package com.imyeyu.compress;

import com.imyeyu.io.IO;
import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;

import java.io.File;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Gzip 解压器
 * 当前实现保持与原行为一致，实际按 tar.gz 解压
 *
 * @author 夜雨
 * @version 2024-06-30 19:47
 */
public class GZipDecompressor extends Decompressor {

	@Override
	public void run(File fromFile, String toPath) throws Exception {
		initByteProgress(readTotalSize(fromFile));
		try {
			super.run(fromFile, toPath);
		} finally {
			resetProgress();
		}
	}

	@Override
	public void run(InputStream fromStream, String toPath) throws Exception {
		try (
			GzipCompressorInputStream gzipInputStream = new GzipCompressorInputStream(nonClosing(fromStream));
			TarArchiveInputStream tarInputStream = new TarArchiveInputStream(gzipInputStream)
		) {
			TarArchiveEntry entry;
			boolean processed = false;
			while ((entry = tarInputStream.getNextEntry()) != null) {
				String path = IO.fitPath(toPath) + entry.getName();
				if (entry.isDirectory()) {
					IO.dir(path);
				} else {
					File toFile = IO.file(path);
					try (OutputStream outputStream = IO.getOutputStream(toFile)) {
						transfer(tarInputStream, outputStream);
						outputStream.flush();
					}
					handleFile(toFile);
					processed = true;
				}
			}
			if (processed) {
				finishProgress();
			}
		}
	}

	/**
	 * 读取压缩包解压总字节数
	 *
	 * @param fromFile 压缩文件
	 * @return 总字节数
	 * @throws Exception 读取失败
	 */
	private long readTotalSize(File fromFile) throws Exception {
		long totalSize = 0L;
		try (
			InputStream inputStream = IO.getInputStream(fromFile);
			GzipCompressorInputStream gzipInputStream = new GzipCompressorInputStream(inputStream);
			TarArchiveInputStream tarInputStream = new TarArchiveInputStream(gzipInputStream)
		) {
			TarArchiveEntry entry;
			while ((entry = tarInputStream.getNextEntry()) != null) {
				if (!entry.isDirectory()) {
					totalSize += entry.getSize();
				}
			}
		}
		return totalSize;
	}
}