/*
 * nimbus-jose-jwt
 *
 * Copyright 2012-2016, Connect2id Ltd.
 *
 * 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 com.nimbusds.jose.util;


import java.io.Serializable;
import java.math.BigInteger;

import net.jcip.annotations.Immutable;
import net.minidev.json.JSONAware;
import net.minidev.json.JSONValue;


/**
 * Base64-encoded object.
 *
 * @author Vladimir Dzhuvinov
 * @version 2019-10-04
 */
@Immutable
public class Base64 implements JSONAware, Serializable {


        private static final long serialVersionUID = 1L;


        /**
         * The Base64 value.
         */
        private final String value;


        /**
         * Creates a new Base64-encoded object.
         *
         * @param base64 The Base64-encoded object value. The value is not 
         *               validated for having characters from a Base64 
         *               alphabet. Must not be {@code null}.
         */
        public Base64(final String base64) {

                if (base64 == null) {

                        throw new IllegalArgumentException("The Base64 value must not be null");
                }

                value = base64;
        }


        /**
         * Decodes this Base64 object to a byte array.
         *
         * @return The resulting byte array.
         */
        public byte[] decode() {

                return Base64Codec.decode(value);
        }


        /**
         * Decodes this Base64 object to an unsigned big integer.
         *
         * <p>Same as {@code new BigInteger(1, base64.decode())}.
         *
         * @return The resulting big integer.
         */
        public BigInteger decodeToBigInteger() {

                return new BigInteger(1, decode());
        }


        /**
         * Decodes this Base64 object to a string.
         *
         * @return The resulting string, in the UTF-8 character set.
         */
        public String decodeToString() {

                return new String(decode(), StandardCharset.UTF_8);
        }


        /**
         * Returns a JSON string representation of this object.
         *
         * @return The JSON string representation of this object.
         */
        @Override
        public String toJSONString() {

                return "\"" + JSONValue.escape(value) + "\"";
        }


        /**
         * Returns a Base64 string representation of this object. The string 
         * will be chunked into 76 character blocks separated by CRLF.
         *
         * @return The Base64 string representation, chunked into 76 character 
         *         blocks separated by CRLF.
         */
        @Override
        public String toString() {

                return value;
        }


        /**
         * Overrides {@code Object.hashCode()}.
         *
         * @return The object hash code.
         */
        @Override
        public int hashCode() {

                return value.hashCode();
        }


        /**
         * Overrides {@code Object.equals()}.
         *
         * @param object The object to compare to.
         *
         * @return {@code true} if the objects have the same value, otherwise
         *         {@code false}.
         */
        @Override
        public boolean equals(final Object object) {

                return object != null && 
                       object instanceof Base64 && 
                       this.toString().equals(object.toString());
        }
        
        
        /**
         * Creates a new Base64-encoded object from the specified string.
         *
         * @param base64 The Base64-encoded object value, {@code null} if not
         *               specified. The value is not validated for having
         *               characters from the Base64 alphabet.
         *
         * @return The Base64-encoded object, {@code null} if not specified.
         */
        public static Base64 from(final String base64) {
                
                if (base64 == null) {
                        return null;
                }
                
                return new Base64(base64);
        }


        /**
         * Base64-encodes the specified byte array. 
         *
         * @param bytes The byte array to encode. Must not be {@code null}.
         *
         * @return The resulting Base64 object.
         */
        public static Base64 encode(final byte[] bytes) {

                return new Base64(Base64Codec.encodeToString(bytes, false));
        }


        /**
         * Base64-encodes the specified big integer, without the sign bit.
         *
         * @param bigInt The big integer to encode. Must not be {@code null}.
         *
         * @return The resulting Base64 object.
         */
        public static Base64 encode(final BigInteger bigInt) {

                return encode(BigIntegerUtils.toBytesUnsigned(bigInt));
        }


        /**
         * Base64-encodes the specified string.
         *
         * @param text The string to encode. Must be in the UTF-8 character set
         *             and not {@code null}.
         *
         * @return The resulting Base64 object.
         */
        public static Base64 encode(final String text) {

                return encode(text.getBytes(StandardCharset.UTF_8));
        }
}