package org.jabref.gui.importer;

import java.io.File;
import java.io.IOException;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.Calendar;
import java.util.Collections;
import java.util.List;
import java.util.Locale;
import java.util.Optional;

import org.jabref.Globals;
import org.jabref.JabRefGUI;
import org.jabref.gui.IconTheme;
import org.jabref.gui.externalfiletype.ExternalFileType;
import org.jabref.gui.externalfiletype.ExternalFileTypes;
import org.jabref.logic.xmp.XMPUtil;
import org.jabref.model.entry.BibEntry;
import org.jabref.pdfimport.PdfImporter;
import org.jabref.pdfimport.PdfImporter.ImportPdfFilesResult;
import org.jabref.preferences.JabRefPreferences;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDDocumentInformation;

/**
 * Uses XMPUtils to get one BibEntry for a PDF-File.
 * Also imports the non-XMP Data (PDDocument-Information) using XMPUtil.getBibtexEntryFromDocumentInformation.
 * If data from more than one entry is read by XMPUtil then this entys are merged into one.
 * @author Dan
 * @version 12.11.2008 | 22:12:48
 *
 */
public class EntryFromPDFCreator extends EntryFromFileCreator {

    public EntryFromPDFCreator() {
        super(EntryFromPDFCreator.getPDFExternalFileType());
    }

    private static ExternalFileType getPDFExternalFileType() {
        Optional<ExternalFileType> pdfFileType = ExternalFileTypes.getInstance().getExternalFileTypeByExt("pdf");
        if (!pdfFileType.isPresent()) {
            return new ExternalFileType("PDF", "pdf", "application/pdf", "evince", "pdfSmall", IconTheme.JabRefIcon.PDF_FILE.getSmallIcon());
        }
        return pdfFileType.get();
    }

    /**
     * Accepts all Files having as suffix ".PDF" (in ignore case mode).
     */
    @Override
    public boolean accept(File f) {
        return (f != null) && f.getName().toUpperCase(Locale.ROOT).endsWith(".PDF");
    }

    @Override
    protected Optional<BibEntry> createBibtexEntry(File pdfFile) {

        if (!accept(pdfFile)) {
            return Optional.empty();
        }

        PdfImporter pi = new PdfImporter(JabRefGUI.getMainFrame(), JabRefGUI.getMainFrame().getCurrentBasePanel(), JabRefGUI.getMainFrame().getCurrentBasePanel().getMainTable(), -1);
        ImportPdfFilesResult res = pi.importPdfFiles(Collections.singletonList(pdfFile.toString()));
        if (res.getEntries().size() == 1) {
            return Optional.of(res.getEntries().get(0));
        } else {
            return Optional.empty();
        }

        /*addEntryDataFromPDDocumentInformation(pdfFile, entry);
        addEntryDataFromXMP(pdfFile, entry);

        if (entry.getField(FieldName.TITLE) == null) {
        	entry.setField(FieldName.TITLE, pdfFile.getName());
        }

        return entry;*/
    }

    /** Adds entry data read from the PDDocument information of the file.
     * @param pdfFile
     * @param entry
     */
    private void addEntryDataFromPDDocumentInformation(File pdfFile, BibEntry entry) {
        try (PDDocument document = PDDocument.load(pdfFile.getAbsoluteFile())) {
            PDDocumentInformation pdfDocInfo = document
                    .getDocumentInformation();

            if (pdfDocInfo != null) {
                Optional<BibEntry> entryDI = XMPUtil
                        .getBibtexEntryFromDocumentInformation(document
                        .getDocumentInformation());
                if (entryDI.isPresent()) {
                    addEntryDataToEntry(entry, entryDI.get());
                    Calendar creationDate = pdfDocInfo.getCreationDate();
                    if (creationDate != null) {
                        // default time stamp follows ISO-8601. Reason: https://xkcd.com/1179/
                        String date = LocalDate.of(Calendar.YEAR, Calendar.MONTH + 1, Calendar.DAY_OF_MONTH)
                                .format(DateTimeFormatter.ISO_LOCAL_DATE);
                        appendToField(entry, Globals.prefs.get(JabRefPreferences.TIME_STAMP_FIELD), date);
                    }

                    if (pdfDocInfo.getCustomMetadataValue("bibtex/bibtexkey") != null) {
                        entry.setId(pdfDocInfo
                                .getCustomMetadataValue("bibtex/bibtexkey"));
                    }
                }
            }
        } catch (IOException e) {
            // no canceling here, just no data added.
        }
    }

    /**
     * Adds all data Found in all the entries of this XMP file to the given
     * entry. This was implemented without having much knowledge of the XMP
     * format.
     *
     * @param aFile
     * @param entry
     */
    private void addEntryDataFromXMP(File aFile, BibEntry entry) {
        try {
            List<BibEntry> entrys = XMPUtil.readXMP(aFile.getAbsoluteFile(), Globals.prefs.getXMPPreferences());
            addEntrysToEntry(entry, entrys);
        } catch (IOException e) {
            // no canceling here, just no data added.
        }
    }

    @Override
    public String getFormatName() {
        return "PDF";
    }

}