/**
 * Copyright (C) 2019 Adrien Hopkins
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.unitConverter.converterGUI;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.util.ArrayList;
import java.util.Collection;
import java.util.function.Predicate;

import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;

/**
 * @author Adrien Hopkins
 * @since 2019-04-13
 */
final class SearchBoxList extends JPanel {

	/**
	 * @since 2019-04-13
	 */
	private static final long serialVersionUID = 6226930279415983433L;

	/**
	 * The text to place in an empty search box.
	 */
	private static final String EMPTY_TEXT = "Search...";
	/**
	 * The color to use for an empty foreground.
	 */
	private static final Color EMPTY_FOREGROUND = new Color(192, 192, 192);

	// the components
	private final Collection<String> itemsToFilter;
	private final DelegateListModel<String> listModel;
	private final JTextField searchBox;
	private final JList<String> searchItems;

	private boolean searchBoxEmpty = true;

	// I need to do this because, for some reason, Swing is auto-focusing my search box without triggering a focus
	// event.
	private boolean searchBoxFocused = false;

	private Predicate<String> searchFilter = o -> true;

	/**
	 * Creates the {@code SearchBoxList}.
	 * 
	 * @since 2019-04-13
	 */
	public SearchBoxList(final Collection<String> itemsToFilter) {
		super(new BorderLayout(), true);
		this.itemsToFilter = itemsToFilter;

		// create the components
		this.listModel = new DelegateListModel<>(new ArrayList<>(itemsToFilter));
		this.searchItems = new JList<>(this.listModel);

		this.searchBox = new JTextField(EMPTY_TEXT);
		this.searchBox.setForeground(EMPTY_FOREGROUND);

		// add them to the panel
		this.add(this.searchBox, BorderLayout.PAGE_START);
		this.add(new JScrollPane(this.searchItems), BorderLayout.CENTER);

		// set up the search box
		this.searchBox.addFocusListener(new FocusListener() {
			@Override
			public void focusGained(final FocusEvent e) {
				SearchBoxList.this.searchBoxFocusGained(e);
			}

			@Override
			public void focusLost(final FocusEvent e) {
				SearchBoxList.this.searchBoxFocusLost(e);
			}
		});

		this.searchBox.addCaretListener(e -> this.searchBoxTextChanged());
		this.searchBoxEmpty = true;
	}

	/**
	 * Adds an additional filter for searching.
	 * 
	 * @param filter
	 *            filter to add.
	 * @since 2019-04-13
	 */
	public void addSearchFilter(final Predicate<String> filter) {
		this.searchFilter = this.searchFilter.and(filter);
	}

	/**
	 * Resets the search filter.
	 * 
	 * @since 2019-04-13
	 */
	public void clearSearchFilters() {
		this.searchFilter = o -> true;
	}

	/**
	 * @return value selected in item list
	 * @since 2019-04-13
	 */
	public String getSelectedValue() {
		return this.searchItems.getSelectedValue();
	}

	/**
	 * Re-applies the filters.
	 * 
	 * @since 2019-04-13
	 */
	public void reapplyFilter() {
		final String searchText = this.searchBoxEmpty ? "" : this.searchBox.getText();
		final FilterComparator comparator = new FilterComparator(searchText);

		this.listModel.clear();
		this.itemsToFilter.forEach(string -> {
			if (string.toLowerCase().contains(searchText.toLowerCase())) {
				this.listModel.add(string);
			}
		});

		// applies the custom filters
		this.listModel.removeIf(this.searchFilter.negate());

		// sorts the remaining items
		this.listModel.sort(comparator);
	}

	/**
	 * Runs whenever the search box gains focus.
	 * 
	 * @param e
	 *            focus event
	 * @since 2019-04-13
	 */
	private void searchBoxFocusGained(final FocusEvent e) {
		this.searchBoxFocused = true;
		if (this.searchBoxEmpty) {
			this.searchBox.setText("");
			this.searchBox.setForeground(Color.BLACK);
		}
	}

	/**
	 * Runs whenever the search box loses focus.
	 * 
	 * @param e
	 *            focus event
	 * @since 2019-04-13
	 */
	private void searchBoxFocusLost(final FocusEvent e) {
		this.searchBoxFocused = false;
		if (this.searchBoxEmpty) {
			this.searchBox.setText(EMPTY_TEXT);
			this.searchBox.setForeground(EMPTY_FOREGROUND);
		}
	}

	private void searchBoxTextChanged() {
		if (this.searchBoxFocused) {
			this.searchBoxEmpty = this.searchBox.getText().equals("");
		}
		final String searchText = this.searchBoxEmpty ? "" : this.searchBox.getText();
		final FilterComparator comparator = new FilterComparator(searchText);

		// initialize list with items that match the filter then sort
		this.listModel.clear();
		this.itemsToFilter.forEach(string -> {
			if (string.toLowerCase().contains(searchText.toLowerCase())) {
				this.listModel.add(string);
			}
		});

		// applies the custom filters
		this.listModel.removeIf(this.searchFilter.negate());

		// sorts the remaining items
		this.listModel.sort(comparator);
	}
}