/*
    * GordianKnot: Security Suite
    * Copyright 2012-2026. Tony Washer
    *
    * Licensed under the Apache License, Version 2.0 (the "License"); you may not
    * use this file except in compliance with the License.  You may obtain a copy
    * of the License at
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   */
  package io.github.tonywasher.joceanus.gordianknot.api.keypair;
  
  import io.github.tonywasher.joceanus.gordianknot.api.keypair.GordianLMSKeySpec.GordianHSSKeySpec;
  import io.github.tonywasher.joceanus.gordianknot.api.keypair.GordianXMSSKeySpec.GordianXMSSDigestType;
  
  import java.util.ArrayList;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Objects;
  
  /**
   * Asymmetric KeyPair Specification.
   */
  public class GordianKeyPairSpec {
      /**
       * The Separator.
       */
      private static final String SEP = "-";
  
      /**
       * The keyPairType.
       */
      private final GordianKeyPairType theKeyPairType;
  
      /**
       * The SubKeyType.
       */
      private final Object theSubKeyType;
  
      /**
       * The Validity.
       */
      private final boolean isValid;
  
      /**
       * The String name.
       */
      private String theName;
  
      /**
       * Constructor.
       *
       * @param pKeyType    the keyType
       * @param pSubKeyType the subKeyType
       */
      public GordianKeyPairSpec(final GordianKeyPairType pKeyType,
                                final Object pSubKeyType) {
          theKeyPairType = pKeyType;
          theSubKeyType = pSubKeyType;
          isValid = checkValidity();
      }
  
      /**
       * Obtain the keyPairType.
       *
       * @return the keyPairType.
       */
      public GordianKeyPairType getKeyPairType() {
          return theKeyPairType;
      }
  
      /**
       * Obtain the subKeyType.
       *
       * @return the keyType.
       */
      public Object getSubKeyType() {
          return theSubKeyType;
      }
  
      /**
       * Is the keySpec valid?
       *
       * @return true/false.
       */
      public boolean isValid() {
          return isValid;
      }
  
      /**
       * Obtain the RSAmodulus.
       *
       * @return the modulus.
      */
     public GordianRSAModulus getRSAModulus() {
         if (theSubKeyType instanceof GordianRSAModulus myMod) {
             return myMod;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the DSA keyType.
      *
      * @return the keyType.
      */
     public GordianDSAKeyType getDSAKeyType() {
         if (theSubKeyType instanceof GordianDSAKeyType myType) {
             return myType;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the DH Group.
      *
      * @return the dhGroup.
      */
     public GordianDHGroup getDHGroup() {
         if (theSubKeyType instanceof GordianDHGroup myGroup) {
             return myGroup;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the elliptic curve.
      *
      * @return the curve.
      */
     public GordianElliptic getElliptic() {
         if (theSubKeyType instanceof GordianElliptic myElliptic) {
             return myElliptic;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the elliptic curve.
      *
      * @return the curve.
      */
     public GordianEdwardsElliptic getEdwardsElliptic() {
         if (theSubKeyType instanceof GordianEdwardsElliptic myElliptic) {
             return myElliptic;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the lms keySpec.
      *
      * @return the keySpec.
      */
     public GordianLMSKeySpec getLMSKeySpec() {
         if (theSubKeyType instanceof GordianLMSKeySpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the hss keySpec.
      *
      * @return the keySpec.
      */
     public GordianHSSKeySpec getHSSKeySpec() {
         if (theSubKeyType instanceof GordianHSSKeySpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the XMSS keySpec.
      *
      * @return the keySpec.
      */
     public GordianXMSSKeySpec getXMSSKeySpec() {
         if (theSubKeyType instanceof GordianXMSSKeySpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the XMSS digestType.
      *
      * @return the digestType.
      */
     public GordianXMSSDigestType getXMSSDigestType() {
         return getXMSSKeySpec().getDigestType();
     }
 
     /**
      * Obtain the SLHDSA keySpec.
      *
      * @return the keySpec.
      */
     public GordianSLHDSASpec getSLHDSAKeySpec() {
         if (theSubKeyType instanceof GordianSLHDSASpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the CMCE keySpec.
      *
      * @return the keySpec.
      */
     public GordianCMCESpec getCMCEKeySpec() {
         if (theSubKeyType instanceof GordianCMCESpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the FRODO keySpec.
      *
      * @return the keySpec.
      */
     public GordianFRODOSpec getFRODOKeySpec() {
         if (theSubKeyType instanceof GordianFRODOSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the Saber keySpec.
      *
      * @return the keySpec.
      */
     public GordianSABERSpec getSABERKeySpec() {
         if (theSubKeyType instanceof GordianSABERSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the MLKEM keySpec.
      *
      * @return the keySpec.
      */
     public GordianMLKEMSpec getMLKEMKeySpec() {
         if (theSubKeyType instanceof GordianMLKEMSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the MLDSA keySpec.
      *
      * @return the keySpec.
      */
     public GordianMLDSASpec getMLDSAKeySpec() {
         if (theSubKeyType instanceof GordianMLDSASpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the HQC keySpec.
      *
      * @return the keySpec.
      */
     public GordianHQCSpec getHQCKeySpec() {
         if (theSubKeyType instanceof GordianHQCSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the Bike keySpec.
      *
      * @return the keySpec.
      */
     public GordianBIKESpec getBIKEKeySpec() {
         if (theSubKeyType instanceof GordianBIKESpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the NTRU keySpec.
      *
      * @return the keySpec.
      */
     public GordianNTRUSpec getNTRUKeySpec() {
         if (theSubKeyType instanceof GordianNTRUSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the NTRUPRIME keySpec.
      *
      * @return the keySpec.
      */
     public GordianNTRUPrimeSpec getNTRUPrimeKeySpec() {
         if (theSubKeyType instanceof GordianNTRUPrimeSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the Falcon keySpec.
      *
      * @return the keySpec.
      */
     public GordianFalconSpec getFalconKeySpec() {
         if (theSubKeyType instanceof GordianFalconSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the Mayo keySpec.
      *
      * @return the keySpec.
      */
     public GordianMayoSpec getMayoKeySpec() {
         if (theSubKeyType instanceof GordianMayoSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the Snova keySpec.
      *
      * @return the keySpec.
      */
     public GordianSnovaSpec getSnovaKeySpec() {
         if (theSubKeyType instanceof GordianSnovaSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the Picnic keySpec.
      *
      * @return the keySpec.
      */
     public GordianPicnicSpec getPicnicKeySpec() {
         if (theSubKeyType instanceof GordianPicnicSpec mySpec) {
             return mySpec;
         }
         throw new IllegalArgumentException();
     }
 
     /**
      * Obtain the composite keySpec iterator.
      *
      * @return the keySpec iterator.
      */
     @SuppressWarnings("unchecked")
     public Iterator<GordianKeyPairSpec> keySpecIterator() {
         if (theSubKeyType instanceof List) {
             return ((List<GordianKeyPairSpec>) theSubKeyType).iterator();
         }
         throw new IllegalArgumentException();
     }
 
     @Override
     public String toString() {
         /* If we have not yet loaded the name */
         if (theName == null) {
             /* If the keySpec is valid */
             if (isValid) {
                 /* Derive the name */
                 deriveName();
             } else {
                 /* Report invalid spec */
                 theName = "InvalidKeyPairSpec: " + theKeyPairType + ":" + theSubKeyType;
             }
         }
 
         /* return the name */
         return theName;
     }
 
     /**
      * Derive name.
      */
     private void deriveName() {
         /* Load the name */
         theName = theKeyPairType.toString();
         if (theSubKeyType != null) {
             switch (theKeyPairType) {
                 case XMSS:
                     theName = theSubKeyType.toString();
                     break;
                 case EDDSA:
                     theName = "Ed" + ((GordianEdwardsElliptic) theSubKeyType).getSuffix();
                     break;
                 case XDH:
                     theName = "X" + ((GordianEdwardsElliptic) theSubKeyType).getSuffix();
                     break;
                 case COMPOSITE:
                     final Iterator<GordianKeyPairSpec> myIterator = keySpecIterator();
                     final StringBuilder myBuilder = new StringBuilder(theName);
                     while (myIterator.hasNext()) {
                         myBuilder.append(SEP).append(myIterator.next().toString());
                     }
                     theName = myBuilder.toString();
                     break;
                 default:
                     theName += SEP + theSubKeyType;
                     break;
             }
         }
     }
 
     @Override
     public boolean equals(final Object pThat) {
         /* Handle the trivial cases */
         if (this == pThat) {
             return true;
         }
         if (pThat == null) {
             return false;
         }
 
         /* Check KeyPairType and subKeyType */
         return pThat instanceof GordianKeyPairSpec myThat
                 && theKeyPairType == myThat.getKeyPairType()
                 && Objects.equals(theSubKeyType, myThat.theSubKeyType);
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(theKeyPairType, theSubKeyType);
     }
 
     /**
      * Check spec validity.
      *
      * @return valid true/false
      */
     private boolean checkValidity() {
         /* Handle null keyPairType */
         if (theKeyPairType == null) {
             return false;
         }
 
         /* Switch on keyPairType */
         switch (theKeyPairType) {
             case RSA:
                 return theSubKeyType instanceof GordianRSAModulus;
             case DSA:
                 return theSubKeyType instanceof GordianDSAKeyType;
             case DH:
             case ELGAMAL:
                 return theSubKeyType instanceof GordianDHGroup;
             case EC:
                 return theSubKeyType instanceof GordianDSAElliptic;
             case SM2:
                 return theSubKeyType instanceof GordianSM2Elliptic;
             case GOST2012:
                 return theSubKeyType instanceof GordianGOSTElliptic;
             case DSTU4145:
                 return theSubKeyType instanceof GordianDSTU4145Elliptic;
             case XMSS:
                 return theSubKeyType instanceof GordianXMSSKeySpec s && s.isValid();
             case SLHDSA:
                 return theSubKeyType instanceof GordianSLHDSASpec;
             case CMCE:
                 return theSubKeyType instanceof GordianCMCESpec;
             case FRODO:
                 return theSubKeyType instanceof GordianFRODOSpec;
             case SABER:
                 return theSubKeyType instanceof GordianSABERSpec;
             case MLKEM:
                 return theSubKeyType instanceof GordianMLKEMSpec;
             case MLDSA:
                 return theSubKeyType instanceof GordianMLDSASpec;
             case HQC:
                 return theSubKeyType instanceof GordianHQCSpec;
             case BIKE:
                 return theSubKeyType instanceof GordianBIKESpec;
             case NTRU:
                 return theSubKeyType instanceof GordianNTRUSpec;
             case NTRUPRIME:
                 return theSubKeyType instanceof GordianNTRUPrimeSpec;
             case FALCON:
                 return theSubKeyType instanceof GordianFalconSpec;
             case MAYO:
                 return theSubKeyType instanceof GordianMayoSpec;
             case SNOVA:
                 return theSubKeyType instanceof GordianSnovaSpec;
             case PICNIC:
                 return theSubKeyType instanceof GordianPicnicSpec;
             case NEWHOPE:
                 return theSubKeyType == null;
             case LMS:
                 return (theSubKeyType instanceof GordianLMSKeySpec ls && ls.isValid())
                         || (theSubKeyType instanceof GordianHSSKeySpec hs && hs.isValid());
             case EDDSA:
             case XDH:
                 return theSubKeyType instanceof GordianEdwardsElliptic;
             case COMPOSITE:
                 return theSubKeyType instanceof List && checkComposite();
             default:
                 return false;
         }
     }
 
     /**
      * Check composite spec validity.
      *
      * @return valid true/false
      */
     private boolean checkComposite() {
         Boolean stateAware = null;
         final List<GordianKeyPairType> myExisting = new ArrayList<>();
         final Iterator<GordianKeyPairSpec> myIterator = keySpecIterator();
         while (myIterator.hasNext()) {
             /* Check that we have not got a null */
             final GordianKeyPairSpec mySpec = myIterator.next();
             if (mySpec == null) {
                 return false;
             }
 
             /* Check that we have not got a duplicate or COMPOSITE */
             final GordianKeyPairType myType = mySpec.getKeyPairType();
             if (myExisting.contains(myType) || myType == GordianKeyPairType.COMPOSITE) {
                 return false;
             }
 
             /* Check that stateAwareness is identical */
             if (stateAware == null) {
                 stateAware = mySpec.isStateAware();
             } else if (mySpec.isStateAware() != stateAware) {
                 return false;
             }
 
             /* Add to list */
             myExisting.add(myType);
         }
 
         /* Make sure there are at least two */
         return myExisting.size() > 1;
     }
 
     /**
      * is the use subType for signatures?
      *
      * @return true/false
      */
     public boolean isStateAware() {
         switch (theKeyPairType) {
             case XMSS:
             case LMS:
                 return true;
             case COMPOSITE:
                 return keySpecIterator().next().isStateAware();
             default:
                 return false;
         }
     }
 }