/**
 * Copyright 2010-2014 The Kuali Foundation
 *
 * Licensed under the Educational Community 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.opensource.org/licenses/ecl2.php
 *
 * 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.kuali.common.util.encrypt.openssl;

import static org.kuali.common.util.base.Precondition.checkMin;
import static org.kuali.common.util.base.Precondition.checkNotBlank;
import static org.kuali.common.util.encrypt.EncryptionStrength.STRONG_ENCRYPTION_STRENGTH;

import org.kuali.common.util.encrypt.EncryptionStrength;

public final class OpenSSLContext {

        private final int iterations;
        private final String saltPrefix;
        private final int saltSize;
        private final int keySizeBits;
        private final String transformation;
        private final String digestAlgorithm;
        private final String algorithm;

        private OpenSSLContext(Builder builder) {
                this.iterations = builder.iterations;
                this.saltSize = builder.saltSize;
                this.saltPrefix = builder.saltPrefix;
                this.keySizeBits = builder.keySizeBits;
                this.transformation = builder.transformation;
                this.digestAlgorithm = builder.digestAlgorithm;
                this.algorithm = builder.algorithm;
        }

        /**
         * <p>
         * <code>EncryptionStrength.STRONG_ENCRYPTION_STRENGTH</code> means AES 256, otherwise AES 128.
         * <p>
         * 
         * <p>
         * <strong>WARNING:</strong> AES 256 causes an exception to be thrown unless you've installed java's "unlimited strength jurisdiction policy files"
         * </p>
         */
        public static OpenSSLContext buildOpenSSLContext(EncryptionStrength strength) {
                if (STRONG_ENCRYPTION_STRENGTH.equals(strength)) {
                        return builder().withKeySizeBits(Builder.STRONG_KEY_SIZE_BITS).build();
                } else {
                        return buildDefaultOpenSSLContext();
                }
        }

        /**
         * Returns a context for 128 bit AES encryption compatible with OpenSSL
         */
        public static OpenSSLContext buildDefaultOpenSSLContext() {
                return builder().build();
        }

        public static Builder builder() {
                return new Builder();
        }

        public static class Builder implements org.apache.commons.lang3.builder.Builder<OpenSSLContext> {

                private static final int STRONG_KEY_SIZE_BITS = 256;

                private int iterations = 1;
                private String saltPrefix = "Salted__";
                private int saltSize = 8;
                private int keySizeBits = 128;
                private String transformation = "AES/CBC/PKCS5Padding";
                private String digestAlgorithm = "MD5";
                private String algorithm = "AES";

                private static OpenSSLContext validate(OpenSSLContext instance) {
                        checkMin(instance.iterations, 0, "iterations");
                        checkNotBlank(instance.saltPrefix, "saltPrefix");
                        checkMin(instance.saltSize, 0, "saltSize");
                        checkMin(instance.keySizeBits, 0, "keySizeBits");
                        checkNotBlank(instance.transformation, "transformation");
                        checkNotBlank(instance.digestAlgorithm, "digest");
                        checkNotBlank(instance.algorithm, "algorithm");
                        return instance;
                }

                @Override
                public OpenSSLContext build() {
                        return validate(new OpenSSLContext(this));
                }

                public Builder withAlgorithm(String algorithm) {
                        this.algorithm = algorithm;
                        return this;
                }

                public Builder withSaltPrefix(String saltPrefix) {
                        this.saltPrefix = saltPrefix;
                        return this;
                }

                public Builder withDigestAlgorithm(String digestAlgorithm) {
                        this.digestAlgorithm = digestAlgorithm;
                        return this;
                }

                public Builder withTransformation(String transformation) {
                        this.transformation = transformation;
                        return this;
                }

                public Builder withIterations(int iterations) {
                        this.iterations = iterations;
                        return this;
                }

                public Builder withSaltSize(int saltSize) {
                        this.saltSize = saltSize;
                        return this;
                }

                public Builder withKeySizeBits(int keySizeBits) {
                        this.keySizeBits = keySizeBits;
                        return this;
                }

                public int getIterations() {
                        return iterations;
                }

                public void setIterations(int iterations) {
                        this.iterations = iterations;
                }

                public String getSaltPrefix() {
                        return saltPrefix;
                }

                public void setSaltPrefix(String saltPrefix) {
                        this.saltPrefix = saltPrefix;
                }

                public int getSaltSize() {
                        return saltSize;
                }

                public void setSaltSize(int saltSize) {
                        this.saltSize = saltSize;
                }

                public int getKeySizeBits() {
                        return keySizeBits;
                }

                public void setKeySizeBits(int keySizeBits) {
                        this.keySizeBits = keySizeBits;
                }

                public String getTransformation() {
                        return transformation;
                }

                public void setTransformation(String transformation) {
                        this.transformation = transformation;
                }

                public String getDigestAlgorithm() {
                        return digestAlgorithm;
                }

                public void setDigestAlgorithm(String digest) {
                        this.digestAlgorithm = digest;
                }

                public String getAlgorithm() {
                        return algorithm;
                }

                public void setAlgorithm(String algorithm) {
                        this.algorithm = algorithm;
                }
        }

        public int getIterations() {
                return iterations;
        }

        public int getSaltSize() {
                return saltSize;
        }

        public int getKeySizeBits() {
                return keySizeBits;
        }

        public String getTransformation() {
                return transformation;
        }

        public String getDigestAlgorithm() {
                return digestAlgorithm;
        }

        public String getAlgorithm() {
                return algorithm;
        }

        public String getSaltPrefix() {
                return saltPrefix;
        }
}