package eu.dnetlib.data.mdstore.hadoop;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.Predicate;
import java.util.stream.Stream;

import org.apache.avro.generic.GenericRecord;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import com.fasterxml.jackson.databind.ObjectMapper;

import eu.dnetlib.errors.MDStoreManagerException;
import parquet.avro.AvroParquetReader;
import parquet.hadoop.ParquetReader;

@Component
public class HdfsClient {

	@Value("${dhp.mdstore-manager.hadoop.cluster}")
	private String hadoopCluster;

	@Value("${dhp.mdstore-manager.hadoop.user}")
	private String hadoopUser;

	@Value("${dhp.mdstore-manager.hdfs.base-path}")
	private String hdfsBasePath;

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

	public void deletePath(final String path) throws MDStoreManagerException {

		try (final FileSystem fs = FileSystem.get(conf())) {
			fs.delete(new Path(path), true);
			log.info("HDFS Path deleted: " + path);
		} catch (final FileNotFoundException e) {
			log.warn("Missing path: " + hdfsBasePath);
		} catch (IllegalArgumentException | IOException e) {
			log.error("Eror deleting path: " + path, e);
			throw new MDStoreManagerException("Eror deleting path: " + path, e);
		}
	}

	public Set<String> listHadoopDirs() {
		final Set<String> res = new LinkedHashSet<>();

		try (final FileSystem fs = FileSystem.get(conf())) {
			for (final FileStatus mdDir : fs.listStatus(new Path(hdfsBasePath))) {
				if (isMdStoreOrVersionDir(mdDir)) {
					res.add(String.format("%s/%s", hdfsBasePath, mdDir.getPath().getName()));
					for (final FileStatus verDir : fs.listStatus(mdDir.getPath())) {
						if (isMdStoreOrVersionDir(verDir)) {
							res.add(String.format("%s/%s/%s", hdfsBasePath, mdDir.getPath().getName(), verDir.getPath().getName()));
						}
					}
				}
			}
		} catch (final FileNotFoundException e) {
			log.warn("Missing path: " + hdfsBasePath);
		} catch (final Exception e) {
			log.error("Error Listing path: " + hdfsBasePath, e);
		}

		return res;
	}

	public Set<String> listContent(final String path, final Predicate<FileStatus> condition) {

		// TODO: remove the following line (it is only for tests)
		// if (1 != 2) { return
		// Sets.newHashSet("file:///Users/michele/Desktop/part-00000-e3675dc3-69fb-422e-a159-78e34cfe14d2-c000.snappy.parquet"); }

		final Set<String> res = new LinkedHashSet<>();
		try (final FileSystem fs = FileSystem.get(conf())) {
			for (final FileStatus f : fs.listStatus(new Path(path))) {
				if (condition.test(f)) {
					res.add(String.format("%s/%s", path, f.getPath().getName()));
				}
			}
		} catch (final FileNotFoundException e) {
			log.warn("Missing path: " + hdfsBasePath);
		} catch (final Exception e) {
			log.error("Error Listing path: " + path, e);
		}
		return res;
	}

	@SuppressWarnings("unchecked")
	public <T> List<T> readParquetFiles(final String path, final long limit, final Class<T> clazz) throws MDStoreManagerException {

		final List<T> list = new ArrayList<>();

		final Configuration conf = conf();

		long i = 0;

		final Set<String> fields = new LinkedHashSet<>();

		for (final String f : listContent(path, HdfsClient::isParquetFile)) {
			if (i < limit) {
				log.info("Opening parquet file: " + f);

				try (final ParquetReader<GenericRecord> reader = AvroParquetReader.<GenericRecord> builder(new Path(f)).withConf(conf).build()) {
					log.debug("File parquet OPENED");

					final ObjectMapper mapper = new ObjectMapper();

					GenericRecord rec = null;
					while (i++ < limit && (rec = reader.read()) != null) {
						if (fields.isEmpty()) {
							rec.getSchema().getFields().forEach(field -> fields.add(field.name()));
							log.debug("Found schema: " + fields);
						}
						final Map<String, String> map = new LinkedHashMap<>();
						for (final String field : fields) {
							final Object v = rec.get(field);
							map.put(field, v != null ? v.toString() : "");
						}

						list.add(mapper.convertValue(map, clazz));

						log.debug("added record");
					}
				} catch (final FileNotFoundException e) {
					log.warn("Missing path: " + hdfsBasePath);
				} catch (final Throwable e) {
					log.error("Error reading parquet file: " + f, e);
					throw new MDStoreManagerException("Error reading parquet file: " + f, e);
				}
			}
		}
		return list;
	}

	public <T> Stream<T> streamParquetFiles(final String path, final Class<T> clazz) throws MDStoreManagerException {

		// TODO Re-implement the method without list
		final List<T> list = new ArrayList<>();

		final Configuration conf = conf();

		final Set<String> fields = new LinkedHashSet<>();

		for (final String f : listContent(path, HdfsClient::isParquetFile)) {

			log.info("Opening parquet file: " + f);

			try (final ParquetReader<GenericRecord> reader = AvroParquetReader.<GenericRecord> builder(new Path(f)).withConf(conf).build()) {
				log.debug("File parquet OPENED");

				final ObjectMapper mapper = new ObjectMapper();

				GenericRecord rec = null;
				while ((rec = reader.read()) != null) {
					if (fields.isEmpty()) {
						rec.getSchema().getFields().forEach(field -> fields.add(field.name()));
						log.debug("Found schema: " + fields);
					}
					final Map<String, String> map = new LinkedHashMap<>();
					for (final String field : fields) {
						final Object v = rec.get(field);
						map.put(field, v != null ? v.toString() : "");
					}

					list.add(mapper.convertValue(map, clazz));

					log.debug("added record");
				}
			} catch (final FileNotFoundException e) {
				log.warn("Missing path: " + hdfsBasePath);
			} catch (final Throwable e) {
				log.error("Error reading parquet file: " + f, e);
				throw new MDStoreManagerException("Error reading parquet file: " + f, e);
			}
		}

		return list.stream();

	}

	/*
	 *
	 * private String printGroup(final Group g) { final StringWriter sw = new StringWriter();
	 *
	 * final int fieldCount = g.getType().getFieldCount(); for (int field = 0; field < fieldCount; field++) { final int valueCount =
	 * g.getFieldRepetitionCount(field);
	 *
	 * final Type fieldType = g.getType().getType(field); final String fieldName = fieldType.getName();
	 *
	 * for (int index = 0; index < valueCount; index++) { if (fieldType.isPrimitive()) { sw.append(fieldName + " " +
	 * g.getValueToString(field, index)); sw.append("\n"); } } } return sw.toString(); }
	 *
	 * public List<String> readParquetFile(final String file, final long n) throws MDStoreManagerException {
	 *
	 * final Configuration conf = conf(); final Path path = new Path(file); final List<String> list = new ArrayList<>(); try { final
	 * ParquetMetadata readFooter = ParquetFileReader.readFooter(conf, path, ParquetMetadataConverter.NO_FILTER); final MessageType schema =
	 * readFooter.getFileMetaData().getSchema(); final ParquetFileReader r = new ParquetFileReader(conf, path, readFooter);
	 *
	 * PageReadStore pages = null; try { while (null != (pages = r.readNextRowGroup())) { final long rows = pages.getRowCount();
	 * System.out.println("Number of rows: " + rows);
	 *
	 * final MessageColumnIO columnIO = new ColumnIOFactory().getColumnIO(schema); final RecordReader<Group> recordReader =
	 * columnIO.getRecordReader(pages, new GroupRecordConverter(schema)); for (int i = 0; i < rows; i++) { final Group g =
	 * recordReader.read(); list.add(printGroup(g)); } } } finally { r.close(); } } catch (final IOException e) {
	 * System.out.println("Error reading parquet file."); e.printStackTrace(); } return list; }
	 *
	 *
	 */

	public static boolean isParquetFile(final FileStatus fileStatus) {
		return fileStatus.isFile() && fileStatus.getPath().getName().endsWith(".parquet");
	}

	public static boolean isMdStoreOrVersionDir(final FileStatus fileStatus) {
		return fileStatus.isDirectory() && fileStatus.getPath().getName().startsWith("md-");
	}

	private Configuration conf() throws MDStoreManagerException {
		final Configuration conf = new Configuration();

		System.setProperty("HADOOP_USER_NAME", hadoopUser);

		if (hadoopCluster.equalsIgnoreCase("OCEAN")) {
			conf.addResource(getClass().getResourceAsStream("/hadoop/OCEAN/core-site.xml"));
			conf.addResource(getClass().getResourceAsStream("/hadoop/OCEAN/ocean-hadoop-conf.xml"));
		} else if (hadoopCluster.equalsIgnoreCase("GARR")) {
			conf.addResource(getClass().getResourceAsStream("/hadoop/GARR/core-site.xml"));
			conf.addResource(getClass().getResourceAsStream("/hadoop/GARR/garr-hadoop-conf.xml"));
		} else if (hadoopCluster.equalsIgnoreCase("MOCK")) {
			// NOTHING
		} else {
			log.error("Invalid Haddop Cluster: " + hadoopCluster);
			throw new MDStoreManagerException("Invalid Haddop Cluster: " + hadoopCluster);
		}
		return conf;
	}

	public String getHadoopCluster() {
		return hadoopCluster;
	}

	public void setHadoopCluster(final String hadoopCluster) {
		this.hadoopCluster = hadoopCluster;
	}

	public String getHadoopUser() {
		return hadoopUser;
	}

	public void setHadoopUser(final String hadoopUser) {
		this.hadoopUser = hadoopUser;
	}
}