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/*
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sha1 hash functionality
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*/
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import { createHash, type BinaryToTextEncoding } from "crypto";
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// compute sha1 hash of data in hex
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export function sha1(
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  data: Buffer | string,
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  encoding: BinaryToTextEncoding = "hex",
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): string {
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  const sha1sum = createHash("sha1");
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  if (typeof data === "string") {
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    sha1sum.update(data, "utf8");
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  } else {
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    // Convert Buffer to Uint8Array
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    const uint8Array = new Uint8Array(
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      data.buffer,
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      data.byteOffset,
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      data.byteLength,
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    );
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    sha1sum.update(uint8Array);
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  }
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  return sha1sum.digest(encoding);
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}
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export function sha1base64(data: Buffer | string): string {
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  return sha1(data, "base64");
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}
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// Compute a uuid v4 from the Sha-1 hash of data.
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// Optionally, if knownSha1 is given, just uses that, rather than recomputing it.
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// WARNING: try to avoid using this, since it discards information!
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export function uuidsha1(data: Buffer | string, knownSha1?: string): string {
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  const s = knownSha1 ?? sha1(data);
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  let i = -1;
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  return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, (c) => {
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    i += 1;
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    switch (c) {
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      case "x":
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        return s[i] ?? "0";
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      case "y":
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        // take 8 + low order 3 bits of hex number.
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        return ((parseInt("0x" + s[i], 16) & 0x3) | 0x8).toString(16);
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    }
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    return "0";
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  });
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}
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