package ftp;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
import java.nio.charset.StandardCharsets;
import java.util.Map;

import javax.swing.JOptionPane;
import javax.swing.SwingWorker;

import models.Image;
import models.SessionData;

import org.apache.commons.io.FileUtils;
import org.apache.log4j.Logger;
import org.apache.thrift.TException;
import org.openslx.filetransfer.DataReceivedCallback;
import org.openslx.filetransfer.Downloader;
import org.openslx.filetransfer.FileRange;
import org.openslx.filetransfer.WantRangeCallback;
import org.openslx.thrifthelper.ThriftManager;

import util.ResourceLoader;

/**
 * Execute file download in a background thread and update the progress.
 * 
 * @author www.codejava.net
 * 
 */
public class DownloadTask extends SwingWorker<Void, Void> {

	/**
	 * Logger instance for this class.
	 */
	private final static Logger LOGGER = Logger.getLogger(DownloadTask.class);

	private static final double UPDATE_INTERVAL_SECONDS = 0.6;
	private static final double UPDATE_INTERVAL_MS = UPDATE_INTERVAL_SECONDS * 1000;
	private static final double BYTES_PER_MIB = 1024 * 1024;
	private static final long CHUNK_SIZE = 16 * 1024 * 1024;

	private final String host;
	private final int port;
	private final String downloadToken;
	private final String saveDir;
	private final long fileSize;
	private boolean success = false;

	public DownloadTask(String host, int port, String downloadToken, String saveDir, long fileSize) {
		this.host = host;
		this.port = port;
		this.downloadToken = downloadToken;
		this.saveDir = saveDir;
		this.fileSize = fileSize;
	}

	class Callbacks implements WantRangeCallback, DataReceivedCallback {
		// initialize the counters needed for speed calculations
		private long currentRequestedOffset = -1;
		private long totalBytesRead = 0;
		private long lastUpdate = 0;
		private long lastBytes = 0;
		private long currentBytes = 0;
		private final RandomAccessFile file;

		public Callbacks(RandomAccessFile file) {
			this.file = file;
		}

		@Override
		public FileRange get() {
			if (currentRequestedOffset == -1)
				currentRequestedOffset = 0;
			else
				currentRequestedOffset += CHUNK_SIZE;
			if (currentRequestedOffset >= fileSize)
				return null;
			long end = currentRequestedOffset + CHUNK_SIZE;
			if (end > fileSize)
				end = fileSize;
			return new FileRange(currentRequestedOffset, end);
		}

		@Override
		public boolean dataReceived(final long fileOffset, final int dataLength, final byte[] data) {
			try {
				file.seek(fileOffset);
				file.write(data, 0, dataLength);
			} catch (Exception e) {
				LOGGER.error("Could not write to file at offset " + fileOffset, e);
				return false;
			}
			currentBytes += dataLength;
			totalBytesRead += dataLength;
			final long now = System.currentTimeMillis();
			if (lastUpdate + UPDATE_INTERVAL_MS < now) {
				final int percentCompleted = (int) ((totalBytesRead * 100) / fileSize);
				setProgress(percentCompleted);
				lastBytes = (lastBytes * 2 + currentBytes) / 3;
				final double speed = lastBytes / UPDATE_INTERVAL_SECONDS;
				firePropertyChange("speed", 0, speed / BYTES_PER_MIB);
				firePropertyChange("bytesread", 0, totalBytesRead);
				lastUpdate = now;
				currentBytes = 0;
			}
			return true;
		}

	}

	/**
	 * Executed in background thread
	 */
	@Override
	protected Void doInBackground() throws Exception {
		boolean ret = false;
		// show filesize in the GUI
		firePropertyChange("filesize", 0, fileSize);

		Downloader download = null;
		RandomAccessFile file = null;
		try {
			download = new Downloader(host, port, null, downloadToken); // TODO: SSL
			try {
				file = new RandomAccessFile(new File(saveDir), "rw");
			} catch (Exception e2) {
				JOptionPane.showMessageDialog(null, "Could not open destination file:\n" + saveDir + "\n"
						+ e2.getMessage(), "Error", JOptionPane.ERROR_MESSAGE);
				e2.printStackTrace();
				setProgress(0);
				return null;
			}

			Callbacks cb = new Callbacks(file);

			ret = download.download(cb, cb);
		} finally {
			if (file != null) {
				try {
					file.close();
				} catch (Exception e) {
				}
			}
			if (download != null)
				download.close(null);
		}

		// if the download succeeded, set the progress to 100% manually again here to make
		// sure the GUI knows about it.
		if (ret) {
			setProgress(100);
			firePropertyChange("bytesread", 0, fileSize);
			firePropertyChange("success", false, true);
			success = true;
		}

		return null;
	}

	/**
	 * Executed in Swing's event dispatching thread
	 */
	@Override
	protected void done() {
		if (isCancelled())
			return;
		if (success) {
			LOGGER.info("Datei erfolgreich heruntergeladen.");
			String vmxResult = "";
			vmxResult = generateVmx() ? "Passende VMX generiert." : "Keine passende VMX generiert!";
			JOptionPane.showMessageDialog(null, "Datei erfolgreich heruntergeladen. " + vmxResult, "Message",
					JOptionPane.INFORMATION_MESSAGE);
		} else {
			LOGGER.error("Datei wurde unvollständig heruntergeladen.");
			JOptionPane.showMessageDialog(null,
					"Datei wurde unvollständig heruntergeladen. Bitte wiederholen.", "Message",
					JOptionPane.INFORMATION_MESSAGE);
		}
	}

	/**
	 * Helper to generate the vmx for the downloaded image
	 * TODO: Not really related to DownloadTask...
	 * 
	 * @return true|false indicating the success of the file creation
	 */
	private boolean generateVmx() {
		String vmxTemplate = ResourceLoader.getTextFile("/txt/vmx_template");
		// TODO: sanity checks on vmxTemplate would be good here... just to be safe

		// now we replace the placeholder variables with the real data
		// for this, we first need to get the image information from the server
		LOGGER.debug("Image's ID: " + Image.ImageId);
		Map<String, String> imageData = null;
		try {
			imageData = ThriftManager.getSatClient().getImageData(Image.ImageId, Image.Version,
					SessionData.authToken);
		} catch (TException e) {
			LOGGER.error("Thrift exception during transfer, see trace: ", e);
			return false;
		}

		// sanity check, shouldn't happen.
		if (imageData == null) {
			LOGGER.error("Could not query the image information from the server!");
			LOGGER.error("Image's ID: " + Image.ImageId);
			LOGGER.error("Image's version: " + Image.Version);
			return false;
		}
		int hardwareVersion = extractHardwareVersion(saveDir + File.separator
				+ imageData.get("path").replaceFirst("^prod/", ""));
		if (hardwareVersion == 0) {
			LOGGER.error("'extractHardwareVersion' returned 0 indicating some problem. See logs.");
			LOGGER.error("Falling back to default hardware version of '10'.");
			hardwareVersion = 10;
		}
		// TODO: sanity checks on the content of imageData would be good here...
		// use the information we received about the image
		vmxTemplate = vmxTemplate.replace("%VM_DISPLAY_NAME%", imageData.get("name"));
		vmxTemplate = vmxTemplate.replace("%VM_GUEST_OS%", imageData.get("os"));
		vmxTemplate = vmxTemplate.replace("%VM_CPU_COUNT%", imageData.get("cpu"));
		vmxTemplate = vmxTemplate.replace("%VM_RAM_SIZE%",
				String.valueOf(Integer.valueOf(imageData.get("ram")) * 1024));
		vmxTemplate = vmxTemplate.replace("%VM_DISK_PATH%", imageData.get("path").replaceFirst("^prod/", ""));
		vmxTemplate = vmxTemplate.replace("%VM_HW_VERSION%", String.valueOf(hardwareVersion));

		// build filename for the vmx, basicly the same as the path of the vmdk
		// just without the leading "prod/" and "vmx" instead of "vmdk" at the end.
		String targetFilename = saveDir + File.separator
				+ imageData.get("path").replaceFirst("^prod/", "").replaceFirst("\\.vmdk$", "") + ".vmx";
		try {
			// try to write it to file
			FileUtils.writeStringToFile(new File(targetFilename), vmxTemplate, StandardCharsets.UTF_8);
		} catch (IOException e) {
			LOGGER.error("Could not write vmx-template to '" + targetFilename + "'. See trace: ", e);
			return false;
		}
		return true;
	}

	/**
	 * Helper to extract the hardware version of the VMDK file by inspecting its
	 * content.
	 * 
	 * @return value of hardware version as integer. A return value of 0
	 *         indicates
	 *         an error.
	 */
	private int extractHardwareVersion(String path) {
		BufferedReader br = null;
		try {
			try {
				br = new BufferedReader(new InputStreamReader(new FileInputStream(path)));
				String line;
				// first 4 characters of a VMDK file start with 'KDMV'
				// first lets check if this is the case
				line = br.readLine();
				if (!line.subSequence(0, 4).equals("KDMV")) {
					LOGGER.error("Did not see 'KDMV' as first chars of the VMDK! Returning 0.");
					LOGGER.debug("First line was: " + line);
					LOGGER.debug("First 4 characters of it: " + line.subSequence(0, 4));
					return 0;
				}
				// only read a maximum of 25 lines, just in case...
				int round = 0;
				while ((line = br.readLine()) != null && round < 25) {
					if (line.startsWith("ddb.virtualHWVersion")) {
						String[] tmp = line.split("=");
						// we should get 2 strings only after the split, lets be sure
						if (tmp.length != 2) {
							LOGGER.debug("Splitting returned more than 2 parts, this should not happen!");
							return 0;
						}
						int candidate = Integer.parseInt(tmp[1].trim().replace("\"", ""));
						LOGGER.debug("Considering hardware version: " + candidate);
						if (candidate > 0) {
							LOGGER.debug("Valid value of the candidate. Using hardware version of: "
									+ candidate);
							return candidate;
						} else {
							LOGGER.error("Candidate is not > 0! Returning 0.");
							return 0;
						}
					}
					round++;
				}
				LOGGER.error("Failed to find hardware version. Tried " + round + " rounds.");
			} catch (NumberFormatException e) {
				// Not a number?
				return 0;
			} finally {
				br.close();
			}
		} catch (FileNotFoundException e) {
			LOGGER.debug("File not found, see trace: ", e);
		} catch (IOException e) {
			LOGGER.debug("I/O Exception, see trace: ", e);
		}
		return 0;
	}
}