/*
    * 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.agree;
  
  import io.github.tonywasher.joceanus.gordianknot.api.keypair.GordianKeyPairSpec;
  import io.github.tonywasher.joceanus.gordianknot.api.keypair.GordianKeyPairType;
  
  import java.util.Objects;
  
  /**
   * KeyPair Agreement Specification.
   */
  public final class GordianAgreementSpec {
      /**
       * The Separator.
       */
      private static final String SEP = "-";
  
      /**
       * KeyPairSpec.
       */
      private final GordianKeyPairSpec theKeyPairSpec;
  
      /**
       * AgreementType.
       */
      private final GordianAgreementType theAgreementType;
  
      /**
       * KDFType.
       */
      private final GordianAgreementKDF theKDFType;
  
      /**
       * With Confirmation?.
       */
      private final Boolean withConfirm;
  
      /**
       * The Validity.
       */
      private final boolean isValid;
  
      /**
       * The String name.
       */
      private String theName;
  
      /**
       * Constructor.
       *
       * @param pKeyPairSpec   the keyPairSpec
       * @param pAgreementType the agreement type
       * @param pKDFType       the KDF type
       */
      public GordianAgreementSpec(final GordianKeyPairSpec pKeyPairSpec,
                                  final GordianAgreementType pAgreementType,
                                  final GordianAgreementKDF pKDFType) {
          this(pKeyPairSpec, pAgreementType, pKDFType, Boolean.FALSE);
      }
  
      /**
       * Constructor.
       *
       * @param pKeyPairSpec   the keyPairSpec
       * @param pAgreementType the agreement type
       * @param pKDFType       the KDF type
       * @param pConfirm       with key confirmation
       */
      public GordianAgreementSpec(final GordianKeyPairSpec pKeyPairSpec,
                                  final GordianAgreementType pAgreementType,
                                  final GordianAgreementKDF pKDFType,
                                  final Boolean pConfirm) {
          theKeyPairSpec = pKeyPairSpec;
          theAgreementType = pAgreementType;
          theKDFType = pKDFType;
          withConfirm = pConfirm;
          isValid = checkValidity();
      }
  
      /**
       * Obtain the keyPairSpec.
       *
       * @return the keyPairSpec
       */
     public GordianKeyPairSpec getKeyPairSpec() {
         return theKeyPairSpec;
     }
 
     /**
      * Obtain the agreementType.
      *
      * @return the agreementType
      */
     public GordianAgreementType getAgreementType() {
         return theAgreementType;
     }
 
     /**
      * Obtain the kdfType.
      *
      * @return the kdfType
      */
     public GordianAgreementKDF getKDFType() {
         return theKDFType;
     }
 
     /**
      * Is this agreement with key confirmation?
      *
      * @return true/false
      */
     public Boolean withConfirm() {
         return withConfirm;
     }
 
     /**
      * Is this Agreement supported?
      *
      * @return true/false
      */
     public boolean isSupported() {
         final GordianKeyPairType myType = theKeyPairSpec.getKeyPairType();
         return theAgreementType.isSupported(myType) && theKDFType.isSupported(myType, theAgreementType);
     }
 
     /**
      * Is the agreementSpec valid?
      *
      * @return true/false.
      */
     public boolean isValid() {
         return isValid;
     }
 
     /**
      * Check spec validity.
      *
      * @return valid true/false
      */
     private boolean checkValidity() {
         /* All components must be non-null */
         if (theKeyPairSpec == null
                 || theAgreementType == null
                 || theKDFType == null
                 || withConfirm == null) {
             return false;
         }
 
         /* Confirmation is restricted to certain agreement types */
         if (Boolean.TRUE.equals(withConfirm)) {
             switch (theAgreementType) {
                 case UNIFIED:
                 case MQV:
                 case SM2:
                     return true;
                 default:
                     return false;
             }
         }
 
         /* Valid if supported */
         return isSupported();
     }
 
     @Override
     public String toString() {
         /* If we have not yet loaded the name */
         if (theName == null) {
             /* If the agreementSpec is valid */
             if (isValid) {
                 /* Load the name */
                 theName = theKeyPairSpec.toString()
                         + SEP + theAgreementType;
 
                 /* Add KDF type if present */
                 if (GordianAgreementKDF.NONE != theKDFType) {
                     theName += SEP + theKDFType;
                 }
 
                 /* Add Confirm if present */
                 if (Boolean.TRUE.equals(withConfirm)) {
                     theName += SEP + "CONFIRM";
                 }
             } else {
                 /* Report invalid spec */
                 theName = "InvalidAgreementSpec: " + theKeyPairSpec + ":" + theAgreementType + ":" + theKDFType;
             }
         }
 
         /* 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;
         }
 
         /* Match subfields */
         return pThat instanceof GordianAgreementSpec myThat
                 && Objects.equals(theKeyPairSpec, myThat.getKeyPairSpec())
                 && theAgreementType == myThat.getAgreementType()
                 && theKDFType == myThat.getKDFType()
                 && withConfirm == myThat.withConfirm();
     }
 
     @Override
     public int hashCode() {
         return Objects.hash(theKeyPairSpec, theAgreementType, theKDFType, withConfirm);
     }
 }