/* ========================================================================
 * PlantUML : a free UML diagram generator
 * ========================================================================
 *
 * (C) Copyright 2009-2024, Arnaud Roques
 *
 * Project Info:  https://plantuml.com
 * 
 * If you like this project or if you find it useful, you can support us at:
 * 
 * https://plantuml.com/patreon (only 1$ per month!)
 * https://plantuml.com/paypal
 * 
 * This file is part of PlantUML.
 *
 * PlantUML is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * PlantUML 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 General Public
 * License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 *
 * Original Author:  Arnaud Roques
 *
 *
 */
package net.sourceforge.plantuml.mindmap;

import java.util.Iterator;
import java.util.SortedSet;
import java.util.TreeSet;

public class StripeFrontier {

	private final SortedSet<Stripe> stripes = new TreeSet<>();

	public StripeFrontier() {
		this.stripes.add(new Stripe(-Double.MAX_VALUE, Double.MAX_VALUE, -Double.MAX_VALUE));
	}

	public boolean isEmpty() {
		return stripes.size() == 1;
	}

	@Override
	public String toString() {
		return stripes.toString();
	}

	public boolean contains(double x, double y) {
		for (Stripe stripe : stripes)
			if (stripe.contains(x))
				return y <= stripe.getValue();

		throw new UnsupportedOperationException();
	}

	public double getContact(double x1, double x2) {
		final SortedSet<Stripe> collisions = collisionning(x1, x2);
		double result = -Double.MAX_VALUE;
		for (Stripe strip : collisions)
			result = Math.max(result, strip.getValue());

		return result;

	}

	public void addSegment(double x1, double x2, double value) {
		if (x2 <= x1) {
			System.err.println("x1=" + x1);
			System.err.println("x2=" + x2);
			throw new IllegalArgumentException();
		}
		final SortedSet<Stripe> collisions = collisionning(x1, x2);
		if (collisions.size() > 1) {
			final Iterator<Stripe> it = collisions.iterator();
			it.next();
			double x = x1;
			while (it.hasNext()) {
				final Stripe tmp = it.next();
				addSegment(x, tmp.getStart(), value);
				x = tmp.getStart();
			}
			addSegment(x, x2, value);
			// System.err.println("x1=" + x1);
			// System.err.println("x2=" + x2);
			// System.err.println("All=" + stripes);
			// System.err.println("collisions" + collisions);
			// throw new UnsupportedOperationException();
		} else {
			final Stripe touch = collisions.iterator().next();
			addSingleInternal(x1, x2, value, touch);
		}
	}

	private void addSingleInternal(double x1, double x2, double value, final Stripe touch) {
		if (value <= touch.getValue())
			return;

		final boolean ok = this.stripes.remove(touch);
		assert ok;
		if (touch.getStart() != x1)
			this.stripes.add(new Stripe(touch.getStart(), x1, touch.getValue()));

		this.stripes.add(new Stripe(x1, x2, value));
		if (x2 != touch.getEnd())
			this.stripes.add(new Stripe(x2, touch.getEnd(), touch.getValue()));

		assert checkConsistent();
	}

	private boolean checkConsistent() {
		Stripe last = null;
		for (Stripe stripe : stripes) {
			if (last == null && stripe.getStart() != -Double.MAX_VALUE)
				return false;

			if (last != null && last.getEnd() != stripe.getStart())
				return false;

			last = stripe;
		}
		if (last.getEnd() != Double.MAX_VALUE)
			return false;

		return true;
	}

	private SortedSet<Stripe> collisionning(double x1, double x2) {
		final SortedSet<Stripe> result = new TreeSet<>();
		for (Iterator<Stripe> it = stripes.iterator(); it.hasNext();) {
			Stripe stripe = it.next();
			if (x1 >= stripe.getEnd())
				continue;

			result.add(stripe);
			if (x2 <= stripe.getEnd())
				return result;

		}
		throw new UnsupportedOperationException();
	}
}
