package org.expeditee.gio;

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.LinkedList;
import java.util.List;
import java.util.StringTokenizer;

import org.expeditee.core.Point;
import org.expeditee.gui.DisplayController;
import org.expeditee.gui.FreeItems;
import org.expeditee.importer.FileImporter;
import org.expeditee.importer.FilePathImporter;
import org.expeditee.importer.ImageImporter;
import org.expeditee.importer.TextImporter;
import org.expeditee.importer.pdfImporter;
import org.expeditee.items.Item;
import org.expeditee.items.Text;

/** TODO: Comment. cts16 */
public abstract class DragAndDropManager {
	
	/** The list of custom file importers registered with the DnD manager. */
	private List<FileImporter> _customFileImporters = new LinkedList<FileImporter>();

	/** The list of standard file importers registered with the DnD manager. */
	private List<FileImporter> _standardFileImporters = new LinkedList<FileImporter>();
	
	/** Standard constructor. */
	protected DragAndDropManager()
	{
		// Set up the standard file importers
		_standardFileImporters.add(new ImageImporter());
		_standardFileImporters.add(new pdfImporter());
		_standardFileImporters.add(new TextImporter());
		_standardFileImporters.add(new FilePathImporter()); // Filepath importer as last resort
	}

	/**
	 * Adds a custom importer. If an importer competes with another importer for
	 * handling the same file types, the importer that was added first will have
	 * first serve.
	 * 
	 * @param importer
	 *            The importer to add. Must not be null
	 * 
	 * @throws NullPointerException
	 *             if importer is null.
	 */
	public void addCustomFileImporter(FileImporter importer)
	{
		if (importer == null) throw new NullPointerException("importer");
		
		if (!_customFileImporters.contains(importer)) {
			_customFileImporters.add(importer);
		}
	}

	/**
	 * Removes a custom importer.
	 * 
	 * @param importer
	 *            The importer to remove.
	 * 
	 * @throws NullPointerException
	 *             if importer is null.
	 */
	public void removeCustomFileImporter(FileImporter importer)
	{
		if (importer == null) throw new NullPointerException("importer");
		
		_customFileImporters.remove(importer);
	}

	/**
	 * Imports a string into expeditee's current frame
	 * 
	 * @param text
	 *            The text content.
	 * @param expediteeDropPoint
	 *            The location in the current expeditee frame of where to drop
	 *            the text item.
	 * @param attachToFreeItems TODO
	 */
	public static Text importString(String text, Point expediteeDropPoint, boolean attachToFreeItems)
	{
		assert (DisplayController.getCurrentFrame() != null);
		assert (text != null && text.length() > 0);

		Text importedTextItem = new Text(DisplayController.getCurrentFrame().getNextItemID(), text);
		importedTextItem.setPosition(expediteeDropPoint);

		if (attachToFreeItems) {
			FreeItems.getInstance().add(importedTextItem);
			
		} else {
			DisplayController.getCurrentFrame().addItem(importedTextItem);
		}
		DisplayController.requestRefresh(true);

		return importedTextItem;
	}

	/** Imports a list of files into Expeditee's current frame. 
	 * @param attachToFreeItems TODO*/
	public void importFileList(List<? extends File> files, Point expediteeDropPoint, boolean attachToFreeItems) throws IOException {
		Point currentPoint = new Point(expediteeDropPoint);

		 // import files one by one
		for (File fileToImport : files) {

			Item lastItem = importFile(fileToImport, currentPoint, attachToFreeItems);
			
			if (lastItem == null) {
				currentPoint.setY(currentPoint.getY() + 30);
			} else {
				currentPoint.setY(currentPoint.getY() + lastItem.getBoundsHeight());
			}
			// of the item that was created

			// TODO: Better placement strategy
			// if (currentPoint.y > (Browser._theBrowser.getHeight() - 20))
			// currentPoint.y = Browser._theBrowser.getHeight() - 20;
		}
	}

	/**
	 * Imports a file into Expeditee. Any custom importers registered get first attempt,
	 * followed by the standard importers.
	 * 
	 * @param f
	 *            The file to import.
	 * @param expediteeDropPoint
	 * @param attachToFreeItems If true, instead of adding to generated item at {@code expediteeDropPoint}, add to free items.
	 * 
	 * @throws IOException
	 */
	public Item importFile(File f, Point expediteeDropPoint, boolean attachToFreeItems) throws IOException
	{
		assert (f != null);

		// Check for custom importers first. They get preference to standard
		// importing routines...
		Item lastCreatedItem;
		if (null == (lastCreatedItem = performFileImport(_customFileImporters, f, expediteeDropPoint, attachToFreeItems))) {
			// Standard file importing
			lastCreatedItem = performFileImport(_standardFileImporters, f, expediteeDropPoint, attachToFreeItems);
		}
		
		return lastCreatedItem;
	}

	/**
	 * Imports a single file into Expeditee's current frame. Importers are given the opportunity to
	 * interpret the file in order of their addition to the list.
	 * @param attachToFreeItems If true, instead of adding to generated item at {@code expediteeDropPoint}, add to free items.
	 */
	private Item performFileImport(List<FileImporter> importers, File f, Point expediteeDropPoint, boolean attachToFreeItems) throws IOException
	{
		for (FileImporter fi : importers) {
			Item lastCreated = fi.importFile(f, expediteeDropPoint, attachToFreeItems);
			
			if (lastCreated != null) return lastCreated;
		}

		return null;
	}
	
	/**
	 * Converts a string formatted as a list of URIs into a list of Files.
	 * 
	 * Code adopted from SUN - java BUG ID 4899516 workaround for KDE/GNOME
	 * Desktops
	 * 
	 * @param uriListString
	 *            Formatted according to RFC 2483
	 * 
	 * @return The list of FILES in the uriListString. Never null.
	 */
	protected List<File> textURIListToFileList(String uriListString)
	{
		List<File> fileList = new LinkedList<File>();

		for (StringTokenizer st = new StringTokenizer(uriListString, "\r\n"); st.hasMoreTokens();) {

			String s = st.nextToken();

			if (s.startsWith("#")) {
				// the line is a comment (as per the RFC 2483)
				continue;
			}

			try {

				URI uri = new URI(s);
				File file = new File(uri);
				fileList.add(file);

			} catch (URISyntaxException e) {
				// malformed URI
			} catch (IllegalArgumentException e) {
				// the URI is not a valid 'file:' URI
			}
		}

		return fileList;
	}
}