/*
 * Copyright (C) 2022 NotEnoughUpdates contributors
 *
 * This file is part of NotEnoughUpdates.
 *
 * NotEnoughUpdates 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.
 *
 * NotEnoughUpdates 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 NotEnoughUpdates. If not, see <https://www.gnu.org/licenses/>.
 */

package io.github.moulberry.notenoughupdates.util;

public class LerpingFloat {
	private int timeSpent;
	private long lastMillis;
	private final int timeToReachTarget;

	private float targetValue;
	private float lerpValue;

	public LerpingFloat(float initialValue, int timeToReachTarget) {
		this.targetValue = this.lerpValue = initialValue;
		this.timeToReachTarget = timeToReachTarget;
	}

	public LerpingFloat(int initialValue) {
		this(initialValue, 200);
	}

	public void tick() {
		int lastTimeSpent = timeSpent;
		this.timeSpent += System.currentTimeMillis() - lastMillis;

		float lastDistPercentToTarget = lastTimeSpent / (float) timeToReachTarget;
		float distPercentToTarget = timeSpent / (float) timeToReachTarget;
		float fac = (1 - lastDistPercentToTarget) / lastDistPercentToTarget;

		float startValue = lerpValue - (targetValue - lerpValue) / fac;

		float dist = targetValue - startValue;
		if (dist == 0) return;

		float oldLerpValue = lerpValue;
		if (distPercentToTarget >= 1) {
			lerpValue = targetValue;
		} else {
			lerpValue = startValue + dist * distPercentToTarget;
		}

		if (lerpValue == oldLerpValue) {
			timeSpent = lastTimeSpent;
		} else {
			this.lastMillis = System.currentTimeMillis();
		}
	}

	public void resetTimer() {
		this.timeSpent = 0;
		this.lastMillis = System.currentTimeMillis();
	}

	public void setTarget(float targetValue) {
		this.targetValue = targetValue;
	}

	public void setValue(float value) {
		this.targetValue = this.lerpValue = value;
	}

	public float getValue() {
		return lerpValue;
	}

	public float getTarget() {
		return targetValue;
	}
}