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;
020
021import java.nio.file.Path;
022import java.util.Optional;
023
024/**
025 * Resolves a file path to an HTTP {@code Content-Type} value.
026 * <p>
027 * Implementations used with {@link StaticFiles} must be thread-safe; {@link StaticFiles} invokes
028 * resolvers concurrently from request-handling threads.
029 * <p>
030 * {@link StaticFiles}' default resolver uses a curated deterministic extension map for common web
031 * assets. It does not call {@link java.nio.file.Files#probeContentType(Path)}. A custom resolver
032 * fully replaces that default, and {@link Optional#empty()} means no {@code Content-Type} header is
033 * emitted.
034 *
035 * @author <a href="https://www.revetkn.com">Mark Allen</a>
036 */
037@FunctionalInterface
038public interface MimeTypeResolver {
039        /**
040         * Resolves the {@code Content-Type} for {@code path}.
041         * <p>
042         * When configured through {@link StaticFiles.Builder#mimeTypeResolver(MimeTypeResolver)}, this
043         * resolver fully replaces the default resolver. To extend Soklet's default extension map, delegate
044         * to {@link #defaultInstance()} for paths your implementation does not handle.
045         *
046         * @param path the resolved file path being served
047         * @return the content type to emit, or {@link Optional#empty()} to omit it
048         */
049        @NonNull
050        Optional<String> contentTypeFor(@NonNull Path path);
051
052        /**
053         * Acquires Soklet's default threadsafe {@link MimeTypeResolver}.
054         * <p>
055         * The default resolver uses a curated deterministic extension map for common web assets and returns
056         * {@link Optional#empty()} for unknown extensions.
057         *
058         * @return the default {@code MimeTypeResolver}
059         */
060        @NonNull
061        static MimeTypeResolver defaultInstance() {
062                return DefaultMimeTypeResolver.defaultInstance();
063        }
064}