/*
 * This file is part of the PDF Split And Merge source code
 * Created on 1 mag 2019
 * Copyright 2017 by Sober Lemur S.a.s di Vacondio Andrea (info@pdfsam.org).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.pdfsam.pdf;

import static java.util.Objects.isNull;
import static java.util.function.Predicate.not;
import static java.util.stream.Collectors.toList;

import java.io.File;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.function.Function;
import java.util.stream.Stream;

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Andrea Vacondio
 */
class PdfListParser implements Function<Path, List<File>> {
    private static final Logger LOG = LoggerFactory.getLogger(PdfListParser.class);

    /**
     * Given a Path to text/csv file, it parses is returning a list of PDF files contained in the parsed file
     *
     * @param listFile
     * @return
     */
    @Override
    public List<File> apply(Path listFile) {
        if (isNull(listFile)) {
            return Collections.emptyList();
        }
        List<Charset> charsets = List.of(StandardCharsets.UTF_8, StandardCharsets.ISO_8859_1, Charset.defaultCharset());
        for (Charset charset : charsets) {
            try {
                return Files.lines(listFile, charset).filter(StringUtils::isNoneBlank).map(PdfListParser::parseLine)
                        .map(String::trim).filter(s -> s.toUpperCase().endsWith("PDF")).map(Paths::get)
                        .filter(Files::exists).filter(not(Files::isDirectory)).map(Path::toFile).collect(toList());
            } catch (UncheckedIOException e) {
                LOG.warn("Unable to read lines from " + listFile + " using charset " + charset, e);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }
        throw new RuntimeException("Unable to read lines from " + listFile);

    }

    private static String parseLine(String line) {
        boolean hasQuotes = false;
        boolean lastWasQuote = false;
        StringBuilder field = new StringBuilder();
        for (char c : line.toCharArray()) {
            if (field.length() == 0 && c == '"') {
                hasQuotes = true;
            } else {
                if (c == ',' && !hasQuotes) {
                    return field.toString();
                } else if (c == ',' && lastWasQuote) {
                    field.setLength(field.length() - 1);
                    return field.toString();
                }
                lastWasQuote = c == '"';
                field.append(c);

            }
        }
        return field.toString();
    }
}
