package view;

import controller.PhotoAlbumController;
import model.Photo;
import model.PhotoAlbumModel;

import javax.swing.*;
import java.awt.*;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * A view that displays a photo album user interface.
 * <p>
 * This class is responsible for displaying the photo album's graphical interface,
 * including the list of photos, current photo display, and control buttons.
 * The view implements the {@link PhotoAlbumModel.ModelChangeListener} interface
 * to receive notifications of model changes.
 * <p>
 * The view provides user interface components for:
 * <ul>
 * <li>Displaying a list of photos with thumbnails and details
 * <li>Showing the currently selected photo
 * <li>Navigation controls (previous/next)
 * <li>Photo management (add/delete)
 * <li>Sorting options
 * </ul>
 *
 * @author Yuri Tatishchev
 * @version 0.1 2025-03-26
 * @see PhotoAlbumModel
 * @see PhotoAlbumController
 * @see Photo
 */
public class PhotoAlbumView extends JFrame implements PhotoAlbumModel.ModelChangeListener {
    private PhotoAlbumModel model;

    private JList<String> photoList;
    private DefaultListModel<String> listModel;
    private JLabel currentPhotoLabel;
    private JButton addButton;
    private JButton deleteButton;
    private JButton previousButton;
    private JButton nextButton;
    private JComboBox<String> sortingCombo;

    public PhotoAlbumView() {
        initializeComponents();
        setupLayout();
    }

    /**
     * Initializes all UI components of the photo album view.
     * <p>
     * Sets up the frame properties, creates buttons, list components,
     * and initializes them with default states.
     */
    private void initializeComponents() {
        setTitle("Photo Album Manager");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(800, 600);

        listModel = new DefaultListModel<>();
        photoList = new JList<>(listModel);
        currentPhotoLabel = new JLabel("No photo selected", SwingConstants.CENTER);

        addButton = new JButton("Add Photo");
        deleteButton = new JButton("Delete Photo");
        previousButton = new JButton("Previous");
        nextButton = new JButton("Next");
        // Disable navigation buttons by default
        previousButton.setEnabled(false);
        nextButton.setEnabled(false);
        deleteButton.setEnabled(false);

        String[] sortOptions = {"Sort by Name", "Sort by Date", "Sort by Size"};
        sortingCombo = new JComboBox<>(sortOptions);

        listModel = new DefaultListModel<>();
        photoList = new JList<>(listModel);
        photoList.setEnabled(false);
        photoList.setCellRenderer(new PhotoListCellRenderer());
        photoList.setFixedCellHeight(60); // Accommodate thumbnails
    }


    /**
     * Sets up the layout of the photo album view.
     * <p>
     * Arranges the UI components using BorderLayout with:
     * <ul>
     * <li>Photo list in the WEST
     * <li>Current photo display in the CENTER
     * <li>Control buttons in the SOUTH
     * </ul>
     */
    private void setupLayout() {
        setLayout(new BorderLayout());

        // Left panel with photo list
        JScrollPane listScrollPane = new JScrollPane(photoList);
        listScrollPane.setPreferredSize(new Dimension(200, 0));
        add(listScrollPane, BorderLayout.WEST);

        // Center panel with current photo
        JPanel centerPanel = new JPanel(new BorderLayout());
        centerPanel.add(currentPhotoLabel, BorderLayout.CENTER);
        add(centerPanel, BorderLayout.CENTER);

        // Bottom panel with controls
        JPanel controlPanel = new JPanel();
        controlPanel.add(previousButton);
        controlPanel.add(nextButton);
        controlPanel.add(addButton);
        controlPanel.add(deleteButton);
        controlPanel.add(sortingCombo);
        add(controlPanel, BorderLayout.SOUTH);
    }

    /**
     * Sets the controller for the photo album view.
     * <p>
     * Attaches the controller to the view and sets up event listeners
     * for the control buttons and sorting combo box.
     *
     * @param controller the controller to set
     */
    public void setController(PhotoAlbumController controller) {
        this.model = controller.getModel();
        model.addListener(this);

        addButton.addActionListener(e -> controller.handleAddPhoto());
        deleteButton.addActionListener(e -> controller.handleDeletePhoto());
        nextButton.addActionListener(e -> controller.handleNext());
        previousButton.addActionListener(e -> controller.handlePrevious());
        sortingCombo.addActionListener(e -> controller.handleSort(sortingCombo.getSelectedIndex()));

        // Select default sorting option
        sortingCombo.setSelectedIndex(1);
    }

    @Override
    public void onModelChanged() {
        updatePhotoList();
        updateCurrentPhoto();
        updateNavigationButtons();
    }

    /**
     * Updates the list of photos displayed in the sidebar.
     * <p>
     * Clears the current list model and populates it with
     * names of photos from the model.
     */
    private void updatePhotoList() {
        listModel.clear();
        List<Photo> photos = model.getPhotos();
        for (Photo photo : photos) {
            listModel.addElement(photo.name());
        }
    }

    /**
     * Updates the display of the current photo in the main view area.
     * <p>
     * If a photo is selected, loads and displays its image.
     * If loading fails, displays an error message.
     * If no photo is selected, displays a default message.
     */
    private void updateCurrentPhoto() {
        Photo current = model.getCurrentPhoto();
        if (current != null) {
            ImageIcon icon = loadImage(current.filePath());
            if (icon != null) {
                currentPhotoLabel.setIcon(icon);
                currentPhotoLabel.setText("");
            } else {
                currentPhotoLabel.setIcon(null);
                currentPhotoLabel.setText("Unable to load image");
            }
        } else {
            currentPhotoLabel.setIcon(null);
            currentPhotoLabel.setText("No photo selected");
        }
    }

    /**
     * Updates the enabled state of navigation buttons.
     * <p>
     * Enables or disables the previous/next buttons based on
     * the current position in the photo album.
     * Enables the delete button only when the album is not empty.
     */
    private void updateNavigationButtons() {
        previousButton.setEnabled(model.hasPrevious());
        nextButton.setEnabled(model.hasNext());
        deleteButton.setEnabled(model.getCurrentPhoto() != null);
    }

    /**
     * Loads and scales an image from the given path.
     * <p>
     * Creates a scaled version of the image suitable for the main display area.
     *
     * @param path the file path of the image to load
     * @return a scaled ImageIcon, or null if loading fails
     */
    private ImageIcon loadImage(String path) {
        try {
            ImageIcon icon = new ImageIcon(path);
            Image img = icon.getImage();
            Image scaledImg = img.getScaledInstance(400, 300, Image.SCALE_SMOOTH);
            return new ImageIcon(scaledImg);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * A custom list cell renderer for displaying photos with thumbnails and details.
     * <p>
     * This inner class renders each photo in the list with:
     * <ul>
     * <li>A thumbnail image
     * <li>The photo name
     * <li>Additional details (date and file size)
     * </ul>
     * <p>
     * It also implements thumbnail caching to improve performance.
     */
    private class PhotoListCellRenderer extends JPanel implements ListCellRenderer<String> {
        private final JLabel imageLabel = new JLabel();
        private final JLabel textLabel = new JLabel();
        private final JLabel detailsLabel = new JLabel();

        private final Map<String, ImageIcon> thumbnailCache = new HashMap<>();

        public PhotoListCellRenderer() {
            setLayout(new BorderLayout(5, 0));

            // Left side - image
            imageLabel.setPreferredSize(new Dimension(50, 50));
            add(imageLabel, BorderLayout.WEST);

            // Center - name and details
            JPanel textPanel = new JPanel(new GridLayout(2, 1));
            textPanel.setOpaque(false);
            textLabel.setFont(textLabel.getFont().deriveFont(Font.BOLD));
            detailsLabel.setForeground(Color.GRAY);
            detailsLabel.setFont(detailsLabel.getFont().deriveFont(10.0f));
            textPanel.add(textLabel);
            textPanel.add(detailsLabel);
            add(textPanel, BorderLayout.CENTER);

            setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
            setOpaque(true);
        }

        @Override
        public Component getListCellRendererComponent(JList<? extends String> list,
                                                      String name,
                                                      int index,
                                                      boolean isSelected,
                                                      boolean cellHasFocus
        ) {
            textLabel.setText(name);

            Photo photo = model.getPhotos().get(index);
            ImageIcon thumbnail = thumbnailCache.computeIfAbsent(photo.filePath(), this::loadThumbnail);
            // ImageIcon thumbnail = loadThumbnail(photo.filePath());
            imageLabel.setIcon(thumbnail);

            // Format date
            String date = String.format("%tF", photo.dateAdded());
            // Format file size
            String size = formatFileSize(photo.fileSize());
            detailsLabel.setText(date + " • " + size);

            return this;
        }

        /**
         * Formats a file size in bytes to a human-readable string.
         * <p>
         * Converts the size to kilobytes or megabytes with one decimal place.
         *
         * @param size the file size in bytes
         * @return a formatted string with the size in KB or MB
         */
        private String formatFileSize(long size) {
            if (size < 1024 * 1024) {
                return String.format("%.1f KB", size / 1024.0);
            } else {
                return String.format("%.1f MB", size / (1024.0 * 1024));
            }
        }

        /**
         * Loads and scales a thumbnail image from the given path.
         * <p>
         * Creates a scaled version of the image suitable for the list display.
         *
         * @param path the file path of the image to load
         * @return a scaled ImageIcon, or null if loading fails
         */
        private ImageIcon loadThumbnail(String path) {
            try {
                ImageIcon icon = new ImageIcon(path);
                Image img = icon.getImage();
                Image scaledImg = img.getScaledInstance(50, 50, Image.SCALE_AREA_AVERAGING);
                return new ImageIcon(scaledImg);
            } catch (Exception e) {
                return null;
            }
        }
    }
}