/*
    * Copyright (c) 2002-2026 Gargoyle Software Inc.
    *
    * 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
    * https://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 org.htmlunit.javascript.host.crypto;
  
  import java.math.BigInteger;
  import java.nio.ByteBuffer;
  import java.util.Set;
  
  import org.htmlunit.corejs.javascript.Scriptable;
  import org.htmlunit.corejs.javascript.ScriptableObject;
  import org.htmlunit.corejs.javascript.VarScope;
  import org.htmlunit.corejs.javascript.typedarrays.NativeArrayBuffer;
  import org.htmlunit.corejs.javascript.typedarrays.NativeArrayBufferView;
  import org.htmlunit.corejs.javascript.typedarrays.NativeUint8Array;
  import org.htmlunit.javascript.JavaScriptEngine;
  
  /**
   * Internal helper representing RSA hashed key algorithm parameters.
   * Used by {@link SubtleCrypto} for RSA key operations.
   *
   * @author Lai Quang Duong
   * @author Ronald Brill
   */
  final class RsaHashedKeyAlgorithm {
  
      static final Set<String> SUPPORTED_NAMES = Set.of("RSASSA-PKCS1-v1_5", "RSA-PSS", "RSA-OAEP");
      static final Set<String> SUPPORTED_HASH_ALGORITHMS = Set.of("SHA-1", "SHA-256", "SHA-384", "SHA-512");
  
      private final String name_;
      private final int modulusLength_;
      private final byte[] publicExponent_;
      private final String hash_;
  
      RsaHashedKeyAlgorithm(final String name, final int modulusLength,
              final byte[] publicExponent, final String hash) {
          if (!SUPPORTED_NAMES.contains(name)) {
              throw new UnsupportedOperationException("RSA " + name);
          }
          name_ = name;
  
          if (modulusLength <= 0) {
              throw new IllegalArgumentException("Data provided to an operation does not meet requirements");
          }
          modulusLength_ = modulusLength;
  
          if (publicExponent == null || publicExponent.length == 0) {
              throw new IllegalArgumentException("Data provided to an operation does not meet requirements");
          }
          publicExponent_ = publicExponent.clone();
  
          if (!SUPPORTED_HASH_ALGORITHMS.contains(hash)) {
              throw new UnsupportedOperationException("RSA hash " + hash);
          }
          hash_ = hash;
      }
  
      /**
       * Parses RSA hashed key algorithm parameters from a JS object.
       *
       * @param keyGenParams the JS algorithm parameters object
       * @return the parsed RsaHashedKeyAlgorithm
       */
      static RsaHashedKeyAlgorithm from(final Scriptable keyGenParams) {
          final Object nameProp = ScriptableObject.getProperty(keyGenParams, "name");
          if (!(nameProp instanceof String name)) {
              throw new IllegalArgumentException("An invalid or illegal string was specified");
          }
  
          final Object modulusLengthProp = ScriptableObject.getProperty(keyGenParams, "modulusLength");
          if (!(modulusLengthProp instanceof Number numModulusLength)) {
              throw new IllegalArgumentException("An invalid or illegal string was specified");
          }
  
          final Object publicExponentProp = ScriptableObject.getProperty(keyGenParams, "publicExponent");
          final byte[] publicExponent = extractBytes(publicExponentProp);
          if (publicExponent == null) {
              throw new IllegalArgumentException("An invalid or illegal string was specified");
          }
  
          final Object hashProp = ScriptableObject.getProperty(keyGenParams, "hash");
          final String hash = SubtleCrypto.resolveAlgorithmName(hashProp);
  
          return new RsaHashedKeyAlgorithm(name, numModulusLength.intValue(), publicExponent, hash);
      }
  
      private static byte[] extractBytes(final Object value) {
          if (value instanceof NativeArrayBufferView view) {
             final NativeArrayBuffer buf = view.getBuffer();
             if (buf != null) {
                 final byte[] result = new byte[view.getByteLength()];
                 final ByteBuffer bb = buf.getByteBuffer();
                 bb.position(view.getByteOffset());
                 bb.get(result, 0, result.length);
                 return result;
             }
         }
         if (value instanceof NativeArrayBuffer buf) {
             final ByteBuffer bb = buf.getByteBuffer();
             final byte[] result = new byte[bb.remaining()];
             bb.get(result);
             return result;
         }
         return null;
     }
 
     static boolean isSupported(final String name) {
         return SUPPORTED_NAMES.contains(name);
     }
 
     String getName() {
         return name_;
     }
 
     int getModulusLength() {
         return modulusLength_;
     }
 
     byte[] getPublicExponent() {
         return publicExponent_.clone();
     }
 
     /**
      * Returns the public exponent as a BigInteger.
      *
      * @return the public exponent as a BigInteger
      */
     BigInteger getPublicExponentAsBigInteger() {
         return new BigInteger(1, publicExponent_);
     }
 
     String getHash() {
         return hash_;
     }
 
     /**
      * Returns the Java hash algorithm name (e.g. "SHA256" from "SHA-256").
      *
      * @return the Java hash algorithm name (e.g. "SHA256" from "SHA-256")
      */
     String getJavaHash() {
         return hash_.replace("-", "");
     }
 
     /**
      * Converts to a JS object matching the {@code RsaHashedKeyAlgorithm} dictionary:
      * {@code {name: "RSASSA-PKCS1-v1_5", modulusLength: 2048, publicExponent: Uint8Array, hash: {name: "SHA-256"}}}.
      *
      * @param scope the JS scope for prototype/parent setup
      * @return the JS algorithm object
      */
     Scriptable toScriptableObject(final VarScope scope) {
         final Scriptable hashObj = JavaScriptEngine.newObject(scope);
         ScriptableObject.putProperty(hashObj, "name", getHash());
 
         final NativeUint8Array uint8Array = JavaScriptEngine.newUint8Array(scope, publicExponent_);
 
         final Scriptable algorithm = JavaScriptEngine.newObject(scope);
         ScriptableObject.putProperty(algorithm, "name", getName());
         ScriptableObject.putProperty(algorithm, "hash", hashObj);
         ScriptableObject.putProperty(algorithm, "modulusLength", getModulusLength());
         ScriptableObject.putProperty(algorithm, "publicExponent", uint8Array);
         return algorithm;
     }
 }