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/*
 * Copyright (C) 2024 Parisi Alessandro - [email protected]
 * This file is part of VirtualizedFX (https://github.com/palexdev/VirtualizedFX)
 *
 * VirtualizedFX is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 3 of the License,
 * or (at your option) any later version.
 *
 * VirtualizedFX 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with VirtualizedFX. If not, see .
 */

package io.github.palexdev.virtualizedfx.utils;

import javafx.geometry.Orientation;

import java.util.Objects;

/**
 * Wrapper class to express the bounds of a scrollable area. It contains four pieces of data:
 * the width and height of the content, the width and the height of the view area (also called 'viewport').
 * 
 * The reason this is not a {@code record} is to allow methods to be overridden if needed.
 */
public final class ScrollBounds {
	//================================================================================
	// Static Properties
	//================================================================================
	public static final ScrollBounds ZERO = new ScrollBounds();

	//================================================================================
	// Properties
	//================================================================================
	private final double contentWidth;
	private final double contentHeight;
	private final double viewportWidth;
	private final double viewportHeight;


	//================================================================================
	// Constructors
	//================================================================================
	private ScrollBounds() {
		this(0, 0, 0, 0);
	}

	public ScrollBounds(double contentWidth, double contentHeight, double viewportWidth, double viewportHeight) {
		this.contentWidth = contentWidth;
		this.contentHeight = contentHeight;
		this.viewportWidth = viewportWidth;
		this.viewportHeight = viewportHeight;
	}

	//================================================================================
	// Methods
	//================================================================================

	/**
	 * Computes how much content is visible by using its size and the view area's size. The value is a percentage in
	 * the range [0.0, 1.0].
	 *
	 * @param o the orientation determines which size to use, width or height
	 */
	public double visibleAmount(Orientation o) {
		return (o == Orientation.VERTICAL) ?
			viewportHeight / contentHeight :
			viewportWidth / contentWidth;
	}

	/**
	 * Computes the maximum number of scrollable pixels by using the content's size and the view area's size:
	 * {@code Math.max(0, contentSize - viewportSize)}.
	 * 
	 *
	 * @param o the orientation determines which size to use, width or height
	 */
	public double maxScroll(Orientation o) {
		if (o == Orientation.VERTICAL) {
			return Math.max(0, contentHeight - viewportHeight);
		}
		return Math.max(0, contentWidth - viewportWidth);
	}

	//================================================================================
	// Getters
	//================================================================================

	/**
	 * @return the content's width
	 */
	public double contentWidth() {return contentWidth;}

	/**
	 * @return the content's height
	 */
	public double contentHeight() {return contentHeight;}

	/**
	 * @return the view area's width
	 */
	public double viewportWidth() {return viewportWidth;}

	/**
	 * @return the view area's height
	 */
	public double viewportHeight() {return viewportHeight;}

	//================================================================================
	// Overridden Methods
	//================================================================================
	@Override
	public boolean equals(Object obj) {
		if (obj == this) return true;
		if (obj == null || obj.getClass() != this.getClass()) return false;
		var that = (ScrollBounds) obj;
		return Double.doubleToLongBits(this.contentWidth) == Double.doubleToLongBits(that.contentWidth) &&
			Double.doubleToLongBits(this.contentHeight) == Double.doubleToLongBits(that.contentHeight) &&
			Double.doubleToLongBits(this.viewportWidth) == Double.doubleToLongBits(that.viewportWidth) &&
			Double.doubleToLongBits(this.viewportHeight) == Double.doubleToLongBits(that.viewportHeight);
	}

	@Override
	public int hashCode() {
		return Objects.hash(contentWidth, contentHeight, viewportWidth, viewportHeight);
	}

	@Override
	public String toString() {
		return "ScrollBounds[" +
			"contentWidth=" + contentWidth + ", " +
			"contentHeight=" + contentHeight + ", " +
			"viewportWidth=" + viewportWidth + ", " +
			"viewportHeight=" + viewportHeight + ']';
	}

}