/**
 * EdDSA-Java by str4d
 *
 * <p>To the extent possible under law, the person who associated CC0 with EdDSA-Java has waived all
 * copyright and related or neighboring rights to EdDSA-Java.
 *
 * <p>You should have received a copy of the CC0 legalcode along with this work. If not, see
 * <https://creativecommons.org/publicdomain/zero/1.0/>.
 */
package org.mariadb.jdbc.plugin.authentication.standard.ed25519.spec;

import java.io.Serializable;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import org.mariadb.jdbc.plugin.authentication.standard.ed25519.math.Curve;
import org.mariadb.jdbc.plugin.authentication.standard.ed25519.math.GroupElement;
import org.mariadb.jdbc.plugin.authentication.standard.ed25519.math.ScalarOps;

/**
 * Parameter specification for an EdDSA algorithm.
 *
 * @author str4d
 */
public class EdDSAParameterSpec implements AlgorithmParameterSpec, Serializable {
  private static final long serialVersionUID = 8274987108472012L;
  private final Curve curve;
  private final String hashAlgo;
  private final ScalarOps sc;
  private final GroupElement B;

  /**
   * @param curve the curve
   * @param hashAlgo the JCA string for the hash algorithm
   * @param sc the parameter L represented as ScalarOps
   * @param B the parameter B
   * @throws IllegalArgumentException if hash algorithm is unsupported or length is wrong
   */
  public EdDSAParameterSpec(Curve curve, String hashAlgo, ScalarOps sc, GroupElement B) {
    try {
      MessageDigest hash = MessageDigest.getInstance(hashAlgo);
      // EdDSA hash function must produce 2b-bit output
      if (curve.getField().getb() / 4 != hash.getDigestLength())
        throw new IllegalArgumentException("Hash output is not 2b-bit");
    } catch (NoSuchAlgorithmException e) {
      throw new IllegalArgumentException("Unsupported hash algorithm");
    }

    this.curve = curve;
    this.hashAlgo = hashAlgo;
    this.sc = sc;
    this.B = B;
  }

  public Curve getCurve() {
    return curve;
  }

  public String getHashAlgorithm() {
    return hashAlgo;
  }

  /**
   * @return the base (generator)
   */
  public GroupElement getB() {
    return B;
  }

  @Override
  public int hashCode() {
    return hashAlgo.hashCode() ^ curve.hashCode() ^ B.hashCode();
  }

  @Override
  public boolean equals(Object o) {
    if (o == this) return true;
    if (!(o instanceof EdDSAParameterSpec)) return false;
    EdDSAParameterSpec s = (EdDSAParameterSpec) o;
    return hashAlgo.equals(s.getHashAlgorithm())
        && curve.equals(s.getCurve())
        && B.equals(s.getB());
  }
}