//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   Licensed under the Apache License, Version 2.0 (the "License");
//   you may not use this file except in compliance with the License.
//   You may obtain a copy of the License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the License is distributed on an "AS IS" BASIS,
//   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//   See the License for the specific language governing permissions and
//   limitations under the License.

package de.ugoe.cs.autoquest.eventcore.gui;

import java.util.LinkedList;
import java.util.List;

import de.ugoe.cs.autoquest.eventcore.Event;
import de.ugoe.cs.autoquest.eventcore.IEventTarget;

/**
 * <p>
 * This class condenses mouse clicks, i.e. it reduces a sequence of mouse button down, mouse button
 * up and possibly a subsequent mouse click with the same button on the same event target and the
 * same coordinates to a single mouse click with that button on that target at the coordinates.
 * The mouse button down and mouse button up events are discarded. For this, it iterates the
 * provided sequence and identifies any match of the named event sequence pattern. This match is
 * condensed to the mouse click event.
 * </p>
 * 
 * @version 1.0
 * @author Patrick Harms
 */
public class MouseClickCondenser {

    /**
     * <p>
     * This method performs the work described in the description of the class. A new list is
     * instantiated and returned. This list is filled with the events provided by the sequence being
     * the parameter of the method except for mouse button down and mouse button up events which are
     * followed by a mouse click event with the same button on the same target.
     * </p>
     * 
     * @param sequence
     *            the event sequence to condense the mouse clicks in
     * 
     * @return the resulting sequence, in which mouse clicks are condensed to single mouse click
     *         events
     */
    public List<Event> condenseMouseClicks(List<Event> sequence) {
        List<Event> resultingSequence = new LinkedList<Event>();

        int index = 0;
        boolean mouseClickHandled;
        while (index < sequence.size())
        {
            mouseClickHandled = false;
            if ((index + 1) < sequence.size()) {
                Event mbDown = sequence.get(index);
                Event mbUp = sequence.get(index + 1);
                
                if (((index + 2) < sequence.size()) &&
                    mouseClickSequenceFound(mbDown, mbUp, sequence.get(index + 2)))
                {
                    // skip the mouse button down and mouse button up event and add the mouse click
                    index += 2;
                    resultingSequence.add(sequence.get(index));
                    index++;
                    mouseClickHandled = true;
                }
                else if (mouseClickSequenceFound(mbDown, mbUp)) {
                    // replace the mouse button down and mouse button up event with a generated
                    // mouse click
                    index += 2;
                    resultingSequence.add(createClick(mbDown, mbUp));
                    mouseClickHandled = true;
                }
                else if (mouseDragAndDropSequenceFound(mbDown, mbUp)) {
                    // replace the mouse button down and mouse button up event with a generated
                    // mouse drag and drop
                    index += 2;
                    resultingSequence.add(createDragAndDrop(mbDown, mbUp));
                    mouseClickHandled = true;
                }
                else if (mouseDoubleClickSequenceFound(mbDown, mbUp)) {
                    // replace the two mouse click events with a generated mouse double click
                    index += 2;
                    resultingSequence.add(createDoubleClick(mbDown, mbUp));
                    mouseClickHandled = true;
                }
            }

            if (!mouseClickHandled) {
                resultingSequence.add(sequence.get(index));
                index++;
            }
            
            if (resultingSequence.size() > 1) {
                // check for double clicks
                int resultingSequenceIndex = resultingSequence.size() - 1;
                Event click1 = resultingSequence.get(resultingSequenceIndex - 1);
                Event click2 = resultingSequence.get(resultingSequenceIndex);
                if (mouseDoubleClickSequenceFound(click1, click2)) {
                    resultingSequence.remove(resultingSequenceIndex);
                    resultingSequence.remove(resultingSequenceIndex - 1);
                    resultingSequence.add(createDoubleClick(click1, click2));
                }
            }
        }

        return resultingSequence;
    }

    /**
     * 
     */
    private boolean mouseClickSequenceFound(Event mouseButtonDown,
                                            Event mouseButtonUp,
                                            Event mouseClick)
    {
        if (!mouseClickSequenceFound(mouseButtonDown, mouseButtonUp)) {
            return false;
        }
        
        // check the third node for validity
        if (!(mouseClick.getType() instanceof MouseClick)) {
            return false;
        }

        if (!targetsEqual(mouseButtonDown, mouseClick)) {
            return false;
        }
        
        if (!buttonsEqual(mouseButtonDown, mouseClick)) {
            return false;
        }

        if (!coordinatesEqual(mouseButtonDown, mouseClick)) {
            return false;
        }
        
        return true;
    }

    /**
     * 
     */
    private boolean mouseClickSequenceFound(Event mouseButtonDown,
                                            Event mouseButtonUp)
    {
        // check the first in a row of three for validity
        if (!(mouseButtonDown.getType() instanceof MouseButtonDown)) {
            return false;
        }

        // check the second node for validity
        if (!(mouseButtonUp.getType() instanceof MouseButtonUp)) {
            return false;
        }

        if (!targetsEqual(mouseButtonDown, mouseButtonUp)) {
            return false;
        }
        
        if (!buttonsEqual(mouseButtonDown, mouseButtonUp)) {
            return false;
        }

        if (!coordinatesEqual(mouseButtonDown, mouseButtonUp)) {
            return false;
        }
        
        return true;
    }

    /**
     * 
     */
    private boolean mouseDragAndDropSequenceFound(Event mouseButtonDown,
                                                  Event mouseButtonUp)
    {
        // check the first in a row of three for validity
        if (!(mouseButtonDown.getType() instanceof MouseButtonDown)) {
            return false;
        }

        // check the second node for validity
        if (!(mouseButtonUp.getType() instanceof MouseButtonUp)) {
            return false;
        }

        if (!targetsEqual(mouseButtonDown, mouseButtonUp)) {
            return false;
        }
        
        MouseButtonInteraction.Button button =
            ((MouseButtonDown) mouseButtonDown.getType()).getButton();
        
        if (MouseButtonInteraction.Button.LEFT != button) {
            return false;
        }
        
        if (!buttonsEqual(mouseButtonDown, mouseButtonUp)) {
            return false;
        }

        if (coordinatesEqual(mouseButtonDown, mouseButtonUp)) {
            return false;
        }
        
        return true;
    }

    /**
     * 
     */
    private boolean mouseDoubleClickSequenceFound(Event click1,
                                                  Event click2)
    {
        // check the first in a row of three for validity
        if (!(click1.getType() instanceof MouseClick)) {
            return false;
        }

        if (((MouseClick) click1.getType()).getButton() != MouseButtonInteraction.Button.LEFT) {
            return false;
        }
        
        // check the second node for validity
        if (!(click2.getType() instanceof MouseClick)) {
            return false;
        }

        // use 500 milliseconds as timestamp difference as this is more or less similar to default
        // values in Microsoft Windows 
        if (!timestampDifferenceSmallerThan(click1, click2, 500)) {
            return false;
        }
        
        if (!targetsEqual(click1, click2)) {
            return false;
        }

        if (!buttonsEqual(click1, click2)) {
            return false;
        }

        if (!coordinatesEqual(click1, click2)) {
            return false;
        }
        
        return true;
    }

    /**
     *
     */
    private Event createClick(Event mouseButtonDown, Event mouseButtonUp) {
        MouseButtonInteraction.Button button =
            ((MouseButtonDown) mouseButtonDown.getType()).getButton();
        
        int x = ((MouseButtonDown) mouseButtonDown.getType()).getX();
        int y = ((MouseButtonDown) mouseButtonDown.getType()).getY();

        Event click = new Event(new MouseClick(button, x, y), mouseButtonDown.getTarget());
        click.setTimestamp(mouseButtonDown.getTimestamp());
        return click;
    }

    /**
     *
     */
    private Event createDoubleClick(Event click1, Event click2) {
        MouseButtonInteraction.Button button = ((MouseClick) click1.getType()).getButton();
       
        int x = ((MouseClick) click1.getType()).getX();
        int y = ((MouseClick) click1.getType()).getY();

        Event doubleClick = new Event(new MouseDoubleClick(button, x, y), click1.getTarget());
        doubleClick.setTimestamp(click1.getTimestamp());
        return doubleClick;
    }

    /**
     *
     */
    private Event createDragAndDrop(Event mouseButtonDown, Event mouseButtonUp) {
        int xStart = ((MouseButtonDown) mouseButtonDown.getType()).getX();
        int yStart = ((MouseButtonDown) mouseButtonDown.getType()).getY();
        int xEnd = ((MouseButtonUp) mouseButtonUp.getType()).getX();
        int yEnd = ((MouseButtonUp) mouseButtonUp.getType()).getY();

        Event dragAndDrop = new Event
            (new MouseDragAndDrop(xStart, yStart, xEnd, yEnd), mouseButtonDown.getTarget());
        
        dragAndDrop.setTimestamp(mouseButtonDown.getTimestamp());
        return dragAndDrop;
    }

    /**
     *
     */
    private boolean targetsEqual(Event event1, Event event2) {
        IEventTarget target1 = event1.getTarget();
        IEventTarget target2 = event2.getTarget();

        return target1 == null ? target2 == null : target1.equals(target2);
    }

    /**
     *
     */
    private boolean buttonsEqual(Event event1, Event event2) {
        MouseButtonInteraction.Button button1 =
            (event1.getType() instanceof MouseButtonInteraction) ?
                ((MouseButtonInteraction) event1.getType()).getButton() : null;
                
        MouseButtonInteraction.Button button2 =
            (event2.getType() instanceof MouseButtonInteraction) ?
                ((MouseButtonInteraction) event2.getType()).getButton() : null;

        return button1 == null ? button2 == null : button1.equals(button2);
    }

    /**
     *
     */
    private boolean timestampDifferenceSmallerThan(Event event1, Event event2, long difference) {
        long timestamp1 = event1.getTimestamp();
        
        if (timestamp1 < 0) {
            return false;
        }
        
        long timestamp2 = event2.getTimestamp();
        
        if (timestamp2 < 0) {
            return false;
        }
        
        return (Math.abs((timestamp2 - timestamp1))) < difference;
    }

    /**
     *
     */
    private boolean coordinatesEqual(Event event1, Event event2) {
        int x1 =
            (event1.getType() instanceof MouseButtonInteraction) ?
                ((MouseButtonInteraction) event1.getType()).getX() : -1;
               
        int x2 =
            (event2.getType() instanceof MouseButtonInteraction) ?
                ((MouseButtonInteraction) event2.getType()).getX() : -1;
        
        // allow a deviation of one pixel to identify it as click anyway
        if ((x1 == -1) || (x2 == -1) || (x2 < (x1 - 1)) || ((x1 + 1) < x2)) {
            return false;
        }

        int y1 =
            (event1.getType() instanceof MouseButtonInteraction) ?
                ((MouseButtonInteraction) event1.getType()).getY() : -1;
                           
        int y2 =
            (event2.getType() instanceof MouseButtonInteraction) ?
                ((MouseButtonInteraction) event2.getType()).getY() : -1;

        return (y1 != -1) && (y2 != -1) && ((y1 - 1) < y2) && (y2 < (y1 + 1));
   }

}