import { createHash } from "node:crypto";
import fs from "node:fs";

export function sha256Bytes(data: Uint8Array): string {
  return createHash("sha256").update(data).digest("hex");
}

export function sha256Text(value: string): string {
  return createHash("sha256").update(value, "utf8").digest("hex");
}

export async function sha256File(filePath: string): Promise<string> {
  const hash = createHash("sha256");
  await new Promise<void>((resolve, reject) => {
    const stream = fs.createReadStream(filePath);
    stream.on("data", (chunk) => hash.update(chunk));
    stream.on("error", reject);
    stream.on("end", resolve);
  });
  return hash.digest("hex");
}

export function shortHash(value: string, length = 16): string {
  return sha256Text(value).slice(0, Math.max(0, Math.trunc(length)));
}

const CRC32_TABLE = (() => {
  const table = new Uint32Array(256);
  for (let index = 0; index < table.length; index++) {
    let value = index;
    for (let bit = 0; bit < 8; bit++) value = (value & 1) ? 0xedb88320 ^ (value >>> 1) : value >>> 1;
    table[index] = value >>> 0;
  }
  return table;
})();

export function crc32(data: Uint8Array): number {
  let crc = 0xffffffff;
  for (const byte of data) crc = CRC32_TABLE[(crc ^ byte) & 0xff] ^ (crc >>> 8);
  return (crc ^ 0xffffffff) >>> 0;
}