package eu.openaire.urls_controller.util;

import com.google.common.collect.SetMultimap;
import eu.openaire.urls_controller.models.Payload;
import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
import org.apache.commons.compress.compressors.zstandard.ZstdCompressorInputStream;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;

@Component
public class FileDecompressor {

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

    @Autowired
    private FileUtils fileUtils;


    boolean decompressAndUploadFullTexts(String zstdFileFullPath, Path curBatchPath, String targetDirectory, List<String> fileNamesForCurBatch, int batchCounter, SetMultimap<String, Payload> allFileNamesWithPayloads, long assignmentsBatchCounter)
    {
        try {
            decompressFiles(zstdFileFullPath, curBatchPath);
            String[] extractedFileNames = new File(targetDirectory).list();
            if ( extractedFileNames == null ) {
                logger.error("There was an error when acquiring the list of extracted files of directory: " + targetDirectory);
                return false;
            } else if ( extractedFileNames.length == 0 ) {    // The directory might have only two files, the "tar-file" and the "tar.zstd-file", if the full-texts failed to be decompressed or untarred..
                logger.error("No full-texts' fleNames where extracted from directory: " + targetDirectory);
                return false;
            } else if ( extractedFileNames.length != fileNamesForCurBatch.size() ) {
                logger.warn("The number of extracted files (" + extractedFileNames.length + ") was not equal to the number of files (" + fileNamesForCurBatch.size() + ") of the current batch_" + batchCounter);
                // We do NOT have to find and cross-reference the missing files with the urlReports, in order to set their locations to <null>,
                // since, in the end of each assignments-batch, an iteration will be made and for all the non-retrieved and non-uploaded full-texts, the app will set them to null.
            }
            fileUtils.uploadFullTexts(extractedFileNames, targetDirectory, allFileNamesWithPayloads, batchCounter);
            return true;
        } catch (Exception e) {
            logger.error("Could not extract and upload the full-texts for batch_" + batchCounter + " of assignments_" + assignmentsBatchCounter + GenericUtils.endOfLine + e.getMessage(), e);   // It shows the response body (after Spring v.2.5.6).
            return false;
        } finally {
            fileUtils.deleteDirectory(curBatchPath.toFile());
        }
    }

    public void decompressFiles(String zstdSource, Path targetDir) throws Exception
    {
        // Decompress the zstd file.
        String tarPathStr = StringUtils.replace(zstdSource, ".zstd", "", 1); // Remove the ".zstd" extension.
        Path tarPath = Paths.get(tarPathStr);
        int readByte = -1;

        try ( ZstdCompressorInputStream zsIn = new ZstdCompressorInputStream(new BufferedInputStream(Files.newInputStream(Paths.get(zstdSource)), FileUtils.tenMb));
              BufferedOutputStream out = new BufferedOutputStream(Files.newOutputStream(tarPath), FileUtils.tenMb) )
        {
            while ( (readByte = zsIn.read()) != -1 )
                out.write(readByte);
        } finally {
            fileUtils.deleteFile(zstdSource);   // Delete the initial zstd file.
        }

        // Now we have a decompressed tar-file, which we will Un-tar, in order to extract the full-text files.
        try ( TarArchiveInputStream tarInput = new TarArchiveInputStream(new BufferedInputStream(Files.newInputStream(tarPath)), FileUtils.tenMb) )
        {
            TarArchiveEntry entry;
            while ( ((entry = (TarArchiveEntry) tarInput.getNextEntry()) != null) )
            {
                // Copy an individual entry.
                try ( BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(Files.newOutputStream(targetDir.resolve(entry.getName())), FileUtils.tenMb) ) {
                    while ( (readByte = tarInput.read()) != -1 )
                        bufferedOutputStream.write(readByte);
                }   // The exception will be given to the caller method.
                // No need to close the tarEntry (no "close()" method is provided).
            }
        } finally {
            fileUtils.deleteFile(tarPathStr);   // Delete the decompressed tar file.
        }

        // Now we have a batch-directory which contains the tar-file along with the extracted full-text files.
        // After uploading the full-texts, the batch-directories will be deleted.
    }

}