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/*
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Return best(=biggest or svg) logo for the kernel, e.g.,
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  {filename:"logo-svg.svg", base64:"base-64 version of logo-svg.svg"}.
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Throws error if there is no logo for the given kernel.
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If we get a logo successfully, we cache it for an hour, unless the noCache option is given.
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*/
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import { get_kernel_data } from "@cocalc/jupyter/kernel/kernel-data";
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import { join } from "path";
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import { readdir, readFile } from "fs/promises";
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import LRU from "lru-cache";
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interface Logo {
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  filename: string;
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  base64: string;
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}
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const cache = new LRU<string, Logo>({
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  ttl: 60 * 60 * 1000,
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  max: 30,
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});
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function getKernel(kernelData, name) {
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  for (const k of kernelData) {
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    if (k.name == name) {
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      return k;
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    }
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  }
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  return null;
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}
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export async function logo(
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  kernelName: string,
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  { noCache }: { noCache?: boolean } = {},
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): Promise<Logo> {
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  if (!noCache && cache.has(kernelName)) {
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    return cache.get(kernelName)!;
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  }
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  const kernelData = await get_kernel_data({ noCache });
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  const kernel = getKernel(kernelData, kernelName);
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  if (kernel == null) {
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    const msg = `no such kernel '${kernelName}'`;
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    throw Error(msg);
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  }
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  const resource_dir = kernel.resource_dir;
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  // get the files from resource_dir, which may include:
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  //    logo-32x32.png  logo-64x64.png  logo-svg.svg
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  // and sort in reverse alphabetical order and select first.
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  // This gets 64x64 above 32x32 and 128x128 above 64x64, but
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  // svg very first, since it's the best.
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  // get the files from resource_dir
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  const files = (await readdir(resource_dir)).filter((name) =>
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    name.startsWith("logo-"),
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  );
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  // sort in reverse alphabetical order
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  files.sort((a, b) => b.localeCompare(a));
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  // select the first file, if any
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  const selectedFile = files[0];
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  let base64;
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  if (selectedFile) {
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    // Read the file and encode it in base64
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    const filePath = join(resource_dir, selectedFile);
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    const fileBuffer = await readFile(filePath);
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    base64 = fileBuffer.toString("base64");
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  } else {
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    base64 = "";
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  }
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  const x = { filename: selectedFile, base64 };
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  cache.set(kernelName, x);
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  return x;
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}
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