package eu.openaire.urls_controller.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;


public class FileUnZipper {

    private static final Logger logger = LoggerFactory.getLogger(FileUnZipper.class);


    public static void unzipFolder(Path source, Path target) throws Exception
    {
        try ( ZipInputStream zis = new ZipInputStream(new FileInputStream(source.toFile())) )
        {
            // Iterate over the files in zip and un-zip them.
            ZipEntry zipEntry = zis.getNextEntry();
            while ( zipEntry != null )
            {
                Path targetPath = zipSlipProtect(zipEntry, target);

                if ( zipEntry.getName().endsWith(File.separator) )  // If we have a directory.
                    Files.createDirectories(targetPath);
                else {
                    // Some zip -files store only the file-paths and not separate directories. We need to create parent directories, e.g data/folder/file.txt
                    Path parentPath = targetPath.getParent();
                    if ( (parentPath != null) && Files.notExists(parentPath) ) {
                        Files.createDirectories(parentPath);
                    }
                    Files.copy(zis, targetPath, StandardCopyOption.REPLACE_EXISTING);   // Copy an individual entry.
                }
                zipEntry = zis.getNextEntry();
            }
            zis.closeEntry();
        }
    }


    // Protect from a Zip Slip attack:  https://snyk.io/research/zip-slip-vulnerability
    public static Path zipSlipProtect(ZipEntry zipEntry, Path targetDir) throws IOException
    {
        Path targetDirResolved = targetDir.resolve(zipEntry.getName());
        // Make sure normalized file still has targetDir as its prefix, else throw an exception.
        Path normalizePath = targetDirResolved.normalize();
        if ( !normalizePath.startsWith(targetDir) ) {
            throw new IOException("Bad zip entry: " + zipEntry.getName());
        }
        return normalizePath;
    }

}