001/*
002 * Copyright 2022-2026 Revetware LLC.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.soklet;
018
019import org.jspecify.annotations.NonNull;
020import org.jspecify.annotations.Nullable;
021
022import javax.annotation.concurrent.ThreadSafe;
023import java.util.Map;
024import java.util.Objects;
025import java.util.Optional;
026import java.util.Set;
027
028import static com.soklet.Utilities.trimAggressivelyToEmpty;
029import static com.soklet.Utilities.trimAggressivelyToNull;
030import static java.util.Objects.requireNonNull;
031
032/**
033 * Encapsulates <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS">non-preflight CORS</a> HTTP request data.
034 * <p>
035 * Data for <a href="https://developer.mozilla.org/en-US/docs/Glossary/Preflight_request">preflight</a> requests is represented by {@link CorsPreflight}.
036 * <p>
037 * Instances can be acquired via these factory methods:
038 * <ul>
039 *   <li>{@link #fromOrigin(HttpMethod, String)} (uses {@code Origin} header value)</li>
040 *   <li>{@link #fromHeaders(HttpMethod, Map)} (parses raw headers)</li>
041 * </ul>
042 * <p>
043 * See <a href="https://www.soklet.com/docs/cors">https://www.soklet.com/docs/cors</a> for detailed documentation.
044 *
045 * @author <a href="https://www.revetkn.com">Mark Allen</a>
046 */
047@ThreadSafe
048public final class Cors {
049        @Nullable
050        private final HttpMethod httpMethod;
051        @NonNull
052        private final String origin;
053
054        /**
055         * Acquires a CORS <strong>non-preflight</strong> request representation for the given HTTP request data.
056         *
057         * @param httpMethod the request's HTTP method
058         * @param origin     HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin">{@code Origin}</a> request header value
059         * @return a {@link Cors} instance
060         */
061        @NonNull
062public static Cors fromOrigin(@NonNull HttpMethod httpMethod,
063                                                                                                                                @NonNull String origin) {
064                requireNonNull(httpMethod);
065                requireNonNull(origin);
066
067                return new Cors(httpMethod, origin);
068        }
069
070        /**
071         * Extracts a CORS <strong>non-preflight</strong> request representation from the given HTTP request data.
072         *
073         * @param httpMethod the request's HTTP method
074         * @param headers    the request headers
075         * @return the CORS non-preflight data for this request, or {@link Optional#empty()} if insufficent data is present
076         */
077        @NonNull
078        public static Optional<Cors> fromHeaders(@NonNull HttpMethod httpMethod,
079                                                                                                                                                                         @NonNull Map<@NonNull String, @NonNull Set<@NonNull String>> headers) {
080                requireNonNull(httpMethod);
081                requireNonNull(headers);
082
083                Set<String> originHeaderValues = headers.entrySet().stream()
084                                .filter(e -> e.getKey() != null && "origin".equalsIgnoreCase(trimAggressivelyToEmpty(e.getKey())))
085                                .map(Map.Entry::getValue)
086                                .filter(Objects::nonNull)
087                                .findFirst()
088                                .orElse(null);
089
090                if (originHeaderValues == null || originHeaderValues.size() == 0)
091                        return Optional.empty();
092
093                String originHeaderValue = trimAggressivelyToNull(originHeaderValues.stream().findFirst().orElse(null));
094
095                if (originHeaderValue == null)
096                        return Optional.empty();
097
098                return Optional.of(new Cors(httpMethod, originHeaderValue));
099        }
100
101        private Cors(@NonNull HttpMethod httpMethod,
102                                                         @NonNull String origin) {
103                requireNonNull(httpMethod);
104                requireNonNull(origin);
105
106                this.httpMethod = httpMethod;
107                this.origin = origin;
108        }
109
110        @Override
111        @NonNull
112        public String toString() {
113                return String.format("%s{httpMethod=%s, origin=%s}", getClass().getSimpleName(), getHttpMethod().name(), getOrigin());
114        }
115
116        @Override
117        public boolean equals(@Nullable Object object) {
118                if (this == object)
119                        return true;
120
121                if (!(object instanceof Cors cors))
122                        return false;
123
124                return Objects.equals(getHttpMethod(), cors.getHttpMethod())
125                                && Objects.equals(getOrigin(), cors.getOrigin());
126        }
127
128        @Override
129        public int hashCode() {
130                return Objects.hash(getHttpMethod(), getOrigin());
131        }
132
133        /**
134         * The HTTP method for this request.
135         *
136         * @return the HTTP method
137         */
138        @Nullable
139        public HttpMethod getHttpMethod() {
140                return this.httpMethod;
141        }
142
143        /**
144         * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin">{@code Origin}</a> header value for this request.
145         *
146         * @return the header value
147         */
148        @NonNull
149        public String getOrigin() {
150                return this.origin;
151        }
152}