/*******************************************************************************
 * Copyright (c) 2007, 2011 Wind River Systems, Inc. and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * Michael Scharf (Wind River) - initial API and implementation
 * Michael Scharf (Wind River) - [240098] The cursor should not blink when the terminal is disconnected
 * Uwe Stieber (Wind River) - [281328] The very first few characters might be missing in the terminal control if opened and connected programmatically
 * Martin Oberhuber (Wind River) - [294327] After logging in, the remote prompt is hidden
 * Anton Leherbauer (Wind River) - [294468] Fix scroller and text line rendering
 * Uwe Stieber (Wind River) - [205486] Fix ScrollLock always moving to line 1
 * Anton Leherbauer (Wind River) - [219589] Copy an entire line selection
 * Anton Leherbauer (Wind River) - [196465] Resizing Terminal changes Scroller location
 * Anton Leherbauer (Wind River) - [324608] Terminal has strange scrolling behaviour
 *******************************************************************************/
package org.eclipse.tm.internal.terminal.textcanvas;


import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.Clipboard;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.events.FocusEvent;
import org.eclipse.swt.events.FocusListener;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseListener;
import org.eclipse.swt.events.MouseMoveListener;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.Composite;

/**
 * A cell oriented Canvas. Maintains a list of "cells".
 * It can either be vertically or horizontally scrolled.
 * The CellRenderer is responsible for painting the cell.
 */
public class TextCanvas extends GridCanvas {
	protected final ITextCanvasModel fCellCanvasModel;
	/** Renders the cells */
	private final ILinelRenderer fCellRenderer;
	private boolean fScrollLock;
	private Point fDraggingStart;
	private Point fDraggingEnd;
	private boolean fHasSelection;
	private ResizeListener fResizeListener;

	// The minSize is meant to determine the minimum size of the backing store
	// (grid) into which remote data is rendered. If the viewport is smaller
	// than that minimum size, the backing store size remains at the minSize,
	// and a scrollbar is shown instead. In reality, this has the following
	// issues or effects today:
	//  (a) Bug 281328: For very early data coming in before the widget is 
	//      realized, the minSize determines into what initial grid that is 
	//      rendered. See also @link{#addResizeHandler(ResizeListener)}.
	//  (b) Bug 294468: Since we have redraw and size computation problems 
	//      with horizontal scrollers, for now the minColumns must be small
	//      enough to avoid a horizontal scroller appearing in most cases.
	//  (b) Bug 294327: since we have problems with the vertical scroller
	//      showing the correct location, minLines must be small enough
	//      to avoid a vertical scroller or new data may be rendered off-screen.
	// As a compromise, we have been working with a 20x4 since the Terminal
	// inception, though many users would want a 80x24 minSize and backing
	// store. Pros and cons of the small minsize:
	//   + consistent "remote size==viewport size", vi works as expected
	//   - dumb terminals which expect 80x24 render garbled on small viewport.
	// If bug 294468 were resolved, an 80 wide minSize would be preferrable
	// since it allows switching the terminal viewport small/large as needed,
	// without destroying the backing store. For a complete solution, 
	// Bug 196462 tracks the request for a user-defined fixed-widow-size-mode.
	private int fMinColumns=80;
	private int fMinLines=4;
	private boolean fCursorEnabled;
	private boolean fResizing;
	
	/**
	 * Create a new CellCanvas with the given SWT style bits.
	 * (SWT.H_SCROLL and SWT.V_SCROLL are automatically added).
	 */
	public TextCanvas(Composite parent, ITextCanvasModel model, int style,ILinelRenderer cellRenderer) {
		super(parent, style | SWT.H_SCROLL | SWT.V_SCROLL);
		fCellRenderer=cellRenderer;
		setCellWidth(fCellRenderer.getCellWidth());
		setCellHeight(fCellRenderer.getCellHeight());
		fCellCanvasModel=model;
		fCellCanvasModel.addCellCanvasModelListener(new ITextCanvasModelListener(){
    	public void rangeChanged(int col, int line, int width, int height) {
    		repaintRange(col,line,width,height);
    	}
    	public void dimensionsChanged(int cols, int rows) {
    		calculateGrid();
    	}
    	public void terminalDataChanged() {
    		if(isDisposed())
    			return;
    		// scroll to end (unless scroll lock is active)
    		if (!fResizing) {
    			calculateGrid();
    			scrollToEnd();
    		}
    	}
    });
		// let the cursor blink if the text canvas gets the focus...
		addFocusListener(new FocusListener(){
			public void focusGained(FocusEvent e) {
				fCellCanvasModel.setCursorEnabled(fCursorEnabled);
			}
			public void focusLost(FocusEvent e) {
				fCellCanvasModel.setCursorEnabled(false);
			}});
		addMouseListener(new MouseListener(){
			public void mouseDoubleClick(MouseEvent e) {
			}
			public void mouseDown(MouseEvent e) {
				if(e.button==1) { // left button
					fDraggingStart=screenPointToCell(e.x, e.y);
					fHasSelection=false;
					if((e.stateMask&SWT.SHIFT)!=0) {
						Point anchor=fCellCanvasModel.getSelectionAnchor();
						if(anchor!=null)
							fDraggingStart=anchor;
					} else {
						fCellCanvasModel.setSelectionAnchor(fDraggingStart);
					}
					fDraggingEnd=null;
				}
			}
			public void mouseUp(MouseEvent e) {
				if(e.button==1) { // left button
					updateHasSelection(e);
					if(fHasSelection)
						setSelection(screenPointToCell(e.x, e.y));
					else
						fCellCanvasModel.setSelection(-1,-1,-1,-1);
					fDraggingStart=null;
				}
			}
		});
		addMouseMoveListener(new MouseMoveListener() {

			public void mouseMove(MouseEvent e) {
				if (fDraggingStart != null) {
					updateHasSelection(e);
					setSelection(screenPointToCell(e.x, e.y));
				}
			}
		});
		serVerticalBarVisible(true);
		setHorizontalBarVisible(false);
	}

	/**
	 * The user has to drag the mouse to at least one character to make a selection.
	 * Once this is done, even a one char selection is OK.
	 *
	 * @param e
	 */
	private void updateHasSelection(MouseEvent e) {
		if(fDraggingStart!=null) {
			Point p=screenPointToCell(e.x, e.y);
			if(fDraggingStart.x!=p.x||fDraggingStart.y!=p.y)
				fHasSelection=true;
		}
	}

	void setSelection(Point p) {
		if (fDraggingStart !=null && !p.equals(fDraggingEnd)) {
			fDraggingEnd = p;
			if (compare(p, fDraggingStart) < 0) {
				// bug 219589 - make sure selection start coordinates are non-negative
				int startColumn = Math.max(0, p.x);
				int startRow = Math.max(p.y, 0);
				fCellCanvasModel.setSelection(startRow, fDraggingStart.y, startColumn, fDraggingStart.x);
			} else {
				fCellCanvasModel.setSelection(fDraggingStart.y, p.y, fDraggingStart.x, p.x);

			}
		}
	}

	int compare(Point p1, Point p2) {
		if (p1.equals(p2))
			return 0;
		if (p1.y == p2.y) {
			if (p1.x > p2.x)
				return 1;
			else
				return -1;
		}
		if (p1.y > p2.y) {
			return 1;
		} else {
			return -1;
		}
	}
	public ILinelRenderer getCellRenderer() {
		return fCellRenderer;
	}

	public int getMinColumns() {
		return fMinColumns;
	}

	public void setMinColumns(int minColumns) {
		fMinColumns = minColumns;
	}

	public int getMinLines() {
		return fMinLines;
	}

	public void setMinLines(int minLines) {
		fMinLines = minLines;
	}

	protected void onResize(boolean init) {
		if(fResizeListener!=null) {
			Rectangle bonds=getClientArea();
			int cellHeight = getCellHeight();
			int cellWidth = getCellWidth();
			int lines=bonds.height/cellHeight;
			int columns=bonds.width/cellWidth;
			// when the view is minimised, its size is set to 0
			// we don't sent this to the terminal!
			if((lines>0 && columns>0) || init) {
				if(columns<fMinColumns) {
					if(!isHorizontalBarVisble()) {
						setHorizontalBarVisible(true);
						bonds=getClientArea();
						lines=bonds.height/cellHeight;
					}
					columns=fMinColumns;
				} else if(columns>=fMinColumns && isHorizontalBarVisble()) {
					setHorizontalBarVisible(false);
					bonds=getClientArea();
					lines=bonds.height/cellHeight;
					columns=bonds.width/cellWidth;
				}
				if(lines<fMinLines)
					lines=fMinLines;
				fResizeListener.sizeChanged(lines, columns);
			}
		}
		super.onResize();
		calculateGrid();
	}

	protected void onResize() {
		fResizing = true;
		try {
			onResize(false);
		} finally {
			fResizing = false;
		}
	}

	private void calculateGrid() {
		Rectangle virtualBounds = getVirtualBounds();
		setRedraw(false);
		try {
			setVirtualExtend(getCols()*getCellWidth(),getRows()*getCellHeight());
			getParent().layout();
			if (fResizing) {
				// scroll to end if view port was near last line
				Rectangle viewRect = getViewRectangle();
				if (virtualBounds.height - (viewRect.y + viewRect.height) < getCellHeight() * 2)
					scrollToEnd();
			}
		} finally {
			setRedraw(true);
		}
	}
	void scrollToEnd() {
		if(!fScrollLock) {
			int y=-(getRows()*getCellHeight()-getClientArea().height);
			if (y > 0) {
				y = 0;
			}
			Rectangle v=getViewRectangle();
			if(v.y!=-y) {
				setVirtualOrigin(v.x,y);
			}
			// make sure the scroll area is correct:
			scrollY(getVerticalBar());
			scrollX(getHorizontalBar());
		}
	}
	/**
	 *
	 * @return true if the cursor should be shown on output....
	 */
	public boolean isScrollLock() {
		return fScrollLock;
	}
	/**
	 * If set then if the size changes
	 */
	public void setScrollLock(boolean scrollLock) {
		fScrollLock=scrollLock;
	}
	protected void repaintRange(int col, int line, int width, int height) {
		Point origin=cellToOriginOnScreen(col,line);
		Rectangle r=new Rectangle(origin.x,origin.y,width*getCellWidth(),height*getCellHeight());
		repaint(r);
	}
	protected void drawLine(GC gc, int line, int x, int y, int colFirst, int colLast) {
		fCellRenderer.drawLine(fCellCanvasModel, gc,line,x,y,colFirst, colLast);
	}
	protected Color getTerminalBackgroundColor() {
		return fCellRenderer.getDefaultBackgroundColor();
	}
	protected void visibleCellRectangleChanged(int x, int y, int width, int height) {
		fCellCanvasModel.setVisibleRectangle(y,x,height,width);
		update();
	}
	protected int getCols() {
		return fCellCanvasModel.getTerminalText().getWidth();
	}
	protected int getRows() {
		return fCellCanvasModel.getTerminalText().getHeight();
	}
	public String getSelectionText() {
		// TODO -- create a hasSelectionMethod!
		return fCellCanvasModel.getSelectedText();
	}
	public void copy() {
		Clipboard clipboard = new Clipboard(getDisplay());
		clipboard.setContents(new Object[] { getSelectionText() }, new Transfer[] { TextTransfer.getInstance() });
		clipboard.dispose();
	}
	public void selectAll() {
		fCellCanvasModel.setSelection(0, fCellCanvasModel.getTerminalText().getHeight(), 0, fCellCanvasModel.getTerminalText().getWidth());
		fCellCanvasModel.setSelectionAnchor(new Point(0,0));
	}
	public boolean isEmpty() {
		return false;
	}
	/**
	 * Gets notified when the visible size of the terminal changes.
	 * This should update the model!
	 *
	 */
	public interface ResizeListener {
		void sizeChanged(int lines, int columns);
	}
	/**
	 * @param listener this listener gets notified, when the size of
	 * the widget changed. It should change the dimensions of the underlying
	 * terminaldata
	 */
	public void addResizeHandler(ResizeListener listener) {
		if(fResizeListener!=null)
			throw new IllegalArgumentException("There can be at most one listener at the moment!"); //$NON-NLS-1$
		fResizeListener=listener;

		// Bug 281328: [terminal] The very first few characters might be missing in
		//             the terminal control if opened and connected programmatically
		//
		// In case the terminal had not been visible yet or is too small (less than one
		// line visible), the terminal should have a minimum size to avoid RuntimeExceptions.
		Rectangle bonds=getClientArea();
		if (bonds.height<getCellHeight() || bonds.width<getCellWidth()) {
			//Widget not realized yet, or minimized to < 1 item:
			//Just tell the listener our min size
			fResizeListener.sizeChanged(getMinLines(), getMinColumns());
		} else {
			//Widget realized: compute actual size and force telling the listener
			onResize(true);
		}
	}

	public void onFontChange() {
		fCellRenderer.onFontChange();
		setCellWidth(fCellRenderer.getCellWidth());
		setCellHeight(fCellRenderer.getCellHeight());
		calculateGrid();
	}

	public void setInvertedColors(boolean invert) {
		fCellRenderer.setInvertedColors(invert);
		redraw();
	}

	/**
	 * @return true if the cursor is enabled (blinking). By default the cursor is not enabled.
	 */
	public boolean isCursorEnabled() {
		return fCursorEnabled;
	}

	/**
	 * @param enabled enabling means that the cursor blinks
	 */
	public void setCursorEnabled(boolean enabled) {
		if(enabled!=fCursorEnabled) {
			fCursorEnabled=enabled;
			fCellCanvasModel.setCursorEnabled(fCursorEnabled);
		}

	}

  public void resetColors(RGB background, RGB foreground) {
    fCellRenderer.resetColors(background, foreground);
  }
}