/*
 * Copyright 2017 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.groovy.scripts.internal;

import org.gradle.api.UncheckedIOException;
import org.gradle.groovy.scripts.ScriptSource;
import org.gradle.internal.hash.FileHasher;
import org.gradle.internal.hash.HashCode;
import org.gradle.internal.hash.Hashing;
import org.gradle.internal.hash.PrimitiveHasher;
import org.gradle.internal.resource.TextResource;

import java.io.File;
import java.io.FileNotFoundException;

public class DefaultScriptSourceHasher implements ScriptSourceHasher {
    private static final HashCode SIGNATURE = Hashing.signature(DefaultScriptSourceHasher.class);

    private final FileHasher fileHasher;

    public DefaultScriptSourceHasher(FileHasher fileHasher) {
        this.fileHasher = fileHasher;
    }

    @Override
    public HashCode hash(ScriptSource scriptSource) {
        TextResource resource = scriptSource.getResource();
        if (resource.isContentCached()) {
            return hashText(resource.getText());
        }
        File file = resource.getFile();
        if (file == null) {
            return hashText(resource.getText());
        }
        return hashFile(file, scriptSource.getDisplayName());
    }

    private HashCode hashFile(File file, String displayName) {
        try {
            return fileHasher.hash(file);
        } catch (UncheckedIOException e) {
            if (e.getCause() instanceof FileNotFoundException) {
                throw new UncheckedIOException("Could not read " + displayName + " as it does not exist.", e.getCause());
            }
            throw e;
        }
    }

    private HashCode hashText(String text) {
        PrimitiveHasher hasher = Hashing.newPrimitiveHasher();
        hasher.putHash(SIGNATURE);
        hasher.putString(text);
        return hasher.hash();
    }
}
