package ftp;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
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.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 int BUFFER_SIZE = 8 * 1024 * 1024;
	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 String host;
	private int port;
	private String username;
	private String password;
	private String downloadPath;
	private String saveDir;
	private int percentCompleted;

	public DownloadTask(String host, int port, String username, String password,
			String downloadPath, String saveDir) {
		this.host = host;
		this.port = port;
		this.username = username;
		this.password = password;
		this.downloadPath = downloadPath;
		this.saveDir = saveDir;
	}

	/**
	 * Executed in background thread
	 */
	@Override
	protected Void doInBackground() throws Exception {
		FTPUtility util = new FTPUtility(host, port, username, password);
		try {
			util.connect();

			// show filesize in the GUI
			long fileSize = util.getFileSize(downloadPath);
			firePropertyChange("filesize", 0, fileSize);
			util.downloadFile(downloadPath);

			// prepare the input/output streams
			String fileName = new File(downloadPath).getName();
			File downloadFile = new File(saveDir + File.separator + fileName);
			FileOutputStream outputStream = new FileOutputStream(downloadFile);
			InputStream inputStream = util.getInputStream();

			// initialize the counters needed for speed calculations
			percentCompleted = 0;
			byte[] buffer = new byte[BUFFER_SIZE];
			int bytesRead = -1;
			long totalBytesRead = 0;
			long lastUpdate = 0;
			long lastBytes = 0;
			long currentBytes = 0;
			while ((bytesRead = inputStream.read(buffer)) != -1 && !isCancelled()) {
				outputStream.write(buffer, 0, bytesRead);
				currentBytes += bytesRead;
				totalBytesRead += bytesRead;
				long now = System.currentTimeMillis();
				if (lastUpdate + UPDATE_INTERVAL_MS < now) {
					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;
				}
			}
			// finalize the download by updating the progress bar one last time
			// (in case we didn't get to do it because of the time interval)
			percentCompleted = (int) ((totalBytesRead * 100) / fileSize);
			setProgress(percentCompleted);
			firePropertyChange("bytesread", 0, totalBytesRead);
			outputStream.close();
			util.finish();
		} catch (FTPException ex) {
			JOptionPane.showMessageDialog(null,
					"Error downloading file: " + ex.getMessage(), "Error",
					JOptionPane.ERROR_MESSAGE);
			ex.printStackTrace();
			setProgress(0);
			cancel(true);
		} finally {
			util.disconnect();
		}

		return null;
	}

	/**
	 * Executed in Swing's event dispatching thread
	 */
	@Override
	protected void done() {
		if (!isCancelled() && percentCompleted == 100) {
			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 if (!isCancelled() && percentCompleted != 100) {
			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
	 *
	 * @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 20 lines, just in case...
				int round = 0;
				while ((line = br.readLine()) != null && round < 20) {
					if (line.matches("^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.");
			} 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;
	}
}