/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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 com.android.tradefed.result;

import com.android.tradefed.log.LogUtil.CLog;
import com.android.tradefed.util.FileUtil;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * A File-backed InputStreamSource.  Creates a snapshot of original {@link InputStream} contents to
 * ensure that {@link #createInputStream()} will return identically-behaving {@link InputStream}s as
 * required.
 */
public class SnapshotInputStreamSource implements InputStreamSource {
    private File mBackingFile;
    private boolean mIsCancelled = false;

    /** Constructor for a file-backed {@link InputStreamSource} */
    public SnapshotInputStreamSource(String name, InputStream stream) {
        if (stream == null) {
            throw new NullPointerException();
        }

        try {
            mBackingFile = createBackingFile(name, stream);
        } catch (IOException e) {
            // Log an error and invalidate ourself
            CLog.e("Received IOException while trying to wrap a stream");
            CLog.e(e);
            close();
        }
    }

    /**
     * Create the backing file and fill it with the contents of {@code stream}.
     *
     * <p>Exposed for unit testing
     */
    File createBackingFile(String name, InputStream stream) throws IOException {
        File backingFile =
                FileUtil.createTempFile(name + "_" + this.getClass().getSimpleName() + "_", ".txt");
        FileUtil.writeToFile(stream, backingFile);
        return backingFile;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public synchronized InputStream createInputStream() {
        if (mIsCancelled) {
            return null;
        }

        try {
            return new FileInputStream(mBackingFile);
        } catch (IOException e) {
            return null;
        }
    }

    /** {@inheritDoc} */
    @Override
    public synchronized void close() {
        mIsCancelled = true;
        FileUtil.deleteFile(mBackingFile);
        mBackingFile = null;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public long size() {
        return mBackingFile.length();
    }
}