/*
 * 10/08/2011
 *
 * FoldIndicator.java - Gutter component allowing the user to expand and
 * collapse folds.
 * 
 * This library is distributed under a modified BSD license.  See the included
 * RSyntaxTextArea.License.txt file for details.
 */
package org.fife.ui.rtextarea;

import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.Icon;
import javax.swing.JToolTip;
import javax.swing.ToolTipManager;
import javax.swing.event.DocumentEvent;
import javax.swing.event.MouseInputAdapter;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.View;

import org.fife.ui.rsyntaxtextarea.RSyntaxTextArea;
import org.fife.ui.rsyntaxtextarea.Token;
import org.fife.ui.rsyntaxtextarea.focusabletip.TipUtil;
import org.fife.ui.rsyntaxtextarea.folding.Fold;
import org.fife.ui.rsyntaxtextarea.folding.FoldManager;


/**
 * Component in the gutter that displays +/- icons to expand and collapse
 * fold regions in the editor.
 *
 * @author Robert Futrell
 * @version 1.0
 */
public class FoldIndicator extends AbstractGutterComponent {

	/**
	 * Used in {@link #paintComponent(Graphics)} to prevent reallocation on
	 * each paint.
	 */
	private Insets textAreaInsets;

	/**
	 * Used in {@link #paintComponent(Graphics)} to prevent reallocation on
	 * each paint.
	 */
	private Rectangle visibleRect;

	/**
	 * The fold to show the outline line for.
	 */
	private Fold foldWithOutlineShowing;

	/**
	 * The color to use for fold icon backgrounds, if the default icons
	 * are used.
	 */
	private Color foldIconBackground;

	/**
	 * The icon used for collapsed folds.
	 */
	private Icon collapsedFoldIcon;

	/**
	 * The icon used for expanded folds.
	 */
	private Icon expandedFoldIcon;

	/**
	 * Whether tool tips are displayed showing the contents of collapsed
	 * fold regions.
	 */
	private boolean showFoldRegionTips;

	/**
	 * The color used to paint fold outlines.
	 */
	static final Color DEFAULT_FOREGROUND = Color.gray;

	/**
	 * The default color used to paint the "inside" of fold icons.
	 */
	static final Color DEFAULT_FOLD_BACKGROUND = Color.white;

	/**
	 * Listens for events in this component.
	 */
	private Listener listener;

	/**
	 * Width of this component.
	 */
	private static final int WIDTH = 12;


	public FoldIndicator(RTextArea textArea) {
		super(textArea);
	}


	/**
	 * Overridden to use the editor's background if it's detected that the
	 * user isn't using white as the editor bg, but the system's tool tip
	 * background is yellow-ish.
	 *
	 * @return The tool tip.
	 */
	@Override
	public JToolTip createToolTip() {
		JToolTip tip = super.createToolTip();
		Color textAreaBG = textArea.getBackground();
		if (textAreaBG!=null && !Color.white.equals(textAreaBG)) {
			Color bg = TipUtil.getToolTipBackground();
			// If current L&F's tool tip color is close enough to "yellow",
			// and we're not using the default text background of white, use
			// the editor background as the tool tip background.
			if (bg.getRed()>=240 && bg.getGreen()>=240 && bg.getBlue()>=200) {
				tip.setBackground(textAreaBG);
			}
		}
		return tip;
	}


	private Fold findOpenFoldClosestTo(Point p) {

		Fold fold = null;

		RSyntaxTextArea rsta = (RSyntaxTextArea)textArea;
		if (rsta.isCodeFoldingEnabled()) { // Should always be true
			int offs = rsta.viewToModel(p); // TODO: Optimize me
			if (offs>-1) {
				try {
					int line = rsta.getLineOfOffset(offs);
					FoldManager fm = rsta.getFoldManager();
					fold = fm.getFoldForLine(line);
					if (fold==null) {
						fold = fm.getDeepestOpenFoldContaining(offs);
					}
				} catch (BadLocationException ble) {
					ble.printStackTrace(); // Never happens
				}
			}
		}
	
		return fold;

	}


	/**
	 * Returns the color to use for the "background" of fold icons.  This
	 * is be ignored if custom icons are used.
	 *
	 * @return The background color.
	 * @see #setFoldIconBackground(Color)
	 */
	public Color getFoldIconBackground() {
		return foldIconBackground;
	}


	@Override
	public Dimension getPreferredSize() {
		int h = textArea!=null ? textArea.getHeight() : 100; // Arbitrary
		return new Dimension(WIDTH, h);
	}


	/**
	 * Returns whether tool tips are displayed showing the contents of
	 * collapsed fold regions when the mouse hovers over a +/- icon.
	 *
	 * @return Whether these tool tips are displayed.
	 * @see #setShowCollapsedRegionToolTips(boolean)
	 */
	public boolean getShowCollapsedRegionToolTips() {
		return showFoldRegionTips;
	}


	/**
	 * Positions tool tips to be aligned in the text component, so that the
	 * displayed content is shown (almost) exactly where it would be in the
	 * editor.
	 *
	 * @param e The mouse location.
	 */
	@Override
	public Point getToolTipLocation(MouseEvent e) {

		// ToolTipManager requires both location and text to be null to hide
		// a currently-visible tool tip window.  If text is null but location
		// has some value, it will show a tool tip with empty content, the size
		// of its border (!).
		String text = getToolTipText(e);
		if (text==null) {
			return null;
		}

		// Try to overlap the tip's text directly over the code
		Point p = e.getPoint();
		p.y = (p.y/textArea.getLineHeight()) * textArea.getLineHeight();
		p.x = getWidth() + textArea.getMargin().left;
		Gutter gutter = getGutter();
		int gutterMargin = gutter.getInsets().right;
		p.x += gutterMargin;
		JToolTip tempTip = createToolTip();
		p.x -= tempTip.getInsets().left;
		p.y += 16;
		return p;
	}


	/**
	 * Overridden to show the content of a collapsed fold on mouse-overs.
	 *
	 * @param e The mouse location.
	 */
	@Override
	public String getToolTipText(MouseEvent e) {

		String text = null;

		RSyntaxTextArea rsta = (RSyntaxTextArea)textArea;
		if (rsta.isCodeFoldingEnabled()) {
			FoldManager fm = rsta.getFoldManager();
			int pos = rsta.viewToModel(new Point(0, e.getY()));
			if (pos>=0) { // Not -1
				int line = 0;
				try {
					line = rsta.getLineOfOffset(pos);
				} catch (BadLocationException ble) {
					ble.printStackTrace(); // Never happens
					return null;
				}
				Fold fold = fm.getFoldForLine(line);
				if (fold!=null && fold.isCollapsed()) {

					int endLine = fold.getEndLine();
					if (fold.getLineCount()>25) { // Not too big
						endLine = fold.getStartLine() + 25;
					}

					StringBuilder sb = new StringBuilder("<html><nobr>");
					while (line<=endLine && line<rsta.getLineCount()) { // Sanity
						Token t = rsta.getTokenListForLine(line);
						while (t!=null && t.isPaintable()) {
							t.appendHTMLRepresentation(sb, rsta, true, true);
							t = t.getNextToken();
						}
						sb.append("<br>");
						line++;
					}

					text = sb.toString();

				}
			}
		}

		return text;

	}


	@Override
	void handleDocumentEvent(DocumentEvent e) {
		int newLineCount = textArea.getLineCount();
		if (newLineCount!=currentLineCount) {
			currentLineCount = newLineCount;
			repaint();
		}
	}


	@Override
	protected void init() {
		super.init();
		setForeground(DEFAULT_FOREGROUND);
		setFoldIconBackground(DEFAULT_FOLD_BACKGROUND);
		collapsedFoldIcon = new FoldIcon(true);
		expandedFoldIcon = new FoldIcon(false);
		listener = new Listener(this);
		visibleRect = new Rectangle();
		setShowCollapsedRegionToolTips(true);
	}


	@Override
	void lineHeightsChanged() {
		// TODO Auto-generated method stub
	}


	@Override
	protected void paintComponent(Graphics g) {

		if (textArea==null) {
			return;
		}

		visibleRect = g.getClipBounds(visibleRect);
		if (visibleRect==null) { // ???
			visibleRect = getVisibleRect();
		}
		//System.out.println("FoldIndicator repainting: " + visibleRect);
		if (visibleRect==null) {
			return;
		}

		Color bg = getBackground();
		if (getGutter()!=null) { // Should always be true
			bg = getGutter().getBackground();
		}
		g.setColor(bg);
		g.fillRect(0,visibleRect.y, getWidth(),visibleRect.height);

		RSyntaxTextArea rsta = (RSyntaxTextArea)textArea;
		if (!rsta.isCodeFoldingEnabled()) { 
			return; // We should be hidden in this case, but still...
		}

		if (textArea.getLineWrap()) {
			paintComponentWrapped(g);
			return;
		}

		// Get where to start painting (top of the row).
		// We need to be "scrolled up" up just enough for the missing part of
		// the first line.
		textAreaInsets = textArea.getInsets(textAreaInsets);
		if (visibleRect.y<textAreaInsets.top) {
			visibleRect.height -= (textAreaInsets.top - visibleRect.y);
			visibleRect.y = textAreaInsets.top;
		}
		int cellHeight = textArea.getLineHeight();
		int topLine = (visibleRect.y-textAreaInsets.top)/cellHeight;
		int y = topLine*cellHeight +
			(cellHeight-collapsedFoldIcon.getIconHeight())/2;
		y += textAreaInsets.top;

		// Get the first and last lines to paint.
		FoldManager fm = rsta.getFoldManager();
		topLine += fm.getHiddenLineCountAbove(topLine, true);

		int width = getWidth();
		int x = width - 10;
		int line = topLine;
		boolean paintingOutlineLine = foldWithOutlineShowing!=null &&
				foldWithOutlineShowing.containsLine(line);

		while (y<visibleRect.y+visibleRect.height) {
			if (paintingOutlineLine) {
				g.setColor(getForeground());
				int w2 = width/2;
				if (line==foldWithOutlineShowing.getEndLine()) {
					int y2 = y+cellHeight/2;
					g.drawLine(w2,y, w2,y2);
					g.drawLine(w2,y2, width-2,y2);
					paintingOutlineLine = false;
				}
				else {
					g.drawLine(w2,y, w2,y+cellHeight);
				}
			}
			Fold fold = fm.getFoldForLine(line);
			if (fold!=null) {
				if (fold==foldWithOutlineShowing && !fold.isCollapsed()) {
					g.setColor(getForeground());
					int w2 = width/2;
					g.drawLine(w2,y+cellHeight/2, w2,y+cellHeight);
					paintingOutlineLine = true;
				}
				if (fold.isCollapsed()) {
					collapsedFoldIcon.paintIcon(this, g, x, y);
					// Skip to next line to paint, taking extra care for lines with
					// block ends and begins together, e.g. "} else {"
					do {
						int hiddenLineCount = fold.getLineCount();
						if (hiddenLineCount==0) {
							// Fold parser identified a zero-line fold region.
							// This is really a bug, but we'll be graceful here
							// and avoid an infinite loop.
							break;
						}
						line += hiddenLineCount;
						fold = fm.getFoldForLine(line);
					} while (fold!=null && fold.isCollapsed());
				}
				else {
					expandedFoldIcon.paintIcon(this, g, x, y);
				}
			}
			line++;
			y += cellHeight;
		}

	}


	/**
	 * Paints folding icons when line wrapping is enabled.
	 *
	 * @param g The graphics context.
	 */
	private void paintComponentWrapped(Graphics g) {

		// The variables we use are as follows:
		// - visibleRect is the "visible" area of the text area; e.g.
		// [0,100, 300,100+(lineCount*cellHeight)-1].
		// actualTop.y is the topmost-pixel in the first logical line we
		// paint.  Note that we may well not paint this part of the logical
		// line, as it may be broken into many physical lines, with the first
		// few physical lines scrolled past.  Note also that this is NOT the
		// visible rect of this line number list; this line number list has
		// visible rect == [0,0, insets.left-1,visibleRect.height-1].
		// - offset (<=0) is the y-coordinate at which we begin painting when
		// we begin painting with the first logical line.  This can be
		// negative, signifying that we've scrolled past the actual topmost
		// part of this line.

		// The algorithm is as follows:
		// - Get the starting y-coordinate at which to paint.  This may be
		//   above the first visible y-coordinate as we're in line-wrapping
		//   mode, but we always paint entire logical lines.
		// - Paint that line's indicator, if appropriate.  Increment y to be
		//   just below the are we just painted (i.e., the beginning of the
		//   next logical line's view area).
		// - Get the ending visual position for that line.  We can now loop
		//   back, paint this line, and continue until our y-coordinate is
		//   past the last visible y-value.

		// We avoid using modelToView/viewToModel where possible, as these
		// methods trigger a parsing of the line into syntax tokens, which is
		// costly.  It's cheaper to just grab the child views' bounds.

		// Some variables we'll be using.
		int width = getWidth();

		RTextAreaUI ui = (RTextAreaUI)textArea.getUI();
		View v = ui.getRootView(textArea).getView(0);
		Document doc = textArea.getDocument();
		Element root = doc.getDefaultRootElement();
		int topPosition = textArea.viewToModel(
								new Point(visibleRect.x,visibleRect.y));
		int topLine = root.getElementIndex(topPosition);
		int cellHeight = textArea.getLineHeight();
		FoldManager fm = ((RSyntaxTextArea)textArea).getFoldManager();

		// Compute the y at which to begin painting text, taking into account
		// that 1 logical line => at least 1 physical line, so it may be that
		// y<0.  The computed y-value is the y-value of the top of the first
		// (possibly) partially-visible view.
		Rectangle visibleEditorRect = ui.getVisibleEditorRect();
		Rectangle r = LineNumberList.getChildViewBounds(v, topLine,
												visibleEditorRect);
		int y = r.y;
		y += (cellHeight-collapsedFoldIcon.getIconHeight())/2;

		int visibleBottom = visibleRect.y + visibleRect.height;
		int x = width - 10;
		int line = topLine;
		boolean paintingOutlineLine = foldWithOutlineShowing!=null &&
				foldWithOutlineShowing.containsLine(line);
		int lineCount = root.getElementCount();

		while (y<visibleBottom && line<lineCount) {

			int curLineH = LineNumberList.getChildViewBounds(v, line,
					visibleEditorRect).height;

			if (paintingOutlineLine) {
				g.setColor(getForeground());
				int w2 = width/2;
				if (line==foldWithOutlineShowing.getEndLine()) {
					int y2 = y + curLineH - cellHeight/2;
					g.drawLine(w2,y, w2,y2);
					g.drawLine(w2,y2, width-2,y2);
					paintingOutlineLine = false;
				}
				else {
					g.drawLine(w2,y, w2,y+curLineH);
				}
			}
			Fold fold = fm.getFoldForLine(line);
			if (fold!=null) {
				if (fold==foldWithOutlineShowing && !fold.isCollapsed()) {
					g.setColor(getForeground());
					int w2 = width/2;
					g.drawLine(w2,y+cellHeight/2, w2,y+curLineH);
					paintingOutlineLine = true;
				}
				if (fold.isCollapsed()) {
					collapsedFoldIcon.paintIcon(this, g, x, y);
					y += LineNumberList.getChildViewBounds(v, line,
								visibleEditorRect).height;
					line += fold.getLineCount() + 1;
				}
				else {
					expandedFoldIcon.paintIcon(this, g, x, y);
					y += curLineH;
					line++;
				}
			}
			else {
				y += curLineH;
				line++;
			}
		}

	}


	private int rowAtPoint(Point p) {

		int line = 0;

		try {
			int offs = textArea.viewToModel(p);
			if (offs>-1) {
				line = textArea.getLineOfOffset(offs);
			}
		} catch (BadLocationException ble) {
			ble.printStackTrace(); // Never happens
		}

		return line;

	}


	/**
	 * Sets the color to use for the "background" of fold icons.  This will
	 * be ignored if custom icons are used.
	 *
	 * @param bg The new background color.
	 * @see #getFoldIconBackground()
	 */
	public void setFoldIconBackground(Color bg) {
		foldIconBackground = bg;
	}


	/**
	 * Sets the icons to use to represent collapsed and expanded folds.
	 *
	 * @param collapsedIcon The collapsed fold icon.  This cannot be
	 *        <code>null</code>.
	 * @param expandedIcon The expanded fold icon.  This cannot be
	 *        <code>null</code>.
	 */
	public void setFoldIcons(Icon collapsedIcon, Icon expandedIcon) {
		this.collapsedFoldIcon = collapsedIcon;
		this.expandedFoldIcon = expandedIcon;
		revalidate(); // Icons may be different sizes.
		repaint();
	}


	/**
	 * Toggles whether tool tips should be displayed showing the contents of
	 * collapsed fold regions when the mouse hovers over a +/- icon.
	 *
	 * @param show Whether to show these tool tips.
	 * @see #getShowCollapsedRegionToolTips()
	 */
	public void setShowCollapsedRegionToolTips(boolean show) {
		if (show!=showFoldRegionTips) {
			if (show) {
				ToolTipManager.sharedInstance().registerComponent(this);
			}
			else {
				ToolTipManager.sharedInstance().unregisterComponent(this);
			}
			showFoldRegionTips = show;
		}
	}


	/**
	 * Overridden so we can track when code folding is enabled/disabled.
	 */
	@Override
	public void setTextArea(RTextArea textArea) {
		if (this.textArea!=null) {
			this.textArea.removePropertyChangeListener(
					RSyntaxTextArea.CODE_FOLDING_PROPERTY, listener);
		}
		super.setTextArea(textArea);
		if (this.textArea!=null) {
			this.textArea.addPropertyChangeListener(
					RSyntaxTextArea.CODE_FOLDING_PROPERTY, listener);
		}
	}


	/**
	 * The default +/- icon for expanding and collapsing folds.
	 */
	private class FoldIcon implements Icon {

		private boolean collapsed;

		public FoldIcon(boolean collapsed) {
			this.collapsed = collapsed;
		}

		public int getIconHeight() {
			return 8;
		}

		public int getIconWidth() {
			return 8;
		}

		public void paintIcon(Component c, Graphics g, int x, int y) {
			g.setColor(foldIconBackground);
			g.fillRect(x,y, 8,8);
			g.setColor(getForeground());
			g.drawRect(x,y, 8,8);
			g.drawLine(x+2,y+4, x+2+4,y+4);
			if (collapsed) {
				g.drawLine(x+4,y+2, x+4,y+6);
			}
		}
		
	}


	/**
	 * Listens for events in this component.
	 */
	private class Listener extends MouseInputAdapter
			implements PropertyChangeListener {

		public Listener(FoldIndicator fgc) {
			fgc.addMouseListener(this);
			fgc.addMouseMotionListener(this);
		}

		@Override
		public void mouseClicked(MouseEvent e) {

//			// TODO: Implement code folding with word wrap enabled
//			if (textArea.getLineWrap()) {
//				UIManager.getLookAndFeel().provideErrorFeedback(textArea);
//				return;
//			}

			Point p = e.getPoint();
			int line = rowAtPoint(p);

			RSyntaxTextArea rsta = (RSyntaxTextArea)textArea;
			FoldManager fm = rsta.getFoldManager();

			Fold fold = fm.getFoldForLine(line);
			if (fold!=null) {
				fold.toggleCollapsedState();
				getGutter().repaint();
				textArea.repaint();
			}

		}

		@Override
		public void mouseExited(MouseEvent e) {
			if (foldWithOutlineShowing!=null) {
				foldWithOutlineShowing = null;
				repaint();
			}
		}

		@Override
		public void mouseMoved(MouseEvent e) {
			Fold newSelectedFold = findOpenFoldClosestTo(e.getPoint());
			if (newSelectedFold!=foldWithOutlineShowing &&
					newSelectedFold!=null && !newSelectedFold.isOnSingleLine()) {
				foldWithOutlineShowing = newSelectedFold;
				repaint();
			}
		}

		public void propertyChange(PropertyChangeEvent e) {
			// Whether folding is enabled in the editor has changed.
			repaint();
		}

	}


}