package net.messagevortex.asn1;

// ************************************************************************************
// * Copyright (c) 2018 Martin Gwerder (martin@gwerder.net)
// *
// * Permission is hereby granted, free of charge, to any person obtaining a copy
// * of this software and associated documentation files (the "Software"), to deal
// * in the Software without restriction, including without limitation the rights
// * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// * copies of the Software, and to permit persons to whom the Software is
// * furnished to do so, subject to the following conditions:
// *
// * The above copyright notice and this permission notice shall be included in all
// * copies or substantial portions of the Software.
// *
// * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// * SOFTWARE.
// ************************************************************************************

import net.messagevortex.asn1.encryption.DumpType;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.asn1.ASN1Object;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERTaggedObject;

import java.io.IOException;
import java.io.Serializable;

import static net.messagevortex.asn1.BlendingParameter.BlendingParameterChoice.F5;
import static net.messagevortex.asn1.BlendingParameter.BlendingParameterChoice.OFFSET;

/**
 * <p>Blending Parameter Block representation.</p>
 */
public class BlendingParameter extends AbstractBlock implements Serializable, Dumpable {

  public static final long serialVersionUID = 100000000004L;

  public enum BlendingParameterChoice {
    OFFSET(1),
    F5(2);

    final int id;

    BlendingParameterChoice(int i) {
      id = i;
    }

    /***
     * <p>Gets a blender parameter enum by its Id.</p>
     *
     * @param i the id to be looked up
     * @return the enum or null if not found
     */
    public static BlendingParameterChoice getById(int i) {
      for (BlendingParameterChoice e : values()) {
        if (e.id == i) {
          return e;
        }
      }
      return null;
    }

    public int getId() {
      return id;
    }
  }

  int offset = -1;
  SymmetricKey symmetricKey = null;

  /***
   * <p>Create object from ASN.1 code.</p>
   *
   * @param e the ASN.1 code
   * @throws IOException if parsing of ASN.1 code fails
   */
  public BlendingParameter(ASN1Encodable e) throws IOException {
    parse(e);
  }

  /***
   * <p>Creates a blender parameter set.</p>
   *
   * @param choice       the type of blender
   * @throws IOException if creation of the symmetric key failed
   */
  public BlendingParameter(BlendingParameterChoice choice) throws IOException {
    if (choice == OFFSET) {
      offset = 0;
    } else {
      symmetricKey = new SymmetricKey();
    }
  }

  @Override
  protected final void parse(ASN1Encodable to) throws IOException {
    ASN1TaggedObject t = ASN1TaggedObject.getInstance(to);
    if (to == null || t == null) {
      throw new IOException("unknown blender parameter choice detected (tagged object is null)");
    }
    BlendingParameterChoice bpc = BlendingParameterChoice.getById(t.getTagNo());
    if (bpc == null) {
      throw new IOException("unknown blender parameter choice detected (" + t.getTagNo() + ")");
    }
    switch (bpc) {
      case OFFSET:
        offset = ASN1Integer.getInstance(t.getObject()).getValue().intValue();
        break;
      case F5:
        symmetricKey = new SymmetricKey(t.getObject().getEncoded());
        break;
      default:
        throw new IOException("unknown blender parameter choice detected (" + t.getTagNo() + ")");
    }
  }

  /***
   * <p>Gets the choice type of the blender parameter.</p>
   *
   * @return the choice type
   */
  public BlendingParameterChoice getChoice() {
    if (offset > -1) {
      return OFFSET;
    } else if (symmetricKey != null) {
      return F5;
    }
    return null;
  }

  @Override
  public String dumpValueNotation(String prefix, DumpType dumptype) throws IOException {
    StringBuilder sb = new StringBuilder();
    switch (getChoice()) {
      case OFFSET:
        sb.append("offset ").append(offset);
        break;
      case F5:
        sb.append("symmetricKey ").append(symmetricKey.dumpValueNotation(prefix, dumptype));
        break;
      default:
        throw new IOException("unable to dump " + getChoice());
    }
    return sb.toString();
  }

  @Override
  public ASN1Object toAsn1Object(DumpType dumpType) throws IOException {
    switch (getChoice()) {
      case OFFSET:
        return new DERTaggedObject(getChoice().getId(), new ASN1Integer(offset));
      case F5:
        return new DERTaggedObject(getChoice().getId(), symmetricKey.toAsn1Object(dumpType));
      default:
        throw new IOException("unable to convert to ASN.1 (" + getChoice() + ")");
    }
  }

  @Override
  public boolean equals(Object t) {
    if (t == null || t.getClass() != this.getClass()) {
      return false;
    }
    BlendingParameter o = (BlendingParameter) t;
    try {
      return dumpValueNotation("", DumpType.ALL).equals(o.dumpValueNotation("", DumpType.ALL));
    } catch (IOException ioe) {
      return false;
    }
  }

  @Override
  public int hashCode() {
    // this methode is required for code sanity
    try {
      return dumpValueNotation("", DumpType.ALL).hashCode();
    } catch (IOException ioe) {
      return "FAILED".hashCode();
    }
  }

}