/*
    * 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.base.GordianLength;
  import org.bouncycastle.pqc.crypto.lms.LMOtsParameters;
  import org.bouncycastle.pqc.crypto.lms.LMSParameters;
  import org.bouncycastle.pqc.crypto.lms.LMSigParameters;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Objects;
  
  /**
   * LMS KeyTypes.
   */
  public class GordianLMSKeySpec {
      /**
       * The Separator.
       */
      private static final String SEP = "-";
  
      /**
       * Invalid length error.
       */
      private static final String INVALID_LENGTH = "Invalid Length: ";
  
      /**
       * The hash.
       */
      private final GordianLMSHash theHash;
  
      /**
       * The width.
       */
      private final GordianLMSWidth theWidth;
  
      /**
       * The height.
       */
      private final GordianLMSHeight theHeight;
  
      /**
       * The length.
       */
      private final GordianLength theLength;
  
      /**
       * The Parameters.
       */
      private final LMSParameters theParams;
  
      /**
       * The Validity.
       */
      private final boolean isValid;
  
      /**
       * The String name.
       */
      private String theName;
  
      /**
       * Constructor.
       *
       * @param pHashType the hashType
       * @param pHeight   the height
       * @param pWidth    the width
       * @param pLength   the length
       */
      public GordianLMSKeySpec(final GordianLMSHash pHashType,
                               final GordianLMSHeight pHeight,
                               final GordianLMSWidth pWidth,
                               final GordianLength pLength) {
          /* Store parameters */
          theHash = pHashType;
          theWidth = pWidth;
          theHeight = pHeight;
          theLength = pLength;
  
          /* Check validity */
          isValid = checkValidity();
  
          /* Calculate parameters */
          final LMSigParameters mySig = isValid ? theHeight.getSigParameter(theHash, theLength) : null;
         final LMOtsParameters myOts = isValid ? theWidth.getOtsParameter(theHash, theLength) : null;
         theParams = isValid ? new LMSParameters(mySig, myOts) : null;
     }
 
     /**
      * Obtain the hash.
      *
      * @return the hash
      */
     public GordianLMSHash getHash() {
         return theHash;
     }
 
     /**
      * Obtain the width.
      *
      * @return the width
      */
     public GordianLMSHeight getHeight() {
         return theHeight;
     }
 
     /**
      * Obtain the width.
      *
      * @return the width
      */
     public GordianLMSWidth getWidth() {
         return theWidth;
     }
 
     /**
      * Obtain the legth.
      *
      * @return the width
      */
     public GordianLength getLength() {
         return theLength;
     }
 
     /**
      * Obtain the parameters.
      *
      * @return the parameters
      */
     public LMSParameters getParameters() {
         return theParams;
     }
 
     /**
      * Is the keySpec high (height ≥ 15)?
      *
      * @return true/false.
      */
     public boolean isHigh() {
         return isValid && theHeight.isHigh();
     }
 
     /**
      * Is the keySpec valid?
      *
      * @return true/false.
      */
     public boolean isValid() {
         return isValid;
     }
 
     /**
      * Check spec validity.
      *
      * @return valid true/false
      */
     private boolean checkValidity() {
         if (theWidth == null || theHeight == null || theHash == null || theLength == null) {
             return false;
         }
         switch (theLength) {
             case LEN_192:
             case LEN_256:
                 return true;
             default:
                 return false;
         }
     }
 
     @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 = theHash.toString() + SEP + theWidth.toString() + SEP + theHeight.toString() + SEP + theLength.toString();
             } else {
                 /* Report invalid spec */
                 theName = "InvalidLMSKeySpec: " + theHash + SEP + theWidth + SEP + theHeight + SEP + theLength;
             }
         }
 
         /* 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 fields */
         return pThat instanceof GordianLMSKeySpec myThat
                 && theHash == myThat.theHash
                 && theLength == myThat.theLength
                 && theWidth == myThat.theWidth
                 && theHeight == myThat.theHeight;
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(theHash, theHeight, theWidth, theLength);
     }
 
     /**
      * Obtain a list of all possible specs.
      *
      * @return the list
      */
     public static List<GordianLMSKeySpec> listPossibleKeySpecs() {
         /* Create the list */
         final List<GordianLMSKeySpec> mySpecs = new ArrayList<>();
 
         /* Add the specs */
         for (final GordianLMSHeight myHeight : GordianLMSHeight.values()) {
             for (final GordianLMSWidth myWidth : GordianLMSWidth.values()) {
                 mySpecs.add(new GordianLMSKeySpec(GordianLMSHash.SHA256, myHeight, myWidth, GordianLength.LEN_256));
                 mySpecs.add(new GordianLMSKeySpec(GordianLMSHash.SHA256, myHeight, myWidth, GordianLength.LEN_192));
                 mySpecs.add(new GordianLMSKeySpec(GordianLMSHash.SHAKE256, myHeight, myWidth, GordianLength.LEN_256));
                 mySpecs.add(new GordianLMSKeySpec(GordianLMSHash.SHAKE256, myHeight, myWidth, GordianLength.LEN_192));
             }
         }
 
         /* Return the list */
         return mySpecs;
     }
 
     /**
      * Match keySpec against LMSParameters.
      *
      * @param pSigParams the sigParameters
      * @param pOtsParams the otsParameters
      * @return the matching keySpec
      */
     public static GordianLMSKeySpec determineKeySpec(final LMSigParameters pSigParams,
                                                      final LMOtsParameters pOtsParams) {
         final List<GordianLMSKeySpec> mySpecs = listPossibleKeySpecs();
         for (GordianLMSKeySpec mySpec : mySpecs) {
             if (pSigParams.equals(mySpec.getParameters().getLMSigParam())
                     && pOtsParams.equals(mySpec.getParameters().getLMOTSParam())) {
                 return mySpec;
             }
         }
         throw new IllegalArgumentException("Unsupported LMSSpec");
     }
 
     /**
      * HSS keySpec.
      */
     public static class GordianHSSKeySpec {
         /**
          * Max depth for HSS key.
          */
         public static final int MAX_DEPTH = 8;
 
         /**
          * The top level keySpec.
          */
         private final GordianLMSKeySpec theKeySpec;
 
         /**
          * The tree depth.
          */
         private final int theDepth;
 
         /**
          * The Validity.
          */
         private final boolean isValid;
 
         /**
          * The String name.
          */
         private String theName;
 
         /**
          * Constructor.
          *
          * @param pKeySpec the keySpecs
          * @param pDepth   the tree depth
          */
         GordianHSSKeySpec(final GordianLMSKeySpec pKeySpec,
                           final int pDepth) {
             /* Create the list of keySpecs */
             theKeySpec = pKeySpec;
             theDepth = pDepth;
             isValid = checkValidity();
         }
 
         /**
          * Obtain the parameters.
          *
          * @return the parameters.
          */
         public GordianLMSKeySpec getKeySpec() {
             /* If we are valid */
             return isValid
                     ? theKeySpec
                     : null;
         }
 
         /**
          * Obtain the treeDepth.
          *
          * @return the treeDepth.
          */
         public int getTreeDepth() {
             /* If we are valid */
             return isValid
                     ? theDepth
                     : -1;
         }
 
         /**
          * Is the keySpec valid?
          *
          * @return true/false.
          */
         public boolean isValid() {
             return isValid;
         }
 
         /**
          * Check spec validity.
          *
          * @return valid true/false
          */
         private boolean checkValidity() {
             /* Depth must be at least 1 and  no more that MAX */
             if (theDepth < 1 || theDepth > MAX_DEPTH) {
                 return false;
             }
 
             /* Check keySpec */
             return theKeySpec != null && theKeySpec.isValid;
         }
 
         @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 = "HSS-" + theDepth + "-" + theKeySpec;
 
                 } else {
                     /* Report invalid spec */
                     theName = "InvalidHSSKeySpec: " + theDepth + ":" + theKeySpec;
                 }
             }
 
             /* 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;
             }
 
             /* Make sure that the object is hssSpec */
             if (pThat.getClass() != this.getClass()) {
                 return false;
             }
 
             /* Access the target hssSpec */
             final GordianHSSKeySpec myThat = (GordianHSSKeySpec) pThat;
 
             /* Check depth and keySpec are identical */
             return theDepth == myThat.theDepth
                     && Objects.equals(theKeySpec, myThat.theKeySpec);
         }
 
         @Override
         public int hashCode() {
             return theKeySpec.hashCode() + theDepth;
         }
     }
 
     /**
      * LMS hash.
      */
     public enum GordianLMSHash {
         /**
          * Sha256.
          */
         SHA256,
 
         /**
          * Shake256.
          */
         SHAKE256;
     }
 
     /**
      * LMS height.
      */
     public enum GordianLMSHeight {
         /**
          * H5.
          */
         H5,
 
         /**
          * H10.
          */
         H10,
 
         /**
          * H15.
          */
         H15,
 
         /**
          * H20.
          */
         H20,
 
         /**
          * H25.
          */
         H25;
 
         /**
          * Obtain the sigParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMSigParameters getSigParameter(final GordianLMSHash pHash,
                                                 final GordianLength pLength) {
             switch (this) {
                 case H5:
                     return getH5Parameter(pHash, pLength);
                 case H10:
                     return getH10Parameter(pHash, pLength);
                 case H15:
                     return getH15Parameter(pHash, pLength);
                 case H20:
                     return getH20Parameter(pHash, pLength);
                 case H25:
                     return getH25Parameter(pHash, pLength);
                 default:
                     throw new IllegalStateException();
             }
         }
 
         /**
          * Obtain the H5 sigParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMSigParameters getH5Parameter(final GordianLMSHash pHash,
                                                final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n24_h5 : LMSigParameters.lms_shake256_n24_h5;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n32_h5 : LMSigParameters.lms_shake256_n32_h5;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the H10 sigParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMSigParameters getH10Parameter(final GordianLMSHash pHash,
                                                 final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n24_h10 : LMSigParameters.lms_shake256_n24_h10;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n32_h10 : LMSigParameters.lms_shake256_n32_h10;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the H15 sigParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMSigParameters getH15Parameter(final GordianLMSHash pHash,
                                                 final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n24_h15 : LMSigParameters.lms_shake256_n24_h15;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n32_h15 : LMSigParameters.lms_shake256_n32_h15;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the H20 sigParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMSigParameters getH20Parameter(final GordianLMSHash pHash,
                                                 final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n24_h20 : LMSigParameters.lms_shake256_n24_h20;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n32_h20 : LMSigParameters.lms_shake256_n32_h20;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the H25 sigParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMSigParameters getH25Parameter(final GordianLMSHash pHash,
                                                 final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n24_h25 : LMSigParameters.lms_shake256_n24_h25;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMSigParameters.lms_sha256_n32_h25 : LMSigParameters.lms_shake256_n32_h25;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Is the parameter high (height &ge; 15)?
          *
          * @return true/false.
          */
         public boolean isHigh() {
             switch (this) {
                 case H15:
                 case H20:
                 case H25:
                     return true;
                 default:
                     return false;
             }
         }
     }
 
     /**
      * LMS Width.
      */
     public enum GordianLMSWidth {
         /**
          * W1.
          */
         W1,
 
         /**
          * W2.
          */
         W2,
 
         /**
          * W4.
          */
         W4,
 
         /**
          * W8.
          */
         W8;
 
         /**
          * Obtain the otsParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMOtsParameters getOtsParameter(final GordianLMSHash pHash,
                                                 final GordianLength pLength) {
             switch (this) {
                 case W1:
                     return getW1Parameter(pHash, pLength);
                 case W2:
                     return getW2Parameter(pHash, pLength);
                 case W4:
                     return getW4Parameter(pHash, pLength);
                 case W8:
                     return getW8Parameter(pHash, pLength);
                 default:
                     throw new IllegalStateException();
             }
         }
 
         /**
          * Obtain the W1 otsParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMOtsParameters getW1Parameter(final GordianLMSHash pHash,
                                                final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n24_w1 : LMOtsParameters.shake256_n24_w1;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n32_w1 : LMOtsParameters.shake256_n32_w1;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the W2 otsParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMOtsParameters getW2Parameter(final GordianLMSHash pHash,
                                                final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n24_w2 : LMOtsParameters.shake256_n24_w2;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n32_w2 : LMOtsParameters.shake256_n32_w2;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the W4 otsParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMOtsParameters getW4Parameter(final GordianLMSHash pHash,
                                                final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n24_w4 : LMOtsParameters.shake256_n24_w4;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n32_w4 : LMOtsParameters.shake256_n32_w4;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
 
         /**
          * Obtain the W8 otsParameter.
          *
          * @param pHash   the hash
          * @param pLength the length
          * @return the parameter
          */
         private LMOtsParameters getW8Parameter(final GordianLMSHash pHash,
                                                final GordianLength pLength) {
             switch (pLength) {
                 case LEN_192:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n24_w8 : LMOtsParameters.shake256_n24_w8;
                 case LEN_256:
                     return pHash == GordianLMSHash.SHA256 ? LMOtsParameters.sha256_n32_w8 : LMOtsParameters.shake256_n32_w8;
                 default:
                     throw new IllegalArgumentException(INVALID_LENGTH + pLength);
             }
         }
     }
 }