// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import type {TextureLevel} from '@loaders.gl/schema';
import {read} from 'ktx-parse';
import {extractMipmapImages} from '../utils/extract-mipmap-images';
import {mapVkFormatToWebGL} from '../utils/ktx-format-helper';

const KTX2_ID = [
  // '´', 'K', 'T', 'X', '2', '0', 'ª', '\r', '\n', '\x1A', '\n'
  0xab, 0x4b, 0x54, 0x58, 0x20, 0x32, 0x30, 0xbb, 0x0d, 0x0a, 0x1a, 0x0a
];

// eslint-disable-next-line complexity
export function isKTX(data: ArrayBuffer) {
  // const id = new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
  const id = new Uint8Array(data);
  const notKTX =
    id.byteLength < KTX2_ID.length ||
    id[0] !== KTX2_ID[0] || // '´'
    id[1] !== KTX2_ID[1] || // 'K'
    id[2] !== KTX2_ID[2] || // 'T'
    id[3] !== KTX2_ID[3] || // 'X'
    id[4] !== KTX2_ID[4] || // ' '
    id[5] !== KTX2_ID[5] || // '2'
    id[6] !== KTX2_ID[6] || // '0'
    id[7] !== KTX2_ID[7] || // 'ª'
    id[8] !== KTX2_ID[8] || // '\r'
    id[9] !== KTX2_ID[9] || // '\n'
    id[10] !== KTX2_ID[10] || // '\x1A'
    id[11] !== KTX2_ID[11]; // '\n'

  return !notKTX;
}

export function parseKTX(arrayBuffer: ArrayBuffer): TextureLevel[] {
  const uint8Array = new Uint8Array(arrayBuffer);
  const ktx = read(uint8Array);
  const mipMapLevels = Math.max(1, ktx.levels.length);
  const width = ktx.pixelWidth;
  const height = ktx.pixelHeight;
  const internalFormat = mapVkFormatToWebGL(ktx.vkFormat);

  return extractMipmapImages(ktx.levels, {
    mipMapLevels,
    width,
    height,
    sizeFunction: (level: any): number => level.uncompressedByteLength,
    internalFormat
  });
}