package eu.dnetlib.data.collector.plugins;

import java.io.*;
import java.net.URL;
import java.util.Iterator;
import java.util.Set;

import com.google.common.collect.Iterators;
import eu.dnetlib.data.collector.plugin.AbstractCollectorPlugin;
import eu.dnetlib.data.collector.plugins.oai.engine.XmlCleaner;
import eu.dnetlib.data.collector.rmi.CollectorServiceException;
import eu.dnetlib.data.collector.rmi.InterfaceDescriptor;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.io.input.BOMInputStream;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;

/**
 * The Class HttpCSVCollectorPlugin.
 */
public class HttpCSVCollectorPlugin extends AbstractCollectorPlugin {

	private static final Log log = LogFactory.getLog(HttpCSVCollectorPlugin.class);

	public static final String UTF8_BOM = "\uFEFF";

	/**
	 * The Class HTTPCSVIterator.
	 */
	class HTTPCSVIterator implements Iterable<String> {

		/** The descriptor. */
		private InterfaceDescriptor descriptor;

		/**
		 * Instantiates a new HTTPCSV iterator.
		 *
		 * @param descriptor
		 *            the descriptor
		 */
		public HTTPCSVIterator(final InterfaceDescriptor descriptor) {
			this.descriptor = descriptor;
		}

		/**
		 * Iterator.
		 *
		 * @return the iterator
		 */
		@SuppressWarnings("resource")
		@Override
		public Iterator<String> iterator() {

			try {
				final String separator = descriptor.getParams().get("separator");
				final String identifier = descriptor.getParams().get("identifier");
				final String quote = descriptor.getParams().get("quote");
				final URL url = new URL(descriptor.getBaseUrl());
				long nLines = 0;

				// FIX
				// This code should skip the lines with invalid quotes
				final File tempFile = File.createTempFile("csv-", ".tmp");
				try (InputStream is = url.openConnection().getInputStream();
						BOMInputStream bomIs = new BOMInputStream(is);
						BufferedReader reader = new BufferedReader(new InputStreamReader(bomIs));
						FileWriter fw = new FileWriter(tempFile)) {

					String line;
					while ((line = reader.readLine()) != null) {
						if (StringUtils.isBlank(quote) || (quote.charAt(0) != '"') || verifyQuotes(line, separator.charAt(0))) {
							fw.write(line);
							fw.write("\n");
							nLines++;
						}
					}
				}
				// END FIX

				final CSVFormat format = CSVFormat.EXCEL
						.withHeader()
						.withDelimiter(separator.equals("\\t") || StringUtils.isBlank(separator) ? '\t' : separator.charAt(0))
						.withQuote(StringUtils.isBlank(quote) ? null : quote.charAt(0))
						.withTrim();

				final CSVParser parser = new CSVParser(new FileReader(tempFile), format);
				final Set<String> headers = parser.getHeaderMap().keySet();

				final long nRecords = nLines - 1;

				return Iterators.transform(parser.iterator(), input -> {
					try {
						final Document document = DocumentHelper.createDocument();
						final Element root = document.addElement("csvRecord");
						for (final String key : headers) {
							final Element row = root.addElement("column");
							row.addAttribute("name", key).addText(XmlCleaner.cleanAllEntities(input.get(key)));
							if (key.equals(identifier)) {
								row.addAttribute("isID", "true");
							}
						}

						return document.asXML();
					} finally {
						log.debug(tempFile.getAbsolutePath());
						if (parser.getRecordNumber() == nRecords) {
							log.debug("DELETING " + tempFile.getAbsolutePath());
							tempFile.delete();
						}
					}
				});
			} catch (final Exception e) {
				log.error("Error iterating csv lines", e);
				return null;
			}
		}

	}

	/*
	 * (non-Javadoc)
	 *
	 * @see eu.dnetlib.data.collector.plugin.CollectorPlugin#collect(eu.dnetlib.data.collector.rmi.InterfaceDescriptor, java.lang.String,
	 * java.lang.String)
	 */
	@Override
	public Iterable<String> collect(final InterfaceDescriptor descriptor, final String fromDate, final String untilDate) throws CollectorServiceException {

		return new HTTPCSVIterator(descriptor);
	}

	public boolean verifyQuotes(final String line, final char separator) {
		final char[] cs = line.trim().toCharArray();
		boolean inField = false;
		boolean skipNext = false;
		for (int i = 0; i < cs.length; i++) {
			if (skipNext) {
				skipNext = false;
			} else if (inField) {
				if ((cs[i] == '\"') && ((i == (cs.length - 1)) || (cs[i + 1] == separator))) {
					inField = false;
				} else if ((cs[i] == '\"') && (i < (cs.length - 1))) {
					if ((cs[i + 1] == '\"')) {
						skipNext = true;
					} else {
						log.warn("Skipped invalid line: " + line);
						return false;
					}
				}
			} else {
				if ((cs[i] == '\"') && ((i == 0) || (cs[i - 1] == separator))) {
					inField = true;
				}
			}
		}

		if (inField) {
			log.warn("Skipped invalid line: " + line);
			return false;
		}

		return true;
	}

}