' });
                let url = URL.createObjectURL(blob);
                let promise: Promise<void>;

                if (typeof Image === "undefined" || ThinEngine.Features.forceBitmapOverHTMLImageElement) {
                    promise = createImageBitmap(blob, { premultiplyAlpha: "none" }).then((img) => {
                        return this._OnImageReadyAsync(img, engine, expandTexture, rgbdPostProcess, url, face, i, generateNonLODTextures, lodTextures, cubeRtt, texture);
                    });
                } else {
                    let image = new Image();
                    image.src = url;

                    // Enqueue promise to upload to the texture.
                    promise = new Promise<void>((resolve, reject) => {
                        image.onload = () => {
                            this._OnImageReadyAsync(image, engine, expandTexture, rgbdPostProcess, url, face, i, generateNonLODTextures, lodTextures, cubeRtt, texture)
                            .then(() => resolve())
                            .catch((reason) => {
                                reject(reason);
                            });
                        };
                        image.onerror = (error) => {
                            reject(error);
                        };
                    });
                }
                promises.push(promise);
            }
        }

        // Fill remaining mipmaps with black textures.
        if (imageData.length < mipmapsCount) {
            let data: ArrayBufferView;
            const size = Math.pow(2, mipmapsCount - 1 - imageData.length);
            const dataLength = size * size * 4;
            switch (texture.type) {
                case Constants.TEXTURETYPE_UNSIGNED_INT: {
                    data = new Uint8Array(dataLength);
                    break;
                }
                case Constants.TEXTURETYPE_HALF_FLOAT: {
                    data = new Uint16Array(dataLength);
                    break;
                }
                case Constants.TEXTURETYPE_FLOAT: {
                    data = new Float32Array(dataLength);
                    break;
                }
            }
            for (let i = imageData.length; i < mipmapsCount; i++) {
                for (let face = 0; face < 6; face++) {
                    engine._uploadArrayBufferViewToTexture(texture, data!, face, i);
                }
            }
        }

        // Once all done, finishes the cleanup and return
        return Promise.all(promises).then(() => {
            // Release temp RTT.
            if (cubeRtt) {
                engine._releaseFramebufferObjects(cubeRtt);
                engine._releaseTexture(texture);
                cubeRtt._swapAndDie(texture);
            }
            // Release temp Post Process.
            if (rgbdPostProcess) {
                rgbdPostProcess.dispose();
            }
            // Flag internal texture as ready in case they are in use.
            if (generateNonLODTextures) {
                if (texture._lodTextureHigh && texture._lodTextureHigh._texture) {
                    texture._lodTextureHigh._texture.isReady = true;
                }
                if (texture._lodTextureMid && texture._lodTextureMid._texture) {
                    texture._lodTextureMid._texture.isReady = true;
                }
                if (texture._lodTextureLow && texture._lodTextureLow._texture) {
                    texture._lodTextureLow._texture.isReady = true;
                }
            }
        });
    }

    /**
     * Uploads spherical polynomials information to the texture.
     * @param texture defines the texture we are trying to upload the information to
     * @param info defines the environment texture info retrieved through the GetEnvInfo method
     */
    public static UploadEnvSpherical(texture: InternalTexture, info: EnvironmentTextureInfo): void {
        if (info.version !== 1) {
            Logger.Warn('Unsupported babylon environment map version "' + info.version + '"');
        }

        let irradianceInfo = info.irradiance as EnvironmentTextureIrradianceInfoV1;
        if (!irradianceInfo) {
            return;
        }

        const sp = new SphericalPolynomial();
        Vector3.FromArrayToRef(irradianceInfo.x, 0, sp.x);
        Vector3.FromArrayToRef(irradianceInfo.y, 0, sp.y);
        Vector3.FromArrayToRef(irradianceInfo.z, 0, sp.z);
        Vector3.FromArrayToRef(irradianceInfo.xx, 0, sp.xx);
        Vector3.FromArrayToRef(irradianceInfo.yy, 0, sp.yy);
        Vector3.FromArrayToRef(irradianceInfo.zz, 0, sp.zz);
        Vector3.FromArrayToRef(irradianceInfo.yz, 0, sp.yz);
        Vector3.FromArrayToRef(irradianceInfo.zx, 0, sp.zx);
        Vector3.FromArrayToRef(irradianceInfo.xy, 0, sp.xy);
        texture._sphericalPolynomial = sp;
    }

    /** @hidden */
    public static _UpdateRGBDAsync(internalTexture: InternalTexture, data: ArrayBufferView[][], sphericalPolynomial: Nullable<SphericalPolynomial>, lodScale: number, lodOffset: number): Promise<void> {
        internalTexture._source = InternalTextureSource.CubeRawRGBD;
        internalTexture._bufferViewArrayArray = data;
        internalTexture._lodGenerationScale = lodScale;
        internalTexture._lodGenerationOffset = lodOffset;
        internalTexture._sphericalPolynomial = sphericalPolynomial;

        return EnvironmentTextureTools.UploadLevelsAsync(internalTexture, data).then(() => {
            internalTexture.isReady = true;
        });
    }
}

// References the dependencies.
InternalTexture._UpdateRGBDAsync = EnvironmentTextureTools._UpdateRGBDAsync;