Experience.java

/*
 * Copyright (c) 2017, Adam <Adam@sigterm.info>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package net.runelite.api;

/**
 * A utility class used for calculating experience related values.
 * <p>
 * Skill levels calculated and handled by this class are within (inclusive)
 * the range 1-126 rather than 1-99 to account for virtual levels obtained
 * when reaching the 200M experience limit.
 */
public class Experience
{
	/**
	 * Maximum effective skill level at 13,034,431 experience.
	 */
	public static final int MAX_REAL_LEVEL = 99;

	/**
	 * The maximum virtual skill level for any skill (200M experience).
	 */
	public static final int MAX_VIRT_LEVEL = 126;
	public static final int MAX_SKILL_XP = 200_000_000;

	/**
	 * The maximum possible combat level.
	 */
	public static final int MAX_COMBAT_LEVEL = 126;

	/**
	 * The total experience required for each skill level.
	 */
	private static final int[] XP_FOR_LEVEL = new int[MAX_VIRT_LEVEL];

	static
	{
		int xp = 0;

		for (int level = 1; level <= MAX_VIRT_LEVEL; ++level)
		{
			XP_FOR_LEVEL[level - 1] = xp / 4;

			int difference = (int) ((double) level + 300.0 * Math.pow(2.0, (double) level / 7.0));
			xp += difference;
		}
	}

	/**
	 * Gets the total experience required to obtain the passed skill
	 * level.
	 *
	 * @param level the skill level
	 * @return the required experience for the level
	 * @throws IllegalArgumentException if skill level is invalid
	 */
	public static int getXpForLevel(int level)
	{
		if (level < 1 || level > MAX_VIRT_LEVEL)
		{
			throw new IllegalArgumentException(level + " is not a valid level");
		}

		// XP_FOR_LEVEL[0] is XP for level 1
		return XP_FOR_LEVEL[level - 1];
	}

	/**
	 * Gets the skill level for the passed total experience.
	 *
	 * @param xp the passed experience (non-negative)
	 * @return the skill level
	 */
	public static int getLevelForXp(int xp)
	{
		if (xp < 0)
		{
			throw new IllegalArgumentException("XP (" + xp + ") must not be negative");
		}

		int low = 0;
		int high = XP_FOR_LEVEL.length - 1;

		while (low <= high)
		{
			int mid = low + (high - low) / 2;
			int xpForLevel = XP_FOR_LEVEL[mid];

			if (xp < xpForLevel)
			{
				high = mid - 1;
			}
			else if (xp > xpForLevel)
			{
				low = mid + 1;
			}
			else
			{
				return mid + 1;
			}
		}

		return high + 1;
	}

	private static double getMeleeRangeOrMagicCombatLevelContribution(int attackLevel, int strengthLevel, int magicLevel, int rangeLevel)
	{
		double melee = 0.325 * (attackLevel + strengthLevel);
		double range = 0.325 * (rangeLevel / 2 + rangeLevel);
		double magic = 0.325 * (magicLevel / 2 + magicLevel);

		return Math.max(melee, Math.max(range, magic));
	}

	/**
	 * Calculates a non-virtual high-precision combat level without integer
	 * rounding.
	 * <p>
	 * Combat levels range between 1.15 and ~126.1.
	 *
	 * @param attackLevel the attack level
	 * @param strengthLevel the strength level
	 * @param defenceLevel the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel the magic level
	 * @param rangeLevel the range level
	 * @param prayerLevel the prayer level
	 * @return the non-virtual combat level
	 */
	public static double getCombatLevelPrecise(int attackLevel, int strengthLevel,
		int defenceLevel, int hitpointsLevel, int magicLevel,
		int rangeLevel, int prayerLevel)
	{
		double base = 0.25 * (defenceLevel + hitpointsLevel + (prayerLevel / 2));

		double typeContribution = getMeleeRangeOrMagicCombatLevelContribution(attackLevel, strengthLevel, magicLevel, rangeLevel);

		return base + typeContribution;
	}

	/**
	 * Calculates a regular combat level.
	 *
	 * @param attackLevel the attack level
	 * @param strengthLevel the strength level
	 * @param defenceLevel the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel the magic level
	 * @param rangeLevel the range level
	 * @param prayerLevel the prayer level
	 * @return the combat level, rounded down
	 */
	public static int getCombatLevel(int attackLevel, int strengthLevel,
		int defenceLevel, int hitpointsLevel, int magicLevel,
		int rangeLevel, int prayerLevel)
	{
		return (int) getCombatLevelPrecise(attackLevel, strengthLevel, defenceLevel, hitpointsLevel, magicLevel, rangeLevel, prayerLevel);
	}

	/**
	 * Calculate number of attack/strength levels required to increase combat level.
	 *
	 * @param attackLevel    the attack level
	 * @param strengthLevel  the strength level
	 * @param defenceLevel   the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel     the magic level
	 * @param rangeLevel     the range level
	 * @param prayerLevel    the prayer level
	 * @return the number of levels required
	 */
	public static int getNextCombatLevelMelee(int attackLevel, int strengthLevel, int defenceLevel, int hitpointsLevel,
		int magicLevel, int rangeLevel, int prayerLevel)
	{
		int nextCombatLevel = Experience.getCombatLevel(attackLevel, strengthLevel, defenceLevel, hitpointsLevel, magicLevel, rangeLevel, prayerLevel) + 1;
		return (int) Math.ceil(-10. / 13 * (defenceLevel + hitpointsLevel + Math.floor(prayerLevel / 2) - 4 * nextCombatLevel)) - strengthLevel - attackLevel;
	}

	/**
	 * Calculate number of hitpoints/defence levels required to increase combat level.
	 *
	 * @param attackLevel    the attack level
	 * @param strengthLevel  the strength level
	 * @param defenceLevel   the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel     the magic level
	 * @param rangeLevel     the range level
	 * @param prayerLevel    the prayer level
	 * @return the number of levels required
	 */
	public static int getNextCombatLevelHpDef(int attackLevel, int strengthLevel, int defenceLevel, int hitpointsLevel,
		int magicLevel, int rangeLevel, int prayerLevel)
	{
		int nextCombatLevel = Experience.getCombatLevel(attackLevel, strengthLevel, defenceLevel, hitpointsLevel, magicLevel, rangeLevel, prayerLevel) + 1;
		double typeContribution = Experience.getMeleeRangeOrMagicCombatLevelContribution(attackLevel, strengthLevel, magicLevel, rangeLevel);
		return (int) Math.ceil(4 * nextCombatLevel - Math.floor(prayerLevel / 2) - 4 * typeContribution) - hitpointsLevel - defenceLevel;
	}

	/**
	 * Calculate number of magic levels required to increase combat level.
	 *
	 * @param attackLevel    the attack level
	 * @param strengthLevel  the strength level
	 * @param defenceLevel   the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel     the magic level
	 * @param rangeLevel     the range level
	 * @param prayerLevel    the prayer level
	 * @return the number of levels required
	 */
	public static int getNextCombatLevelMagic(int attackLevel, int strengthLevel, int defenceLevel, int hitpointsLevel,
		int magicLevel, int rangeLevel, int prayerLevel)
	{
		int nextCombatLevel = Experience.getCombatLevel(attackLevel, strengthLevel, defenceLevel, hitpointsLevel, magicLevel, rangeLevel, prayerLevel) + 1;
		return (int) Math.ceil(2. / 3 * Math.ceil(-10. / 13 * (hitpointsLevel + defenceLevel - 4 * nextCombatLevel + Math.floor(prayerLevel / 2)))) - magicLevel;
	}

	/**
	 * Calculate number of ranged levels required to increase combat level.
	 *
	 * @param attackLevel    the attack level
	 * @param strengthLevel  the strength level
	 * @param defenceLevel   the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel     the magic level
	 * @param rangeLevel     the range level
	 * @param prayerLevel    the prayer level
	 * @return the number of levels required
	 */
	public static int getNextCombatLevelRange(int attackLevel, int strengthLevel, int defenceLevel, int hitpointsLevel,
		int magicLevel, int rangeLevel, int prayerLevel)
	{
		int nextCombatLevel = Experience.getCombatLevel(attackLevel, strengthLevel, defenceLevel, hitpointsLevel, magicLevel, rangeLevel, prayerLevel) + 1;
		return (int) Math.ceil(2. / 3 * Math.ceil(-10. / 13 * (hitpointsLevel + defenceLevel - 4 * nextCombatLevel + Math.floor(prayerLevel / 2)))) - rangeLevel;
	}

	/**
	 * Calculate number of prayer levels required to increase combat level.
	 *
	 * @param attackLevel    the attack level
	 * @param strengthLevel  the strength level
	 * @param defenceLevel   the defence level
	 * @param hitpointsLevel the hitpoints level
	 * @param magicLevel     the magic level
	 * @param rangeLevel     the range level
	 * @param prayerLevel    the prayer level
	 * @return the number of levels required
	 */
	public static int getNextCombatLevelPrayer(int attackLevel, int strengthLevel, int defenceLevel, int hitpointsLevel,
		int magicLevel, int rangeLevel, int prayerLevel)
	{
		int nextCombatLevel = Experience.getCombatLevel(attackLevel, strengthLevel, defenceLevel, hitpointsLevel, magicLevel, rangeLevel, prayerLevel) + 1;
		double typeContribution = Experience.getMeleeRangeOrMagicCombatLevelContribution(attackLevel, strengthLevel, magicLevel, rangeLevel);
		return 2 * (int) Math.ceil(-hitpointsLevel - defenceLevel + 4 * nextCombatLevel - 4 * typeContribution) - prayerLevel;
	}
}