// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.gui.layer.geoimage;

import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.swing.JComponent;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.tools.ExifReader;

public class ImageDisplay extends JComponent {

    /** The file that is currently displayed */
    private File file;

    /** The image currently displayed */
    private transient Image image;

    /** The image currently displayed */
    private boolean errorLoading;

    /** The rectangle (in image coordinates) of the image that is visible. This rectangle is calculated
     * each time the zoom is modified */
    private Rectangle visibleRect;

    /** When a selection is done, the rectangle of the selection (in image coordinates) */
    private Rectangle selectedRect;

    /** The tracker to load the images */
    private final MediaTracker tracker = new MediaTracker(this);

    private String osdText;

    private static final int DRAG_BUTTON = Main.pref.getBoolean("geoimage.agpifo-style-drag-and-zoom", false) ? 1 : 3;
    private static final int ZOOM_BUTTON = DRAG_BUTTON == 1 ? 3 : 1;

    /** The thread that reads the images. */
    private class LoadImageRunnable implements Runnable {

        private final File file;
        private final int orientation;

        LoadImageRunnable(File file, Integer orientation) {
            this.file = file;
            this.orientation = orientation == null ? -1 : orientation;
        }

        @Override
        public void run() {
            Image img = Toolkit.getDefaultToolkit().createImage(file.getPath());
            tracker.addImage(img, 1);

            // Wait for the end of loading
            while (!tracker.checkID(1, true)) {
                if (this.file != ImageDisplay.this.file) {
                    // The file has changed
                    tracker.removeImage(img);
                    return;
                }
                try {
                    Thread.sleep(5);
                } catch (InterruptedException e) {
                    Main.warn("InterruptedException in "+getClass().getSimpleName()+" while loading image "+file.getPath());
                }
            }

            boolean error = tracker.isErrorID(1);
            if (img.getWidth(null) < 0 || img.getHeight(null) < 0) {
                error = true;
            }

            synchronized (ImageDisplay.this) {
                if (this.file != ImageDisplay.this.file) {
                    // The file has changed
                    tracker.removeImage(img);
                    return;
                }

                if (!error) {
                    ImageDisplay.this.image = img;
                    visibleRect = new Rectangle(0, 0, img.getWidth(null), img.getHeight(null));

                    final int w = (int) visibleRect.getWidth();
                    final int h = (int) visibleRect.getHeight();

                    if (ExifReader.orientationNeedsCorrection(orientation)) {
                        final int hh, ww;
                        if (ExifReader.orientationSwitchesDimensions(orientation)) {
                            ww = h;
                            hh = w;
                        } else {
                            ww = w;
                            hh = h;
                        }
                        final BufferedImage rot = new BufferedImage(ww, hh, BufferedImage.TYPE_INT_RGB);
                        final AffineTransform xform = ExifReader.getRestoreOrientationTransform(orientation, w, h);
                        final Graphics2D g = rot.createGraphics();
                        g.drawImage(image, xform, null);
                        g.dispose();

                        visibleRect.setSize(ww, hh);
                        image.flush();
                        ImageDisplay.this.image = rot;
                    }
                }

                selectedRect = null;
                errorLoading = error;
            }
            tracker.removeImage(img);
            ImageDisplay.this.repaint();
        }
    }

    private class ImgDisplayMouseListener implements MouseListener, MouseWheelListener, MouseMotionListener {

        private boolean mouseIsDragging;
        private long lastTimeForMousePoint;
        private Point mousePointInImg;

        /** Zoom in and out, trying to preserve the point of the image that was under the mouse cursor
         * at the same place */
        @Override
        public void mouseWheelMoved(MouseWheelEvent e) {
            File file;
            Image image;
            Rectangle visibleRect;

            synchronized (ImageDisplay.this) {
                file = ImageDisplay.this.file;
                image = ImageDisplay.this.image;
                visibleRect = ImageDisplay.this.visibleRect;
            }

            mouseIsDragging = false;
            selectedRect = null;

            if (image == null)
                return;

            // Calculate the mouse cursor position in image coordinates, so that we can center the zoom
            // on that mouse position.
            // To avoid issues when the user tries to zoom in on the image borders, this point is not calculated
            // again if there was less than 1.5seconds since the last event.
            if (e.getWhen() - lastTimeForMousePoint > 1500 || mousePointInImg == null) {
                lastTimeForMousePoint = e.getWhen();
                mousePointInImg = comp2imgCoord(visibleRect, e.getX(), e.getY());
            }

            // Applicate the zoom to the visible rectangle in image coordinates
            if (e.getWheelRotation() > 0) {
                visibleRect.width = visibleRect.width * 3 / 2;
                visibleRect.height = visibleRect.height * 3 / 2;
            } else {
                visibleRect.width = visibleRect.width * 2 / 3;
                visibleRect.height = visibleRect.height * 2 / 3;
            }

            // Check that the zoom doesn't exceed 2:1
            if (visibleRect.width < getSize().width / 2) {
                visibleRect.width = getSize().width / 2;
            }
            if (visibleRect.height < getSize().height / 2) {
                visibleRect.height = getSize().height / 2;
            }

            // Set the same ratio for the visible rectangle and the display area
            int hFact = visibleRect.height * getSize().width;
            int wFact = visibleRect.width * getSize().height;
            if (hFact > wFact) {
                visibleRect.width = hFact / getSize().height;
            } else {
                visibleRect.height = wFact / getSize().width;
            }

            // The size of the visible rectangle is limited by the image size.
            checkVisibleRectSize(image, visibleRect);

            // Set the position of the visible rectangle, so that the mouse cursor doesn't move on the image.
            Rectangle drawRect = calculateDrawImageRectangle(visibleRect);
            visibleRect.x = mousePointInImg.x + ((drawRect.x - e.getX()) * visibleRect.width) / drawRect.width;
            visibleRect.y = mousePointInImg.y + ((drawRect.y - e.getY()) * visibleRect.height) / drawRect.height;

            // The position is also limited by the image size
            checkVisibleRectPos(image, visibleRect);

            synchronized (ImageDisplay.this) {
                if (ImageDisplay.this.file == file) {
                    ImageDisplay.this.visibleRect = visibleRect;
                }
            }
            ImageDisplay.this.repaint();
        }

        /** Center the display on the point that has been clicked */
        @Override
        public void mouseClicked(MouseEvent e) {
            // Move the center to the clicked point.
            File file;
            Image image;
            Rectangle visibleRect;

            synchronized (ImageDisplay.this) {
                file = ImageDisplay.this.file;
                image = ImageDisplay.this.image;
                visibleRect = ImageDisplay.this.visibleRect;
            }

            if (image == null)
                return;

            if (e.getButton() != DRAG_BUTTON)
                return;

            // Calculate the translation to set the clicked point the center of the view.
            Point click = comp2imgCoord(visibleRect, e.getX(), e.getY());
            Point center = getCenterImgCoord(visibleRect);

            visibleRect.x += click.x - center.x;
            visibleRect.y += click.y - center.y;

            checkVisibleRectPos(image, visibleRect);

            synchronized (ImageDisplay.this) {
                if (ImageDisplay.this.file == file) {
                    ImageDisplay.this.visibleRect = visibleRect;
                }
            }
            ImageDisplay.this.repaint();
        }

        /** Initialize the dragging, either with button 1 (simple dragging) or button 3 (selection of
         * a picture part) */
        @Override
        public void mousePressed(MouseEvent e) {
            if (image == null) {
                mouseIsDragging = false;
                selectedRect = null;
                return;
            }

            Image image;
            Rectangle visibleRect;

            synchronized (ImageDisplay.this) {
                image = ImageDisplay.this.image;
                visibleRect = ImageDisplay.this.visibleRect;
            }

            if (image == null)
                return;

            if (e.getButton() == DRAG_BUTTON) {
                mousePointInImg = comp2imgCoord(visibleRect, e.getX(), e.getY());
                mouseIsDragging = true;
                selectedRect = null;
            } else if (e.getButton() == ZOOM_BUTTON) {
                mousePointInImg = comp2imgCoord(visibleRect, e.getX(), e.getY());
                checkPointInVisibleRect(mousePointInImg, visibleRect);
                mouseIsDragging = false;
                selectedRect = new Rectangle(mousePointInImg.x, mousePointInImg.y, 0, 0);
                ImageDisplay.this.repaint();
            } else {
                mouseIsDragging = false;
                selectedRect = null;
            }
        }

        @Override
        public void mouseDragged(MouseEvent e) {
            if (!mouseIsDragging && selectedRect == null)
                return;

            File file;
            Image image;
            Rectangle visibleRect;

            synchronized (ImageDisplay.this) {
                file = ImageDisplay.this.file;
                image = ImageDisplay.this.image;
                visibleRect = ImageDisplay.this.visibleRect;
            }

            if (image == null) {
                mouseIsDragging = false;
                selectedRect = null;
                return;
            }

            if (mouseIsDragging) {
                Point p = comp2imgCoord(visibleRect, e.getX(), e.getY());
                visibleRect.x += mousePointInImg.x - p.x;
                visibleRect.y += mousePointInImg.y - p.y;
                checkVisibleRectPos(image, visibleRect);
                synchronized (ImageDisplay.this) {
                    if (ImageDisplay.this.file == file) {
                        ImageDisplay.this.visibleRect = visibleRect;
                    }
                }
                ImageDisplay.this.repaint();

            } else if (selectedRect != null) {
                Point p = comp2imgCoord(visibleRect, e.getX(), e.getY());
                checkPointInVisibleRect(p, visibleRect);
                Rectangle rect = new Rectangle(
                        p.x < mousePointInImg.x ? p.x : mousePointInImg.x,
                        p.y < mousePointInImg.y ? p.y : mousePointInImg.y,
                        p.x < mousePointInImg.x ? mousePointInImg.x - p.x : p.x - mousePointInImg.x,
                        p.y < mousePointInImg.y ? mousePointInImg.y - p.y : p.y - mousePointInImg.y);
                checkVisibleRectSize(image, rect);
                checkVisibleRectPos(image, rect);
                ImageDisplay.this.selectedRect = rect;
                ImageDisplay.this.repaint();
            }

        }

        @Override
        public void mouseReleased(MouseEvent e) {
            if (!mouseIsDragging && selectedRect == null)
                return;

            File file;
            Image image;

            synchronized (ImageDisplay.this) {
                file = ImageDisplay.this.file;
                image = ImageDisplay.this.image;
            }

            if (image == null) {
                mouseIsDragging = false;
                selectedRect = null;
                return;
            }

            if (mouseIsDragging) {
                mouseIsDragging = false;

            } else if (selectedRect != null) {
                int oldWidth = selectedRect.width;
                int oldHeight = selectedRect.height;

                // Check that the zoom doesn't exceed 2:1
                if (selectedRect.width < getSize().width / 2) {
                    selectedRect.width = getSize().width / 2;
                }
                if (selectedRect.height < getSize().height / 2) {
                    selectedRect.height = getSize().height / 2;
                }

                // Set the same ratio for the visible rectangle and the display area
                int hFact = selectedRect.height * getSize().width;
                int wFact = selectedRect.width * getSize().height;
                if (hFact > wFact) {
                    selectedRect.width = hFact / getSize().height;
                } else {
                    selectedRect.height = wFact / getSize().width;
                }

                // Keep the center of the selection
                if (selectedRect.width != oldWidth) {
                    selectedRect.x -= (selectedRect.width - oldWidth) / 2;
                }
                if (selectedRect.height != oldHeight) {
                    selectedRect.y -= (selectedRect.height - oldHeight) / 2;
                }

                checkVisibleRectSize(image, selectedRect);
                checkVisibleRectPos(image, selectedRect);

                synchronized (ImageDisplay.this) {
                    if (file == ImageDisplay.this.file) {
                        ImageDisplay.this.visibleRect = selectedRect;
                    }
                }
                selectedRect = null;
                ImageDisplay.this.repaint();
            }
        }

        @Override
        public void mouseEntered(MouseEvent e) {
        }

        @Override
        public void mouseExited(MouseEvent e) {
        }

        @Override
        public void mouseMoved(MouseEvent e) {
        }

        private void checkPointInVisibleRect(Point p, Rectangle visibleRect) {
            if (p.x < visibleRect.x) {
                p.x = visibleRect.x;
            }
            if (p.x > visibleRect.x + visibleRect.width) {
                p.x = visibleRect.x + visibleRect.width;
            }
            if (p.y < visibleRect.y) {
                p.y = visibleRect.y;
            }
            if (p.y > visibleRect.y + visibleRect.height) {
                p.y = visibleRect.y + visibleRect.height;
            }
        }
    }

    public ImageDisplay() {
        ImgDisplayMouseListener mouseListener = new ImgDisplayMouseListener();
        addMouseListener(mouseListener);
        addMouseWheelListener(mouseListener);
        addMouseMotionListener(mouseListener);
    }

    public void setImage(File file, Integer orientation) {
        synchronized (this) {
            this.file = file;
            image = null;
            selectedRect = null;
            errorLoading = false;
        }
        repaint();
        if (file != null) {
            new Thread(new LoadImageRunnable(file, orientation), LoadImageRunnable.class.getName()).start();
        }
    }

    public void setOsdText(String text) {
        this.osdText = text;
        repaint();
    }

    @Override
    public void paintComponent(Graphics g) {
        Image image;
        File file;
        Rectangle visibleRect;
        boolean errorLoading;

        synchronized (this) {
            image = this.image;
            file = this.file;
            visibleRect = this.visibleRect;
            errorLoading = this.errorLoading;
        }

        if (file == null) {
            g.setColor(Color.black);
            String noImageStr = tr("No image");
            Rectangle2D noImageSize = g.getFontMetrics(g.getFont()).getStringBounds(noImageStr, g);
            Dimension size = getSize();
            g.drawString(noImageStr,
                    (int) ((size.width - noImageSize.getWidth()) / 2),
                    (int) ((size.height - noImageSize.getHeight()) / 2));
        } else if (image == null) {
            g.setColor(Color.black);
            String loadingStr;
            if (!errorLoading) {
                loadingStr = tr("Loading {0}", file.getName());
            } else {
                loadingStr = tr("Error on file {0}", file.getName());
            }
            Rectangle2D noImageSize = g.getFontMetrics(g.getFont()).getStringBounds(loadingStr, g);
            Dimension size = getSize();
            g.drawString(loadingStr,
                    (int) ((size.width - noImageSize.getWidth()) / 2),
                    (int) ((size.height - noImageSize.getHeight()) / 2));
        } else {
            Rectangle target = calculateDrawImageRectangle(visibleRect);
            g.drawImage(image,
                    target.x, target.y, target.x + target.width, target.y + target.height,
                    visibleRect.x, visibleRect.y, visibleRect.x + visibleRect.width, visibleRect.y + visibleRect.height,
                    null);
            if (selectedRect != null) {
                Point topLeft = img2compCoord(visibleRect, selectedRect.x, selectedRect.y);
                Point bottomRight = img2compCoord(visibleRect,
                        selectedRect.x + selectedRect.width,
                        selectedRect.y + selectedRect.height);
                g.setColor(new Color(128, 128, 128, 180));
                g.fillRect(target.x, target.y, target.width, topLeft.y - target.y);
                g.fillRect(target.x, target.y, topLeft.x - target.x, target.height);
                g.fillRect(bottomRight.x, target.y, target.x + target.width - bottomRight.x, target.height);
                g.fillRect(target.x, bottomRight.y, target.width, target.y + target.height - bottomRight.y);
                g.setColor(Color.black);
                g.drawRect(topLeft.x, topLeft.y, bottomRight.x - topLeft.x, bottomRight.y - topLeft.y);
            }
            if (errorLoading) {
                String loadingStr = tr("Error on file {0}", file.getName());
                Rectangle2D noImageSize = g.getFontMetrics(g.getFont()).getStringBounds(loadingStr, g);
                Dimension size = getSize();
                g.drawString(loadingStr,
                        (int) ((size.width - noImageSize.getWidth()) / 2),
                        (int) ((size.height - noImageSize.getHeight()) / 2));
            }
            if (osdText != null) {
                FontMetrics metrics = g.getFontMetrics(g.getFont());
                int ascent = metrics.getAscent();
                Color bkground = new Color(255, 255, 255, 128);
                int lastPos = 0;
                int pos = osdText.indexOf('\n');
                int x = 3;
                int y = 3;
                String line;
                while (pos > 0) {
                    line = osdText.substring(lastPos, pos);
                    Rectangle2D lineSize = metrics.getStringBounds(line, g);
                    g.setColor(bkground);
                    g.fillRect(x, y, (int) lineSize.getWidth(), (int) lineSize.getHeight());
                    g.setColor(Color.black);
                    g.drawString(line, x, y + ascent);
                    y += (int) lineSize.getHeight();
                    lastPos = pos + 1;
                    pos = osdText.indexOf('\n', lastPos);
                }

                line = osdText.substring(lastPos);
                Rectangle2D lineSize = g.getFontMetrics(g.getFont()).getStringBounds(line, g);
                g.setColor(bkground);
                g.fillRect(x, y, (int) lineSize.getWidth(), (int) lineSize.getHeight());
                g.setColor(Color.black);
                g.drawString(line, x, y + ascent);
            }
        }
    }

    private Point img2compCoord(Rectangle visibleRect, int xImg, int yImg) {
        Rectangle drawRect = calculateDrawImageRectangle(visibleRect);
        return new Point(drawRect.x + ((xImg - visibleRect.x) * drawRect.width) / visibleRect.width,
                drawRect.y + ((yImg - visibleRect.y) * drawRect.height) / visibleRect.height);
    }

    private Point comp2imgCoord(Rectangle visibleRect, int xComp, int yComp) {
        Rectangle drawRect = calculateDrawImageRectangle(visibleRect);
        return new Point(visibleRect.x + ((xComp - drawRect.x) * visibleRect.width) / drawRect.width,
                visibleRect.y + ((yComp - drawRect.y) * visibleRect.height) / drawRect.height);
    }

    private static Point getCenterImgCoord(Rectangle visibleRect) {
        return new Point(visibleRect.x + visibleRect.width / 2,
                visibleRect.y + visibleRect.height / 2);
    }

    private Rectangle calculateDrawImageRectangle(Rectangle visibleRect) {
        return calculateDrawImageRectangle(visibleRect, new Rectangle(0, 0, getSize().width, getSize().height));
    }

    /**
     * calculateDrawImageRectangle
     *
     * @param imgRect the part of the image that should be drawn (in image coordinates)
     * @param compRect the part of the component where the image should be drawn (in component coordinates)
     * @return the part of compRect with the same width/height ratio as the image
     */
    static Rectangle calculateDrawImageRectangle(Rectangle imgRect, Rectangle compRect) {
        int x, y, w, h;
        x = 0;
        y = 0;
        w = compRect.width;
        h = compRect.height;

        int wFact = w * imgRect.height;
        int hFact = h * imgRect.width;
        if (wFact != hFact) {
            if (wFact > hFact) {
                w = hFact / imgRect.height;
                x = (compRect.width - w) / 2;
            } else {
                h = wFact / imgRect.width;
                y = (compRect.height - h) / 2;
            }
        }
        return new Rectangle(x + compRect.x, y + compRect.y, w, h);
    }

    public void zoomBestFitOrOne() {
        File file;
        Image image;
        Rectangle visibleRect;

        synchronized (this) {
            file = this.file;
            image = this.image;
            visibleRect = this.visibleRect;
        }

        if (image == null)
            return;

        if (visibleRect.width != image.getWidth(null) || visibleRect.height != image.getHeight(null)) {
            // The display is not at best fit. => Zoom to best fit
            visibleRect = new Rectangle(0, 0, image.getWidth(null), image.getHeight(null));

        } else {
            // The display is at best fit => zoom to 1:1
            Point center = getCenterImgCoord(visibleRect);
            visibleRect = new Rectangle(center.x - getWidth() / 2, center.y - getHeight() / 2,
                    getWidth(), getHeight());
            checkVisibleRectPos(image, visibleRect);
        }

        synchronized (this) {
            if (file == this.file) {
                this.visibleRect = visibleRect;
            }
        }
        repaint();
    }

    private static void checkVisibleRectPos(Image image, Rectangle visibleRect) {
        if (visibleRect.x < 0) {
            visibleRect.x = 0;
        }
        if (visibleRect.y < 0) {
            visibleRect.y = 0;
        }
        if (visibleRect.x + visibleRect.width > image.getWidth(null)) {
            visibleRect.x = image.getWidth(null) - visibleRect.width;
        }
        if (visibleRect.y + visibleRect.height > image.getHeight(null)) {
            visibleRect.y = image.getHeight(null) - visibleRect.height;
        }
    }

    private static void checkVisibleRectSize(Image image, Rectangle visibleRect) {
        if (visibleRect.width > image.getWidth(null)) {
            visibleRect.width = image.getWidth(null);
        }
        if (visibleRect.height > image.getHeight(null)) {
            visibleRect.height = image.getHeight(null);
        }
    }
}
