/*
    * 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.mac;
  
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianKeySpec;
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianLength;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.GordianSymKeySpec;
  import io.github.tonywasher.joceanus.gordianknot.api.cipher.GordianSymKeyType;
  import io.github.tonywasher.joceanus.gordianknot.api.digest.GordianDigestSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.digest.GordianDigestSubSpec.GordianDigestState;
  import io.github.tonywasher.joceanus.gordianknot.api.digest.GordianDigestType;
  
  import java.util.Objects;
  
  /**
   * Mac Specification.
   */
  public final class GordianMacSpec
          implements GordianKeySpec {
      /**
       * The Separator.
       */
      static final String SEP = "-";
  
      /**
       * The Mac Type.
       */
      private final GordianMacType theMacType;
  
      /**
       * The KeyLength.
       */
      private final GordianLength theKeyLength;
  
      /**
       * The SubSpec.
       */
      private final Object theSubSpec;
  
      /**
       * The Validity.
       */
      private final boolean isValid;
  
      /**
       * The String name.
       */
      private String theName;
  
      /**
       * hMac/skeinMac Constructor.
       *
       * @param pMacType    the macType
       * @param pKeyLength  the keyLength
       * @param pDigestSpec the digestSpec
       */
      public GordianMacSpec(final GordianMacType pMacType,
                            final GordianLength pKeyLength,
                            final GordianDigestSpec pDigestSpec) {
          /* Store parameters */
          theMacType = pMacType;
          theKeyLength = pKeyLength;
          theSubSpec = pDigestSpec;
          isValid = checkValidity();
      }
  
      /**
       * gMac/Poly1305 Constructor.
       *
       * @param pMacType the macType
       * @param pKeySpec the keySpec
       */
      public GordianMacSpec(final GordianMacType pMacType,
                            final GordianSymKeySpec pKeySpec) {
          /* Store macType */
          theMacType = pMacType;
  
          /* Special handling for Poly1305 */
          theKeyLength = GordianMacType.POLY1305 == pMacType
                  ? GordianLength.LEN_256
                  : pKeySpec.getKeyLength();
          theSubSpec = pKeySpec;
          isValid = checkValidity();
      }
  
     /**
      * zucMac Constructor.
      *
      * @param pMacType   the macType
      * @param pKeyLength the keyLength
      * @param pLength    the length
      */
     public GordianMacSpec(final GordianMacType pMacType,
                           final GordianLength pKeyLength,
                           final GordianLength pLength) {
         /* Store parameters */
         theMacType = pMacType;
         theKeyLength = pKeyLength;
         theSubSpec = pLength;
         isValid = checkValidity();
     }
 
     /**
      * sipHash Constructor.
      *
      * @param pMacType the macType
      * @param pSpec    the SipHashSpec
      */
     public GordianMacSpec(final GordianMacType pMacType,
                           final GordianSipHashSpec pSpec) {
         /* Store parameters */
         theMacType = pMacType;
         theKeyLength = GordianLength.LEN_128;
         theSubSpec = pSpec;
         isValid = checkValidity();
     }
 
     /**
      * vmpcMac/raw poly1305Mac Constructor.
      *
      * @param pKeyLength the keyLength
      * @param pMacType   the macType
      */
     public GordianMacSpec(final GordianMacType pMacType,
                           final GordianLength pKeyLength) {
         theMacType = pMacType;
         theKeyLength = pKeyLength;
         theSubSpec = null;
         isValid = checkValidity();
     }
 
     /**
      * Obtain Mac Type.
      *
      * @return the MacType
      */
     public GordianMacType getMacType() {
         return theMacType;
     }
 
     @Override
     public GordianLength getKeyLength() {
         return theKeyLength;
     }
 
     /**
      * Obtain SubSpec.
      *
      * @return the SubSpec
      */
     public Object getSubSpec() {
         return theSubSpec;
     }
 
     /**
      * Is the macSpec valid?
      *
      * @return true/false.
      */
     public boolean isValid() {
         return isValid;
     }
 
     /**
      * Obtain DigestSpec.
      *
      * @return the DigestSpec
      */
     public GordianDigestSpec getDigestSpec() {
         return theSubSpec instanceof GordianDigestSpec mySpec
                 ? mySpec
                 : null;
     }
 
     /**
      * Obtain DigestState.
      *
      * @return the State
      */
     private GordianDigestState getDigestState() {
         return theSubSpec instanceof GordianDigestSpec mySpec
                 ? mySpec.getDigestState()
                 : null;
     }
 
     /**
      * Obtain DigestLength.
      *
      * @return the Length
      */
     private GordianLength getDigestLength() {
         return theSubSpec instanceof GordianDigestSpec mySpec
                 ? mySpec.getDigestLength()
                 : null;
     }
 
     /**
      * Obtain SymKeySpec.
      *
      * @return the SymKeySpec
      */
     public GordianSymKeySpec getSymKeySpec() {
         return theSubSpec instanceof GordianSymKeySpec mySpec
                 ? mySpec
                 : null;
     }
 
     /**
      * Obtain SymKeyType.
      *
      * @return the Type
      */
     private GordianSymKeyType getSymKeyType() {
         return theSubSpec instanceof GordianSymKeySpec mySpec
                 ? mySpec.getSymKeyType()
                 : null;
     }
 
     /**
      * Obtain SymKeyBlockLength.
      *
      * @return the BlockLength
      */
     private GordianLength getSymKeyBlockLength() {
         return theSubSpec instanceof GordianSymKeySpec mySpec
                 ? mySpec.getBlockLength()
                 : null;
     }
 
     /**
      * Obtain SymKeyBlockLength.
      *
      * @return the BlockLength
      */
     private int getSymKeyBlockByteLength() {
         return theSubSpec instanceof GordianSymKeySpec mySpec
                 ? Objects.requireNonNull(mySpec.getBlockLength()).getByteLength()
                 : 0;
     }
 
     /**
      * Obtain SymKeyHalfBlockLength.
      *
      * @return the HalfBlockLength
      */
     private GordianLength getSymKeyHalfBlockLength() {
         return theSubSpec instanceof GordianSymKeySpec mySpec
                 ? mySpec.getHalfBlockLength()
                 : null;
     }
 
     /**
      * Obtain SipHashSpec.
      *
      * @return the Spec
      */
     public GordianSipHashSpec getSipHashSpec() {
         return theSubSpec instanceof GordianSipHashSpec mySpec
                 ? mySpec
                 : null;
     }
 
     /**
      * Obtain MacLength.
      *
      * @return the Length
      */
     public GordianLength getMacLength() {
         switch (theMacType) {
             case HMAC:
             case BLAKE2:
             case BLAKE3:
             case SKEIN:
             case KUPYNA:
             case KMAC:
                 return getDigestLength();
             case GMAC:
             case POLY1305:
                 return GordianLength.LEN_128;
             case CMAC:
             case KALYNA:
                 return getSymKeyBlockLength();
             case CBCMAC:
             case CFBMAC:
                 return getSymKeyHalfBlockLength();
             case ZUC:
                 return (GordianLength) theSubSpec;
             case VMPC:
                 return GordianLength.LEN_160;
             case GOST:
                 return GordianLength.LEN_32;
             case SIPHASH:
                 return ((GordianSipHashSpec) theSubSpec).getOutLength();
             default:
                 return GordianLength.LEN_64;
         }
     }
 
     /**
      * Obtain the IV length.
      *
      * @return the IV Length
      */
     public int getIVLen() {
         switch (theMacType) {
             case VMPC:
             case SKEIN:
                 return GordianLength.LEN_128.getByteLength();
             case POLY1305:
                 return theSubSpec == null
                         ? 0
                         : GordianLength.LEN_128.getByteLength();
             case BLAKE2:
                 return Objects.requireNonNull(getDigestState()).isBlake2bState()
                         ? GordianLength.LEN_128.getByteLength()
                         : GordianLength.LEN_64.getByteLength();
             case GMAC:
                 return GordianLength.LEN_96.getByteLength();
             case CBCMAC:
             case CFBMAC:
                 return getSymKeyBlockByteLength();
             case GOST:
                 return GordianLength.LEN_64.getByteLength();
             case ZUC:
                 return GordianLength.LEN_128 == theKeyLength
                         ? GordianLength.LEN_128.getByteLength()
                         : GordianLength.LEN_200.getByteLength();
             default:
                 return 0;
         }
     }
 
     /**
      * Check spec validity.
      *
      * @return valid true/false
      */
     private boolean checkValidity() {
         /* Make sure that macType and keyLength are non-null */
         if (theMacType == null || theKeyLength == null) {
             return false;
         }
 
         /* Switch on MacType */
         switch (theMacType) {
             case HMAC:
                 return checkDigestValidity(null);
             case KUPYNA:
                 return checkDigestValidity(GordianDigestType.KUPYNA);
             case SKEIN:
                 return checkDigestValidity(GordianDigestType.SKEIN);
             case BLAKE2:
                 return checkBlake2Validity();
             case BLAKE3:
                 return checkDigestValidity(GordianDigestType.BLAKE3);
             case KALYNA:
                 return checkSymKeyValidity(GordianSymKeyType.KALYNA);
             case KMAC:
                 return checkKMACValidity();
             case CMAC:
             case GMAC:
             case CBCMAC:
             case CFBMAC:
                 return checkSymKeyValidity(null);
             case POLY1305:
                 return checkPoly1305Validity();
             case ZUC:
                 return checkZucValidity();
             case SIPHASH:
                 return theSubSpec instanceof GordianSipHashSpec
                         && theKeyLength == GordianLength.LEN_128;
             case GOST:
                 return theSubSpec == null
                         && theKeyLength == GordianLength.LEN_256;
             case VMPC:
                 return theSubSpec == null;
             default:
                 return false;
         }
     }
 
     /**
      * Check digest validity.
      *
      * @param pDigestType required digestType (or null)
      * @return valid true/false
      */
     private boolean checkDigestValidity(final GordianDigestType pDigestType) {
         /* Check that the digestSpec is valid */
         if (!(theSubSpec instanceof GordianDigestSpec)
                 || !((GordianDigestSpec) theSubSpec).isValid()) {
             return false;
         }
 
         /* Check for digestType restrictions */
         final GordianDigestType myType = ((GordianDigestSpec) theSubSpec).getDigestType();
         return pDigestType == null
                 ? myType.supportsLargeData()
                 : myType == pDigestType;
     }
 
     /**
      * Check symKey validity.
      *
      * @param pSymKeyType required symKeyType (or null)
      * @return valid true/false
      */
     private boolean checkSymKeyValidity(final GordianSymKeyType pSymKeyType) {
         /* Check that the symKeySpec is valid */
         if (!(theSubSpec instanceof GordianSymKeySpec)
                 || !((GordianSymKeySpec) theSubSpec).isValid()) {
             return false;
         }
 
         /* Check for symKeyType restrictions */
         return pSymKeyType == null
                 || ((GordianSymKeySpec) theSubSpec).getSymKeyType() == pSymKeyType;
     }
 
     /**
      * Check poly1305 validity.
      *
      * @return valid true/false
      */
     private boolean checkPoly1305Validity() {
         /* Check that the subSpec is reasonable */
         if (theSubSpec != null
                 && !checkSymKeyValidity(null)) {
             return false;
         }
 
         /* Restrict keyLengths */
         final GordianSymKeySpec mySpec = (GordianSymKeySpec) theSubSpec;
         return theKeyLength == GordianLength.LEN_256
                 && (mySpec == null
                 || mySpec.getKeyLength() == GordianLength.LEN_128);
     }
 
     /**
      * Check blake validity.
      *
      * @return valid true/false
      */
     private boolean checkBlake2Validity() {
         /* Check that the spec is reasonable */
         if (!checkDigestValidity(GordianDigestType.BLAKE2)) {
             return false;
         }
 
         /* Check keyLength */
         return checkBlake2KeyLength(theKeyLength, (GordianDigestSpec) theSubSpec);
     }
 
     /**
      * Check blake2 keyLength validity.
      *
      * @param pKeyLen the keyLength
      * @param pSpec   the digestSpec
      * @return valid true/false
      */
     private static boolean checkBlake2KeyLength(final GordianLength pKeyLen,
                                                 final GordianDigestSpec pSpec) {
         /* Key length must be less or equal to the stateLength */
         return pKeyLen.getLength() <= pSpec.getDigestState().getLength().getLength();
     }
 
     /**
      * Check blake validity.
      *
      * @return valid true/false
      */
     private boolean checkKMACValidity() {
         /* Check that the spec is reasonable */
         if (!checkDigestValidity(GordianDigestType.SHAKE)) {
             return false;
         }
 
         /* Check keyLength */
         return checkKMACKeyLength(theKeyLength, (GordianDigestSpec) theSubSpec);
     }
 
     /**
      * Check KMAC keyLength validity.
      *
      * @param pKeyLen the keyLength
      * @param pSpec   the digestSpec
      * @return valid true/false
      */
     private static boolean checkKMACKeyLength(final GordianLength pKeyLen,
                                               final GordianDigestSpec pSpec) {
         /* Key length must be greater or equal to the stateLength */
         return pKeyLen.getLength() >= pSpec.getDigestState().getLength().getLength();
     }
 
     /**
      * Check zuc validity.
      *
      * @return valid true/false
      */
     private boolean checkZucValidity() {
         switch (theKeyLength) {
             case LEN_128:
                 return GordianLength.LEN_32 == theSubSpec;
             case LEN_256:
                 return GordianLength.LEN_32 == theSubSpec
                         || GordianLength.LEN_64 == theSubSpec
                         || GordianLength.LEN_128 == theSubSpec;
             default:
                 return false;
         }
     }
 
     /**
      * Is this a Xof Mac?
      *
      * @return true/false
      */
     public boolean isXof() {
         switch (theMacType) {
             case KMAC:
             case BLAKE3:
                 return true;
             case BLAKE2:
             case SKEIN:
                 return Objects.requireNonNull(getDigestSpec()).isXof();
             default:
                 return false;
         }
     }
 
     @Override
     public String toString() {
         /* If we have not yet loaded the name */
         if (theName == null) {
             /* If the macSpec is invalid */
             if (!isValid) {
                 /* Report invalid spec */
                 theName = "InvalidMacSpec: " + theMacType + ":" + theSubSpec + ":" + theKeyLength;
                 return theName;
             }
 
             /* Load the name */
             theName = theMacType.toString();
             switch (theMacType) {
                 case SIPHASH:
                     theName = theSubSpec.toString();
                     break;
                 case POLY1305:
                     theName += theSubSpec == null ? "" : SEP + getSymKeyType();
                     break;
                 case GMAC:
                 case CMAC:
                 case CFBMAC:
                 case CBCMAC:
                     theName += SEP + theSubSpec.toString();
                     break;
                 case KALYNA:
                     theName += getSymKeyBlockLength() + SEP + theKeyLength;
                     break;
                 case KUPYNA:
                     theName += SEP + getDigestLength() + SEP + theKeyLength;
                     break;
                 case KMAC:
                     theName += getDigestState() + SEP + theKeyLength;
                     break;
                 case SKEIN:
                     final boolean isSkeinXof = Objects.requireNonNull(getDigestSpec()).isXofMode();
                     theName = GordianDigestType.SKEIN
                             + (isSkeinXof ? "X" : "")
                             + "Mac"
                             + SEP + getDigestState()
                             + (isSkeinXof ? "" : SEP + getDigestLength())
                             + SEP + theKeyLength;
                     break;
                 case HMAC:
                 case ZUC:
                     theName += theSubSpec.toString() + SEP + theKeyLength;
                     break;
                 case BLAKE2:
                     final boolean isBlakeXof = Objects.requireNonNull(getDigestSpec()).isXofMode();
                     theName = GordianDigestType.BLAKE2
                             + Objects.requireNonNull(getDigestState())
                             .getBlake2Algorithm(isBlakeXof)
                             + "Mac" + (isBlakeXof ? "" : SEP + getDigestLength())
                             + SEP + theKeyLength;
                     break;
                 case BLAKE3:
                     theName += SEP + getDigestLength();
                     break;
                 case VMPC:
                     theName += theKeyLength;
                     break;
                 case GOST:
                 default:
                     break;
             }
         }
 
         /* return the name */
         return theName;
     }
 
     @Override
     public boolean equals(final Object pThat) {
         /* Handle the trivial cases */
         if (this == pThat) {
             return true;
         }
         if (pThat == null) {
             return false;
         }
 
         /* Check MacType, keyLength and subSpec */
         return pThat instanceof GordianMacSpec myThat
                 && theMacType == myThat.getMacType()
                 && theKeyLength == myThat.getKeyLength()
                 && Objects.equals(theSubSpec, myThat.getSubSpec());
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(theMacType, theKeyLength, theSubSpec);
     }
 }