/*
    * 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.digest;
  
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianIdSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.base.GordianLength;
  import io.github.tonywasher.joceanus.gordianknot.api.digest.GordianDigestSubSpec.GordianDigestState;
  
  import java.util.Objects;
  
  /**
   * Digest Specification.
   */
  public class GordianDigestSpec
          implements GordianIdSpec {
      /**
       * The Separator.
       */
      private static final String SEP = "-";
  
      /**
       * The Digest Type.
       */
      private final GordianDigestType theDigestType;
  
      /**
       * The Digest SubSpec.
       */
      private final GordianDigestSubSpec theSubSpec;
  
      /**
       * The Digest Length.
       */
      private final GordianLength theLength;
  
      /**
       * Is this a Xof mode?
       */
      private final Boolean isXofMode;
  
      /**
       * The Validity.
       */
      private final boolean isValid;
  
      /**
       * The String name.
       */
      private String theName;
  
      /**
       * Constructor.
       *
       * @param pDigestType the digestType
       */
      public GordianDigestSpec(final GordianDigestType pDigestType) {
          this(pDigestType, pDigestType.getDefaultLength());
      }
  
      /**
       * Constructor.
       *
       * @param pDigestType the digestType
       * @param pLength     the length
       */
      public GordianDigestSpec(final GordianDigestType pDigestType,
                               final GordianLength pLength) {
          /* Store parameters */
          this(pDigestType, pLength, Boolean.FALSE);
      }
  
      /**
       * Constructor.
       *
       * @param pDigestType the digestType
       * @param pLength     the length
       * @param pXofMode    is this an explicit Xof?
       */
      public GordianDigestSpec(final GordianDigestType pDigestType,
                               final GordianLength pLength,
                               final Boolean pXofMode) {
          this(pDigestType, GordianDigestSubSpec.getDefaultSubSpecForTypeAndLength(pDigestType, pLength), pLength, pXofMode);
      }
  
      /**
      * Constructor.
      *
      * @param pDigestType the digestType
      * @param pState      the digestState
      * @param pLength     the length
      */
     public GordianDigestSpec(final GordianDigestType pDigestType,
                              final GordianDigestSubSpec pState,
                              final GordianLength pLength) {
         this(pDigestType, pState, pLength, Boolean.FALSE);
     }
 
     /**
      * Constructor.
      *
      * @param pDigestType the digestType
      * @param pState      the digestState
      * @param pLength     the length
      * @param pXofMode    is this an explicit Xof?
      */
     public GordianDigestSpec(final GordianDigestType pDigestType,
                              final GordianDigestSubSpec pState,
                              final GordianLength pLength,
                              final Boolean pXofMode) {
         /* Store parameters */
         theDigestType = pDigestType;
         theSubSpec = pState;
         theLength = pLength;
         isXofMode = pXofMode;
         isValid = checkValidity();
     }
 
     /**
      * Obtain Digest Type.
      *
      * @return the DigestType
      */
     public GordianDigestType getDigestType() {
         return theDigestType;
     }
 
     /**
      * Obtain DigestSubSpec.
      *
      * @return the SubSpec
      */
     public GordianDigestSubSpec getSubSpec() {
         return theSubSpec;
     }
 
     /**
      * Obtain DigestState.
      *
      * @return the State
      */
     public GordianDigestState getDigestState() {
         return theSubSpec instanceof GordianDigestState myState
                 ? myState
                 : null;
     }
 
     /**
      * Obtain Digest Length.
      *
      * @return the Length
      */
     public GordianLength getDigestLength() {
         return theLength;
     }
 
     /**
      * Is the digestSpec a Xof mode?
      *
      * @return true/false.
      */
     public Boolean isXofMode() {
         return isXofMode;
     }
 
     /**
      * Is the digestSpec a Xof?
      *
      * @return true/false.
      */
     public Boolean isXof() {
         return isXofMode || theDigestType.isXof();
     }
 
     /**
      * Is the digestSpec valid?
      *
      * @return true/false.
      */
     public boolean isValid() {
         return isValid;
     }
 
     /**
      * Is this a sha2 hybrid state.
      *
      * @return true/false
      */
     public boolean isSha2Hybrid() {
         return GordianDigestType.SHA2.equals(theDigestType)
                 && GordianDigestState.STATE512.equals(theSubSpec)
                 && (GordianLength.LEN_224.equals(theLength)
                 || GordianLength.LEN_256.equals(theLength));
     }
 
     /**
      * Check spec validity.
      *
      * @return valid true/false
      */
     private boolean checkValidity() {
         /* Handle null type */
         if (theDigestType == null || theLength == null || isXofMode == null) {
             return false;
         }
 
         /* Switch on keyType */
         switch (theDigestType) {
             case SHA2:
             case SHAKE:
             case KANGAROO:
             case HARAKA:
                 return theSubSpec instanceof GordianDigestState
                         && !isXofMode
                         && getDigestState().validForTypeAndLength(theDigestType, theLength);
             case SKEIN:
             case BLAKE2:
                 return theSubSpec instanceof GordianDigestState
                         && (isXofMode ? getDigestState().lengthForXofType(theDigestType) == theLength
                         : getDigestState().validForTypeAndLength(theDigestType, theLength));
             case ASCON:
                 return theSubSpec == null
                         && theDigestType.isLengthValid(theLength);
             default:
                 return theSubSpec == null
                         && !isXofMode
                         && theDigestType.isLengthValid(theLength);
         }
     }
 
     @Override
     public String toString() {
         /* If we have not yet loaded the name */
         if (theName == null) {
             /* If the keySpec is valid */
             if (isValid) {
                 /* Load the name */
                 theName = theDigestType.toString();
                 switch (theDigestType) {
                     case SHA2:
                         if (isSha2Hybrid()) {
                             theName += SEP + theSubSpec;
                         }
                         theName += SEP + theLength;
                         break;
                     case SHAKE:
                         theName += theSubSpec;
                         break;
                     case SKEIN:
                         if (Boolean.TRUE.equals(isXofMode)) {
                             theName += "X" + SEP + theSubSpec;
                         } else {
                             theName += SEP + theSubSpec + SEP + theLength;
                         }
                         break;
                     case BLAKE2:
                         theName += getDigestState().getBlake2Algorithm(isXofMode);
                         if (!Boolean.TRUE.equals(isXofMode)) {
                             theName += SEP + theLength;
                         }
                         break;
                     case KANGAROO:
                         theName = getDigestState().getKangarooAlgorithm();
                         break;
                     case HARAKA:
                         theName += SEP + theSubSpec;
                         break;
                     case ASCON:
                         theName += Boolean.TRUE.equals(isXofMode) ? "X" : "";
                         break;
                     default:
                         if (theDigestType.getSupportedLengths().length > 1) {
                             theName += SEP + theLength;
                         }
                         break;
                 }
             } else {
                 /* Report invalid spec */
                 theName = "InvalidDigestSpec: " + theDigestType + ":" + theSubSpec + ":" + theLength + ":" + isXofMode;
             }
         }
 
         /* 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 subFields */
         return pThat instanceof GordianDigestSpec myThat
                 && theDigestType == myThat.getDigestType()
                 && theSubSpec == myThat.getSubSpec()
                 && theLength == myThat.getDigestLength()
                 && isXofMode == myThat.isXofMode();
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(theDigestType, theSubSpec, theLength, isXofMode);
     }
 }