/*
 * The MIT License (MIT)
 * 
 * Copyright (c) 2015 Camil Staps <info@camilstaps.nl>
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
package com.camilstaps.mandelbrot;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Observable;
import java.util.Observer;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;

/**
 * The Grid is both a View and a Controller: it shows a graphical representation
 * of the FractalModel, and allows the user to control that FractalModel by 
 * clicking (zoom in), shift-clicking (zoom out) and dragging (box zoom).
 * @author Camil Staps
 */
public class Grid extends JPanel implements Observer, MouseListener, MouseMotionListener {
    
    /**
     * Hard maximum amount of repetitions and the amount of steps to take to get
     * to that maximum
     */
    private static final int REPETITIONS_MAX = 1000, STEPS = 50;
    
    /**
     * Width and height of the grid
     */
    private static final int WIDTH = 400, HEIGHT = 400;
    
    /**
     * List of colours for visualisation
     */
    private final int[] colors;
    
    /**
     * The FractalModel to visualise
     */
    private final FractalModel fractalModel;
    
    /**
     * Used for visualisation
     */
    private final BufferedImage image;
    private final WritableRaster raster;
    
    /**
     * Count pixels changed to check if we need to repaint
     */
    private int pixelCounter;
    
    /**
     * Updating the view is done by SwingWorkers. The solution provides support
     * for multiple SwingWorkers; Updaters; which are held in this list.
     */
    private final List<Updater> updaters = new ArrayList<>();
    
    /**
     * Used for handling mouse events and zooming
     */
    private int start_x, start_y, old_x, old_y;
    private boolean dragging = false;
    Graphics graphics;
    
    /**
     * A progress bar
     */
    private ProgressView progressView;
    
    /**
     * Whether or not to use multiple SwingWorkers.
     * Using multiple SwingWorkers is *not* faster. The application is already
     * faster by using memory in the MandelbrotFractal class. Using multiple 
     * SwingWorkers does not aid in speed.
     */
    private boolean useMultipleSwingWorkers = false;
    
    /**
     * Create a new Grid to view and control a FractalModel
     * @param fractalModel 
     */
    public Grid(FractalModel fractalModel) {
        this.fractalModel = fractalModel;
        fractalModel.addObserver(this);
        
        image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
        raster = image.getRaster();
        
        setPreferredSize(new Dimension(WIDTH, HEIGHT));
        
        colors = new int[REPETITIONS_MAX + 1];
        for (int i = 0; i <=REPETITIONS_MAX; i++) {
            colors[i] = Color.HSBtoRGB(
                    0.07f, 
                    0.5f + 0.5f * (float) i / (float) REPETITIONS_MAX, 
                    1);
        }
        
        addMouseListener(this);
        addMouseMotionListener(this);
        
        update(fractalModel, null);
    }
    
    /**
     * Get the progress bar (create it if it doesn't exist yet)
     * @return 
     */
    public ProgressView getProgressView() {
        if (progressView == null) {
            progressView = new ProgressView();
        }
        return progressView;
    }
    
    @Override
    public int getWidth() {
        return WIDTH;
    }
    
    @Override
    public int getHeight() {
        return HEIGHT;
    }
    
    /**
     * Change whether we use multiple SwingWorkers or not. This change will
     * take effect when the FractalModel is updated.
     * @param value 
     */
    public void setUseMultipleSwingWorkers(boolean value) {
        useMultipleSwingWorkers = value;
    }

    /**
     * Stop the previous update and start rendering all over again.
     * @param o
     * @param o1 
     */
    @Override
    public final synchronized void update(Observable o, Object o1) {
        if (updaters != null) {
            synchronized (updaters) {
                for (Updater updater : updaters) {
                    updater.stop();
                    updater.cancel(true);
                }
            }
        }
        synchronized (updaters) {
            updaters.clear();
            if (useMultipleSwingWorkers) {
                Updater u1 = new Updater(0, WIDTH / 2, 0, HEIGHT / 2);
                u1.execute();
                updaters.add(u1);
                Updater u2 = new Updater(WIDTH / 2, WIDTH, 0, HEIGHT / 2);
                u2.execute();
                updaters.add(u2);
                Updater u3 = new Updater(0, WIDTH / 2, HEIGHT / 2, HEIGHT);
                u3.execute();
                updaters.add(u3);
                Updater u4 = new Updater(WIDTH / 2, WIDTH, HEIGHT / 2, HEIGHT);
                u4.execute();
                updaters.add(u4);
            } else {
                Updater u = new Updater(0, WIDTH, 0, HEIGHT);
                u.execute();
                updaters.add(u);
            }
        }
    }
    
    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, 0, 0, null);
    }
    
    /**
     * Set a pixel on the grid
     * @param x
     * @param y
     * @param rgb 
     */
    public synchronized void setPixel(int x, int y, int[] rgb) {
        raster.setPixel(x, y, rgb);
        pixelCounter++;
        if (pixelCounter == WIDTH * HEIGHT) {
            pixelCounter = 0;
            repaint();
        }
    }
    
    /**
     * Get the 'mathematical' x coordinate that belongs to a pixel's x coordinate
     * @param pixel_x
     * @return 
     */
    protected double getRealX(int pixel_x) {
        return ((double) pixel_x * (fractalModel.getEndX() - fractalModel.getStartX())
                / (double) WIDTH) + fractalModel.getStartX();
    }
    
    /**
     * Get the 'mathematical' y coordinate that belongs to a pixel's y coordinate
     * @param pixel_y
     * @return 
     */
    protected double getRealY(int pixel_y) {
        return ((double) pixel_y * (fractalModel.getEndY() - fractalModel.getStartY())
                / (double) HEIGHT) + fractalModel.getStartY();
    }

    /**
     * Click to zoom in; Shift-click to zoom out
     * @param me 
     */
    @Override
    public void mouseClicked(MouseEvent me) {
        if ((me.getModifiers() & InputEvent.SHIFT_MASK) != 0) {
            zoomOut(me);
        } else {
            zoomIn(me);
        }
    }

    /**
     * Keep track of mouse data for the box zoom
     * @param me 
     */
    @Override
    public void mousePressed(MouseEvent me) {
        old_x = start_x = me.getX();
        old_y = start_y = me.getY();
    }

    /**
     * If this was a box zoom, ... well, perform a box zoom.
     * @param me 
     */
    @Override
    public synchronized void mouseReleased(MouseEvent me) {
        if (me.getX() != start_x || me.getY() != start_y) {
            zoomBox(me);
        }
        
        dragging = false;
    }
    
    /**
     * Zoom in with factor 2
     * @param me 
     */
    private void zoomIn(MouseEvent me) {
        double offset_x = (fractalModel.getEndX() - fractalModel.getStartX()) / 4;
        double offset_y = (fractalModel.getEndY() - fractalModel.getStartY()) / 4;
        
        double newCenterX = getRealX(me.getX());
        fractalModel.setStartX(newCenterX - offset_x);
        fractalModel.setEndX(newCenterX + offset_x);
        
        double newCenterY = getRealY(me.getY());
        fractalModel.setStartY(newCenterY - offset_y);
        fractalModel.setEndY(newCenterY + offset_y);
    }
    
    /**
     * Zoom out with factor 2
     * @param me 
     */
    private void zoomOut(MouseEvent me) {
        double offset_x = fractalModel.getEndX() - fractalModel.getStartX();
        double offset_y = fractalModel.getEndY() - fractalModel.getStartY();
        
        double newCenterX = getRealX(me.getX());
        fractalModel.setStartX(newCenterX - offset_x);
        fractalModel.setEndX(newCenterX + offset_x);
        
        double newCenterY = getRealY(me.getY());
        fractalModel.setStartY(newCenterY - offset_y);
        fractalModel.setEndY(newCenterY + offset_y);
    }
    
    /**
     * Zoom to the selected box.
     * Intentionally chose to let the user only select squares, otherwise it's too easy to mess up the scale
     * @param me 
     */
    private void zoomBox(MouseEvent me) {
        double newStartX = getRealX(start_x), 
                newEndX = getRealX(me.getX()),
                newStartY = getRealY(start_y),
                newEndY = getRealY(start_y + me.getX() - start_x);
        
        fractalModel.setStartX(newStartX);
        fractalModel.setEndX(newEndX);
        fractalModel.setStartY(newStartY);
        fractalModel.setEndY(newEndY);
    }

    @Override
    public void mouseEntered(MouseEvent me) {}

    @Override
    public void mouseExited(MouseEvent me) {}

    /**
     * Draw the zoombox on dragging
     * @param me 
     */
    @Override
    public void mouseDragged(MouseEvent me) {
        Graphics g = getSafeGraphics();
        if (g != null) {
            if (dragging) {
                eraseZoombox();
            }
            g.drawRect(start_x, start_y, me.getX() - start_x, me.getX() - start_x);
            old_y = old_x = me.getX();
            dragging = true;
        }
    }
    
    /**
     * Semi-singleton construction for graphics
     * @return 
     */
    private Graphics getSafeGraphics() {
        if (graphics == null) {
            graphics = getGraphics();
            graphics.setXORMode(Color.white);
        }
        return graphics;
    }
    
    /**
     * Erase the old zoombox if it exists
     */
    private void eraseZoombox() {
        if (start_x < 0 || start_y < 0 || old_x < 0 || old_y < 0)
            return;
        getSafeGraphics().drawRect(start_x, start_y, old_x - start_x, old_y - start_x);
    }

    @Override
    public void mouseMoved(MouseEvent me) {}
    
    /**
     * A SwingWorker to update the graphics
     */
    protected class Updater extends SwingWorker<Map<Point,Integer>, Map<Point,Integer>> {
        private boolean doneProcessing = true, stop = false;
        
        private final int start_x, end_x, start_y, end_y;
        
        /**
         * Update only the given rectangle
         * @param start_x
         * @param end_x
         * @param start_y
         * @param end_y 
         */
        public Updater(int start_x, int end_x, int start_y, int end_y) {
            super();
            
            this.start_x = start_x;
            this.end_x = end_x;
            this.start_y = start_y;
            this.end_y = end_y;
        }
        
        /**
         * Calculate all points in the rectangle using the FractalModel
         * @return the resulting points
         */
        @Override
        protected Map<Point, Integer> doInBackground() {
            Map<Point,Integer> results = new HashMap<>();
            
            for (int repetitions = REPETITIONS_MAX / STEPS; repetitions <= REPETITIONS_MAX && !stop; repetitions += REPETITIONS_MAX / STEPS) {
                for (int x = start_x; x < end_x && !stop; x++) {
                    for (int y = start_y; y < end_y && !stop; y++) {
                        Point p = new Point(x, y);
                        results.put(p, fractalModel.getMandelNumber(getRealX(x), getRealY(y), repetitions));
                    }
                }
                
                // Since we're always publishing the same object, there's no point in calling publish if process() wasn't called yet
                if (doneProcessing && !stop) {
                    doneProcessing = false;
                    publish(results);
                }
                setProgress(repetitions * 100 / REPETITIONS_MAX);
            }
            
            return results;
        }
        
        /**
         * Process a list of points, and update the progress bar
         * @param results 
         */
        @Override
        protected void process(List<Map<Point,Integer>> results) {
            if (progressView != null) {
                progressView.setValue();
            }
            
            for (Map<Point,Integer> resultMap : results) {
                if (stop || dragging)
                    break;
                
                for (Entry<Point,Integer> result : resultMap.entrySet()) {
                    int rgbValue = colors[result.getValue()];
                    int[] rgb = { (rgbValue >> 16) & 0xff, (rgbValue >> 8) & 0xff, rgbValue & 0xff };
                    setPixel(result.getKey().x, result.getKey().y, rgb);
                }
            }
            
            doneProcessing = true;
        }
        
        /**
         * Tell the updater to stop
         */
        public void stop() {
            stop = true;
        }
    }
    
    /**
     * A point on the grid
     */
    protected class Point {
        int x, y;
        
        public Point(int x, int y) {
            this.x = x;
            this.y = y;
        }
        
        @Override
        public boolean equals(Object another) {
            if (another == null || another.getClass() != Point.class) {
                return false;
            }
            Point that = (Point) another;
            return that.x == x && that.y == y;
        }

        @Override
        public int hashCode() {
            return (x << 8) | y;
        }
    }
    
    /**
     * A special ProgressBar which is hidden when full, and takes the average
     * of the progresses of all Updaters as its value
     */
    protected class ProgressView extends JProgressBar {
        
        public ProgressView() {
            setMaximum(100);
            setMinimum(0);
            setValue(0);
        }
        
        @Override
        public final void setValue(int n) {
            setVisible(n != 100);
            super.setValue(n);
        }
        
        /**
         * Calculate the value as the average of the progresses of all Updaters
         */
        public void setValue() {
            int sum = 0, count = 0;
            for (Updater updater : updaters) {
                sum += updater.getProgress();
                count++;
            }
            setValue(sum / count);
        }
        
    }
    
}