import crypto from "node:crypto";

type Algorithm = "sha256" | "sha512";

class Hasher {
  private algorithm: "sha256" | "sha512";
  private saltLength: number;

  constructor(algorithm: Algorithm = "sha256", saltLength: number = 64) {
    this.algorithm = algorithm;
    this.saltLength = saltLength;
  }

  verify(encoded: string, unencoded: string): boolean {
    const { algorithm, salt } = this.parse(encoded);
    return this.hash(unencoded, algorithm, salt) === encoded;
  }

  encode(string: string): string {
    const salt = crypto.randomBytes(this.saltLength).toString("base64");
    return this.hash(string, this.algorithm, salt);
  }

  hash(string: string, algorithm: Algorithm, salt: string): string {
    const hash = crypto.createHash(algorithm);
    hash.update(string);
    hash.update(salt, "utf8");
    return `${algorithm}:${salt}:${hash.digest("base64")}`;
  }

  private parse(encoded: string): {
    algorithm: Algorithm;
    salt: string;
    digest: string;
  } {
    const parts = encoded.split(":");

    if (parts.length !== 3) {
      throw new Error(
        `Invalid hash string. Expected 3 parts, got ${parts.length}`,
      );
    }

    const algorithm: Algorithm = parts[0] as Algorithm;
    const salt: string = parts[1];
    const digest: string = parts[2];

    return {
      algorithm,
      salt,
      digest,
    };
  }
}

export default new Hasher();

export { Hasher, type Algorithm };