001/*
002 * SPDX-License-Identifier: Apache-2.0
003 *
004 * Copyright 2025 The Enola <https://enola.dev> Authors
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 *     https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package dev.enola.cas;
019
020import com.google.common.io.ByteSource;
021
022import dev.enola.common.io.resource.*;
023
024import io.ipfs.cid.Cid;
025
026import java.io.IOException;
027import java.net.URI;
028
029/** <a href="https://ipfs.tech/">IPFS</a> Resource, via an IPFS Kubo RPC API. */
030public class IPFSApiResource extends BaseResource implements ReadableResource {
031
032    // TODO implement WritableResource
033
034    public static class Provider implements ResourceProvider {
035        private final IPFSBlobStore ipfs;
036
037        public Provider(IPFSBlobStore ipfs) {
038            this.ipfs = ipfs;
039        }
040
041        @Override
042        public Resource getResource(URI uri) {
043            if (isIPFS(uri))
044                return new ReadableButNotWritableDelegatingResource(new IPFSApiResource(ipfs, uri));
045            else return null;
046        }
047    }
048
049    private static boolean isIPFS(URI uri) {
050        return "ipfs".equals(uri.getScheme());
051    }
052
053    private static void check(URI uri) {
054        if (!isIPFS(uri)) throw new IllegalArgumentException(uri.toString());
055    }
056
057    private final IPFSBlobStore ipfs;
058
059    public IPFSApiResource(IPFSBlobStore ipfs, URI uri) {
060        super(uri);
061        check(uri);
062        this.ipfs = ipfs;
063    }
064
065    @Override
066    public ByteSource byteSource() {
067        try {
068            return ipfs.load(Cid.decode(uri().getAuthority()), uri().getPath());
069        } catch (IOException e) {
070            return new ErrorByteSource(e);
071        }
072    }
073}