gradle-master/subprojects/normalization-java/src/main/java/org/gradle/api/internal/changedetection/state/LineEndingNormalizingResourceHasher.java
/*
 * Copyright 2021 the original author or authors.
 *
 * 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 org.gradle.api.internal.changedetection.state;

import org.gradle.internal.fingerprint.LineEndingSensitivity;
import org.gradle.internal.fingerprint.hashing.RegularFileSnapshotContext;
import org.gradle.internal.fingerprint.hashing.ResourceHasher;
import org.gradle.internal.fingerprint.hashing.ZipEntryContext;
import org.gradle.internal.hash.HashCode;
import org.gradle.internal.hash.Hasher;
import org.gradle.internal.io.IoFunction;

import java.io.File;
import java.io.IOException;
import java.util.Optional;

/**
 * A {@link ResourceHasher} that normalizes line endings while hashing the file.  It detects whether a file is text or binary and only
 * normalizes line endings for text files.  If a file is detected to be binary, we fall back to the existing non-normalized hash.
 *
 * See {@link LineEndingNormalizingInputStreamHasher}.
 */
public class LineEndingNormalizingResourceHasher extends FallbackHandlingResourceHasher {
    private final LineEndingNormalizingInputStreamHasher hasher;

    private LineEndingNormalizingResourceHasher(ResourceHasher delegate) {
        super(delegate);
        this.hasher = new LineEndingNormalizingInputStreamHasher();
    }

    public static ResourceHasher wrap(ResourceHasher delegate, LineEndingSensitivity lineEndingSensitivity) {
        switch (lineEndingSensitivity) {
            case DEFAULT:
                return delegate;
            case NORMALIZE_LINE_ENDINGS:
                return new LineEndingNormalizingResourceHasher(delegate);
            default:
                throw new IllegalArgumentException();
        }
    }

    @Override
    boolean filter(RegularFileSnapshotContext context) {
        return true;
    }

    @Override
    boolean filter(ZipEntryContext context) {
        return !context.getEntry().isDirectory();
    }

    @Override
    public void appendConfigurationToHasher(Hasher hasher) {
        super.appendConfigurationToHasher(hasher);
        hasher.putString(getClass().getName());
    }

    @Override
    Optional<HashCode> tryHash(RegularFileSnapshotContext snapshotContext) {
        return Optional.of(snapshotContext)
            .flatMap(IoFunction.wrap(this::hashContent));
    }

    @Override
    Optional<HashCode> tryHash(ZipEntryContext zipEntryContext) {
        return Optional.of(zipEntryContext)
            .flatMap(IoFunction.wrap(this::hashContent));
    }

    private Optional<HashCode> hashContent(RegularFileSnapshotContext snapshotContext) throws IOException {
        return hasher.hashContent(new File(snapshotContext.getSnapshot().getAbsolutePath()));
    }

    private Optional<HashCode> hashContent(ZipEntryContext zipEntryContext) throws IOException {
        return zipEntryContext.getEntry().withInputStream(hasher::hashContent);
    }
}
