package org.openslx.taskmanager.tasks;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;

import org.apache.commons.compress.archivers.ArchiveEntry;
import org.apache.commons.compress.archivers.ArchiveException;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
import org.apache.commons.compress.archivers.tar.TarArchiveOutputStream;
import org.apache.commons.io.FileUtils;
import org.apache.commons.io.FilenameUtils;
import org.openslx.satserver.util.Archive;
import org.openslx.satserver.util.Util;
import org.openslx.taskmanager.api.AbstractTask;

import com.google.gson.annotations.Expose;

public class RecompressArchive extends AbstractTask
{

	@Expose
	private String[] inputFiles;

	@Expose
	private String outputFile;

	/*
	 * Own vars/constants not being deserialized
	 */

	protected static final String[] ALLOWED_DIRS =
	{ "/tmp/", "/opt/openslx/configs/" };

	private Output status = new Output();

	/*
	 * Code
	 */

	@Override
	protected boolean execute()
	{
		String fn = new File( this.outputFile ).getName();
		String tmpFile = "/tmp/bwlp-" + System.nanoTime() + "-" + fn;
		if ( execute2( tmpFile ) ) {
			try {
				FileUtils.deleteQuietly( new File( this.outputFile ) );
				Files.move( Paths.get( tmpFile ), Paths.get( this.outputFile ) );
				return true;
			} catch ( Exception e ) {
				status.error = e.toString();
				status.errorCode = Output.ErrorCode.WRITE_FAILED;
			}
		}
		FileUtils.deleteQuietly( new File( tmpFile ) );
		return false;
	}

	private boolean execute2( String archiveFile )
	{
		// Open output file archive
		TarArchiveOutputStream outArchive = null;
		try {
			try {
				FileUtils.forceMkdir( new File( new File( this.outputFile ).getParent() ) );
				outArchive = Archive.createTarArchive( archiveFile );
			} catch ( IOException e2 ) {
				status.error = e2.toString();
				status.errorCode = Output.ErrorCode.WRITE_FAILED;
				return false;
			}

			// Open input file archives, one by one
			for ( final String inputFile : this.inputFiles ) {
				ArchiveInputStream inArchive = null;
				try {
					try {
						inArchive = Archive.getArchiveInputStream( inputFile );
					} catch ( FileNotFoundException e1 ) {
						status.error = "(" + inputFile + ") " + e1.getMessage();
						status.errorCode = Output.ErrorCode.NOT_FOUND;
						return false;
					} catch ( IllegalArgumentException e1 ) {
						status.error = "(" + inputFile + ") " + e1.getMessage();
						status.errorCode = Output.ErrorCode.UNKNOWN_ERROR;
						return false;
					} catch ( ArchiveException e1 ) {
						status.error = "(" + inputFile + ") " + e1.getMessage();
						status.errorCode = Output.ErrorCode.UNKNOWN_FORMAT;
						return false;
					}
					// It's open
					ArchiveEntry inEntry;

					// Remember all files added, so we can issue warnings for duplicate entries
					Set<String> entries = new HashSet<>();
					// Iterate over every entry
					while ( ( inEntry = inArchive.getNextEntry() ) != null ) {
						if ( !inArchive.canReadEntryData( inEntry ) )
							continue; // Skip unreadable entries
						// Construct TarArchiveEntry - we want unix stuff like uid/gid, links, file/dir mode, so try to get from source archive
						TarArchiveEntry outEntry = Archive.createTarArchiveEntry( inEntry, 0, 0, 0755, 0644 );
						// Ask lib if the entry can be written
						if ( !outArchive.canWriteEntryData( outEntry ) ) {
							status.warnings.add( "Commons-compress says entry '" + outEntry.getName() + "' cannot be written." );
							continue;
						}
						// Dupcheck
						if ( entries.contains( outEntry.getName() ) ) {
							status.warnings.add( "Duplicate entry: " + outEntry.getName() );
						} else {
							entries.add( outEntry.getName() );
						}
						// Actually add entry now
						try {
							outArchive.putArchiveEntry( outEntry );
						} catch (Exception e) {
							status.error = "(" + inputFile + ") Could not putArchiveEntry('" + inEntry.getName() + "'): " + e.getMessage();
							status.errorCode = Output.ErrorCode.TAR_ERROR;
							return false;
						}
						if ( !Util.streamCopy( inArchive, outArchive, outEntry.getSize() ) ) {
							status.error = "(" + inputFile + ") Could not copy entry '" + inEntry.getName() + "' to destination archive.";
							status.errorCode = Output.ErrorCode.WRITE_FAILED;
							return false;
						}
						outArchive.closeArchiveEntry();
					} // End entry
				} catch ( IOException e ) {
					return false;
				} finally {
					Util.multiClose( inArchive );
				}
			} // End of loop over input archives

			return true;
		} finally {
			Util.multiClose( outArchive );
		}
	}

	@Override
	protected boolean initTask()
	{
		this.setStatusObject( this.status );
		// Input files
		if ( this.inputFiles == null ) {
			status.error = "Input: No archives given";
			status.errorCode = Output.ErrorCode.UNKNOWN_ERROR;
			return false;
		}
		for ( int i = 0; i < this.inputFiles.length; ++i ) {
			String inputFile = this.inputFiles[i];
			if ( inputFile == null || inputFile.length() == 0 || inputFile.charAt( 0 ) != '/' ) {
				status.error = "Input: Need absolute path (got: " + inputFile + ")";
				status.errorCode = Output.ErrorCode.INVALID_DIRECTORY;
				return false;
			}
			inputFile = FilenameUtils.normalize( inputFile );
			if ( inputFile == null || !Util.startsWith( inputFile, ALLOWED_DIRS ) ) {
				status.error = "Input: File not in allowed directory";
				status.errorCode = Output.ErrorCode.INVALID_DIRECTORY;
				return false;
			}
			this.inputFiles[i] = inputFile;
		}
		// Output file
		if ( this.outputFile == null || this.outputFile.length() == 0 || this.outputFile.charAt( 0 ) != '/' ) {
			status.error = "Output: Need absolute path.";
			status.errorCode = Output.ErrorCode.INVALID_DIRECTORY;
			return false;
		}
		this.outputFile = FilenameUtils.normalize( this.outputFile );
		if ( !Util.startsWith( this.outputFile, ALLOWED_DIRS ) ) {
			status.error = "Output: File not in allowed directory";
			status.errorCode = Output.ErrorCode.INVALID_DIRECTORY;
			return false;
		}
		return true;
	}

	@SuppressWarnings( "unused" )
	private static class Output
	{
		protected String error = null;

		protected enum ErrorCode
		{
			NOT_FOUND, UNKNOWN_FORMAT, UNKNOWN_ERROR, INVALID_DIRECTORY, WRITE_FAILED, TAR_ERROR
		};

		protected ErrorCode errorCode = null;
		protected List<String> warnings = new CopyOnWriteArrayList<>();

		public static class Entry
		{
			protected String name = null;
			protected boolean isdir = false;
			protected long size = -1;
		}
	}

}