/*
 * Copyright (c) 2015-2018, IGN France.
 * Copyright (c) 2018-2026, Giro3D team.
 * SPDX-License-Identifier: MIT
 */

import type { TextureDataType, TypedArray } from 'three';

import {
    BaseClient,
    BaseResponse,
    fromCustomClient,
    globals as geotiffGlobals,
    Pool,
    type GeoTIFF,
    type GeoTIFFImage,
    type ReadRasterResult,
} from 'geotiff';
import { FloatType, MathUtils, Texture, UnsignedByteType, Vector2 } from 'three';

import type CoordinateSystem from '../core/geographic/CoordinateSystem';
import type { GridExtent } from '../core/geographic/Extent';
import type { CreateDataTextureResult } from '../utils/TextureGenerator';
import type { ImageResponse } from './ImageSource';

import { GlobalCache, type Cache } from '../core/Cache';
import Extent from '../core/geographic/Extent';
import { type GetMemoryUsageContext } from '../core/MemoryUsage';
import Fetcher from '../utils/Fetcher';
import PromiseUtils from '../utils/PromiseUtils';
import TextureGenerator from '../utils/TextureGenerator';
import { nonNull } from '../utils/tsutils';
import ConcurrentDownloader from './ConcurrentDownloader';
import ImageSource, { ImageResult, type ImageSourceOptions } from './ImageSource';

const DEFAULT_RETRIES = 3;
const DEFAULT_TIMEOUT = 10000;

const tmpDim = new Vector2();
const tmpCroppedDim = new Vector2();

let sharedPool: Pool | undefined = undefined;

/**
 * How the samples in the GeoTIFF files (also
 * known as bands), are mapped to the color channels of an RGB(A) image.
 *
 * Must be an array of either 1, 3 or 4 elements. Each element is the index of a sample in the
 * source file. For example, to map the samples 0, 3, and 2 to the R, G, B colors, you can use
 * `[0, 3, 2]`.
 *
 * - 1 element means the resulting image will be a grayscale image
 * - 3 elements means the resulting image will be a RGB image
 * - 4 elements means the resulting image will be a RGB image with an alpha channel.
 *
 * > [!note]
 * > If the channels is `undefined`, then they will be selected automatically with the
 * > following rules: if the image has 3 or more samples, the first 3 samples will be used,
 * > (i.e `[0, 1, 2]`). Otherwise, only the first sample will be used (i.e `[0]`). In any case,
 * > no transparency channel will be selected automatically, as there is no way to determine
 * > if a specific sample represents transparency.
 *
 * ## Examples
 *
 * - I have a color image, but I only want to see the blue channel (sample = 1): `[1]`
 * - I have a grayscale image, with only 1 sample: `[0]`
 * - I have a grayscale image with a transparency channel at index 1: `[0, 0, 0, 1]`
 * - I have a color image without a transparency channel: `[0, 1, 2]`
 * - I have a color image with a transparency channel at index 3: `[0, 1, 2, 3]`
 * - I have a color image with transparency at index 3, but I only want to see the blue channel:
 * `[1, 1, 1, 3]`
 * - I have a color image but in the B, G, R order: `[2, 1, 0]`
 */
export type ChannelMapping = [number] | [number, number, number] | [number, number, number, number];

function getPool(concurrency?: number): Pool | undefined {
    if (sharedPool == null && window.Worker != null) {
        sharedPool = new Pool(concurrency);
    }

    return sharedPool;
}

interface CachedBlock {
    data: ArrayBuffer;
    length: number;
}

/**
 * Determine if an image type is a mask.
 * See https://www.awaresystems.be/imaging/tiff/tifftags/newsubfiletype.html
 * Note: this function is taken from OpenLayers (GeoTIFF.js)
 * @param image - The image.
 * @returns `true` if the image is a mask.
 */
function isMask(image: GeoTIFFImage): boolean {
    const FILETYPE_MASK = 4;
    const fileDirectory = image.fileDirectory;
    const type = fileDirectory.getValue('NewSubfileType') ?? 0;

    return (type & FILETYPE_MASK) === FILETYPE_MASK;
}

/**
 * Determines if we can safely use the `readRGB()` method from geotiff.js for this image.
 */
function canReadRGB(image: GeoTIFFImage): boolean {
    if (image.getSamplesPerPixel() !== 3) {
        return false;
    }

    if (image.getBitsPerSample() > 8) {
        return false;
    }

    const ifd = image.fileDirectory;
    const interpretation: number = ifd.getValue('PhotometricInterpretation');
    const interpretations = geotiffGlobals.photometricInterpretations;
    return (
        interpretation === interpretations.CMYK ||
        interpretation === interpretations.YCbCr ||
        interpretation === interpretations.CIELab ||
        interpretation === interpretations.ICCLab
    );
}

export class FetcherResponse extends BaseResponse {
    public readonly response: Response;

    /**
     * BaseResponse facade for fetch API Response
     *
     * @param response - The response.
     */
    public constructor(response: Response) {
        super();
        this.response = response;
    }

    // @ts-expect-error (the base class does not type this getter)
    public get status(): number {
        return this.response.status;
    }

    public override getHeader(name: string): string {
        return this.response.headers.get(name) as string;
    }

    // @ts-expect-error (incorrectly typed base method, should be a Promise, but is an ArrayBuffer)
    public async getData(): Promise<ArrayBuffer> {
        const data = await this.response.arrayBuffer();
        return data;
    }
}

/**
 * A custom geotiff.js client that uses the Fetcher in order
 * to centralize requests and benefit from the HTTP configuration module.
 */
class FetcherClient extends BaseClient {
    private readonly _downloader: ConcurrentDownloader;
    private readonly _priority: RequestPriority;

    public constructor(
        url: string,
        options: { priority: RequestPriority; retries: number; httpTimeout: number },
    ) {
        super(url);
        this._priority = options.priority;
        this._downloader = new ConcurrentDownloader({
            fetch: Fetcher.fetch,
            retry: options.retries,
            timeout: options.httpTimeout,
        });
    }

    // @ts-expect-error (untyped base method)
    public async request({ headers, credentials, signal } = {}): Promise<FetcherResponse> {
        const response = await this._downloader.fetch(this.url, {
            headers,
            credentials,
            signal,
            priority: this._priority,
        });
        return new FetcherResponse(response);
    }
}

/**
 * A level in the GeoTIFF pyramid.
 */
interface Level {
    image: GeoTIFFImage;
    width: number;
    height: number;
    resolution: number[];
}

interface SizedArray<T> extends Array<T> {
    width: number;
    height: number;
}

function selectDataType(format: number, bitsPerSample: number): TextureDataType {
    switch (format) {
        case 1: // unsigned integer data
            if (bitsPerSample <= 8) {
                return UnsignedByteType;
            }
            break;
        default:
            break;
    }
    return FloatType;
}

export interface GeoTIFFCacheOptions {
    /**
     * The cache size (in number of entries), of the underlying
     * [blocked source](https://geotiffjs.github.io/geotiff.js/BlockedSource_BlockedSource.html).
     * Default is `100`.
     */
    cacheSize?: number;
    /**
     * The block size (in bytes), of the underlying
     * [blocked source](https://geotiffjs.github.io/geotiff.js/BlockedSource_BlockedSource.html).
     * Default is `65536`.
     */
    blockSize?: number;
}

export interface GeoTIFFSourceOptions extends ImageSourceOptions {
    /**
     * The URL to the GeoTIFF image.
     */
    url: string;
    /**
     * The Coordinate Reference System of the image.
     */
    crs: CoordinateSystem;
    /**
     * How to map bands in the source GeoTIFF to color channels in Giro3D textures.
     */
    channels?: ChannelMapping;

    /**
     * Advanced caching options.
     */
    cacheOptions?: GeoTIFFCacheOptions;
    /**
     * The optional HTTP request timeout, in milliseconds.
     *
     * @defaultValue 10000
     */
    httpTimeout?: number;
    /**
     * How many retries to execute when an HTTP request ends up in error.
     * @defaultValue 3
     */
    retries?: number;
    /**
     * Enable web workers.
     * @defaultValue true
     */
    /**
     * Enables web workers for CPU-intensive processing.
     * @defaultValue true
     */
    enableWorkers?: boolean;
    /**
     * The maximum number of workers created by the worker pool.
     * If `undefined`, the maximum number of workers will be allowed.
     * @defaultValue undefined
     */
    workerConcurrency?: number;
}

/**
 * Provides data from a remote GeoTIFF file.
 *
 * Features:
 * - supports tiled and untiled TIFF images
 * - supports [Cloud Optimized GeoTIFF (COG)](https://www.cogeo.org/),
 * - supports various compression (LZW, DEFLATE, JPEG...)
 * - supports RGB and YCbCr color spaces
 * - supports grayscale (e.g elevation data) and color images,
 * - support high-dynamic range colors (8-bit, 16-bit and 32-bit floating point pixels),
 * - dynamic channel mapping,
 *
 * > [!note]
 * > Performance might be degraded if the GeoTIFF is not optimized for streaming. We recommend
 * > using [Cloud Optimized GeoTIFFs (COGs)](https://www.cogeo.org/) for best performance.
 */
class GeoTIFFSource extends ImageSource {
    public readonly isGeoTIFFSource: boolean = true as const;
    public override readonly type = 'GeoTIFFSource' as const;

    public readonly url: string;
    public readonly crs: CoordinateSystem;

    private readonly _cacheId: string = MathUtils.generateUUID();
    private readonly _cacheOptions?: GeoTIFFCacheOptions;
    private readonly _cache: Cache = GlobalCache;
    private readonly _pool: Pool | undefined;
    private readonly _enableWorkers: boolean;
    private readonly _retries: number;
    private readonly _httpTimeout: number;

    private _imageCount: number;
    private _images: Level[];
    private _masks: Level[];
    private _channels: ChannelMapping = [0, 1, 2];

    // Fields available after initialization
    private _tiffImage?: GeoTIFF;
    private _extent?: Extent;
    private _dimensions?: Vector2;
    private _sampleCount?: number;
    private _initialized = false;
    private _origin?: number[];
    private _nodata?: number | null;
    private _initializePromise?: Promise<void>;

    /**
     * Creates a {@link GeoTIFFSource} source.
     *
     * @param options - options
     */
    public constructor(options: GeoTIFFSourceOptions) {
        super({ ...options, flipY: options.flipY ?? true });

        this.url = options.url;
        this.crs = options.crs;
        this._enableWorkers = options.enableWorkers ?? true;
        this._pool = this._enableWorkers ? getPool(options.workerConcurrency) : undefined;
        this._imageCount = 0;
        this._images = [];
        this._masks = [];
        this._channels = options.channels ?? this._channels;
        this._cacheOptions = options.cacheOptions;
        this._retries = options.retries ?? DEFAULT_RETRIES;
        this._httpTimeout = options.httpTimeout ?? DEFAULT_TIMEOUT;
    }

    private getInternalCache(): Map<number, CachedBlock> | undefined {
        if (!this._tiffImage) {
            return undefined;
        }

        const source = this._tiffImage.source;

        if ('blockCache' in source && source.blockCache instanceof Map) {
            return source.blockCache;
        }

        return undefined;
    }

    public override getMemoryUsage(context: GetMemoryUsageContext): void {
        if (!this._tiffImage) {
            return;
        }
        const cache = this.getInternalCache();

        if (cache) {
            let bytes = 0;

            cache.forEach((block: CachedBlock) => {
                bytes += block.data.byteLength;
            });

            context.objects.set(`${this.type}-${this._cacheId}`, {
                cpuMemory: bytes,
                gpuMemory: 0,
            });
        }
    }

    public getExtent(): Extent {
        return nonNull(this._extent);
    }

    public getCrs(): CoordinateSystem {
        return this.crs;
    }

    /**
     * Attemps to compute the exact extent of the TIFF image.
     *
     * @param crs - The CRS.
     * @param tiffImage - The TIFF image.
     */
    public static computeExtent(crs: CoordinateSystem, tiffImage: GeoTIFFImage): Extent {
        const [minx, miny, maxx, maxy] = tiffImage.getBoundingBox();

        const extent = new Extent(crs, minx, maxx, miny, maxy);
        return extent;
    }

    private adjustExtentAndPixelSizeForEquirectangular(
        requestExtent: Extent,
        requestWidth: number,
        requestHeight: number,
        margin = 0,
    ): GridExtent {
        // First, ensure that the input extent is not bigger than our image
        const croppedExtent = requestExtent.clone().intersect(nonNull(this._extent));

        const origDims = requestExtent.dimensions(tmpDim);
        const croppedDims = croppedExtent.dimensions(tmpCroppedDim);

        // Adjust the theoretical dimensions of the cropped image
        const croppedWidth = Math.round((croppedDims.width / origDims.width) * requestWidth);
        const croppedHeight = Math.round((croppedDims.height / origDims.height) * requestHeight);

        const { image } = this.selectLevel(croppedExtent.clone(), croppedWidth, croppedHeight);

        const [pixelWidth, pixelHeight] = image.resolution;

        // Then compute a new extent with the added pixel margins
        const marginExtent = croppedExtent.withMargin(
            Math.abs(pixelWidth * margin),
            Math.abs(pixelHeight * margin),
        );

        // Finally, ensure that this margin extent exactly fits on the geotiff image pixel borders
        const result = marginExtent.fitToGrid(nonNull(this._extent), image.width, image.height);

        return result;
    }

    /**
     * @param requestExtent - The request extent.
     * @param requestWidth - The width, in pixels, of the request extent.
     * @param requestHeight - The height, in pixels, of the request extent.
     * @param margin - The margin, in pixels.
     * @returns The adjusted parameters.
     */
    public override adjustExtentAndPixelSize(
        requestExtent: Extent,
        requestWidth: number,
        requestHeight: number,
        margin = 0,
    ): GridExtent {
        // Special case to avoid the ugly visible seam at the 180° line on
        // spherical panoramas.
        // https://gitlab.com/giro3d/giro3d/-/issues/630
        if (this.crs.id === 'equirectangular') {
            return this.adjustExtentAndPixelSizeForEquirectangular(
                requestExtent,
                requestWidth,
                requestHeight,
                margin,
            );
        }

        const { image } = this.selectLevel(requestExtent, requestWidth, requestHeight);

        const dims = nonNull(this._dimensions);

        const pixelWidth = dims.x / image.width;
        const pixelHeight = dims.y / image.height;

        const marginExtent = requestExtent.withMargin(pixelWidth * margin, pixelHeight * margin);

        const adjustedWidth = Math.floor(marginExtent.dimensions(tmpDim).x / pixelWidth);
        const adjustedHeight = Math.floor(marginExtent.dimensions(tmpDim).y / pixelHeight);

        let width = requestWidth;
        let height = requestHeight;

        // Ensure that we are not returning texture sizes that are too big, which can
        // happen when the source is much smaller than the map that hosts it.
        const threshold = 100; // pixels

        if (
            adjustedWidth < requestWidth + threshold &&
            adjustedHeight < requestHeight + threshold
        ) {
            width = adjustedWidth;
            height = adjustedHeight;
        }

        return {
            extent: marginExtent,
            width,
            height,
        };
    }

    public override initialize(): Promise<void> {
        if (!this._initializePromise) {
            this._initializePromise = this.initializeOnce();
        }

        return this._initializePromise;
    }

    private async initializeOnce(): Promise<void> {
        if (this._initialized) {
            return;
        }

        const opts = {
            cacheSize: this._cacheOptions?.cacheSize,
            blockSize: this._cacheOptions?.blockSize,
        };
        const url = this.url;
        const client = new FetcherClient(url, {
            priority: this.priority,
            retries: this._retries,
            httpTimeout: this._httpTimeout,
        });
        // We are using a custom client to ensure that outgoing requests are done through
        // the Fetcher so we can benefit from automatic HTTP configuration and control over
        // outgoing requests.
        // @ts-expect-error (typing issue with geotiff.js)
        this._tiffImage = await fromCustomClient(client, opts);

        // Get original image header
        const firstImage = await this._tiffImage.getImage();

        this._extent = GeoTIFFSource.computeExtent(this.crs, firstImage);
        this._dimensions = this._extent.dimensions();

        this._origin = firstImage.getOrigin();
        // Samples are equivalent to GDAL's bands
        this._sampleCount = firstImage.getSamplesPerPixel();

        // Automatic selection of channels, if the user did not specify a mapping.
        if (this._sampleCount < this._channels.length) {
            this._channels = [0];
        }

        this._nodata = firstImage.getGDALNoData();

        const format = firstImage.getSampleFormat();
        const bps = firstImage.getBitsPerSample();

        this.datatype = selectDataType(format, bps);

        function makeLevel(image: GeoTIFFImage, resolution: number[]): Level {
            return {
                image,
                width: image.getWidth(),
                height: image.getHeight(),
                resolution,
            };
        }

        this._images.push(makeLevel(firstImage, firstImage.getResolution()));

        const rawImageCount = await this._tiffImage.getImageCount();
        let nonMaskImageCount = 1; // Includes the main image previously pushed

        // We want to preserve the order of the overviews so we await them inside
        // the loop not to have the smallest overviews coming before the biggest

        for (let i = 1; i < rawImageCount; i++) {
            const image = await this._tiffImage.getImage(i);
            const level = makeLevel(image, image.getResolution(firstImage));

            if (isMask(image)) {
                this._masks.push(level);
            } else {
                nonMaskImageCount++;
                this._images.push(level);
            }
        }

        // Number of images (original + overviews)
        this._imageCount = nonMaskImageCount;
        this._initialized = true;
    }

    /**
     * Returns a window in the image's coordinates that matches the requested extent.
     *
     * @param extent - The window extent.
     * @param resolution - The spatial resolution of the window.
     * @returns The window.
     */
    private makeWindowFromExtent(
        extent: Extent,
        resolution: number[],
    ): [number, number, number, number] {
        const [oX, oY] = nonNull(this._origin);
        const [imageResX, imageResY] = resolution;
        const ext = extent.values;

        const wnd = [
            Math.round((ext[0] - oX) / imageResX),
            Math.round((ext[2] - oY) / imageResY),
            Math.round((ext[1] - oX) / imageResX),
            Math.round((ext[3] - oY) / imageResY),
        ];

        const xmin = Math.min(wnd[0], wnd[2]);
        let xmax = Math.max(wnd[0], wnd[2]);
        const ymin = Math.min(wnd[1], wnd[3]);
        let ymax = Math.max(wnd[1], wnd[3]);

        // prevent zero-sized requests
        if (Math.abs(xmax - xmin) === 0) {
            xmax += 1;
        }
        if (Math.abs(ymax - ymin) === 0) {
            ymax += 1;
        }

        return [xmin, ymin, xmax, ymax];
    }

    /**
     * Creates a texture from the pixel buffer(s).
     *
     * @param buffers - The buffers (one buffer per band)
     * @returns The generated texture.
     */
    private async createTexture(buffers: SizedArray<TypedArray>): Promise<CreateDataTextureResult> {
        // Width and height in pixels of the returned data.
        // The geotiff.js patches the arrays with the width and height properties.
        const { width, height }: SizedArray<TypedArray> = buffers;

        const dataType = this.datatype;

        const { texture, min, max } = await TextureGenerator.createDataTextureAsync(
            {
                width,
                height,
                nodata: this._nodata ?? undefined,
                enableWorkers: this._enableWorkers,
            },
            dataType,
            ...buffers,
        );

        return { texture, min, max };
    }

    /**
     * Select the best overview level (or the final image) to match the
     * requested extent and pixel width and height.
     *
     * @param requestExtent - The window extent.
     * @param requestWidth - The pixel width of the window.
     * @param requestHeight - The pixel height of the window.
     * @returns The selected zoom level.
     */
    private selectLevel(
        requestExtent: Extent,
        requestWidth: number,
        requestHeight: number,
    ): { image: Level; mask: Level } {
        // Number of images  = original + overviews if any
        const imageCount = this._imageCount;
        const cropped = requestExtent.clone().intersect(nonNull(this._extent));
        // Dimensions of the requested extent
        const extentDimension = cropped.dimensions(tmpDim);

        const targetResolution = Math.min(
            extentDimension.x / requestWidth,
            extentDimension.y / requestHeight,
        );

        let image: Level = this._images[imageCount - 1];
        let mask: Level = this._masks[imageCount - 1];

        // Select the image with the best resolution for our needs
        for (let i = imageCount - 1; i >= 0; i--) {
            image = this._images[i];
            mask = this._masks[i];

            const dims = nonNull(this._dimensions);

            const sourceResolution = Math.min(dims.x / image.width, dims.y / image.height);

            if (targetResolution >= sourceResolution) {
                break;
            }
        }

        return { image, mask };
    }

    /**
     * Gets or sets the channel mapping.
     */
    public get channels(): ChannelMapping {
        return this._channels;
    }

    public set channels(value: ChannelMapping) {
        if (value == null) {
            throw new Error('expected non-null value');
        }
        const length = value.length;

        if (!(length === 1 || length === 3 || length === 4)) {
            throw new Error(`channels must be either a 1, 3 or 4 element array, got: ${length}`);
        }

        this._channels = value;
        this.update();
    }

    private async loadImage(opts: {
        extent: Extent;
        width: number;
        height: number;
        id: string;
        signal?: AbortSignal;
    }): Promise<ImageResult> {
        const { extent, width, height, id, signal } = opts;

        const { image, mask } = this.selectLevel(extent, width, height);

        const adjusted = extent.fitToGrid(nonNull(this._extent), image.width, image.height, 8, 8);

        const actualExtent = adjusted.extent;

        const buffers = await this.getRegionBuffers(
            actualExtent,
            image,
            this._channels,
            signal,
            id,
        );

        signal?.throwIfAborted();

        let texture: Texture;
        let min: number | undefined = undefined;
        let max: number | undefined = undefined;

        if (buffers == null) {
            texture = new Texture();
        } else {
            if (mask != null && buffers.length === 3) {
                const alpha = await this.processTransparencyMask(mask, actualExtent, signal, id);
                if (alpha) {
                    buffers.push(alpha);
                }
            }

            const result = await this.createTexture(buffers as SizedArray<TypedArray>);
            texture = result.texture;
            min = result.min;
            max = result.max;
        }

        const result = { extent: actualExtent, texture, id, min, max };

        return new ImageResult(result);
    }

    private async processTransparencyMask(
        mask: Level,
        extent: Extent,
        signal: AbortSignal | undefined,
        id: string,
    ): Promise<TypedArray | null> {
        const bufs = await this.getRegionBuffers(extent, mask, [0], signal, id);
        if (!bufs) {
            return null;
        }

        const alpha = bufs[0];

        const is1bit = mask.image.getBitsPerSample() === 1;

        // Peform 8-bit expansion
        if (is1bit) {
            for (let i = 0; i < alpha.length; i++) {
                alpha[i] = alpha[i] * 255;
            }
        }

        return alpha;
    }

    private async readWindow(
        image: GeoTIFFImage,
        window: number[],
        channels: ChannelMapping,
        signal?: AbortSignal,
    ): Promise<ReadRasterResult> {
        if (canReadRGB(image)) {
            return await image.readRGB({
                pool: this._pool,
                window,
                signal,
                interleave: false,
            });
        }

        // TODO possible optimization: instead of letting geotiff.js crop and resample
        // the tiles into the desired region, we could use image.getTileOrStrip() to
        // read individual tiles (aka blocks) and make a texture per block. This way,
        // there would not be multiple concurrent reads for the same block, and we would not
        // waste time resampling the blocks since resampling is already done in the composer.
        // We would create more textures, but it could be worth it.
        const buf = await image.readRasters({
            pool: this._pool,
            fillValue: this._nodata ?? undefined,
            samples: channels,
            window,
            signal,
        });

        return buf;
    }

    /**
     * @param image - The image to read.
     * @param window - The image region to read.
     * @param signal - The abort signal.
     * @returns The buffers.
     */
    private async fetchBuffer(
        image: GeoTIFFImage,
        window: number[],
        channels: ChannelMapping,
        signal?: AbortSignal,
    ): Promise<TypedArray | TypedArray[] | null> {
        signal?.throwIfAborted();

        try {
            return await this.readWindow(image, window, channels, signal);
        } catch (e) {
            if (e instanceof Error) {
                if (e.toString() === 'AggregateError: Request failed') {
                    // Problem with the source that is blocked by another fetch
                    // (request failed in readRasters). See the conversations in
                    // https://github.com/geotiffjs/geotiff.js/issues/218
                    // https://github.com/geotiffjs/geotiff.js/issues/221
                    // https://github.com/geotiffjs/geotiff.js/pull/224
                    // Retry until it is not blocked.
                    // TODO retry counter
                    await PromiseUtils.delay(100);
                    return this.fetchBuffer(image, window, channels, signal);
                }
                if (e.name !== 'AbortError') {
                    console.error(e);
                }
            } else {
                console.error(e);
            }
            return null;
        }
    }

    /**
     * Extract a region from the specified image.
     *
     * @param extent - The request extent.
     * @param imageInfo - The image to sample.
     * @param signal - The abort signal.
     * @param id - The request id.
     * @returns The buffer(s).
     */
    private async getRegionBuffers(
        extent: Extent,
        imageInfo: Level,
        channels: ChannelMapping,
        signal: AbortSignal | undefined,
        id: string,
    ): Promise<TypedArray[] | null> {
        const window = this.makeWindowFromExtent(extent, imageInfo.resolution);

        const cacheKey = `${this._cacheId}-${id}-${channels.join(',')}`;
        const cached = this._cache.get(cacheKey);
        if (cached != null) {
            return cached as TypedArray[];
        }

        const buf = await this.fetchBuffer(imageInfo.image, window, channels, signal);

        if (buf == null) {
            return null;
        }

        let result: TypedArray[];
        let size = 0;

        if (Array.isArray(buf)) {
            size = buf.map(b => b.byteLength).reduce((a, b) => a + b);
            result = buf;
        } else {
            size = buf.byteLength;
            result = [buf];
        }
        this._cache.set(cacheKey, result, { size });

        return result;
    }

    public getImages(options: {
        id: string;
        extent: Extent;
        width: number;
        height: number;
        signal?: AbortSignal;
    }): ImageResponse[] {
        const { signal, id } = options;

        signal?.throwIfAborted();

        const opts = { ...options, id };

        const request = (): Promise<ImageResult> => this.loadImage(opts);

        return [{ id, request }];
    }

    public override dispose(): void {
        this.getInternalCache()?.clear();
    }
}

export function isGeoTIFFSource(obj: unknown): obj is GeoTIFFSource {
    return (obj as GeoTIFFSource).isGeoTIFFSource === true;
}

export default GeoTIFFSource;