// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.gui;

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Collection;
import java.util.LinkedList;

import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Way;

/**
 * Manages the selection of a rectangle. Listening to left and right mouse button
 * presses and to mouse motions and draw the rectangle accordingly.
 *
 * Left mouse button selects a rectangle from the press until release. Pressing
 * right mouse button while left is still pressed enable the rectangle to move
 * around. Releasing the left button fires an action event to the listener given
 * at constructor, except if the right is still pressed, which just remove the
 * selection rectangle and does nothing.
 *
 * The point where the left mouse button was pressed and the current mouse
 * position are two opposite corners of the selection rectangle.
 *
 * It is possible to specify an aspect ratio (width per height) which the
 * selection rectangle always must have. In this case, the selection rectangle
 * will be the largest window with this aspect ratio, where the position the left
 * mouse button was pressed and the corner of the current mouse position are at
 * opposite sites (the mouse position corner is the corner nearest to the mouse
 * cursor).
 *
 * When the left mouse button was released, an ActionEvent is send to the
 * ActionListener given at constructor. The source of this event is this manager.
 *
 * @author imi
 */
public class SelectionManager implements MouseListener, MouseMotionListener, PropertyChangeListener {

    /**
     * This is the interface that an user of SelectionManager has to implement
     * to get informed when a selection closes.
     * @author imi
     */
    public interface SelectionEnded {
        /**
         * Called, when the left mouse button was released.
         * @param r The rectangle that is currently the selection.
         * @param alt Whether the alt key was pressed
         * @param shift Whether the shift key was pressed
         * @param ctrl Whether the ctrl key was pressed
         * @see InputEvent#getModifiersEx()
         */
        public void selectionEnded(Rectangle r, boolean alt, boolean shift, boolean ctrl);
        /**
         * Called to register the selection manager for "active" property.
         * @param listener The listener to register
         */
        public void addPropertyChangeListener(PropertyChangeListener listener);
        /**
         * Called to remove the selection manager from the listener list
         * for "active" property.
         * @param listener The listener to register
         */
        public void removePropertyChangeListener(PropertyChangeListener listener);
    }
    /**
     * The listener that receives the events after left mouse button is released.
     */
    private final SelectionEnded selectionEndedListener;
    /**
     * Position of the map when the mouse button was pressed.
     * If this is not <code>null</code>, a rectangle is drawn on screen.
     */
    private Point mousePosStart;
    /**
     * Position of the map when the selection rectangle was last drawn.
     */
    private Point mousePos;
    /**
     * The Component, the selection rectangle is drawn onto.
     */
    private final NavigatableComponent nc;
    /**
     * Whether the selection rectangle must obtain the aspect ratio of the
     * drawComponent.
     */
    private boolean aspectRatio;

    /**
     * Create a new SelectionManager.
     *
     * @param selectionEndedListener The action listener that receives the event when
     *      the left button is released.
     * @param aspectRatio If true, the selection window must obtain the aspect
     *      ratio of the drawComponent.
     * @param navComp The component, the rectangle is drawn onto.
     */
    public SelectionManager(SelectionEnded selectionEndedListener, boolean aspectRatio, NavigatableComponent navComp) {
        this.selectionEndedListener = selectionEndedListener;
        this.aspectRatio = aspectRatio;
        this.nc = navComp;
    }

    /**
     * Register itself at the given event source.
     * @param eventSource The emitter of the mouse events.
     */
    public void register(NavigatableComponent eventSource) {
        eventSource.addMouseListener(this);
        eventSource.addMouseMotionListener(this);
        selectionEndedListener.addPropertyChangeListener(this);
        eventSource.addPropertyChangeListener("scale", new PropertyChangeListener(){
            public void propertyChange(PropertyChangeEvent evt) {
                if (mousePosStart != null) {
                    paintRect();
                    mousePos = mousePosStart = null;
                }
            }
        });
    }
    /**
     * Unregister itself from the given event source. If a selection rectangle is
     * shown, hide it first.
     *
     * @param eventSource The emitter of the mouse events.
     */
    public void unregister(Component eventSource) {
        eventSource.removeMouseListener(this);
        eventSource.removeMouseMotionListener(this);
        selectionEndedListener.removePropertyChangeListener(this);
    }

    /**
     * If the correct button, from the "drawing rectangle" mode
     */
    public void mousePressed(MouseEvent e) {
        if (e.getButton() == MouseEvent.BUTTON1) {
            mousePosStart = mousePos = e.getPoint();
        }
    }

    /**
     * If the correct button is hold, draw the rectangle.
     */
    public void mouseDragged(MouseEvent e) {
        int buttonPressed = e.getModifiersEx() & (MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON3_DOWN_MASK);


        if (buttonPressed != 0) {
            if (mousePosStart == null) {
                mousePosStart = mousePos = e.getPoint();
            }
            paintRect();
        }

        if (buttonPressed == MouseEvent.BUTTON1_DOWN_MASK) {
            mousePos = e.getPoint();
            paintRect();
        } else if (buttonPressed == (MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON3_DOWN_MASK)) {
            mousePosStart.x += e.getX()-mousePos.x;
            mousePosStart.y += e.getY()-mousePos.y;
            mousePos = e.getPoint();
            paintRect();
        }
    }

    /**
     * Check the state of the keys and buttons and set the selection accordingly.
     */
    public void mouseReleased(MouseEvent e) {
        if (e.getButton() != MouseEvent.BUTTON1)
            return;
        if (mousePos == null || mousePosStart == null)
            return; // injected release from outside

        // disable the selection rect
        paintRect();
        Rectangle r = getSelectionRectangle();
        mousePosStart = null;
        mousePos = null;

        boolean shift = (e.getModifiersEx() & MouseEvent.SHIFT_DOWN_MASK) != 0;
        boolean alt = (e.getModifiersEx() & MouseEvent.ALT_DOWN_MASK) != 0;
        boolean ctrl = (e.getModifiersEx() & MouseEvent.CTRL_DOWN_MASK) != 0;
        if ((e.getModifiersEx() & MouseEvent.BUTTON3_DOWN_MASK) == 0) {
            selectionEndedListener.selectionEnded(r, alt, shift, ctrl);
        }
    }


    /**
     * Draw a selection rectangle on screen. If already a rectangle is drawn,
     * it is removed instead.
     */
    private void paintRect() {
        if (mousePos == null || mousePosStart == null || mousePos == mousePosStart)
            return;
        Graphics g = nc.getGraphics();
        g.setColor(Color.BLACK);
        g.setXORMode(Color.WHITE);

        Rectangle r = getSelectionRectangle();
        g.drawRect(r.x,r.y,r.width,r.height);
    }

    /**
     * Calculate and return the current selection rectangle
     * @return A rectangle that spans from mousePos to mouseStartPos
     */
    private Rectangle getSelectionRectangle() {
        int x = mousePosStart.x;
        int y = mousePosStart.y;
        int w = mousePos.x - mousePosStart.x;
        int h = mousePos.y - mousePosStart.y;
        if (w < 0) {
            x += w;
            w = -w;
        }
        if (h < 0) {
            y += h;
            h = -h;
        }

        if (aspectRatio) {
            /* Keep the aspect ratio by growing the rectangle; the
             * rectangle is always under the cursor. */
            double aspectRatio = (double)nc.getWidth()/nc.getHeight();
            if ((double)w/h < aspectRatio) {
                int neww = (int)(h*aspectRatio);
                if (mousePos.x < mousePosStart.x) {
                    x += w - neww;
                }
                w = neww;
            } else {
                int newh = (int)(w/aspectRatio);
                if (mousePos.y < mousePosStart.y) {
                    y += h - newh;
                }
                h = newh;
            }
        }

        return new Rectangle(x,y,w,h);
    }

    /**
     * If the action goes inactive, remove the selection rectangle from screen
     */
    public void propertyChange(PropertyChangeEvent evt) {
        if (evt.getPropertyName().equals("active") && !(Boolean)evt.getNewValue() && mousePosStart != null) {
            paintRect();
            mousePosStart = null;
            mousePos = null;
        }
    }

    /**
     * Return a list of all objects in the rectangle, respecting the different
     * modifier.
     * @param alt Whether the alt key was pressed, which means select all objects
     *      that are touched, instead those which are completly covered.
     */
    public Collection<OsmPrimitive> getObjectsInRectangle(Rectangle r, boolean alt) {
        Collection<OsmPrimitive> selection = new LinkedList<OsmPrimitive>();

        // whether user only clicked, not dragged.
        boolean clicked = r.width <= 2 && r.height <= 2;
        Point center = new Point(r.x+r.width/2, r.y+r.height/2);

        if (clicked) {
            OsmPrimitive osm = nc.getNearest(center);
            if (osm != null) {
                selection.add(osm);
            }
        } else {
            // nodes
            for (Node n : nc.getCurrentDataSet().getNodes()) {
                if (n.isUsable() && r.contains(nc.getPoint(n))) {
                    selection.add(n);
                }
            }

            // ways
            for (Way w : nc.getCurrentDataSet().getWays()) {
                if (!w.isUsable() || w.getNodesCount() == 0) {
                    continue;
                }
                if (alt) {
                    for (Node n : w.getNodes()) {
                        if (!n.incomplete && r.contains(nc.getPoint(n))) {
                            selection.add(w);
                            break;
                        }
                    }
                } else {
                    boolean allIn = true;
                    for (Node n : w.getNodes()) {
                        if (!n.incomplete && !r.contains(nc.getPoint(n))) {
                            allIn = false;
                            break;
                        }
                    }
                    if (allIn) {
                        selection.add(w);
                    }
                }
            }
        }
        return selection;
    }

    public void mouseClicked(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}
    public void mouseMoved(MouseEvent e) {}
}