import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.util.List;

public final class FileSelectionPanel extends JPanel {

    private final DefaultListModel<File> fileModel;
    private final JList<File> fileList;

    public FileSelectionPanel() {
        super(new BorderLayout(8, 8));

        fileModel = new DefaultListModel<>();
        fileList = new JList<>(fileModel);

        fileList.setCellRenderer((list, file, index, selected, focus) -> {
            String name = file.getName();

            if (name.isEmpty()) {
                name = file.getAbsolutePath();
            }

            JLabel label = new JLabel(
                name + " — " + getFileSize(file)
            );

            label.setOpaque(true);
            label.setBorder(
                BorderFactory.createEmptyBorder(6, 8, 6, 8)
            );

            if (selected) {
                label.setBackground(list.getSelectionBackground());
                label.setForeground(list.getSelectionForeground());
            } else {
                label.setBackground(list.getBackground());
                label.setForeground(list.getForeground());
            }

            return label;
        });

        JButton addFilesButton = new JButton("Añadir archivos");
        JButton addFolderButton = new JButton("Añadir carpeta");
        JButton removeButton = new JButton("Quitar selección");

        addFilesButton.addActionListener(event -> selectFiles());
        addFolderButton.addActionListener(event -> selectFolder());
        removeButton.addActionListener(event -> removeSelectedFiles());

        JPanel buttons = new JPanel(
            new FlowLayout(FlowLayout.LEFT)
        );

        buttons.add(addFilesButton);
        buttons.add(addFolderButton);
        buttons.add(removeButton);

        add(buttons, BorderLayout.NORTH);
        add(new JScrollPane(fileList), BorderLayout.CENTER);
    }

    private void selectFiles() {
        JFileChooser chooser = new JFileChooser();

        chooser.setMultiSelectionEnabled(true);
        chooser.setFileSelectionMode(
            JFileChooser.FILES_ONLY
        );

        int result = chooser.showOpenDialog(this);

        if (result == JFileChooser.APPROVE_OPTION) {
            for (File file : chooser.getSelectedFiles()) {
                addFile(file);
            }
        }
    }

    private void selectFolder() {
        JFileChooser chooser = new JFileChooser();

        chooser.setFileSelectionMode(
            JFileChooser.DIRECTORIES_ONLY
        );

        int result = chooser.showOpenDialog(this);

        if (result == JFileChooser.APPROVE_OPTION) {
            addFile(chooser.getSelectedFile());
        }
    }

    private void addFile(File file) {
        if (!file.exists()) {
            return;
        }

        for (int i = 0; i < fileModel.size(); i++) {
            if (fileModel.get(i).equals(file)) {
                return;
            }
        }

        if (file.getName().toLowerCase().endsWith(".lbt")) {
            JOptionPane.showMessageDialog(
                this,
                "No se pueden añadir archivos .lbt para comprimir.",
                "Archivo no permitido",
                JOptionPane.WARNING_MESSAGE
            );

            return;
        }

        fileModel.addElement(file);
    }

    private void removeSelectedFiles() {
        List<File> selectedFiles = fileList.getSelectedValuesList();

        for (File file : selectedFiles) {
            fileModel.removeElement(file);
        }
    }

    private String getFileSize(File file) {
        if (file.isDirectory()) {
            return "Carpeta";
        }

        long bytes = file.length();

        if (bytes < 1024) {
            return bytes + " B";
        }

        if (bytes < 1024 * 1024) {
            return String.format("%.1f KB", bytes / 1024.0);
        }

        if (bytes < 1024L * 1024 * 1024) {
            return String.format(
                "%.1f MB",
                bytes / (1024.0 * 1024.0)
            );
        }

        return String.format(
            "%.2f GB",
            bytes / (1024.0 * 1024.0 * 1024.0)
        );
    }

    public List<File> getSelectedFiles() {
        return fileList.getSelectedValuesList();
    }
}