/**
 * ${jpp:disclaimer}
 *
 * ${jpp:copyright}
**/
package hotfolder;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.nio.file.StandardWatchEventKinds;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

import com.inet.pdfc.PDFComparer;
import com.inet.pdfc.error.PdfcException;
import com.inet.pdfc.presenter.DifferencesPDFPresenter;
import com.inet.pdfc.results.ResultModel;

/**
 * A Java app which watches a folder for file changes and automatically compares new PDFs.
 * The idea is that any time two PDFs are added to the folder, we will run a simple comparison of the two
 * PDFs using i-net PDFC, create a report of the comparison and store it in a "reports" folder, and move
 * the source PDFs to a source archive folder.
 * See https://faq.inetsoftware.de/t/automatically-compare-new-pdfs-in-a-folder/47
 */
public class HotFolderService {

    private static Path firstPdfPath;

    public static void main( String[] args ) throws IOException {
        String sourceFolder = "";
        String archiveFolder = "sourceArchive";
        String reportsFolder = "reports";
        for( int i = 0; i < args.length - 1; i += 2 ) {
            if( "-s".equals( args[i] ) ) {
                sourceFolder = args[i + 1];
            } else if( "-a".equals( args[i] ) ) {
                archiveFolder = args[i + 1];
            } else if( "-r".equals( args[i] ) ) {
                reportsFolder = args[i + 1];
            }
        }
        if (sourceFolder.equals(archiveFolder) || sourceFolder.equals(reportsFolder)) {
            throw new IllegalStateException("Source folder must be unique to avoid endless loops.");
        }
        Path sourcePath = Paths.get( sourceFolder );
        Path archivePath = Paths.get( archiveFolder );
        Path reportsPath = Paths.get( reportsFolder );
        if( !Files.exists( sourcePath ) ) {
            Files.createDirectories( sourcePath );
        }
        if( !Files.exists( archivePath ) ) {
            Files.createDirectories( archivePath );
        }
        if( !Files.exists( reportsPath ) ) {
            Files.createDirectories( reportsPath );
        }
        System.out.println( "watching for new files at " + sourcePath.toAbsolutePath() );
        WatchDir.WatchEventListener listener = ( ev, path ) -> {
            try {
                if( ev.kind() == StandardWatchEventKinds.ENTRY_CREATE &&
                                path.getFileName().toString().toLowerCase().endsWith( ".pdf" ) ) {
                    if( firstPdfPath == null ) {
                        firstPdfPath = path;
                    } else {
                        PDFComparer comparer = new PDFComparer();
                        String datetime = DateTimeFormatter.ofPattern( "yyyy-MM-dd" ).format( LocalDateTime.now() );
                        comparer.addPresenter( new DifferencesPDFPresenter(
                                        new File( reportsPath.toFile(), "ComparisonReports-" + datetime ) ) );
                        try (ResultModel result = comparer.compare( firstPdfPath.toFile(), path.toFile() ) ){
	                        System.out.println( "Compared " + firstPdfPath + " to " + path + "." );
	                        System.out.println( "Differences found: " + result.getDifferencesCount( false ) );
                        }
                        Files.move( firstPdfPath, archivePath.resolve( firstPdfPath.getFileName() ), StandardCopyOption.REPLACE_EXISTING );
                        Files.move( path, archivePath.resolve( path.getFileName() ), StandardCopyOption.REPLACE_EXISTING );
                        firstPdfPath = null; // reset for the next pair of Files
                    }
                }
            } catch( IOException ex ) {
                ex.printStackTrace();
            } catch( PdfcException e ) {
                e.printStackTrace();
            }
        };
        WatchDir watcher = new WatchDir( sourcePath, false, listener );
        watcher.processEvents();
    }
}